TW201815999A - Coating liquid, method for producing the same, ink for electronic device production, electronic device, organic electroluminescence device, and photoelectric conversion element - Google Patents

Abstract

The coating liquid of the present invention is characterized by containing an organic compound and an organic solvent, and the dissolved carbon dioxide concentration of the organic solvent under the condition of 50 ° C./atmospheric pressure is within a range of 1 ppm or more and the saturation concentration of the organic solvent or less .

Description

   Coating liquid, manufacturing method thereof, ink for manufacturing electronic device, electronic device, organic electroluminescence element, and photoelectric conversion element   

The present invention relates to a coating solution, a method for manufacturing the same, an ink for manufacturing an electronic device, an electronic device, an organic electroluminescence element, and a photoelectric conversion element, and more particularly, to a method for providing efficient removal of moisture or oxygen adhering to an organic material. Coating liquid for electronic device with good performance, manufacturing method thereof, ink for manufacturing electronic device, electronic device, organic electroluminescence element, and photoelectric conversion element.

1. Popularization of organic electronic devices and current issues

An electronic device using an organic compound includes, for example, an organic electroluminescent diode (also referred to as "OLED", "organic EL element"), and is described in Japanese Patent Application Laid-Open No. 2010-272619 and Japanese Patent Application Laid-Open No. 2014-078742. Gazette, etc. Various electronic devices such as organic photoelectric conversion elements and organic transistors have been developed. With the advancement of these technologies, the popularization in various industries / market fields is also ongoing.

For example, organic electroluminescence elements, which are typical examples of organic electronic devices, have begun to be used in various fields such as displays, lighting, and indicators, and have now entered the current market together with liquid crystal displays or light emitting diodes (LEDs). Life has ushered in a period of leap in popularity since then.

However, in order to promote the development of organic electronic devices such as organic electroluminescence devices, there are still many problems that must be solved in the research / development process. In particular, various problems arising from the use of organic compounds remain common or unique to various organic electronic devices. These problems to be solved are the ultimate issues that are closely related to the further improvement of performance such as quantum efficiency and luminous lifetime, and further improvement of productivity, that is, cost reduction.

Among the above-mentioned ultimate issues, in terms of performance issues, in the field of electronic displays, organic electroluminescent elements have been used in the main screen of smart phones, or large displays larger than 50 inches have become commercially available. Signage also achieves a light emitting efficiency of about 139Lm / W, which is about twice as high as that of a fluorescent lamp with a white element, or a white phosphorescent element or a green phosphorescent element that achieves a half-life of half the brightness and a longevity of 1 million hours, which is the most difficult. The blue phosphorescent element produced also has a result of more than 100,000 hours. Based on this, the organic electroluminescence element can be considered to have reached a sufficient practical level through the delicate layer structure or careful attention to the film formation process.

On the other hand, with regard to productivity, that is, the issue of cost, as will be described in detail later, the original RGB side by side display of the advantages of organic electroluminescence devices has not yet produced energy in large displays. Or, the manufacturing method based on the coating method developed for the purpose of reducing the production load, there is still much room for improvement in the purification and processing of solvents or organic materials.

In short, solving the problem of low productivity can be said to be a necessary condition for the development of organic electroluminescent devices. In addition, this is also necessary for other organic electronic devices, such as organic photoelectric conversion elements.

Therefore, in the following, the problems of the prior art regarding the production of organic electroluminescence elements, which are typical examples of organic electronic devices, will be described from the viewpoint of the ultimate issue related to productivity.

2. Questions about organic functional layer formation

First, a method that results from forming an organic functional layer, that is, a vacuum evaporation method (also referred to as a "vacuum evaporation film-forming method") and a wet coating method (also referred to as a "wet coating method", "Wet coating into magic").

2.1 Influence of moisture and oxygen on the organic functional layer

The basic principle of an organic electroluminescent device is to inject electrons and positive holes in a light-emitting material (commonly also referred to as a "dopant") existing in the light-emitting layer of one of the organic functional layers. The exciton emits light when it returns to the ground state.

This exciton, as its name is a very active chemical species in an excited state, easily reacts with water molecules or oxygen molecules, easily causes chemical changes or state changes such as decomposition or denaturation, and reduces luminescence. In short, it is one of the reasons for the decrease in the luminous lifetime.

That is, when forming an organic functional layer such as a light-emitting layer, it is necessary to perform the formation process in an environment where water or oxygen cannot enter at all.

On the other hand, in an organic electroluminescence element, unlike an LED, an organic compound constituting a light-emitting layer exists in a state that is not crystalline but that amorphous is a condition for high-efficiency light emission. That is, in order to form a homogeneous amorphous film, it is expected that the molecular state (amorphous state) of the organic compound in the film formation and the surrounding environment must be maintained.

That is, because of the reasons for preventing the above-mentioned disadvantages caused by moisture or oxygen, and the necessity of making the organic compound into an amorphous state, a method for forming an organic functional layer of an organic EL element that has exhibited good performance so far, It is a vacuum evaporation method. Organic electroluminescence displays for smart phones that have been mass-produced, or organic electroluminescence displays used in large televisions, have been deposited on organic functional layers by evaporation.

2.2 Problems in forming organic functional layers according to the vacuum evaporation method

However, when an organic electroluminescence device is produced by a vacuum evaporation method, the following problems are caused with respect to the emission color reproduction method.

Organic electroluminescence is self-luminous, and the emission color is fundamentally determined by the light-emitting material constituting the light-emitting layer, so it is basically every pixel of red (Red: R), green (Green: G), and blue (Blue: B) A method is adopted in which organic electroluminescence elements that make separate emission colors are arrayed to form a display (RGB side by side method).

In the case of the RGB side by side method, it is necessary to form different light-emitting layers for the RGB pixels. In order to form a large-area light-emitting layer, it is generally used to shade the pixels and gradually form each picture. Vegetarian method. At this time, the method for forming (filming) the light-emitting layer or the like is a vacuum vapor deposition method, so that the shadow mask thermally expands due to radiant heat from the vapor deposition source, causing a decisive problem of pixel deviation.

Because of this decisive problem, the small to medium-sized displays used in smart phones, even in the RGB side by side method, can produce hundreds of millions of panels per year. In the production of large displays over 50 inches, due to the shadow mask Thermal deformation results in low manufacturing productivity, and large-scale production is not possible.

On the other hand, as another method for reproducing full color, a method in which white light obtained by an organic electroluminescence element is passed through a color filter and color is divided into RGB to reproduce full color (color filter) Film mode). For large-scale displays that have already been mass-produced, for each pixel, an organic electroluminescence element that emits white light is arrayed. In the color filter method, there is no way to fully utilize the high-contrast luminescence with independent pixels. Problems with the advantages / characteristics of organic electroluminescence elements.

2.3 Possibility of organic functional layer formation by wet coating method

The organic functional layer constituting the organic electroluminescence element has a laminated structure of about 4 to 7 layers, and the entire layer (film) thickness is about 100 to 200 nm. If it is thinner than this, the anode and the cathode are short-circuited due to the influence of the surface roughness of the electrode serving as the lower layer, causing a current leakage phenomenon.

In addition, if it is thicker than this, the charge conduction mechanism of the organic electroluminescence element is different from the Ohm's law. According to the Child-Langmuir's space charge limited current (SCLC), the current density and the distance between the electrodes are different. The third power is inversely proportional, so it causes a large increase in driving voltage, which causes a problem of increased power consumption.

The organic functional layer of an organic electroluminescent device generally deposits a low-molecular compound into a film, but instead of using a low-molecular compound, a π-conjugated system such as polyparaphenylene vinylene or polyfluorene is used. The polymer is used in a light emitting polymer (LEP) method in which the carrier moves and emits light. The polymer material cannot be vapor-deposited into a film, and therefore an organic functional layer is produced by a wet coating method (wet film-forming method, wet coating method) such as spin coating or spot coating, letterpress printing, or inkjet printing.

In addition, even for vaporizable low-molecular compounds, by properly selecting the molecular structure of the compound and the solvent used to dissolve it, a smooth coating film can be formed at the nanometer level. In 2010, Konica Minolta Corporation announced four-layer coating. A low-molecular compound, a prototype of a phosphorescent white element that can emit light efficiently.

Nowadays, companies or research institutes in the world are actively researching and developing organic electroluminescence devices using this method, that is, using low-molecular materials by wet coating (wet coating method) (for example, refer to Patent Document 1).

However, as will be described in detail later, in the purification and handling of a solvent or an organic material (a solute), the problem caused by the easily soluble water or oxygen contained in the coating liquid has not been sufficiently solved.

[Prior technical literature]

[Patent Literature]

[Patent Document 1] Japanese Patent No. 4389494

The present invention is an invention made in view of the foregoing problems and situations, and a solution thereof is to provide a coating liquid capable of efficiently removing moisture or oxygen adhering to an organic material, etc., and producing a high-performance electronic device, a method for manufacturing the same, and an electronic device. Production ink, electronic device, organic electroluminescence element and photoelectric conversion element.

In order to solve the aforementioned problems, the inventor of the present case, in the course of reviewing the causes and the like of the aforementioned problems, found that the coating solution containing an organic compound and an organic solvent was used for the above-mentioned conditions under 50 ° C / atmospheric The organic solvent enables the dissolved carbon dioxide concentration to be within a specific range, and can provide a coating liquid capable of efficiently removing water or oxygen, and a method for producing the same, thereby completing the present invention. In addition, by using this coating liquid, inks for producing electronic devices, electronic devices, organic electroluminescence elements, and photoelectric conversion elements with good performance can be provided.

That is, the subject concerning this invention is solved by the following means.

In order to make the present invention easier to understand, the basic policy and research / development process related to the present invention will be described later.

A coating liquid comprising an organic compound and an organic solvent, and a dissolved carbon dioxide concentration of the organic solvent under a condition of 50 ° C./atmospheric pressure is in a range of 1 ppm or more and a saturated concentration of the organic solvent or less Inside.

2. The coating liquid according to item 1, wherein the concentration of the dissolved carbon dioxide is within a range of 5 to 1000 ppm under the foregoing conditions.

3. The coating liquid according to item 1 or 2, wherein when the oxygen in the coating liquid is 1 ppm or more, the dissolved carbon dioxide concentration is contained within the range of 1.0 to 100,000 times the dissolved oxygen concentration under the aforementioned conditions.

4. The coating liquid according to any one of items 1 to 3, wherein the coating liquid is a coating liquid for manufacturing an electronic device.

5. The coating liquid according to item 4, wherein the electronic device is a light-emitting device.

6. The coating liquid according to any one of items 1 to 5, wherein the organic compound is an organic electroluminescent material.

7. The coating liquid according to any one of items 1 to 6, wherein the coating liquid is an inkjet ink.

8. A method for producing a coating liquid, characterized in that the coating liquid of any one of items 1 to 7 has a step of mixing the aforementioned organic compound and carbon dioxide.

9. The method for producing a coating liquid according to item 8, wherein after the step of mixing the organic compound and carbon dioxide, a solution containing the organic compound is used to produce the coating liquid.

10. The method for producing a coating liquid according to item 8 or 9, comprising a step of separating a substance in a solution containing the organic compound using a supercritical fluid.

11. An ink for manufacturing an electronic device, comprising the coating liquid according to any one of items 1 to 7.

12. An electronic device comprising an organic function layer formed using the coating liquid according to any one of items 1 to 7.

13. An organic electroluminescence element comprising an organic functional layer formed using the coating liquid according to any one of items 1 to 7.

14. A photoelectric conversion element comprising an organic functional layer formed using the coating liquid according to any one of items 1 to 7.

(Basic policy and research / development process related to the present invention)

Under the foregoing or later technical background, the technology used in the manufacturing method of the organic electroluminescence element must be presumed to be a selector as disclosed below.

<Basic Policy on Manufacturing Method>

(1) It is better to use low-molecular compounds for organic electroluminescent compounds (poor polymer compounds)

(2) Coating method is used for film formation method (poor evaporation method)

(3) The solvent in the coating liquid is preferably a general-purpose solvent (expensive dehydrated high-purity solvent is not good)

(4) It is better to dissolve in a single molecule state (microcrystalline dispersion is not good)

(5) For purification of compounds, it is better to use the adsorption-desorption balance (heat balance is not good)

First, when adopting the basic policy as described above, the method of creating completely satisfying policies (3) to (5) is the current technical issue. Considering that achieving the other policy is the most valuable technology, iterative measures are repeated for achieving the other policy. Research / development.

As a result, it was found that in order to achieve the above-mentioned "(3) the solvent in the coating solution is preferably a general-purpose solvent", it is not enough to simply use a dehydrating and deoxidizing solvent. Due to the existence of a special gas in the solution, it is preferably close to saturation. Dissolving a gas at a concentration of 50% increases the environmental robustness to water, oxygen, etc. mixed in the day after tomorrow. Although very simple, this constitutes the essence of the present invention. The gas is carbon dioxide.

In previous coating film-forming elements, the coating solution was stored under a nitrogen atmosphere for a long time, so that the dissolved oxygen and nitrogen in the atmosphere were replaced by equilibrium, or the nitrogen was blown out or pressurized to expel oxygen. Or, by using the method according to these, the deoxidation of the coating solution is performed.

However, during the coating process, even if only for a moment, as long as it is exposed to the atmosphere, the coating solution will immediately absorb oxygen or moisture. Even if the best attention is paid to the coating solution that is dehydrated / deoxygenated, it will be completely useless, and This causes a significant deterioration in the characteristics of the organic electroluminescence element, in particular, the luminous lifetime.

What we have discovered is that water or oxygen is discharged in advance in the initial state of the coating solution, but by dissolving the solution with carbon dioxide having a near-saturated concentration, it becomes difficult for the solution itself to absorb water or oxygen.

The following is a brief description of our experience in completing this invention.

As mentioned earlier, during the development of coating low-molecular compounds into films, we discovered a technique for refining organic electroluminescent materials by high performance liquid chromatography (HPLC) of carbon dioxide (Japan) Patent No. 4389494).

However, it has also been found that problems such as contact with air during the film formation process, or traces of moisture attached to the coating device cause contamination, which causes a large change in performance each time a component is manufactured.

As a result of an intensive review by the inventors of the present case to solve the problem, it was found that when supercritical carbon dioxide removes gaseous carbon dioxide from the solution, the completely dissolved oxygen is also taken out of the solution system. In addition, the trace amount of water is also combined with the carbon dioxide. The hydrogen bonds are bonded and discharged, and the remaining carbon dioxide at a concentration close to saturation will prevent oxygen or water from being mixed into the solution system. The dissolving liquid refined by supercritical HPLC can be directly coated to produce complete performance. There are no discrete, well-distributed stable and good elements to complete the present invention.

In addition, it has been found that not only supercritical carbon dioxide, but also carbon dioxide gas can be foamed in the organic solvent solution of ordinary dissolved organic electroluminescent materials, or the same effect can be exhibited.

In summary, the present invention is constituted by the following technical elements.

In addition, the description so far is about the organic electroluminescence element according to the coating film-forming method using a low-molecular compound, but this is only one of the representative and most effective applications. Of course, other electronic devices, such as organic thin-film solar cells, organic transistors, and electrodes using organic compounds, which are formed by molecular compounds, can also apply the same technology.

(a) A solution for coating containing carbon dioxide in a solution in which a low-molecular compound is dissolved at a concentration close to saturation.

(b) A solution for applying carbon dioxide to a solution in a supercritical state

(c) Coating solution for solute dispersed in solvent after adsorption-desorption equilibrium

That is, the eluate refined by supercritical carbon dioxide HPLC is used in a state where it is not concentrated and dried, and the above (a) to (c) are achieved at the same time, but the present invention does not take this as a prerequisite, as long as carbon dioxide is dissolved, and After the adsorption-desorption equilibrium, it can be dispersed in the solvent (in short, it is completely dissolved), regardless of the method.

By the aforementioned means of the present invention, it is possible to provide a coating liquid capable of efficiently removing moisture or oxygen adhering to an organic material to produce a good-performance electronic device, a method for manufacturing the same, an ink for manufacturing an electronic device, an electronic device, and an organic electrolyte. Light-emitting element and organic photoelectric conversion element.

Although the presenting mechanism and the acting mechanism of the effect of the present invention are not clear, it can be inferred as follows.

The coating liquid of the present invention contains an organic compound and an organic solvent, and the dissolved carbon dioxide concentration of the organic solvent under the condition of 50 ° C./atmospheric pressure is within a range of 1 ppm or more and the saturated concentration of the organic solvent or less. Carbon dioxide dissolved in the solution before and after coating, when the gaseous carbon dioxide escapes, the dissolved oxygen is also taken out of the solution system. In addition, a small amount of water contained in the solution is also reacted with carbon dioxide by hydrogen. The keys were bonded and removed. Furthermore, by keeping carbon dioxide remaining at a concentration close to saturation, it is possible to prevent oxygen or water from being mixed into the solution system. As a result, a high-performance electronic device can be manufactured, and productivity can be improved. The carbon dioxide of the present invention is dissolved in the coating liquid for the purpose of removing oxygen or water from the coating liquid and preventing the oxygen or water from being mixed into the coating liquid, and is not used as a medium for spraying, for example.

11‧‧‧ supercritical fluid

12‧‧‧ pump

13‧‧‧ modifier

14‧‧‧Injector

15‧‧‧Column

16‧‧‧Column oven

17‧‧‧ Detector

18‧‧‧pressure regulating valve

41‧‧‧Display

53‧‧‧ pixels

55‧‧‧scan line

56‧‧‧ Data Line

60‧‧‧Organic electroluminescence element

61‧‧‧Switching transistor

62‧‧‧Drive transistor

63‧‧‧Capacitor

67‧‧‧Power cord

101‧‧‧ glass substrate

102‧‧‧ITO transparent electrode

103‧‧‧ next door

104‧‧‧Positive hole injection layer

105B, 105G, 105R‧‧‧ luminescent layer

106‧‧‧Electronic transport layer

107‧‧‧ cathode (A1)

200‧‧‧ Bulk-heterojunction type organic photoelectric conversion element

201‧‧‧ substrate

202‧‧‧Transparent electrode (anode)

203‧‧‧ counter electrode (cathode)

204‧‧‧Photoelectric conversion department (block heterogeneous interface layer)

205‧‧‧ charge recombination layer

206‧‧‧Second photoelectric conversion unit

207‧‧‧Positive hole delivery layer

208‧‧‧Electronic transport layer

209‧‧‧The first photoelectric conversion unit

A‧‧‧Display

B‧‧‧Control Department

Fig. 1 is a comparison between a vapor-deposited film and a coating film: analysis results of particle size distribution of organic compound fine particles in the film.

Fig. 2 is a comparison between a vapor-deposited film and an improved coating film: analysis results of particle size distribution of organic compound fine particles in the film.

FIG. 3 is a schematic diagram of an apparatus for filling a tubular string using a supercritical fluid chromatography method.

FIG. 4 is a schematic diagram showing an example of a display device including an organic electroluminescence element.

FIG. 5 is a schematic diagram of the display section A. FIG.

Fig. 6 is a schematic diagram showing a pixel circuit.

FIG. 7 is a schematic diagram of a passive matrix system full-color display device.

FIG. 8 is a cross-sectional view showing a solar cell composed of a bulk heterojunction type organic photoelectric conversion element.

FIG. 9 is a cross-sectional view showing a solar cell composed of an organic photoelectric conversion element including a tandem type bulk heterojunction layer.

FIG. 10A is a schematic configuration diagram of an organic electroluminescence full-color display device.

FIG. 10B is a schematic configuration diagram of an organic electroluminescence full-color display device.

FIG. 10C is a schematic configuration diagram of an organic electroluminescence full-color display device.

FIG. 10D is a schematic configuration diagram of an organic electroluminescence full-color display device.

FIG. 10E is a schematic configuration diagram of an organic electroluminescence full-color display device.

The coating liquid of the present invention is characterized by containing an organic compound and an organic solvent, and a dissolved carbon dioxide concentration of the organic solvent under a condition of 50 ° C./atmospheric pressure is within a range of 1 ppm or more and a saturated concentration of the organic solvent or less. This feature is a technical feature common to or corresponding to the invention related to each claim.

As an embodiment of the present invention, from the standpoint of the effect of the present invention, the dissolved carbon dioxide concentration is preferably within a range of 5 to 1000 ppm under the aforementioned conditions.

When oxygen in the coating solution is 1 ppm or more, the dissolved carbon dioxide concentration is contained in the range of 1.0 to 100,000 times the dissolved oxygen concentration under the aforementioned conditions. From the viewpoint of the stability of a device made using the coating solution, Is better.

The coating liquid is a coating liquid for manufacturing an electronic device, and it is preferable that an electronic device with good performance can be manufactured. The electronic device is preferably a light-emitting device.

The aforementioned organic compound is an organic electroluminescent material, and is preferable in terms of both the life of the light emitting device and the light emitting efficiency.

The coating liquid is preferably an inkjet ink, and it is possible to manufacture various devices.

The manufacturing method of the coating liquid of this invention is characterized by the process of mixing the said organic compound and carbon dioxide.

After the step of mixing the organic compound and carbon dioxide, it is preferable to use a solution containing the organic compound to produce the coating solution. That is, it is preferable that the carbon dioxide contained in the coating solution prevents air from being exposed to the film during the film formation process, or that a small amount of water adhering to the coating device is contaminated in the coating solution. In addition, it is not necessary to condense the purified organic compound to dryness, and then re-dissolve it in a solvent corresponding to the coating film to prepare a coating solution.

A step of separating a substance in a solution containing the organic compound using a supercritical fluid is preferable in terms of improving the efficiency of the purification step.

The coating liquid of the present invention is preferably contained in an ink for manufacturing an electronic device.

The coating liquid of the present invention is suitable for forming each organic functional layer of an electronic device, an organic electroluminescence element, and a photoelectric conversion element.

Hereinafter, the present invention, its constituent elements, and modes / forms for implementing the present invention will be described in detail. In the present invention, "~" means that the numerical values described before and after it are used as the lower limit value and the upper limit value. In the present invention, "ppm" means "mass ppm".

(Outline of the coating liquid of the present invention)

The coating liquid of the present invention is characterized by containing an organic compound and an organic solvent, and the dissolved carbon dioxide concentration of the organic solvent under the condition of 50 ° C./atmospheric pressure is within a range of 1 ppm or more and the saturation concentration of the organic solvent or less .

As described above, the present invention has been completed by reviewing the following basic policies (1) to (5).

(1) The organic electroluminescent compound is preferably a low-molecular compound (a polymer compound is not good)

(2) Coating method is used for film formation method (poor evaporation method)

(3) The solvent in the coating liquid is preferably a general-purpose solvent (expensive dehydrated high-purity solvent is not good)

(4) It is better to dissolve in a single molecule state (microcrystalline dispersion is not good)

(5) For purification of compounds, it is better to use the adsorption-desorption balance (heat balance is not good)

In the following, first, the present invention will be described from the viewpoint of the basic idea of the basis of each of the aforementioned policies, and then specific techniques will be described.

1. The superiority of low molecular compounds relative to high molecular compounds

The formation of the organic functional layer according to the wet coating method illustrates the superiority of the low-molecular compound over the high-molecular compound.

(First reason): the superiority of purity

Comparing low-molecular compounds with high-molecular compounds (so-called polymers) clearly understands the differences. First, low molecular weight compounds are suitable for sublimation purification because the molecular weight is small and recrystallization is preferably one with a small molecular weight distribution. In addition, a method for purifying a low-molecular compound is preferable because a high-performance liquid chromatography (HPLC) method or a column chromatography method with low purification efficiency (low number of theoretical stages) can be used.

Refining of high molecular compounds is carried out repeatedly in almost all cases by reprecipitation using a good solvent and a lean solvent, and it is easy to obtain high purity with low molecular compounds.

In addition, when the polymer compound is a π-conjugated polymer compound, a metal catalyst or a polymerization initiator must be used for initiating the polymerization reaction. At the polymerization terminal, most reactive substituents remain, which is also low. One of the reasons why molecular compounds can achieve high purity.

(Second reason): On the priority of the energy state peculiar to the molecule

Light emitting polymer (LEP), the larger the molecular weight, because it is a π-conjugated polymer, in order to stabilize the molecule to expand the conjugate system, so in principle a singlet (singlet) or triplet (triplet) The energy state difference between the excited state and the ground state (also called "gap between energy states" and "band gap") becomes narrower, making it harder to emit blue light. In addition, blue phosphorescent and light-emitting polymers which require higher energy states (large energy state differences) than blue fluorescence, are difficult to form an excessive metal complex that is a light-emitting substance in structure. Furthermore, even if a light-emitting polymer is used as a host, it is difficult to become a compound having triplet energy (referred to as "high T1 compound") by the aforementioned π-conjugated expansion.

In addition, thermally activated delayed fluorescence (TADF), which has recently attracted much attention, does not have a previous example completed with a π-conjugated polymer, and it is difficult to use it for high-efficiency blue light emission with high market demand.

On the other hand, low-molecular compounds do not have the necessity of linking π-conjugated systems. Although aromatic compound residues that become π-conjugated units are necessary, they can be arbitrarily selected and can be substituted at any position. . That is, in low-molecular compounds, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) can be easily and deliberately adjusted, and the triplet (T1) energy In this step, a blue phosphorescent substance can be produced or used as a host, or a compound that causes a TADF phenomenon can be constructed. It is possible to deliberately design / synthesize an arbitrary electronic state or an arbitrary energy state, which is the reason for the second priority of low molecular compounds.

(3rd reason): Ease of compound synthesis

Although it is a reason (cause) similar to the second reason, low-molecular compounds have no restrictions on the molecular structure that can be synthesized compared to the light-emitting polymer (LEP), especially the π-conjugated main chain of the light-emitting polymer If applicable, the applicable framework or synthesis method will be limited, but it is relatively easy for low-molecular compounds to complete new functions or adjust physical properties (Tg, melting point, solubility, etc.) through molecular structure. This is Third preference of low molecular compounds.

2. The problem of organic functional layer formation based on wet coating method using low molecular compounds

Based on the essential issue of forming an organic functional layer in a wet coating method using a low-molecular compound, the explanation will be divided into several points.

Almost all materials used in organic electroluminescence elements must internally move electrons and positive pores between molecules within the organic electroluminescence element. Basically, the electron follows the LUMO energy state transition, and the positive hole uses the HOMO energy state transition.

That is, if adjacent molecules do not overlap with each other in the π-conjugated system orbitals, such carrier conduction will not be caused. Therefore, it is advantageous to form a molecular structure with π-conjugated system units as much as possible.

For example, in order to improve the solubility in a solvent, if a bulky substituent (secondary butyl, tertiary octyl, or triisopropylsilyl, etc.) is replaced in one molecule by a plurality of molecules, intermolecular The π conjugated system becomes difficult to overlap, and the transition of the bulky substitution base is hindered.

On the other hand, organic electroluminescence elements flow endlessly with current during light emission, so even if, for example, the quantum efficiency is 100%, that is, the probability of carrier recombination is 100%, the thermal deactivation ratio is 0%, and the organic electroluminescence In order for the light-emitting element to continue to flow, it is necessary to provide a potential difference between the Yang pole and the cathode to provide an electric field gradient. Therefore, the equivalent circuit of the organic electroluminescence element becomes a diode and a resistor connected in series.

That is, Joule heat is generated inside the organic electroluminescence element during energizing light emission. Actually, it is known that heat is generated at a temperature of 100 ° C. or higher inside the light emitting layer, particularly in the light-emitting layer where recombination occurs.

In addition, since the organic layer of the entire organic electroluminescence element is a very thin layer having a thickness of about 200 nm, heat is conducted between the layers (films), not only the light emitting layer, but also the high temperature state in all the layers.

When an organic molecule exposed to such a state exceeds its own glass transition temperature (Tg), it causes a phase transition from an amorphous state to a crystalline state.

This crystal gradually grows, and when it exceeds tens of nm, the layer thickness of the compound is exceeded, and functional separation cannot be performed based on the layer as an organic electroluminescence element. As a result, the luminous efficiency is reduced.

Furthermore, if the crystal exceeds the entire organic layer (100 to 200 nm) of the organic electroluminescence element, the anode and the cathode are short-circuited. Then, an electric field is concentrated on the short-circuited portion, and a large current flows in a minute region, causing the organic compound in the portion to be thermally decomposed, and a portion that does not emit light at all, which is a so-called dark spot.

In short, the low-molecular compound of the organic electroluminescence element must be a non-aromatic substituent without a large volume, and must have a glass transition temperature (Tg) of 100 ° C or higher (preferably 150 ° C or higher). molecule.

To construct such a molecule, the π conjugated system is usually enlarged, or the aromatic group is simply connected, but the compound formed in the ordinary case will have extremely low solubility in the solvent, and cannot be used as a coating solution, or Even if it can be applied, it will cause crystal precipitation or partial distribution of substances.

As a way to solve this dilemma, we have developed an epoch-making technology that can form a stable amorphous film and maintain the amorphousness even when the power is turned on (see, for example, Japanese Patent No. 5403179 or Japanese Patent Application Laid-Open No. 2014-196258). Bulletin). Specifically, it does not have a branched alkyl group having a large volume and high flexibility, and only connects an aromatic group as a bisaryl structure. A large number of three-dimensional structures are actively added by a rotation obstacle generated around the CC bond axis. Shape or geometric anisotropy, or multiple molecules (for example, host and dopant) existing in the same layer cause interactions in various shapes / morphologies to increase the number of components in the film, so increase The entropy of the thin film state can form a stable amorphous film.

The inventors of this case, in the production of organic electroluminescence devices based on the wet coating method, improved the molecular structure of low-molecular compounds in accordance with the guidelines described above, sought to optimize drying conditions, and finally achieved a luminous efficiency of 95% of the vapor-deposited element and 90% of the luminous lifetime are achieved, achieving a dramatic improvement. In this way, it was found that the element using a phosphorescent dopant for the light-emitting dopant, especially the blue phosphorescent dopant that has the longest lifespan, can also be applied by the coating film method, which is almost comparable to the previous one. Basic characteristics of vapor deposition method.

However, many problems remain in the organic electroluminescence device having such improved performance.

These problems include, for example, removal of the purity of the low-molecular compound, the trace amount of water adhering to the surface of the compound, the oxygen content of the solvent used, and the water content.

In addition, for example, even for low-molecular compounds that are generally used for coating, in order to exhibit the highest performance, column chromatography and recrystallization are performed after sublimation purification, and then organic compounds are used in a vacuum state when they are used or stored. After that, it was replaced with a nitrogen atmosphere and then used.

In the case where an organic electroluminescence device is produced by a coating method under such strict management as to eliminate adverse effects as much as possible, it is difficult to surpass the performance of an organic electroluminescence device produced by a vapor deposition method.

Furthermore, the productivity of using a vacuum evaporation method is originally low, but because of the large-scale or mass-production of organic electroluminescence devices, in general, it has an adverse effect on cost, so the coating method has attracted attention. When the coating method is performed under such strict management, the productivity is lower than that of the vapor deposition method, which increases the cost.

3. Method for purifying compounds

The advantage of low-molecular compounds is that more purification methods can be used than high-molecular compounds, and high purity can be achieved. However, from the results, almost all of the organic compounds constituting organic electroluminescence devices that are currently practically used are purified by the sublimation purification method.

Sublimation refining is a classical refining method, but compared with recrystallization, column chromatography, HPLC, and other refining methods, the refining efficiency (the number of theoretical stages) is overwhelmingly small, and it is essentially used for the removal of metals or inorganic substances Use the means of solvent removal.

The main reason why sublimation-refined organic compounds for organic electroluminescence are used is mainly because the manufacturing process of the organic electroluminescence element uses a vacuum evaporation method. If the organic compound contains a very small amount of solvent, the solvent in the organic compound will volatilize when the evaporation device is built in a vacuum environment, and the degree of vacuum will be reduced.

As a result, continuous production becomes impossible and becomes a manufacturing problem. Therefore, a sublimation purification method in which the solvent is completely removed during the purification is adopted.

Therefore, when the production method of the organic electroluminescence element is changed from the evaporation method to the coating method, the purification of the organic compound by the sublimation purification method is no longer necessary due to the foregoing reasons.

(re-crystallize)

Next, consider the most general recrystallization as a purification method for low-molecular organic compounds.

This method is a purification method based on the second law of thermodynamics (Equation 1).

-△ G =-△ H + T △ S‧‧‧ (Equation 1)

The shorter the distance of matter with each other, the van der Waals or hydrogen bonding force, π-π interaction force, dipole-dipole interaction force, etc. will increase, and the enthalpy (-△ H) becomes larger.

On the other hand, when the substance is completely dispersed in the medium, that is, when the substance is dissolved, the substance moves freely, so the disorder increases, and the entropy (ΔS) increases.

In the second law of thermodynamics, the Gibbs free energy (-△ G) in all existence states is either kept constant or moved in a direction of increasing.

That is, in order to purify the compound A to be purified by recrystallization, the following method can be considered in a reasonable manner.

In a B solvent that can dissolve A, if A is dissolved at a high temperature, A will exist in a dispersed state. Therefore, the existence distance of A is large, and it is not easy to interact with each other, so the enthalpy (-ΔH) becomes extremely small.

On the other hand, A is free to move in the solution, so the entropy (ΔS) is extremely large. When this high temperature solution is cooled, TΔS multiplied by the absolute temperature T becomes smaller than before cooling. At this time, to keep the Gibbs free energy (-△ G) constant before and after cooling, only the enthalpy (-△ H) can be increased.

In short, the part where the temperature decreases and TΔS becomes smaller will inevitably make the distance between A and A smaller and increase the enthalpy. The limit state is a crystalline state in which the distance between A and A becomes the smallest, so the enthalpy term (-ΔH) gradually increases.

In this way, when the enthalpy gradually increases, the number of components in the system will decrease, so the entropy becomes smaller and the part where the entropy becomes smaller, in addition, crystallization is made to gradually increase the enthalpy.

In this way, the entropy term (T △ S) is reduced first due to the decrease in temperature, and the enthalpy (-△ H) is increased by crystallization in order to compensate for the decrease. In addition, the number of components is reduced, so the entropy term is increased. Reduction of S becomes smaller, and recrystallization is achieved by repeating the thermodynamic equilibrium in which the crystallization occurs.

However, it must be noted that the interaction between solute A and solvent B. Solute A is dissolved by "solvent sum" with solvent B. Therefore, if the interaction between A and B is small, A will not be dissolved in B originally. However, if the interaction is too large, the distance between A and A cannot be shortened beyond the reduction of the entropy term caused by the decrease in cooling (A and A are interposed by B), and it becomes a result that no recrystallization occurs. .

In short, this purification method based on recrystallization can be applied only when the interaction force between A-A and the interaction force between A-B can be adjusted to conditions under which recrystallization can occur. In this recrystallization refining method, a large amount of refining of hundreds of kilograms or more can be refined at a time, so this method has been used in the chemical industry for a long time.

(Column column chromatography)

Next, consider a column chromatography method (hereinafter also referred to as "chromatographic separation method").

The most typical method of column chromatography is to use a fine particle silica gel as a stationary phase, where compound A is adsorbed, and it is slowly dissolved in a mobile phase (B) called an eluent.

At this time, when the interaction (adsorption) between the surface of the silica gel and the compound A and the interaction with the mobile phase (B) are antagonized, A repeats the adsorption-desorption balance between the silica and the mobile phase B. It will dissolve quickly when the interaction with silicon dioxide is small, and it will dissolve slowly when the interaction is large.

At this time, the larger the number of round trips of the adsorption-desorption equilibrium, the larger the number of theoretical stages (that is, the purification efficiency). Therefore, according to the purification efficiency of the color layer separation method, it is proportional to the length of the stationary phase and also to the mobile phase. The speed is also proportional to the surface area of the stationary phase.

This method is realized by high-speed liquid chromatography. This method is widely used in the analysis or quality assurance of organic compounds. This method is due to the rare method that proves the high number of theoretical stages of this theory.

The reason why this chromatographic separation method is superior to recrystallization is that the polarity of the mobile phase B can be arbitrarily changed. For example, a gradient method in which a mobile phase is a mixed solvent of a good solvent and a poor solvent from the beginning is used, and a gradient method of a good solvent ratio is gradually increased during purification, thereby increasing the number of theoretical stages.

In addition, since the temperature can also be changed arbitrarily, the applicable range of the refinable solute is extremely wide, and it can be utilized as the most widely used refining method.

On the other hand, the chromatographic separation method also has disadvantages. As mentioned earlier, the basic principle of increasing the number of theoretical stages is to make use of the adsorption-out of balance.

For example, when the mobile phase uses only the solvent B ' (that is, a good solvent) which interacts strongly with the compound A for the chromatographic separation method, the interaction between A and the mobile phase B ' is more than the interaction between A and the silica gel. If it is stronger, the number of round trips of adsorption-out of balance will decrease sharply, which will reduce the refining effect.

In short, in order to improve the refining effect, in addition to the good solvent B ' , it is necessary to mix a large excess of the lean solvent C to increase the number of round trips of the adsorption-out of balance. However, in this case, the solution of the compound A collected in the purification contains a large amount of excess C, and it is necessary to concentrate this as the biggest problem.

For example, in order to obtain 1 g of A, it is necessary to set the mixing ratio of the good solvent B ′ and the lean solvent C to about 1:99 to 10:90, and generally, about 10 to 100 L of lean solvent C is required. Therefore, HPLC sorting is only suitable for research and development, and is not actually used for mass production.

The solution to the problem of lean solvent concentration is HPLC using supercritical carbon dioxide. Supercritical carbon dioxide makes carbon dioxide become a supercritical fluid under high temperature and pressure. Other substances can also form supercritical fluids in this way. However, because it can achieve a supercritical state at a relatively low pressure and temperature, chromatographic separation or extraction is also mainly used. carbon dioxide.

Here, supercritical carbon dioxide has different characteristics from ordinary fluids or liquids. By changing the temperature and pressure, the polarity of the substance to be dissolved can be continuously changed.

For example, when extracting docosahexaenoic acid (DHA) contained in fish head, this supercritical carbon dioxide is also used. Special clothing using adhesives is cleaned, and sebum is dissolved by temperature and pressure control. But the adhesive does not dissolve in supercritical carbon dioxide.

Although supercritical carbon dioxide can have various polarities in this way, the polarity of supercritical carbon dioxide formed at a relatively low temperature and pressure is about the level of cyclohexane or heptane. In the currently available supercritical HPLC, this level of polar supercritical carbon dioxide can be prepared in the device, mixed with a good solvent into the column, and the compound is purified by the same mechanism as that of ordinary HPLC.

The HPLC system using supercritical carbon dioxide passes through the column and enters the detector, but it is usually maintained at a high temperature and pressure until this stage, and carbon dioxide also exists as a supercritical fluid. From then on, the carbon dioxide is a gas until it is separated at normal temperature and pressure, and it will escape from the solution by itself during the separation, so it is not necessary to concentrate the lean solvent. At this time, carbon dioxide can be recovered by a carbon dioxide recovery device including a gas-liquid separation mechanism described in references (Japanese Biotechnology Society Vol. 88, No. 10, pp. 525-528, 2010), or it can be used again as a super Critical fluids.

Therefore, in the new drug industry which must synthesize most high-purity newly synthesized compounds, recently, this supercritical HPLC has been actively used. Under its influence, the selling price of analytical and sorting machines has also dropped, which is quite considerable. General applications.

Based on such characteristics and experience, the inventors of me and others have utilized this supercritical HPLC (Japanese Patent No. 4389494) for the purification of organic electroluminescent materials requiring high purity.

As mentioned above, in the hope of improving the productivity of the organic electroluminescence industry, there are various methods for purifying low-molecular organic compounds, each with its own advantages and disadvantages. With the characteristics of the manufactured compound, and the requirements of the compound Select the purification method that should be used, or use different methods in combination.

4. Dissolution of organic electroluminescent compounds

First, consider what dissolution is. Generally, the solvent molecule B surrounds the solute A with the interaction force between A and B, dispersing the aggregate of A, and allowing B to exist around A. Even if A is an isolated single molecular state, it is necessary to determine whether this is the case. difficult.

For example, when A is a molecule with extremely low solubility or high crystallinity, if it is a crystal of a size larger than the wavelength of visible light, no dissolution can be easily detected by light scattering or the like. However, for example, in the case of a substance having a low solubility but not a low solubility, even if a small crystal composed of several molecules of A is surrounded by a solvent molecule B, it is considered to be dissolved. In an organic electroluminescence element, there is a possibility that it may cause a large problem in the future.

In short, when a thin film (film) such as a positive hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer is formed by vapor deposition, the compounds constituting each layer are basically vaporized by vacuum evaporation. The isolated single molecule is landed on a substrate or an organic layer, and it becomes a solid thin film and is formed into a film. Therefore, a film is basically formed of a random aggregate of a single molecule, and it becomes an ideal amorphous film.

On the other hand, in the case of the coating film forming method, if it is assumed that the coating solution is a dispersion of microcrystals of an organic electroluminescent compound, it looks completely dissolved in appearance, but the actual situation of the obtained film is microcrystal aggregation. The film. Therefore, for example, the energy state of HOMO or LUMO is not a single-molecule energy state, but an energy state that becomes a stack of conjugates (crystalline state), which will become an important factor of reduced performance.

In addition, as time passes, the microcrystal becomes a nucleus and grows into a coarse crystal. If the functional separation between layers cannot be achieved, or if the large crystal is short-circuited between the anode and the cathode, there will be a large problem of black spots. .

Regarding the coating film-forming element using a low molecular weight, through the above-mentioned long-term review, it is known how the coating solution in the initial state can be approximated to a single-molecular dispersion state, and first of all, it is a necessary condition for deriving the same performance as the vapor deposition method.

Here, in general, it is considered to analyze what kind of molecular dispersion of a coating liquid to be dissolved closely by a small angle X-ray scattering (also called "SAXS"). result.

FIG. 1 shows the particle size distribution curve (horizontal axis: particle size (nm); vertical axis: frequency distribution) of the fine particles of the compound constituting the thin film produced by the evaporation method, and the solid line constitutes the Particle size distribution of compound fine particles. Either side uses the same compound, so you can compare directly.

The particle size distribution width of the fine particles of the vapor-deposited compound is approximately 2 nm, and the particle size corresponding to the position of the maximum peak is close to a monodispersed particle size. This indicates that the molecule has a size of one or two molecules. Therefore, almost a single molecule is randomly arranged to form an amorphous film during vapor deposition.

On the other hand, the particle size distribution width of the fine particles coated with the film-forming compound has a particle size corresponding to the position of the maximum peak of about 4.5 nm, which is wider than the particle size distribution of the vapor-deposited film.

As mentioned earlier, the same compound is used for vapor deposition and coating, so the original crystallinity or agglutination of the compound is the same. The difference here is that the dispersed state of the molecules in the state of the coating solution is not a single isolated molecule, but Microcrystalline dispersion of 5 to 10 molecules.

Of course, this coating solution has not crystallized after being stored in a glove box under a nitrogen atmosphere for more than one week. It is a so-called clear solution, but when analyzed by X-rays, it is a dispersion of several molecular microcrystals, which is mistakenly considered to be dissolved. The solution.

Next, the coating film produced by modifying the compound and using a coating solution for a trial work with an improved coating liquid adjustment method was analyzed by the same analysis and the particle size distribution was examined. The results are shown in FIG. 2.

From this result, it can be seen that the results shown in FIG. 2 show that there is almost no difference in the particle size distribution of the fine particles of the organic compound between the vapor-deposited film and the coating film.

In this way, by improving the molecular structure and working on the dissolution method, a completely dissolved state in which almost a single molecule is dispersed can be produced, which has been confirmed in our inspection of this.

This is a great achievement for demonstrating that the organic electroluminescence element produced by the coating method can exhibit the same performance as that of the organic electroluminescence element according to the vapor deposition method. On the contrary, we also know that in order to make the element according to the coating method It is equivalent to the original according to the vapor deposition method, and how much the process load is.

That is, to maintain the status quo, in order to obtain the same performance as the vapor deposition method by the coating method, even if the coating method should be a productive method that is originally productive, it requires a laborious and time-consuming procedure such as a dissolution method or a storage method. When increasing the production volume, the danger that this procedure will become a rate-determining step is very high, so it is strongly recognized that improving this technical field is indispensable for future mass production.

5. Purity of solvent of organic electroluminescent compound

In an organic electroluminescence element, the phenomenon that light is emitted when a luminescent material in an excited state returns to a base state is a basic function.

In addition, from the electrode to the light-emitting layer, it is necessary to transport electrons and positive holes through a transition phenomenon.

First, for an excited state, for example, when a 5% concentration of a light-emitting material is doped with an organic electroluminescence element, it is necessary to make it continue to emit light at a brightness of 1000 cd / m ² for one year. According to simple calculations, one doped Debris must be exciton about 1 billion times. In this case, even if the exciton reacts with the water molecule only once, it becomes a compound different from the original molecule. In addition, if an exciton reacts with an oxygen molecule, it will cause some kind of oxidation reaction or oxidative coupling reaction. This is the most representative phenomenon in the chemical change that causes the decrease in the function of the organic electroluminescent element.

In addition, materials other than light-emitting materials also become free radical states almost the same number of times. Regardless of the radical anion state or the cationic radical state, they are active species compared to the base state, so they may cause organic electroluminescent devices. Possibility of chemical changes due to reduced performance.

In short, water molecules or oxygen molecules are not allowed in the coating solution, and this is a prerequisite.

However, industrially, high-purity anhydrous solvents are very expensive, and handling is not easy. Therefore, as a result, in order to reduce the cost of the coating method, it is important to use a general-purpose solvent as a solvent for the consumer.

6. Storage of organic electroluminescent materials for solutes

As described above, the presence of water and oxygen is a fatal disadvantage for the performance of the organic electroluminescence element, especially for the life expectancy of the light emitting element.

The most important thing to pay attention to in the coating method is, of course, to prevent the mixing of water and oxygen. Therefore, the solute cannot be maintained in the state of the powder and placed in the air, like ordinary reagents or drugs.

When the inventors of our company made coating film-forming elements, they usually put solute-forming substances into conical flasks or Schlenk flasks, which can be used for decompression and inert gas flushing. They were decompressed with a vacuum pump and heated with air. It is common practice to heat the container with a spray gun, etc., outside these treatments, and seal it with nitrogen, move to a glove box under a nitrogen atmosphere, dissolve it in a dehydration solvent, and maintain coating under nitrogen to form a film.

At this time, in order to completely eliminate oxygen, the dissolution is also carried out with nitrogen, and the dehydrating solvent is reused through an absorption tube of alumina or zeolite before dissolution. Such treatment is performed in the same or based on the test plant or the actual plant, but this procedure takes a lot of time to reduce productivity. As mentioned above, solving this part of the problem is the biggest problem of our inventors.

7. Element technology related to the present invention

[Coating liquid]

The coating liquid of the present invention is characterized by containing an organic compound and an organic solvent, and the dissolved carbon dioxide concentration of the organic solvent under the condition of 50 ° C./atmospheric pressure is within a range of 1 ppm or more and the saturation concentration of the organic solvent or less .

The dissolved carbon dioxide concentration is preferably within a range of 5 to 1000 ppm under the aforementioned conditions.

In addition, when the oxygen in the coating solution is 1 ppm or more, the dissolved carbon dioxide concentration is contained in the range of 1.0 to 100,000 times the dissolved oxygen concentration under the aforementioned conditions, and from the viewpoint of stability of a device made using the coating solution It looks better. That is, when the coating liquid is prepared in the atmosphere, carbon dioxide in the atmosphere may be taken into the coating liquid. However, the ratio of carbon dioxide in the atmosphere is very low (about 0.03 to 0.04%). As a result, the amount of carbon dioxide taken into the coating solution should also be very low. However, the concentration of dissolved carbon dioxide in the coating solution has not been determined so far. The case was reported. In addition, there is no survey insight into its effects. According to the present invention, compared with the concentration of nitrogen and oxygen in the coating liquid, which are the main components in the atmosphere, a state in which the concentration of carbon dioxide is high is actively made. As a result, the effect of suppressing the introduction of oxygen or water into the coating liquid can be expected.

In the present invention, the dissolved carbon dioxide concentration can be measured by, for example, a gas phase chromatography method.

The coating liquid of the present invention is preferably a coating liquid for manufacturing electronic devices or an inkjet ink.

As the electronic device, a light-emitting device such as an organic electroluminescence element, a photoelectric conversion element (solar cell), or a liquid crystal display element is preferred.

(Organic compound)

The organic compound used in the present invention is not limited to a compound of a specific type / specific structure, and is preferably a compound used in various electronic devices from the viewpoint of the effects of the present invention.

For example, when the coating liquid is a coating liquid for producing an organic electroluminescence element, the organic compound is preferably an organic electroluminescence material (hereinafter also referred to as "organic EL material"). The organic electroluminescent material is a compound that can be used in an organic electroluminescent layer (hereinafter also referred to as an “organic functional layer” and an “organic EL layer”) formed between an anode and a cathode described later. In addition, a light-emitting element composed of these anodes, cathodes, and an organic electroluminescent layer using an organic electroluminescent material is called an organic electroluminescent element. Examples of the compound used as the organic electroluminescent material will be described later.

In addition, when the coating liquid is a coating liquid for producing a photoelectric conversion element, the organic compound is preferably a p-type organic semiconductor material or an n-type organic semiconductor material. Examples of compounds used as these p-type organic semiconductor materials and n-type organic semiconductor materials will be described later.

(Organic solvent)

In the present invention, the organic solvent refers to a medium composed of an organic compound capable of dissolving the aforementioned organic compound in the present invention.

Examples of the liquid medium for dissolving or dispersing the organic electroluminescence element material of the present invention include ketones such as dichloromethane, methyl ethyl ketone, tetrahydrofuran, and cyclohexanone; ethyl acetate, isopropyl acetate, and isobutyl acetate Other fatty acid esters, halogenated hydrocarbons such as chlorobenzene, dichlorobenzene, 2,2,3,3-tetrafluoro-1-propanol (TFPO), toluene, xylene, mesitylene, cyclohexylbenzene and other aromatics Group hydrocarbons, aliphatic hydrocarbons such as cyclohexane, decalin, dodecane, alcohols of n-butanol, s-butanol, t-butanol, organic solvents such as DMF, DMSO, etc. From the viewpoint of the amount of the solvent contained in the device, a solvent having a boiling point in the range of 50 to 180 ° C is preferred.

[Manufacturing method of coating liquid]

The method for producing a coating liquid of the present invention is characterized by having a step of mixing the organic compound and carbon dioxide (hereinafter also referred to as a mixing step).

After the aforementioned mixing step, it is preferable to use a solution containing the aforementioned organic compound to produce the aforementioned coating solution.

In addition, the method for producing a coating liquid of the present invention preferably has a step (hereinafter, also referred to as a separation step) of separating a substance (for example, water, oxygen, and an organic compound) in a liquid containing the organic compound using a supercritical fluid. .

The aforementioned mixing step is a step of mixing an organic compound and carbon dioxide. Specifically, as long as carbon dioxide can be dissolved in an organic compound, examples thereof include foaming carbon dioxide in a solution in which an organic solvent and an organic compound are mixed, and mixing the organic compound and carbon dioxide, or using a supercritical fluid chromatography method Mix organic compounds with carbon dioxide.

The foaming of carbon dioxide is preferably performed by foaming high-purity carbon dioxide at a flow rate of 0.01 to 100 ml / min for 1 to 60 minutes.

The coating solution of the present invention can be produced using the solution obtained by foaming carbon dioxide in this way, that is, a solution of an organic solvent and an organic compound in which carbon dioxide is mixed in a mixing step. That is, the solution obtained by the mixing step can be used directly as the coating liquid of the present invention.

The supercritical fluid chromatography method can be used for packed columns, open columns, and capillary columns.

When using a packed column method, as shown in FIG. 3, as long as a supercritical fluid 11 containing an organic solvent (containing carbon dioxide), a pump 12, a modifier 13 used as required, and an organic compound to be separated are injected, The injector 14, followed by the separation string 15, and if necessary, a detector 17, followed by a pressure regulating valve 18, may be used. The column 15 is adjusted in temperature in a column oven 16. As the filler, a silicon dioxide or a surface-modified silicon dioxide used in the previous color separation method can be appropriately selected.

As described above, the method for producing a coating liquid of the present invention preferably has a step (separation step) of separating an organic compound, water, and oxygen using a supercritical fluid containing an organic solvent and carbon dioxide. Next, the coating liquid of the present invention can be produced using a solution containing the separated organic compound and an organic solvent (containing carbon dioxide). That is, the solution obtained by the mixing step can be used directly as the coating liquid of the present invention.

In the present invention, a supercritical fluid is a substance in a supercritical state.

Here, the supercritical state will be described. Matter changes with the change of environmental conditions such as temperature, pressure (or volume) between gas, liquid, and solid. This is determined by the balance between intermolecular force and kinetic energy. The horizontal axis is temperature, and the vertical axis is pressure. Those that show the change of gas-liquid-solid three states are state diagrams (phase diagrams). Among them, the point where gas, liquid, and solid three phases coexist and are in equilibrium is three points. Where the temperature is higher than the three points, the liquid and its vapor are in equilibrium. The pressure at this time is a saturated vapor pressure, and is represented by an evaporation curve (vapor pressure line). At a pressure lower than the pressure indicated by this curve, the liquid is completely vaporized, and when a higher pressure is applied, the vapor is completely liquefied. Making the pressure constant and changing the temperature is also beyond the curve for liquid to vapor or vapor to liquid. This evaporation curve has an end point on the high-temperature and high-pressure side, which is called a critical point. The critical point is an important point to distinguish the characteristics of matter. When the liquid and vapor become indistinguishable from each other, the boundary surface of gas and liquid disappears.

At a higher temperature than the critical point, gas-liquid coexistence does not occur, and it is possible to switch between liquid and gas.

A fluid that is above the critical temperature and above the critical pressure is called a supercritical fluid, and the temperature / pressure region where the supercritical fluid is formed is called the supercritical region. Supercritical fluids can be understood as high-density fluids with high kinetic energy. Dissolving solutes shows the behavior of liquids. Distinguishing the density shows the characteristics of gas. There are various solvent characteristics of supercritical fluids, low viscosity and high diffusivity, and it is important to have excellent permeability to solid materials.

In the supercritical state, for example, in the case of carbon dioxide, the critical temperature (hereinafter also referred to as Tc) is 31 ° C, the critical pressure (hereinafter also referred to as Pc) is 7.38 × 10 ⁶ Pa, and propane (Tc = 96.7 ° C, Pc = 43.4 × 10 ⁵ Pa), ethylene (Tc = 9.9 ℃, Pc = 52.2 × 10 ⁵ Pa), etc. Above this region, the diffusion coefficient of the fluid becomes larger and the viscosity becomes smaller. The movement of the substance and the speed of reaching the equilibrium of the concentration are all It is fast and has a high density like a liquid, so it can perform efficient separations. In addition, by using a substance such as carbon dioxide that is a gas at normal pressure and normal temperature, recovery is quick. In addition, there are no obstacles due to trace solvent residues that are unavoidable due to the purification method using liquid solvents.

As the solvent used for the supercritical fluid, carbon dioxide, nitrous oxide, ammonia, water, methanol, ethanol, 2-propanol, ethane, propane, hexane, pentane, etc. are preferable, and carbon dioxide is more preferable. .

The solvent used as the supercritical fluid may be used alone, or a so-called modifier or azeotropic additive may be added to adjust the polarity.

Examples of the azeotropic additive include hydrocarbon-based solvents such as hexane, cyclohexane, benzene, and toluene; halogenated hydrocarbon-based solvents such as methyl chloride, methylene chloride, dichloroethane, and chlorobenzene; and methanol Alcohol solvents such as ethanol, propanol, butanol, ether solvents such as diethyl ether, tetrahydrofuran, acetal solvents such as acetaldehyde dimethyl acetal, ketone solvents such as acetone, methyl ethyl ketone, ethyl acetate, butyl acetate Ester solvents such as esters, carboxylic acid solvents such as formic acid, acetic acid, and trifluoroacetic acid, nitrogen compound solvents such as acetonitrile, pyridine, and N, N-dimethylformamide, carbon disulfide, dimethylmethylene, etc. Sulfur-based solvents, and water, nitric acid, sulfuric acid, etc.

The use temperature of the supercritical fluid is not particularly limited as long as it is higher than the temperature at which the organic compound of the present invention dissolves, but if the temperature is too low, the organic compound may be dissolved in the supercritical fluid and lack solubility. In addition, if the temperature is too high, organic compounds may be decomposed. Therefore, the use temperature range is preferably 20 to 600 ° C.

The use pressure of the supercritical fluid is basically not limited as long as it is above the critical pressure of the substance used, but if the pressure is too low, there may be cases where organic compounds are dissolved in the supercritical fluid and the solubility is not high. In addition, the pressure is too high. If it is high, problems such as durability of the manufacturing apparatus and safety during operation may occur. Therefore, the use pressure is preferably 1 to 100 MPa.

The device using a supercritical fluid is not limited as long as it has a function of dissolving an organic compound in contact with the supercritical fluid into the supercritical fluid. For example, a batch method for using a locking system for a supercritical fluid Circulation methods that make supercritical fluids circulate or a combination method that combines batch methods and circulation methods can be used.

[Ink for electronic device manufacturing]

The ink for manufacturing an electronic device according to the present invention is characterized by containing the coating liquid. That is, the ink for manufacturing an electronic device of the present invention is characterized by being derived from the coating liquid.

The electronic device is preferably a light-emitting device, and further preferably an organic electroluminescence element, a photoelectric conversion element, or the like.

Each of the layers constituting the electronic device can be formed by an inkjet method using an ink for producing an electronic device containing the coating liquid of the present invention.

[Electronic device]

The electronic device of the present invention is characterized by having an organic function layer formed using the coating liquid. That is, the electronic device of the present invention is characterized by having an organic functional layer derived from the coating liquid, in other words, having an organic functional layer formed by coating the coating liquid.

The electronic device is preferably a light-emitting device, and further preferably an organic electroluminescence element, a photoelectric conversion element, or the like.

[Organic electroluminescence element]

The element of the present invention is characterized by having an organic functional layer formed using the coating solution. That is, the element of the present invention is characterized by having an organic functional layer derived from the coating liquid, in other words, having an organic functional layer formed by coating the coating liquid.

Hereinafter, the details of the organic electroluminescence element will be described.

As mentioned above, the organic electroluminescent device of the present invention has an anode and a cathode on a substrate, and one or more organic functional layers (also referred to as [organic compound layer], [organic Light-emitting layer]).

(Substrate)

The substrate that can be used for the organic electroluminescence element of the present invention is not particularly limited, and a glass substrate, a plastic substrate, or the like can be used, and either transparent or opaque may be used. When light is taken out from the substrate side, the substrate is preferably transparent. Examples of suitable transparent substrates include glass, quartz, and transparent plastic substrates. In addition, in order to prevent the intrusion of oxygen or water from the substrate side, the substrate has a thickness of 1 μm and a water vapor transmission rate of 1 g / (m ² ‧24h‧atm) (25 ° C) in a test in accordance with the Japanese Industrial Standard JIS Z-0208. ) The following is preferred.

Specific examples of the glass substrate include alkali-free glass, low-alkali glass, and soda-lime glass. Among these, alkali-free glass is preferred from the viewpoint of little adsorption of moisture, and any one can be used as long as it is sufficiently dried.

Plastic substrates have attracted attention in recent years for reasons such as high flexibility, light weight, and resistance to breakage, and further reduction in thickness of organic electroluminescent devices.

The resin film used for the base material of the plastic substrate is not particularly limited, and examples thereof include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene, and polypropylene Cellulose esters such as cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate (CAP), cellulose acetate phthalate, nitrocellulose, or These derivatives include polyvinylidene chloride, polyvinyl alcohol, polyethylene-vinyl alcohol, syndiotactic polystyrene (SPS) resin, polycarbonate, norbornene resin, polymethylpentene, polyetherketone, Polyimide, polyether fluorene resin (PES), polyphenylene sulfide, polyfluorene, polyether fluorene amine, polyether ketimide, polyamine, fluororesin, nylon, polymethacrylate Esters (PMMA), acrylic or polyacrylic resins, organic-inorganic mixed resins, etc.

The organic-inorganic mixed resin may be obtained by combining an organic resin and an inorganic polymer (for example, silica, alumina, titania, zirconia, etc.) obtained by a sol-gel reaction. Among these, a norbornene (or cycloolefin-based) resin called ARTON® (manufactured by JSR) or APEL® (manufactured by Mitsui Chemicals) is particularly preferable.

Generally, the plastic substrates produced have high moisture permeability. In addition, there are occasions when the substrate contains moisture. Therefore, when using such a plastic substrate, it is preferable to provide a film (hereinafter referred to as a "barrier film" or a "water vapor sealing film") to prevent the intrusion of water vapor or oxygen on the resin film.

The material constituting the barrier film is not particularly limited, and a coating of an inorganic substance or an organic substance or a mixture of the two is used. The coating may be formed, and the water vapor transmission rate measured according to the method of JIS K 7129-1992 is 0.01 g / (m ² ‧ 24 h) or less at (25 ± 0.5 ° C, relative humidity (90 ± 2)% RH). A barrier film is preferred, and the oxygen transmission rate measured by the method according to JIS K 7126-1987 is 1 × 10 ^-3 mL / (m ² ‧24h‧atm) or less, and the water vapor transmission rate is 1 × 10 ^-5 High barrier film with g / (m ² ‧24h) is preferred.

The material constituting the barrier film is not particularly limited as long as it has a function of suppressing the intrusion of elements that cause deterioration of the device such as moisture or oxygen, and for example, inorganic materials such as metal oxides, metal oxynitrides, or metal nitrides, Organic matter or a mixture of both.

Examples of the metal oxide, metal oxynitride, or metal nitride include silicon oxide, titanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), metal oxides such as aluminum oxide, and metal nitrides such as silicon nitride. , Silicon oxynitride, titanium oxynitride and other metal oxynitrides.

Furthermore, in order to improve the fragility of the film, a laminated structure having a layer composed of these inorganic layers and organic materials is more preferable. There is no particular limitation on the lamination order of the inorganic layer and the organic layer, and it is preferable that the two layers are alternately laminated multiple times.

The barrier film is a barrier film having a water vapor transmission rate of 0.01 g / (m ² ‧ 24 h) or less at (25 ± 0.5 ° C, relative humidity (90 ± 2)% RH) measured in accordance with JIS K 7129-1992. Preferably, the oxygen transmission rate measured by the method according to JIS K 7126-1987 is 10 ^-3 mL / (m ² ‧24h‧atm) or less, and the water vapor transmission rate is 10 ^-5 g / (m ² ‧24h) The following high barrier films are preferred.

The method for forming the barrier film on the aforementioned resin film is not particularly limited, and any method may be used. For example, a vacuum evaporation method, a sputtering method, a reactive sputtering method, a molecular beam epitaxial growth method, a cluster ion beam method, and an ion can be used. Planting method, plasma polymerization method, atmospheric piezoelectric plasma polymerization method, CVD method (chemical vapor deposition: plasma CVD method, laser CVD method, thermal CVD method, etc.), coating method, sol-gel method, and the like. Among them, from the viewpoint that a dense film can be formed, a method using plasma CVD treatment at atmospheric pressure or near atmospheric pressure is preferred.

Examples of the opaque substrate include metal plates such as aluminum and stainless steel, films, opaque resin substrates, and ceramic substrates.

(Anode)

As the anode of the organic electroluminescence element, a metal, an alloy, or an electrically conductive compound of a metal having a large work function (more than 4 eV), or a mixture of these is preferably used as the electrode substance. Here, the "electrically conductive compound of a metal" refers to a person having electrical conductivity among compounds of a metal and other substances, and specifically a person having electrical conductivity, such as an oxide or a halide of a metal.

Specific examples of such an electrode substance include metals such as gold, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO ₂ , and ZnO. The anode can be formed by forming a thin film made of these electrode materials on the substrate by a known method such as evaporation or sputtering.

In addition, a pattern of a desired shape may be formed on the thin film by a photolithography method. In addition, when it is not necessary to pay attention to the accuracy of the pattern (about 100 μm or more), it is necessary to transmit the desired content during the aforementioned electrode substance contention or sputtering. The shaped mask may be patterned.

When light is taken out from the anode, the transmittance is preferably greater than 10%. In addition, the sheet resistance as the anode is preferably several hundreds Ω / sq. Or less. Furthermore, the film thickness of the anode is usually selected from the range of 10 nm to 1 μm, and preferably from 10 nm to 200 nm, depending on the constituent materials.

(Organic function layer)

Organic functional layers (also known as "organic electroluminescent layers" and "organic compound layers") include at least a light-emitting layer. The so-called light-emitting layer, in a broad sense, refers to the light emitted when an electric current is passed to an electrode composed of a cathode and an anode. The layer refers specifically to a layer containing an organic compound that emits light when an electric current is passed to an electrode composed of a cathode and an anode.

The organic electroluminescence element used in the present invention may have a positive hole injection layer, an electron injection layer, a positive hole transport layer, and an electron transport layer in addition to the light emitting layer as required. These layers are supported by a cathode and an anode. Of the structure.

Specifically, you can give

(i) Anode / Light-emitting layer / Cathode

(ii) Anode / positive hole injection layer / light emitting layer / cathode

(iii) Anode / emitting layer / electron injection layer / cathode

(iv) Anode / positive hole injection layer / light emitting layer / electron injection layer / cathode

(v) Anode / positive hole injection layer / positive hole transport layer / light emitting layer / electron transport layer / ’electron injection layer / cathode

(vi) Anode / Positive hole transport layer / Light emitting layer / Electron transport layer / Cathode

And so on.

Furthermore, a cathode buffer layer (for example, lithium fluoride, etc.) may be inserted between the electron injection layer and the cathode, and an anode buffer layer (for example, copper phthalocyanine) may be inserted between the anode and the positive hole injection layer. Etc.) also.

(Light emitting layer)

The light-emitting layer according to the present invention is a layer that emits light by combining electrons and positive holes injected from an electrode or an electron-transporting layer and a positive-electron-transporting layer. The light-emitting portion may be in the layer of the light-emitting layer or It is the interface between the light-emitting layer and the adjacent layer. The light-emitting layer may be a layer having a single composition or a laminated structure composed of a plurality of layers having the same or different compositions.

The light emitting layer itself may be provided with functions such as a positive hole injection layer, an electron injection layer, a positive hole transport layer, and an electron transport layer. That is, at least one of the following functions can be imparted to the light-emitting layer: (1) When an electric field is applied, the positive hole can be injected through the anode or the positive hole injection layer, and the electron injection function can be injected through the cathode or the electron injection layer. (2) Conveyor function to move the injected charge (electrons and positive holes) by the force of an electric field, (3) Provide a place where electrons and positive holes are recombined in the light-emitting layer, and connect this to the light-emitting function . In addition, the light-emitting layer may be different in the ease of injection of the positive holes and the ease of injection of electrons. In addition, there may be a difference in size of the conveyor function represented by the movement of the positive holes and the electrons. It is better to have at least the function of moving one of the charges.

The type of the light-emitting material used in this light-emitting layer is not particularly limited, and a conventionally known material used as a light-emitting material for an organic electroluminescence element may be used. Such a light-emitting material is mainly an organic compound, and according to a desired color tone, for example, the compounds described in Macromol. Symp. 125 巻 17 to 26 can be mentioned. In addition, the light-emitting material may be a polymer material such as p-poly (p-phenylene vinylene) or polyfluorene (polyfluorene). Furthermore, a polymer material in which the light-emitting material is introduced into a side chain or a material in which the light-emitting material is used as a polymer may be used. Polymer material of main chain. In addition, as mentioned above, in addition to the light emitting performance, the light emitting material can also have a positive hole injection function or an electron injection function, so almost all of the positive hole injection material or the electron injection material described below can also be used as a light emitting material. .

In the layer constituting the organic electroluminescence element, when the layer is composed of two or more organic compounds, the main component is the host, and the other components are called dopants. In the light-emitting layer of this patent, the host and the In the case of a dopant, the mixing ratio of the dopant (hereinafter also referred to as a light-emitting dopant) of the light-emitting layer of the host compound as the main component is preferably 0.1% by mass to less than 30% by mass.

The dopants used in the light-emitting layer are roughly classified into two types: a fluorescent dopant that emits fluorescence and a phosphorescent dopant that emits phosphorescence.

Typical examples of the fluorescent dopant include coumarin-based pigments, pyran-based pigments, cyanine-based pigments, croconium pigments, and squarylium-based pigments. , Oxo-benz-anthracene pigment, fluorescein pigment, rhodamine pigment, pyrylium pigment, perylene pigment, stilbene Based pigments, polythiophene based pigments, rare earth based complex phosphors, other conventional fluorescent compounds, and the like.

In the present invention, it is preferable that at least one light-emitting layer contains a phosphorescent compound.

In the present invention, a phosphorescent compound is a compound in which light emission from an excited triplet is observed, and a compound having a phosphorescence quantum yield of 25 ° C or more is 0.001 or more. The phosphorescent quantum yield is preferably 0.01 or more, and even more preferably 0.1 or more. The above-mentioned phosphorescent quantum yield can be measured by a method described in the fourth edition of Experimental Chemistry Lecture 7, Division II, page 398 (1992 edition, published by Maruzen). The phosphorescent quantum yield in solution can be measured using various solvents. For the phosphorescent compound used in the present invention, any one of the solvents may be used as long as the phosphorescent quantum yield is achieved.

The phosphorescent dopant is a phosphorescent compound. As a representative example, it is preferably a complex compound containing metals of groups 8 to 10 on the periodic table, and more preferably an iridium compound, a rhenium compound, a rhodium compound, or a palladium compound. Or a platinum compound (platinum complex compound), among which an iridium compound, a rhodium compound, and a platinum compound are preferable, and an iridium compound is most preferable.

Examples of the dopant include compounds described in the following literatures or patent publications. J.Am.Chem.Soc.123 Vol. 4304 ~ 4312, International Publication No. 2000/70655, International Publication No. 2001/93642, International Publication No. 2002/02714, International Publication No. 2002/15645 International Publication No. 2002/44189, International Publication No. 2002/081488, Japanese Patent Application Publication No. 2002-280178, Japanese Patent Application Publication No. 2001-181616, Japanese Patent Application Publication No. 2002-280179, Japanese Patent Application Publication No. 2002-280179 2001-181617, JP 2002-280180, JP 2001-247859, JP 2002-299060, JP 2001-313178, JP 2002-302671, JP 2001- Gazette No. 345183, Gazette No. 2002-324679, Gazette No. 2002-332291, Gazette No. 2002-50484, Gazette No. 2002-332292, Gazette No. 2002-83684, Gazette No. 2002-540572 Gazette, JP 2002-117978, JP 2002-338588, JP 2002-170684, JP 2002-352960, JP 2002-50483, JP 2002-100476, JP 2002-173674, JP 2002-359082, JP 2002-175884, JP 2002-363552, JP 2002-184582, JP 2003-7469, JP 2002-525808, JP 2003-7471, JP 2002-525833, JP 2003 -31366, JP 2002-226495, JP 2002-234894, JP 2002-235076, JP 2002-241751, JP 2001-319779, JP 2001-319780 Publication No. 2002-62824, Publication No. 2002-100474, Publication No. 2002-203679, Publication No. 2002-343572, Publication No. 2002-203678, and the like.

Specific examples of the phosphorescent dopant are given below, but the present invention is not limited thereto.

Only one kind of the light-emitting dopant may be used, or plural kinds may be used. By simultaneously taking out light emission from these dopants, a light-emitting element having a plurality of emission maximum wavelengths can be constituted. In addition, for example, both a phosphorescent dopant and a fluorescent dopant may be added. When a plurality of light-emitting layers are stacked to constitute an organic electroluminescent device, the light-emitting dopants contained in the respective layers may be the same or different, and may be a single type or a plurality of types.

Furthermore, a polymer material may be used in which the light-emitting dopant is introduced into a polymer chain or the light-emitting dopant is used as a main chain of the polymer.

Examples of the host compound include carbazole derivatives, triarylamine derivatives, aromatic borane derivatives, nitrogen-containing heterocyclic compounds, thiophene derivatives, furan derivatives, and oligomers. Examples of those having a basic skeleton such as an arylene compound, an electron transporting material and a positive hole transporting material described later can be cited as corresponding examples. The blue or white light-emitting element is suitable for display devices and lighting devices. The maximum fluorescence wavelength of the host compound is preferably 415 nm or less. When a phosphorescent dopant is used, 0-0 of the phosphorescence of the host compound can be substituted. Below 450 nm is even better. As a light-emitting host, a compound having a positive hole transporting energy and an electron transporting energy, and preventing a long wavelength of light emission, and a compound having a high Tg (glass transition temperature) is preferable.

As specific examples of the light-emitting host, for example, compounds described in the following documents are suitable.

Japanese Patent Laid-Open No. 2001-257076, Japanese Patent Laid-Open No. 2002-308855, Japanese Patent Laid-Open No. 2001-313179, Japanese Patent Laid-Open No. 2002-319491, Japanese Patent Laid-Open No. 2001-357977, Japanese Patent Laid-Open No. 2002-334786, JP 2002-8860, JP 2002-334787, JP 2002-15871, JP 2002-334788, JP 2002-43056, JP 2002-334789, JP 2002 -75645, Japanese Patent Laid-Open No. 2002-338579, Japanese Patent Laid-Open No. 2002-105445, Japanese Patent Laid-Open No. 2002-343568, Japanese Patent Laid-Open No. 2002-141173, Japanese Patent Laid-Open No. 2002-352957, Japanese Patent Laid-Open No. 2002-203683 Publication No. 2002-363227, Publication No. 2002-231453, Publication No. 2003-3165, Publication No. 2002-234888, Publication No. 2003-27048, Publication No. 2002-255934 JP-A-2002-260861, JP-A-2002-280183, JP-A-2002-299060, JP-A-2002-302516, JP-A-2002-305083, JP-A-2002-305084, Publication No. 2002-308837 and the like.

The light-emitting dopant may be dispersed throughout the layer containing the host compound, or may be partially dispersed. A compound having another function may be further added to the light emitting layer.

The light-emitting layer can be formed by thinning the material using a conventional method such as a vapor deposition method, a spin coating method, a throwing method, an LB method, an inkjet transfer method, or a printing method. Molecular stacking films are preferred. Here, the molecular deposition film is a thin film formed by vapor deposition of the compound, or a film formed by solidifying a molten state or a liquid state of the compound. Generally, this molecular deposition film and the thin film (molecular accumulation film) formed by the LB method can be distinguished by a difference in agglutination structure, high-dimensional structure, or a function due to this.

In the present invention, the phosphorescent dopant and the host compound of the light-emitting material are preferably used as the organic compound of the present invention. That is, the light-emitting layer is formed by applying a solution containing the phosphorescent dopant and the host compound and an organic solvent by spin coating or the like, but it is preferable to form a light-emitting layer composed of a molecular volume film. Next, in the coating liquid containing the phosphorescent dopant, the host compound, and the organic solvent, the dissolved carbon dioxide concentration of the organic solvent at 50 ° C. or lower and atmospheric pressure is 1 ppm or more and the organic solvent is saturated. The concentration is preferably below.

As a means for making the dissolved carbon dioxide concentration fall into the aforementioned range, as described above, a method of foaming carbon dioxide in a solution containing a phosphorescent dopant and a host compound and an organic solvent, or using an organic solvent and carbon dioxide may be used. Chromatographic separation of supercritical fluids.

(Positive hole injection layer and positive hole transport layer)

The positive hole injection material used for the positive hole injection layer is any one having positive hole injection and electron barrier properties. In addition, the positive hole transporting material used for the positive hole transporting layer has an electronic barrier property and simultaneously transports the positive hole to the light emitting layer. That is, in the present invention, the positive hole transport layer is included in the positive hole injection layer. These positive hole injection materials and positive hole transport materials can be organic or inorganic. Specific examples include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, and pyrazolone derivatives. , Phenylenediamine derivative, arylamine derivative, amine substituted chalcone derivative, oxazole derivative, styryl anthracene derivative, fluorenone derivative , Hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline copolymers, porphyrin compounds, thiophene oligomers and other conductive polymers Thing. Among these, arylamine derivatives and porphyrin compounds are preferred. Among the arylamine derivatives, an aromatic tertiary amine compound and a styrylamine compound are preferable, and an aromatic tertiary amine compound is more preferable.

Examples of the aromatic tertiary amine compound and styrylamine (styrylamine) representative examples of the compound include N, N, N ', N ' - tetraphenyl-4,4 '- benzene diamine; N, N '- diphenyl -N, N' -bis (3- methylphenyl) - [1,1 '- biphenyl] -4,4' - diamine (TPD); 2,2- bis (4- two -p- tolyl-aminophenyl) propane; 1,1-bis (4-aminophenyl -p- tolyl) cyclohexane; N, N, N ', N' - four -p- p-4,4 '- diamino biphenyl; 1,1-bis (4-aminophenyl -p- tolyl) -4-phenyl cyclohexane; bis (4-dimethylamino 2-methylphenyl) phenyl methane; bis (4-phenyl -p- tolyl-aminophenyl methane); N, N '- diphenyl -N, N' - bis (4-methoxy ) -4,4 '- diamino biphenyl; N, N, N', N '- tetraphenyl-4,4' - diaminodiphenyl ether; 4,4 '- bis (diphenylphosphino Amino) biphenyl; N, N, N-tris (p-p-tolyl) amine; 4- (di-p-p-tolylamino) -4 ' -[4- (di-p-p-tolylamino) styryl] stilbene; 4-N, N- diphenylamino - (2-phenylethenyl) benzene; 3-methoxy--4 '-N, N- diphenylamino stilbene ; N-phenylcarbazole, further including U.S. Patent No. 5 in the molecule Specification No. 061,569 were two fused aromatic rings disclosed in, for example, 4,4 '- bis [N- (1- naphthyl) -N- phenylamino] biphenyl (hereinafter abbreviated as α-NPD), Japan The triphenylamine unit described in Japanese Patent Application Laid-Open No. 4-308688 is linked to three star-shaped 4,4 ' , 4 " -tris [N- (3-methylphenyl) -N-phenylamino] Triphenylamine (MTDATA), etc. In addition, p-type Si, p-type SiC and other inorganic compounds can also be used as a positive hole injection material.

In addition, in the present invention, the positive hole transporting material of the positive hole transporting layer preferably has a fluorescence maximum wavelength below 415 nm. That is, the positive-electrode-transporting material is preferably a compound having a high Tg, which has positive-electron-transporting energy and prevents emission of a long wavelength.

The positive hole injection layer and the positive hole transport layer can inject the aforementioned positive hole injection material and the positive hole transport material by, for example, a vacuum evaporation method, a spin coating method, a throw method, an LB method, an inkjet method, A conventional method such as a printing method or a printing method is used to form a thin film.

In addition, in the present invention, it is preferable to use the aforementioned positive hole injection material or positive hole transport material as the organic compound of the present invention. That is, it is preferable to form a positive hole transport layer (or positive hole injection layer) by applying a solution containing the positive hole transport material (or positive hole injection material) and an organic solvent by spin coating or the like. In the coating solution containing the positive hole transport material (or positive hole injection material) and the organic solvent, the dissolved carbon dioxide concentration of the organic solvent under the conditions of 50 ° C. and atmospheric pressure is 1 ppm or more and the The saturation concentration of the solvent is preferably below.

As a means of making the dissolved carbon dioxide concentration fall into the aforementioned range, as described above, a method of foaming carbon dioxide with a solution containing a positive pore transport material and an organic solvent, or using a supercritical solution containing an organic solvent and carbon dioxide can be mentioned. Separation of fluids by supercritical fluid chromatography.

The thickness of the positive hole injection layer and the positive hole transport layer is not particularly limited, but is usually about 5 nm to 5 μm. In addition, the positive hole injection layer and the positive hole transport layer may have a one-layer structure composed of one or two or more of the foregoing materials, and may also be laminated with a plurality of layers of the same composition or different compositions. structure. When both the positive hole injection layer and the positive hole transport layer are provided, different materials are usually used among the foregoing materials, but the same material may be used.

(Electron injection layer and electron transport layer)

The electron injection layer is only required to have a function of transmitting electrons injected from the cathode to the light-emitting layer, and its material can be arbitrarily selected and used from among conventionally known compounds. Examples of the material used for this electron injection layer (hereinafter also referred to as an electron injection material) include a nitro-substituted fluorenone derivative, a diphenylquinone derivative, and a thiopyran dioxide. Derivatives, heterocyclic tetracarboxylic anhydrides such as naphthalene perylene, carbodiimide, sulfenylmethane derivatives, anthraquinone dimethane and anthrone derivatives, oxodiazepines (oxadiazole) derivatives and the like.

In particular, a series of electron-transmitting compounds described in Japanese Patent Application Laid-Open No. 59-194393 was disclosed in this publication as a material for forming a light-emitting layer. However, as a result of a review by the inventors of the present case, it was found that they can be injected as electrons Use of materials. Furthermore, in the oxadiazole derivative, a thiadiazole derivative in which an oxygen atom of an oxadiazole ring is replaced by a sulfur atom, and a quinoxaline known as an electron attracting group A cyclic quinoxaline derivative can also be used as an electron injection material.

In addition, metal complexes of 8-hydroxyquinoline derivatives, such as tris (8-hydroxyquinoline) aluminum (abbreviated as Alq3), tris (5,7-dichloro-8-hydroxyquinoline) aluminum, tris ( 5,7-dibromo-8-hydroxyquinoline) aluminum, tris (2-methyl-8-hydroxyquinoline) aluminum, tris (5-methyl-8-hydroxyquinoline) aluminum, bis (8-hydroxyl Quinoline) zinc (Znq), etc., and metal complexes in which the center metal of these metal complexes is replaced with In, Mg, Cu, Ca, Sn, Ga, or Pb can also be used as an electron injection material.

Others, such as metal-free or metal phthalocyanine, or those in which the terminal is replaced with an alkyl group or a sulfonic acid group, can be suitably used as an electron injection material. In addition, similar to the positive hole injection layer, inorganic compounds such as n-type Si and n-type SiC can also be used as electron injection materials.

The preferred compound used in the electron transporting layer is preferably a fluorescent maximum wavelength below 415 nm. That is, the compound used for the electron transporting layer is preferably a compound having a high Tg, which has electron transporting energy and prevents long wavelength emission.

The electron injection layer can be formed by thinning the electron injection material by a conventional method such as a vacuum evaporation method, a spin coating method, a throw method, an LB method, an inkjet method, a transfer method, or a printing method.

In addition, in the present invention, the aforementioned electron injection material is preferably used as the organic compound of the present invention. That is, it is preferable to form a solution containing the electron injecting material and an organic solvent by spin coating or the like to form an electron injecting layer. The coating solution containing the electron injecting material and an organic solvent is preferably 50 ° C or lower. The dissolved carbon dioxide concentration of the organic solvent under atmospheric pressure is preferably 1 ppm or more and less than the saturated concentration of the organic solvent.

As the means for adjusting the dissolved carbon dioxide concentration to the aforementioned range, as described above, a method of foaming carbon dioxide with a solution containing an electron injection material and an organic solvent, or a method using a supercritical fluid containing an organic solvent and carbon dioxide can be mentioned. Supercritical fluid chromatography.

In addition, the thickness of the electron injection layer is not particularly limited, and it is usually selected within a range of 5 nm to 5 μm. The electron injection layer may have a single-layer structure composed of one or two or more of these electron-injection materials, or may be a multilayer structure composed of several layers of the same composition or different compositions.

Further, in the benzene specification, when the ionization energy is larger than the light emitting layer among the electron injection layers, it is particularly referred to as an electron transport layer. That is, in the present invention, the electron transport layer is included in the electron injection layer.

The electron transport layer is also referred to as a hole-block layer, and examples thereof include International Publication No. 2000/70655, Japanese Patent Application Laid-Open No. 2001-313178, and Japanese Patent Application Laid-Open No. 11-204258. Japanese Patent Application Publication No. 11-204359, and page 237 of "The Organic EL Element and Its Industrialization Frontline (issued by NTS Corporation on November 30, 1998)". In particular, a so-called "phosphorescent light-emitting element" using a Directed ortho metalation (DoM) complex-based dopant for the light-emitting layer is used to have an electron transporting layer (positive hole preventing layer) as described in (v) and (vi). ).

(buffer layer)

A buffer layer (electrode interface layer) may be present between the anode and the light emitting layer or the positive hole injection layer, and between the cathode and the light emitting layer or the electron injection layer. The buffer layer refers to a layer provided between an electrode and an organic layer in order to reduce a driving voltage or improve luminous efficiency, and is described in detail in the second part of "the front line of organic EL elements and their industrialization (issued by NTS on November 30, 1998)" Chapter 2 "Electrode Materials" (pages 123 ~ 166) has an anode buffer layer and a cathode buffer layer.

The anode buffer layer is also described in detail in Japanese Patent Application Laid-Open No. 9-45479, Japanese Patent Application Laid-Open No. 9-260062, and Japanese Patent Application Laid-Open No. 8-288069. Specific examples include phthalocyanine buffer layers represented by copper phthalocyanine. , Oxide buffer layers represented by vanadium oxide, amorphous carbon buffer layers, polymer buffer layers using conductive polymers such as polyaniline (emeraldine) or polythiophene, and the like.

The cathode buffer layer is also described in detail in Japanese Unexamined Patent Publication No. 6-325871, Japanese Unexamined Patent Publication No. 9-17574, and Japanese Unexamined Patent Publication No. 10-74586. Specific examples include metal buffers represented by strontium or aluminum. Layer, an alkali metal compound buffer layer represented by lithium fluoride, a soil picking metal compound buffer layer represented by magnesium fluoride, an oxide buffer layer represented by alumina, and the like.

The buffer layer is preferably an extremely thin film, and its thickness is preferably in the range of 0.1 to 100 nm depending on the material. Furthermore, in addition to the basic constituent layers described above, layers having other functions may be appropriately laminated as necessary.

(Cathode)

As described above, as a cathode of an organic electroluminescence element, a metal (hereinafter, referred to as an electron injecting metal), an alloy, an electrically conductive compound of a metal, or a mixture of these is used as an electrode, which has a small work function (less than 4 eV). Substance use.

Specific examples of such electrode materials include sodium, magnesium, lithium, aluminum, indium, rare earth metals, sodium-potassium alloys, magnesium / copper mixtures, magnesium / silver mixtures, magnesium / aluminum mixtures, and magnesium / indium mixtures. , Aluminum / alumina (Al ₂ O ₃ ) mixture, lithium / aluminum mixture, and the like.

In the present invention, it is also possible to use the above-mentioned enumerated substances as the electrode material of the cathode. From the viewpoint that the effect of the benzene invention can be more effectively exhibited, the cathode preferably contains a Group 13 metal element. That is, in the present invention, as described later, by oxidizing the surface of the cathode with a plasma-like oxygen gas, an oxide film is formed on the surface of the cathode to prevent more oxidation of the cathode, thereby improving the durability of the cathode.

That is, as the electrode material of the cathode, a metal having a preferable electron injecting property required by the cathode and a metal having a dense oxide film is preferred.

Specific examples of the electrode material of the cathode containing the Group 13 metal element include aluminum, indium, a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / alumina (Al ₂ O ₃ ) mixture, and lithium. / Aluminum mixture and so on. In addition, the mixing ratio of the components of the mixture may be a conventionally known ratio as the cathode of the organic electroluminescence element, and is not particularly limited. The cathode can be produced by forming a thin film of the electrode substance on the organic compound layer (organic electroluminescent layer) by a method such as evaporation or sputtering.

In addition, the sheet resistance as the cathode is several hundred Ω / sq. The following is preferred, and the film thickness is usually 10 nm to 1 μm, and preferably selected in the range of 50 to 200 nm. In addition, in order to transmit the light-emitting light, if either the anode or the cathode of the organic electroluminescence element is transparent or translucent, the luminous efficiency is improved and it is preferable.

A suitable example of producing a display device including an organic electroluminescence element produced using the coating liquid (organic electroluminescent material) of the present invention will be described below.

[Manufacturing method of organic EL element]

As an example of a method for manufacturing an organic electroluminescent device of the present invention, an organic electroluminescent device composed of an anode / positive hole injection layer / positive hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode will be described. Its production method.

First, a desired electrode substance, such as a thin film made of an anode substance, is formed on a suitable substrate by a method such as vapor deposition or sputtering so as to have a thickness of 1 μm or less, preferably 10 to 200 nm. While making the anode. Secondly, an organic compound film of a positive hole injection layer, a positive hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a positive hole prevention layer of the element material is formed thereon.

As a method for forming a thin film of these organic compound films, as described above, there are a spin coating method, a throwing method, an inkjet method, a vapor deposition method, and a printing method. However, a homogeneous film is easily obtained and pinholes are not easily generated. From a viewpoint, a vacuum vapor deposition method or a spin coating method is preferred. In the present invention, since the coating solution of the present invention can be used, a spin coating method is particularly preferred.

In addition, different film formation methods may be used for each layer. When the vapor deposition method is used for film formation, the vapor deposition conditions vary depending on the type of compound used, etc. Generally, the heating temperature in the boat is 50 to 450 degrees, the vacuum degree is 10 ^-6 to 10 ^-2 Pa, and the evaporation speed is 0.01 to A range of 50 nm / second, a substrate temperature of -50 to 300 ° C, and a thickness of 0.1 nm to 5 µm is appropriately selected.

After forming these layers, a thin film made of a material for a cathode is formed thereon by a method such as vapor deposition or sputtering so that the thickness is 1 μm or less, preferably 50 to 200 nm thick, and The desired organic electroluminescence element is obtained. The production of this organic electroluminescence device is preferably performed by consistently vacuuming the positive electrode hole injection layer to the cathode in one vacuum, and it does not matter if it is taken out in the middle and applied a different film formation method. In this case, it is necessary to consider that the operation is performed in a dry inert gas atmosphere.

[Sealing of organic electroluminescence element]

The sealing method of the organic electroluminescence element is not particularly limited. For example, after sealing the outer peripheral portion of the organic electroluminescence element with a sealing adhesive, the sealing member is disposed so as to cover the light emitting area of the organic electroluminescence element. method.

Examples of the adhesive for sealing include photocurable and thermosetting adhesives having reactive vinyl groups such as acrylic oligomers and methacrylic oligomers, and moisture curing types such as 2-cyanoacrylate. Wait for the adhesive. In addition, thermal and chemical curing types (two-liquid mixing) of epoxy systems and the like can be mentioned. In addition, examples include hot-melt polyamides, polyesters, and polyolefins. In addition, a cation-curing ultraviolet curing epoxy resin adhesive can be mentioned.

As the sealing member, a polymer film and a metal film can be preferably used from the viewpoint that the organic electroluminescence element can be thinned.

In addition to the sealing adhesive, an inert gas such as nitrogen or argon or an inert liquid such as fluorinated hydrocarbon or silicone oil can be injected into the gap between the sealing member and the light-emitting area of the organic electroluminescence element. In addition, the gap between the sealing member and the display area of the organic electroluminescence element may be vacuumed, or a hygroscopic compound may be sealed in the gap.

[Display device]

The multi-color display device using the organic electroluminescence element of the present invention is provided with a shadow mask only when the light-emitting layer is formed, and the other layers are common. Therefore, the patterning of the shadow mask and the like is not necessary. The film is formed by a plating method, a throw method, a spin coating method, an inkjet method, a printing method, or the like.

When only the light emitting layer is patterned, the method is not limited, and a vapor deposition method, an inkjet method, and a printing method are preferred. When a vapor deposition method is used, it is preferable to use a shadow mask for patterning.

In addition, it is also possible to make the cathode, the electron injection layer, the electron transport layer, the light emitting layer, the positive hole transport layer, the positive hole injection layer, and the anode in this order by reversing the manufacturing order.

In the multi-color display device obtained in this way, when a DC voltage is applied, the anode is + and the cathode is-polarity. When a voltage of about 2 to 40 V is applied, light emission can be observed. In addition, when a voltage is applied in the opposite polarity, no current flows, and no light is generated at all. Furthermore, when an AC voltage is applied, light is emitted only when the anode is + and the cathode is-. The waveform of the applied alternating current may be arbitrary.

The multi-color display device can be used as a display device, a display, or various light emitting sources. Display devices and displays can display full color by using three types of organic electroluminescence elements that emit red, blue, and green light.

Examples of the display device and the monitor include a television, a personal computer, a mobile device, an audio and video device, a text broadcast display, and an information display in a car. In particular, it can be used as a display device that reproduces still images or moving pictures. When used as a display device for moving picture reproduction, the driving method may be a simple matrix (passive matrix) method or an active matrix method.

Examples of the light source include home lighting, interior lighting, clock or LCD backlight, signage, traffic signals, light sources for optical memory media, light sources for electronic photocopying machines, light sources for optical communication processors, and light sensors. Light source, etc., but not limited to this.

The organic electroluminescence element according to the present invention may be used as an organic electroluminescence element having a resonator structure.

The purpose of using such an organic electroluminescence element with a resonator structure includes a light source of an optical memory medium, a light source of an electrophotographic copying machine, a light source of an optical communication processor, a light source of a light sensor, etc. Limited. In addition, by oscillating a laser, it can also be used for the said application.

The organic electroluminescence element of the present invention can also be used as a lamp for illumination or an exposure light source, as a projection device in the form of a projected image, or as a display device in the form of a direct visual confirmation of a still image or an animation image ( Monitor). When used as a display device for animation reproduction, the driving method may be a simple matrix (passive matrix) method or an active matrix method. Alternatively, a full-color display device can be manufactured by using two or more organic electroluminescence elements of the present invention having different emission colors.

An example of a display device including the organic electroluminescence element of the present invention will be described below with reference to the drawings.

FIG. 4 is a schematic diagram showing an example of a display device including an organic electroluminescence element. The display of image information is performed by light emission of an organic electroluminescence element, for example, a schematic diagram of a display of a mobile phone or the like. The display 41 is composed of a display unit A having a plurality of pixels, a control unit B that scans an image of the display unit A based on image information, and the like. The control unit B is conductively connected to the display unit A, and sends a scanning signal and an image data signal to the plurality of pixels from the outside according to the image information. The scanning signal causes the pixels of each scanning line to sequentially emit light according to the image data signals. Scan the image and display the image information on the display A.

FIG. 5 is a schematic diagram of the display section A. FIG. The display portion A includes a wiring portion including a plurality of scanning lines 55 and data lines 56 and a plurality of pixels 53 on a substrate. The main components of the display section A will be described below.

FIG. 5 shows a case where the light emitted by the pixel 53 is taken out in the direction of the white arrow (below). The scanning lines 55 and the plurality of data lines 56 of the wiring section are each made of a conductive material. The scanning lines 55 and the data lines 56 are orthogonal to each other in a grid pattern, and are connected to the pixels 53 at orthogonal positions (not shown in detail). The pixel 53 receives the image data signal from the data line 56 when a scanning signal is applied from the scanning line 55, and emits light in response to the received image data. The color of light emission can be achieved by placing the pixels of the red area, the pixels of the green area, and the pixels of the blue area on the same substrate side by side, as appropriate.

Next, a pixel light emission procedure will be described.

Fig. 6 is a schematic diagram of pixels. The pixel includes an organic electroluminescence element 60, a switching transistor 61, a driving transistor 62, a capacitor 63, and the like. In the case of a plurality of pixels, as the organic electroluminescence element 60, by using organic electroluminescence elements that emit red, green, and blue light, these can be placed side by side on the same substrate to perform full-color display.

In FIG. 6, an image data signal is applied from the control unit B (not shown in FIG. 6 and shown in FIG. 4) to the drain of the switching transistor 61 through the data line 56. Next, when the control unit B applies a scanning signal to the gate of the switching transistor 61 through the scanning line 55, the driving of the switching transistor 61 is turned ON, and the image data signal applied to the drain is transmitted to the capacitor 63 and The gate of the driving transistor 62.

By the transmission of the video data signal, the capacitor 63 is charged in response to the potential of the video data signal, and the driving of the driving transistor 62 is turned ON. The driving transistor 62 has a drain connected to a power line 67 and a source connected to an electrode of the organic electroluminescence element 60. In response to the potential of the image data signal applied to the gate, the power is transmitted from the power line 67 to the organic power source. The electroluminescent element 60 supplies a current.

By the sequential scanning of the control unit B, when the scanning signal is moved to the next scanning line 55, the driving of the switching transistor 61 is turned OFF. However, even if the driving of the switching transistor 61 is OFF, the capacitor 63 remains at the potential of the charged image data signal, so the driving of the driving transistor 62 remains ON until the next scanning signal is applied The light emission of the organic electroluminescent element 60 continues. By sequentially scanning and then applying a scanning signal, the driving transistor 62 is driven to cause the organic electroluminescence element 60 to emit light in response to the potential of the next image data signal synchronized with the scanning signal. That is, for the light emission of the organic electroluminescent element 60, for each organic electroluminescent element 60 of a plurality of pixels, a switching transistor 61 and a driving transistor 62 of an active element are provided to perform a plurality of pixels 53 (not shown in FIG. The figure shows the light emission of each organic electroluminescent element 60 in FIG. 5). Such a light emitting method is called an active matrix method.

Here, the light emission of the organic electroluminescence element 60 may be a light emission based on a complex tone of a multi-valued image data signal having a plurality of tone potentials, or a specific light emission amount based on a binary value of the image data signal ON / OFF.

In addition, the potential of the capacitor 63 may be maintained until the next scanning signal is applied, or it may be discharged before the next scanning signal is applied.

In the present invention, it is not limited to the aforementioned active matrix method, and only the passive matrix method of light emission driving in which the organic EL element emits light due to the data signal when the scanning signal is scanned may be used.

FIG. 7 is a schematic diagram of a display device according to a passive matrix method. In FIG. 7, a plurality of scanning lines 55 and a plurality of image data lines 56 face each other with the pixels 53 and are arranged in a grid shape. When the scanning signals of the applied scanning lines 55 are sequentially scanned, the pixels 53 connected to the applied scanning lines 55 emit light in response to the image data signals. In the passive matrix method, there is no active element in the pixel 53, which can reduce the manufacturing cost.

[Photoelectric conversion element and solar cell]

The photoelectric conversion element of the present invention is characterized by having an organic function layer formed using the coating solution. That is, the photoelectric conversion element of the present invention is characterized by having an organic functional layer derived from the coating liquid, in other words, having an organic functional layer formed by coating the coating liquid.

Hereinafter, details of the photoelectric conversion element and the solar cell will be described.

8 is a cross-sectional view showing an example of a solar cell having a single structure (a structure in which a bulk heterojunction layer has a single layer) composed of a bulk-heterojunction type organic photoelectric conversion element.

In FIG. 8, the bulk heterojunction type organic photoelectric conversion element 200 is sequentially laminated with a transparent electrode (anode) 202, a positive hole transport layer 207, and a bulk heterojunction layer on one side of the substrate 201. The photoelectric conversion unit 204, an electron transport layer (also referred to as a buffer layer) 208, and a counter electrode (cathode) 203.

The substrate 201 is a member that holds a transparent electrode 202, a photoelectric conversion unit 204, and a counter electrode 203 that are sequentially laminated. In this embodiment, the photoelectrically converted light is incident from the substrate 201 side, so the substrate 201 can transmit the photoelectrically converted light, that is, the member that is transparent for the wavelength of the light that should be photoelectrically converted is Better. The substrate 201 is, for example, a glass substrate or a resin substrate. This substrate 201 is not necessary. For example, by forming transparent electrodes 202 and counter electrodes 203 on both sides of the photoelectric conversion unit 204, a bulk heterojunction type organic photoelectric conversion element 200 may be formed.

The photoelectric conversion unit 204 is a layer that converts light energy into electric energy, and includes a bulk heterojunction layer that mixes a p-type semiconductor material and an n-type semiconductor material in the same manner. The p-type semiconductor material functions relatively as an electron donor (donor), and the n-type semiconductor material functions relatively as an electron acceptor (acceptor). Here, the electron donor and the electron acceptor are "the electron donor and the electron acceptor that when electrons move from the electron donor to the electron acceptor to form a pair (positive charge separation state) when the electrons are absorbed. The "body" is not a person who only supplies or accepts electrons like an electrode, but a person who supplies or accepts several electrons by photoreaction.

In FIG. 8, light incident through the substrate 201 through the transparent electrode 202 is absorbed by the electron acceptor or the electron donor of the bulk heterojunction layer of the photoelectric conversion unit 204, and the electrons move from the electron donor to the electron acceptor and are absorbed by the electron acceptor. A pair (positive charge separation state) of a positive hole and an electron is formed. When the electric field generated in the electrical part, for example, the working function of the transparent electrode 202 and the counter electrode 203 is different, the potential difference between the transparent electrode 202 and the counter electrode 203 allows electrons to pass between the electron acceptors, or positive electron holes pass through the electrons. Between the donors, the photocurrent is detected by being transported to different electrodes. For example, when the working function of the transparent electrode 202 is greater than the working function of the counter electrode 203, electrons are transferred to the transparent electrode 202, and positive holes are transferred to the counter electrode 203. In addition, if the magnitude of the work function is reversed, the electrons and the positive holes are transported in opposite directions. In addition, by applying a potential between the transparent electrode 202 and the counter electrode 203, the transport direction of the electrons and the positive hole can be controlled.

Although not shown in FIG. 8, other layers such as a positive hole blocking layer, an electron blocking layer, an electron injection layer, a positive hole injection layer, or a smoothing layer may be provided.

In addition, in order to further improve the utilization ratio of sunlight (photoelectric conversion efficiency), a tandem structure (a structure having a plurality of heterogeneous interface layers) of a photoelectric conversion element such as a laminate may be used.

FIG. 9 is a cross-sectional view showing a solar cell composed of an organic photoelectric conversion element including a tandem type bulk heterojunction layer. In the case of a tandem structure, a transparent electrode 202 and a first photoelectric conversion section 209 are sequentially laminated on the substrate 201, and then a charge recombination layer (intermediate electrode 205) is laminated, and then a second photoelectric conversion section is laminated. 205, and then the counter electrode 203 is laminated to form a tandem structure.

Examples of materials that can be used for the layers described above include, for example, n-type semiconductor materials and p-type semiconductor materials described in Japanese Patent Application Laid-Open No. 2015-149483, paragraphs 0045 to 0113.

(Formation method of block heterogeneous interface layer)

Examples of a method for forming a bulk heterojunction layer in which an electron acceptor and an electron donor are mixed include a vapor deposition method, a coating method (including a throwing method, and a spin coating method). Among them, in order to increase the area of the interface where the positive holes and the electrons separate the charges, a device having a high photoelectric conversion efficiency is preferably a coating method. In addition, the coating method is also superior in manufacturing speed.

In the present invention, the n-type semiconductor material and the p-type semiconductor material constituting the aforementioned bulk heterojunction layer can be used as the organic compound of the present invention. That is, it is better to form a bulk heterojunction layer by coating a solution containing the n-type semiconductor material and the p-type semiconductor material with an organic solvent, and including the n-type semiconductor material and the p-type semiconductor material with The coating solution of the organic solvent is preferably such that the dissolved carbon dioxide concentration of the organic solvent at 50 ° C. or lower and atmospheric pressure is 1 ppm or more and the saturated concentration of the organic solvent is less than or equal to the saturation concentration.

As a means for making the dissolved carbon dioxide concentration fall into the aforementioned range, as described above, a method of foaming carbon dioxide for a solution containing an n-type semiconductor material and a p-type semiconductor material, and an organic solvent, or using an organic solvent and Carbon dioxide supercritical fluid by supercritical fluid chromatography.

After the application, heating is preferably performed in order to cause the removal of residual solvents, moisture, and gases, and the crystallization of semiconductor materials to increase the mobility / long-wavelength absorption. In the manufacturing step, if the annealing treatment is performed at a specific temperature, the arrangement or crystallization of a part on the microscopic scale is promoted, and the bulk heterojunction layer can be made into a suitable phase separation structure. As a result, the carrier mobility of the bulk heterojunction layer is improved, and high efficiency can be obtained.

The photoelectric conversion section (block heterojunction layer) 204 can also be constituted by a single layer in which the electron acceptor and the electron donor are uniformly mixed, or it can be constituted by a plurality of layers that change the mixing ratio of the electron acceptor and the electron donor.

Next, the electrodes constituting the organic photoelectric conversion element will be described.

Organic photoelectric conversion elements are the positive and negative charges generated in the heterogeneous interface layer of the block, which are taken out by the transparent electrode and the counter electrode through the p-type organic semiconductor material and the n-type organic semiconductor material, respectively, and function as the battery. For each electrode, characteristics of a carrier suitable for passing through the electrode are required.

(Opposite)

In the present invention, the so-called counter electrode (cathode) is preferably an electrode for taking out electrons. For example, when it is used as a cathode, it may be a single layer of a conductive material, or a resin that retains these may be used in addition to a conductive material.

As the counter electrode material, for example, a conventional conductive material of a cathode described in JP-A-2010-272619, JP-A-2014-078742, and the like can be used.

As the counter electrode material, for example, a conventional conductive material of a cathode described in JP-A-2010-272619, JP-A-2014-078742, and the like can be used.

(Transparent electrode)

In the present invention, the transparent electrode is preferably an anode having a function of taking out a positive hole generated in the photoelectric conversion section. For example, when used as an anode, an electrode that transmits light having a wavelength of 380 to 800 nm is preferred. As the material, for example, conventional materials for anodes described in JP-A-2010-272619 and JP-A-2014-078742 can be used.

(Middle electrode)

In addition, in the case of a series configuration, the material of the intermediate electrode is preferably a layer using a compound having both transparency and conductivity.

As the material, for example, conventional materials for an intermediate electrode described in JP-A-2010-272619, JP-A-2014-078742, and the like can be used.

Next, materials other than the electrode and the bulk heterojunction layer are described.

(Positive hole transport layer and electron blocking layer)

In the organic photoelectric conversion element of the present invention, in order to more efficiently remove the charges generated in the bulk heterojunction layer, a positive hole transport layer / electron blocking layer is provided between the bulk heterojunction layer and the transparent electrode as Better.

As the material for the photoelectric conversion element constituting the positive hole transport layer, for example, conventional materials described in JP-A-2010-272619, JP-A-2014-078742, and the like can be used.

(Electron transport layer, positive hole blocking layer and buffer layer)

In the organic photoelectric conversion element of the present invention, by forming an electron transporting layer / positive hole blocking layer / buffering layer between the bulk heterojunction layer and the counter electrode, the charge generated in the bulk heterojunction layer can be made more It takes out efficiently, so it is better to have these layers.

In addition, as the electron transport layer, known materials described in, for example, Japanese Patent Application Laid-Open No. 2010-272619 and Japanese Patent Application Laid-Open No. 2014-078742 can be used. The electron transport layer has a rectifying effect that prevents the positive holes generated in the heterogeneous interface layer of the block from flowing to the opposite side, and can also be used as a positive hole blocking layer to which the positive hole blocking function is given. In order to be a material of the positive hole blocking layer, for example, a conventional material described in Japanese Patent Application Laid-Open No. 2014-078742 can be used.

(Other layers)

For the purpose of improving energy conversion efficiency or improving device life, a configuration having various intermediate layers in the device may be adopted. Examples of the intermediate layer include a positive hole blocking layer, an electron blocking layer, a positive hole injection layer, an electron injection layer, an exciton blocking layer, a UV absorbing layer, a light reflecting layer, and a wavelength conversion layer.

(Substrate)

When the light to be photoelectrically converted is incident from the substrate side, the substrate can transmit the light to be photoelectrically converted, that is, a member that is transparent to the wavelength of the light to be photoelectrically converted is preferable. As a substrate, a glass substrate, a resin substrate, etc. can be mentioned suitably, and it is preferable to use a transparent resin film from a viewpoint of lightweight and flexibility.

The transparent resin film which can be suitably used as a transparent substrate in the present invention is not particularly limited, and its material, shape, structure, thickness, and the like can be appropriately selected from conventional materials. For example, conventional materials described in JP 2010-272619, JP 2014-078742, and the like can be used.

(Optical Function Layer)

The organic photoelectric conversion element of the present invention may have various optical function layers for the purpose of receiving sunlight more efficiently. For the optical function layer, for example, a light-collecting layer such as an anti-reflection film, a microlens array, or a light-diffusing layer that allows the light reflected by the counter-electron to be incident again on the bulk heterojunction layer may be provided.

The anti-reflection layer, the light-collecting layer, and the light-scattering layer can be used, for example, in JP 2010-272619 and JP 2014-078742, respectively.

Conventional anti-reflection layers, light-collecting layers, and light-scattering layers described in publications and the like.

(Patterned)

There are no particular restrictions on the method or procedure for patterning the electrodes, power generation layer, positive hole transport layer, electron transport layer, etc. of the present invention. For example, Japanese Patent Application Laid-Open No. 2010-272619 and Japanese Patent Application Laid-Open No. 2014-078742 And other known practices.

(Sealed)

In addition, in order to prevent the produced organic photoelectric conversion element from being degraded by oxygen, moisture, and the like in the environment, it is preferable that not only the organic photoelectric conversion element but also the organic electroluminescence element and the like are sealed by a known method. For example, the techniques described in JP 2010-272619, JP 2014-078742, and the like can be used.

[Example]

Hereinafter, the present invention will be specifically described with examples, but the present invention is not limited to these. In the examples shown below, the so-called dry air is dry air produced by a dry air generating device (manufactured by Ikeda Rika Co., Ltd., AT35HS). The so-called air is an experiment set at 25 ° C and 1 atmosphere Under the indoor atmosphere, the so-called nitrogen atmosphere refers to the nitrogen atmosphere supplied by using a G1 nitrogen gas cylinder manufactured by Sun Solar.

The structures of the compounds used in the examples are shown below.

[Example 1]

Under a high-purity nitrogen atmosphere, a solution (s-1) of 5 g of CBP dissolved in 1 liter of p-toluene (Kanto Chemical Co., Ltd., dehydrated toluene) was prepared, and high-purity carbon dioxide gas (sun day Acid, high purity carbon dioxide (> 99.995 vol.%)) For 10 minutes, and then degassed solution s-5 for 10 minutes.

The amount of carbon dioxide contained in s-1 and s-5 was measured with a gas chromatography layer separator. Specifically, the column packing was measured by the absolute calibration curve method using Porapack Type S GC Bulk Packing Material (Mesh80-100) manufactured by Waters Corporation.

The water contents of s-1 and s-5 were measured by the Karl Fischer method. The respective results are shown in Table 1.

In addition, the same treatment was performed for each of the solvents shown in Table 1, and those who did not foam high-purity carbon dioxide gas (s-2 to s-4) and those who foamed (s-6) ~ s-8), the carbon dioxide content and water content of s-2 ~ s-4 and s-6 ~ s-8 were measured. The results are shown in Table 1.

The various solvents used are as follows.

Toluene (Kanto Chemical Co., Ltd., dehydrated toluene), isobutyl acetate (Kanto Chemical Co., Ltd., special isobutyl acetate), TFPO (Tokyo Chemical Industry Co., Ltd., 2, 2, 3, 3-tetrafluoro- 1-propanol).

From the results shown in Table 1, it was found that by mixing carbon dioxide with various solvents, the water content in various solvents can be reduced.

[Example 2]

After the s-1 to s-8 prepared in Example 1 were stored under the conditions shown in Table 2 for one hour, the dissolved oxygen concentration of each sample was measured with a gas chromatography. The respective results are shown in Table 2.

From the results shown in Table 2, it can be seen that the organic solvent containing carbon dioxide reduces the intake of oxygen when stored in dry air and the atmosphere.

[Example 3]

After patterning a substrate (NA45 manufactured by NH Technology) with a 100 nm ITO (indium tin oxide) film on a 100 mm × 100 mm × 1.1 mm glass substrate, a transparent support substrate provided with the ITO transparent electrode was used to Isopropanol was ultrasonically washed, dried with dry nitrogen, and UV ozone washed for 5 minutes. On this substrate, the s-4 produced in Example 1 was formed by an inkjet method (film thickness of about 40 nm), and the mass (w (0)) before the start of drying was measured. Then, the mass (w (t)) when drying at 60 ° C for t minutes and the mass (w (60)) when drying under vacuum for 1 hour were measured.

Using the mass (w (60)) of the substrate dried for 1 hour in vacuum, the mass (w (0)) before the start of drying, and (w (t)) at t minutes, use the following formula to determine the t minutes Dryness (Dry (101)).

Dry101 (t) = (1-((w (t) -w (60)) / (w (0) -w (60))) × 100

The same measurement was performed by replacing s-4 with another solution described in Table 3, and the results in Table 3 were obtained.

From the results shown in Table 3, it was found that when the solution of the present invention (ink for electronic device production) was foamed with carbon dioxide, the drying time of the ink was shortened.

[Example 4]

<Preparation of coating solution for positive hole transport layer (HT layer)>

In a glove box under a nitrogen atmosphere, a solution of 600 mg of polyvinylcarbazole (PVK) dissolved in 100 ml of chlorobenzene (solution s-10) was divided into two, and each of them was processed in the following manner, so that one was solution s- 11. The other party foamed carbon dioxide for 10 minutes as a solution s-12 in a glove box under a nitrogen atmosphere. The carbon dioxide concentration of the solution s-12 was measured by the method of Example 1, and it was confirmed that the carbon dioxide concentration was 200 ppm. Furthermore, the solution s-11 and the solution s-12 were respectively divided into three and processed in the following manner to obtain the solutions shown in Table 4.

Treatment 1: The solution s-11 was stored under a prepared nitrogen atmosphere for 30 minutes to obtain a solution s-111.

Treatment 2: The solution s-11 was stored in a dry air atmosphere for 30 minutes to obtain a solution s-112.

Treatment 3: The solution s-11 was stored in the air for 30 minutes to obtain a solution s-113.

Treatment 4: The solution s-12 was stored under a prepared nitrogen atmosphere for 30 minutes to obtain a solution s-121.

Treatment 5: The solution s-12 was stored in a dry air atmosphere for 30 minutes to obtain a solution s-122.

Treatment 6: The solution s-12 was stored in the atmosphere for 30 minutes to obtain a solution s-123.

<Preparation of coating liquid for light emitting layer (EM layer)>

In a glove box under a nitrogen atmosphere, a solution (solution s-20) of 600 mg of CBP and 30.0 mg of compound Ir-12 dissolved in 60 ml of toluene / isopropyl acetate (1/1) was divided into two, and each was processed in the following manner, One solution was solution s-21, and the other was foamed with carbon dioxide for 10 minutes in a glove box under a nitrogen atmosphere as solution s-22. The carbon dioxide concentration of the solution s-22 was measured by the method of Example 1, and it was confirmed that the carbon dioxide concentration was 250 ppm. Furthermore, the solution s-21 and the solution s-22 were respectively divided into three and processed in the following manner to obtain the solutions shown in Table 4.

Treatment 11: The solution s-21 was stored under a prepared nitrogen atmosphere for 30 minutes to obtain a solution s-211.

Treatment 12: The solution s-21 was stored in a dry air atmosphere for 30 minutes to obtain a solution s-212.

Treatment 13: The solution s-21 was stored in the atmosphere for 30 minutes to obtain a solution s-213.

Treatment 14: The solution s-22 was stored under the prepared nitrogen atmosphere for 30 minutes to obtain a solution s-221.

Treatment 15: The solution s-22 was stored in a dry air atmosphere for 30 minutes to obtain a solution s-222.

Treatment 16: The solution s-22 was stored in the atmosphere for 30 minutes to obtain a solution s-223.

<Coating liquid for electron transport layer (ET layer)>

In a glove box under a nitrogen atmosphere, a solution of 200 mg of bathhoproproine (BCP) dissolved in 60 ml of cyclohexane (solution s-30) was divided into two, and each of them was processed in the following manner, so that one was solution s-31. , The other party foamed carbon dioxide for 10 minutes as a solution s-32 in a glove box under a nitrogen atmosphere. The carbon dioxide concentration of the solution s-32 was measured by the method of Example 1, and it was confirmed that the carbon dioxide concentration was 180 ppm. Furthermore, the solution s-31 and the solution s-32 were divided into three, and the solution shown in Table 4 was obtained by the following method.

Treatment 21: The solution s-31 was stored under a prepared nitrogen atmosphere for 30 minutes to obtain a solution s-311.

Treatment 22: The solution s-31 was stored in a dry air atmosphere for 30 minutes to obtain a solution s-312.

Treatment 23: The solution s-31 was stored in the atmosphere for 30 minutes to obtain a solution s-313.

Treatment 24: The solution s-32 was stored under a prepared nitrogen atmosphere for 30 minutes to obtain a solution s-321.

Treatment 25: The solution s-32 was stored in a dry air atmosphere for 30 minutes to obtain a solution s-322.

Treatment 26: The solution s-32 was stored in the atmosphere for 30 minutes to obtain a solution s-323.

<Production of Organic EL Element>

After a 100 mm × 100 mm × 1.1 mm glass substrate was used as an anode to form a 100 nm ITO (Indium Tin Oxide) film (NA45 manufactured by NH Technology), the substrate was patterned, and the transparent support provided with this ITO transparent electrode was supported. The substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen, and subjected to UV ozone cleaning for 5 minutes. This substrate was mounted on a commercially available spin coater, and the solution s-111 (10 ml) was used for spin coating (layer thickness of about 40 nm) at 1000 rpm and 30 seconds, and dried under vacuum at 60 ° C for 1 hour as a positive hole. Conveying layer. Next, the solution s-211 (6 ml) was used for spin coating (layer thickness of about 40 nm) under conditions of 1000 rpm and 30 seconds, and vacuum-dried at 60 ° C. for 1 hour as a light-emitting layer. Further, solution s-311 (6 ml) was used for spin coating (layer thickness of about 10 nm) at 1000 rpm and 30 seconds, and vacuum drying was performed at 60 ° C. for 1 hour. An electron transporting layer was also provided, which also had the function of blocking positive pores.

Next, this substrate was fixed to a substrate holding gas of a vacuum evaporation device, 200 mg of Alq3 was added to a resistance heating boat made of molybdenum, and the substrate was installed in the vacuum evaporation device. After the vacuum chamber was depressurized to 4 × 10 ^-4 Pa, the heating boat in which Alq3 was placed was heated by heating, and was deposited on the electron transport layer at a deposition rate of 0.1 nm / sec, and electrons with a thickness of 40 nm were set. Injected layer. The substrate temperature during vapor deposition was room temperature.

Next, 0.5 nm of lithium fluoride and 110 nm of aluminum were deposited to form a cathode, and an organic electroluminescence device 1 was produced.

For the production of the organic electroluminescence element 1, a method similar to that of the organic electroluminescence element 1 was prepared except that the solution s-111, the solution s-211, and the solution s-311 were replaced with the solution shown in Table 4. Table 4 shows the organic electroluminescence element.

<Evaluation of organic electroluminescence elements>

The following evaluations were performed on the organic electroluminescence elements shown in Table 4 prepared as described above, and the results are shown in Table 4.

For the produced organic electroluminescence element, continuous lighting was performed under a temperature of 23 ° C. under a dry nitrogen atmosphere under the application of a DC voltage of 10 V, and the time from the luminous brightness at the start of lighting to the brightness halving (hereinafter referred to as the luminous life) ) And luminous efficiency (lm / W). The results are shown in Table 4. However, the light emission lifetime and the light emission efficiency are relative values in which the light emission lifetime and the light emission efficiency of the organic electroluminescent element 1 are 100, respectively. The light emission luminance was measured using CS-1000 manufactured by Konica Minolta.

From the results shown in Table 4, it can be seen that when the organic electroluminescence element using the coating solution containing carbon dioxide of the present invention is stored in dry air or the atmosphere, the luminous efficiency is compared with a coating solution containing no carbon dioxide under the same conditions. There is little deterioration in the evaluation results of the device life.

[Example 5]

<Refining of ink compounds>

CBP was fractionated under the following conditions using a supercritical fluid chromatographic separation system manufactured by JASCO Corporation.

Supercritical CO ₂ pump: SCF-Get

Fully automatic pressure regulating valve: SFC-Bpg

Tubular oven: GC-353B

Injector: 7125i

Column: C18-Silica, 3μm, 4.6mm × 250mm

Moving layer: carbon dioxide / toluene = 9/1

Moving layer flow: 3ml / min

Pressure: 18MPa

Temperature: 40 ° C

Detection: UV detector (210nm)

A toluene solution containing 10% by mass of CPB and 300 ppm of carbon dioxide was obtained under the aforementioned conditions. This solution is composition 1. Next, except that CBP was changed to Ir-14, Ir-1, and Ir-15, respectively, the same procedure was performed to obtain the following composition.

Composition 2: toluene solution containing 10% by mass of Ir-14 and 300 ppm of carbon dioxide

Composition 3: toluene solution containing 10% by mass of Ir-1 and 300 ppm of carbon dioxide

Composition 4: a toluene solution containing 10% by mass of Ir-15 and 300 ppm of carbon dioxide

Next, except that the moving layer was changed to carbon dioxide / TFPO = 9/1 and CBP was changed to BCP, the same procedure was performed to obtain a TFPO solution containing 10 mass percent of BCP and 300 ppm of carbon dioxide. This solution is composition 5.

<Adjustment of Ink>

(Positive hole injection layer composition)

PEDOT / PSS: poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (manufactured by Bayer, Baytron P A1 4083)

(Blue emitting layer composition)

(Green emitting layer composition)

(Red emitting layer composition)

(Composition of electron transport layer)

<Manufacture of organic electroluminescence full-color display device>

FIG. 10 is a schematic configuration diagram of an organic electroluminescence full-color display device. After a 100 nm ITO transparent electrode (102) was formed on a glass substrate 101 as a positive electrode, a substrate (NA45 manufactured by NH Technology) was patterned at a pitch of 100 μm, and then the glass substrate was photoetched between the ITO transparent electrodes. Method to form a non-photosensitive polyimide partition wall 103 (width 20 μm, thickness 2.0 μm). Between the polyimide partition walls on the ITO electrode, an inkjet head ("KM512L" manufactured by Konica Minolta) was used to eject and inject the composition of the positive hole injection layer having the aforementioned composition, and then dried by drying at 200 ° C for 10 minutes to produce A positive hole injection layer 104 having a layer thickness of 40 nm is provided. On the positive hole injection layer, the aforementioned blue light emitting layer composition, green light emitting layer composition, and red light emitting layer composition were also ejected and injected using an inkjet head to form respective light emitting layers (105B, 105G, 105R). Next, an electron-injecting layer composition is ejected in the same manner using an inkjet head, and an electron-transporting layer (106) also having a function of blocking positive holes is formed on each of the light-emitting layers 105. Finally, on the electron transport layer 106, aluminum (107) was vacuum-evaporated as a cathode to produce an organic electroluminescence element.

It can be seen that the produced organic electroluminescence element displays blue, green, and red luminescence by applying voltages to the respective electrodes, and can be used as a full-color display device.

[Example 6]

As the p-type material of the bulk heterojunction layer, a low-band gap polymer described in Macromolecules 2007, 40, 1981 was synthesized and used, as well as a reference to non-patent literature (Nature Mat. Vol. 6 (2007), p497). PCPDTBT. In addition, PCBM (purchased from Frontier Carbon) was used for the n-type material.

<Production of Organic Photoelectric Conversion Element 1>

The transparent conductive film was formed by patterning a transparent conductive film of indium tin oxide (ITO) with a thickness of 140 nm on a glass substrate using a common photo-etching technique and hydrochloric acid etching.

The patterned transparent electrodes are sequentially washed according to the ultrasonic waves of the surfactant and ultrapure water. After being washed according to the ultrasonic waves of ultrapure water, they are dried by blowing with nitrogen, and finally washed by ultraviolet ozone. On this transparent substrate, a conductive polymer of Baytron P4083 (manufactured by Starck V-tec) was spin-coated at a film thickness of 60 nm, and then heated and dried in the air at 140 ° C for 10 minutes.

After that, the substrate was brought into a glove box and operated in a nitrogen atmosphere. First, the substrate was heat-treated at 140 ° C for 10 minutes in a nitrogen atmosphere.

Chlorobenzene was prepared by foaming carbon dioxide gas for 10 minutes, and the concentration of dissolved carbon dioxide was measured by a gas chromatography layer separator, and the concentration was 350 ppm. PCPDTBT with 1.0% by mass of chlorobenzene as a p-type semiconductor material and 2.0% by mass of [6,6] -phenyl C61-butyric acid methyl ester (abbreviated as PCBM) (made by Frontier Carbon) as an n-type semiconductor material were produced. , NANOM SPECTRA E100H), and then dissolved 2.4% by mass of 1,8-octanethiol liquid, filtered through a 0.45 μm filter and spin-coated at 1200 rpm for 60 seconds, and dried at room temperature for 30 minutes to obtain photovoltaic Conversion section (block heterogeneous interface layer).

Next, the substrate forming the heterogeneous interface layer of the block is set in a vacuum evaporation device. The device was installed so that the shadow mask with a width of 2 mm was orthogonal to the transparent electrode. After depressurizing in a vacuum evaporation machine to 10 ^-3 Pa or less, lithium fluoride was deposited by 0.5 nm, and aluminum was deposited by 80 nm. Finally, heating was performed at 120 ° C. for 30 minutes to obtain an organic photoelectric conversion element 1. In addition, the vapor deposition rate was 2 nm / second, and the size was a square of 2 mm. The obtained organic photoelectric conversion element 1 was sealed with an aluminum lid and a UV-curable resin under a nitrogen atmosphere.

<Evaluation of Organic Photoelectric Conversion Elements>

(Evaluation of conversion efficiency)

The organic photoelectric conversion element produced as described above was irradiated with light having an intensity of 100 mW / cm ^{2 in} a solar simulator (AM1.5G filter), and a mask having an effective area of 4.0 mm ² was superimposed on the light receiving section, and formed on the light receiving section. The four light-receiving portions on this element measured the short-circuit current density Jsc (mA / cm ² ), the open voltage Voc (V), and the curve factor (filling factor) FF, respectively, and determined the average value. In addition, the photoelectric conversion efficiency η (%) was determined from Jsc, Voc, and FF according to Equation 2, and was a photoelectric conversion efficiency of 3.9%.

Equation 2 Jsc (mA / cm ² ) × Voc (V) × FF = η (%)

From the above, it can be seen that a highly efficient organic photoelectric conversion element can be produced using the coating liquid of the present invention.

[Industrial use possibility]

The present invention can be used in inks for manufacturing electronic devices, electronic devices, organic electroluminescent elements, and organic photoelectric conversion elements.

Claims (14)

    A coating liquid comprising an organic compound and an organic solvent, and the dissolved carbon dioxide concentration of the organic solvent under a condition of 50 ° C./atmospheric pressure is within a range of 1 ppm or more and a saturated concentration of the organic solvent or less.         For example, the application liquid of the first range of the patent application, wherein the dissolved carbon dioxide concentration is in the range of 5 to 1000 ppm under the aforementioned conditions.         For example, if the coating liquid in the first or second application scope of the patent application contains oxygen in the coating liquid of 1 ppm or more, the dissolved carbon dioxide concentration is contained within the range of 1.0 to 100,000 times the dissolved oxygen concentration under the foregoing conditions. .         For example, the application liquid of any one of claims 1 to 3 of the application scope, wherein the aforementioned coating liquid is a coating liquid for manufacturing electronic devices.         For example, the application liquid of the fourth scope of the patent application, wherein the aforementioned electronic device is a light-emitting device.         For example, the coating liquid according to any one of claims 1 to 5, wherein the aforementioned organic compound is an organic electroluminescent material.         For example, the coating liquid according to any one of claims 1 to 6, wherein the coating liquid is an inkjet ink.         A method for manufacturing a coating liquid, which is characterized in that the coating liquid according to any one of claims 1 to 7 is manufactured, and has a step of mixing the organic compound and carbon dioxide.         For example, the method for manufacturing a coating liquid according to item 8 of the application, wherein after the step of mixing the aforementioned organic compound and carbon dioxide, a solution containing the aforementioned organic compound is used to manufacture the aforementioned coating solution.         For example, the method for manufacturing a coating liquid according to the eighth or ninth aspect of the patent application, which includes a step of separating a substance in a solution containing the aforementioned organic compound using a supercritical fluid.         An ink for manufacturing electronic devices, which is characterized by containing a coating liquid according to any one of claims 1 to 7 of the scope of patent application.         An electronic device is characterized by having an organic function layer formed by using a coating solution according to any one of claims 1 to 7.         An organic electroluminescence element characterized by having an organic function layer formed by using a coating solution according to any one of claims 1 to 7.         A photoelectric conversion element characterized by having an organic function layer formed by using a coating solution according to any one of claims 1 to 7.