JP2009245878A - Organic electroluminescent element and method of manufacturing the same, and organic electroluminescent display - Google Patents

Abstract

A method of manufacturing an organic electroluminescent device capable of improving deterioration in device characteristics of an organic electroluminescent device caused by film formation or storage in an environment containing a lot of moisture during the manufacturing process I will provide a.
A method for manufacturing an organic electroluminescent device having a first electrode, an organic layer, and a second electrode in this order, wherein after the organic layer is formed, the organic layer is formed for at least 30 minutes. It has a preservation | save process preserve | saved for less than a day, and a heating process which heat-processes this organic layer.
[Selection figure] None

Description

  The present invention relates to a method for producing an organic electroluminescent element having an organic layer formed by a wet film-forming method and an organic electroluminescence display using the same.

In recent years, electroluminescent elements using organic layers (organic electroluminescent elements; hereinafter also referred to as “organic EL elements” as appropriate) have been developed. Examples of the method for forming the organic layer in the organic electroluminescence device include a vacuum deposition method and a wet film formation method.
Since the vacuum deposition method is easy to stack, it has an advantage that the charge injection from the anode and / or the cathode is improved, and the exciton light-emitting layer is easily contained. On the other hand, the wet film formation method does not require a vacuum process, is easy to increase in area, and can be easily mixed with a plurality of materials having various functions in one layer (coating liquid). There is.

Here, it is known that when the organic layer formed by these film forming methods is exposed to moisture in the atmosphere, the durability of the organic electroluminescent element finally obtained and the driving voltage are affected. ing. In particular, when the exposed organic layer is a p-doped or n-doped organic layer by the addition of a radical generator or the like, hydrolysis of the compound may occur due to moisture adsorption. Similarly, it has been thought that the compound is irreversibly oxidized by oxygen in the atmosphere, volatile organic substances, etc., and the organic layer is deteriorated.
Therefore, for example, in Patent Document 1, in order to isolate the organic layer from oxygen, moisture, organic contaminants, etc. in the air, a coating solution for forming the organic layer is applied in an atmosphere in an inert gas, and further, Heating drying is performed in an active gas atmosphere or in a vacuum.

JP 2005-135734 A

  However, for example, a method for improving again the characteristics of an organic layer that has been once exposed to atmospheric moisture or volatile organic substances (toluene, xylene, dichloromethane, ethanol, etc.), has been discovered. However, when the organic layer is formed, the atmosphere (humidity, concentration of organic contaminants, etc.) in the film forming process and the storage process is controlled.

  The present invention has been made in view of the above-described problems. For example, the element characteristics of an organic electroluminescent element are deteriorated caused by film formation or storage in an environment containing a lot of moisture during the manufacturing process. The manufacturing method of the organic electroluminescent element which can improve is provided. In other words, even when an organic layer is formed or stored in an atmosphere containing a lot of moisture or volatile organic matter, the luminous efficiency and drive life are the same as those of an organic electroluminescent device manufactured by controlling the atmosphere. And a method for producing an organic electroluminescent device having a driving voltage, and an organic electroluminescent display having the method.

  When manufacturing an organic electroluminescent element, the present inventors diligently studied about the simplification of the atmosphere control in the manufacturing process of the organic layer, which was conventionally considered essential. As a result, the deterioration of the characteristics of the organic layer that occurs in the atmosphere, which has been considered irreversible in the past, is reversible. It was found that it is possible to return to the state, and even when the atmosphere control is simplified, the present invention capable of providing an organic electroluminescence device having a good driving life and driving voltage has been completed. .

The gist of the present invention is a method of manufacturing an organic electroluminescent device having a first electrode, an organic layer, and a second electrode in this order, and after forming the organic layer, the organic layer is formed for 30 minutes or more. And an organic electroluminescence device manufacturing method comprising a storage step of storing 400 days or less and a heating step of heat-treating the organic layer.
At this time, the organic layer is preferably a hole injection layer, and the organic layer is preferably a hole transport layer.

  Moreover, it is preferable that the temperature of the heat processing of this heating process is 100 degreeC or more and 400 degrees C or less.

  Another gist of the present invention resides in an organic electroluminescent device manufactured by the above-described organic electroluminescent device manufacturing method.

  Still another subject matter of the present invention lies in an organic electroluminescence display having an organic electroluminescence device manufactured by the above-described method for manufacturing an organic electroluminescence device.

  According to the method for manufacturing an organic electroluminescent element of the present invention, it is possible to simplify the atmosphere control when the organic layer of the organic electroluminescent element is formed or when the organic layer is stored. Even when the organic layer is formed or stored in an atmosphere containing a large amount of an organic compound, an organic electroluminescence device having good device characteristics, that is, driving life and driving voltage can be produced.

  Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following description, and various modifications can be made without departing from the scope of the present invention.

  The method for producing an organic electroluminescent element of the present invention (hereinafter also referred to as “organic EL element” as appropriate) produces an organic electroluminescent element having a first electrode, an organic layer, and a second electrode in this order. It is a method to do. That is, the organic electroluminescent device produced according to the present invention includes an anode, a cathode formed so as to face the anode, and an organic layer formed between the anode and the cathode. Usually, at least a light emitting layer (in the present invention, mainly refers to an organic light emitting layer) is provided as an organic layer between the anode and the cathode. The organic layer may include other layers such as a hole transport layer, a hole injection layer, an electron transport layer, and an electron transport layer. There is no restriction | limiting in particular in the formation method of these organic layers, For example, it can also form by any methods, such as a vapor deposition method and a wet film-forming method.

  In the method for producing an organic EL element of the present invention, at least one layer (hereinafter also referred to as “specific organic layer”) among the organic layers formed between the anode and the cathode is formed by a specific organic layer forming method. It is characterized by doing. The specific organic layer forming method is a method having a storage step of storing the specific organic layer for a certain period after forming the specific organic layer, and a heating step of heat-treating the organic layer after the storage step. . In addition, there is no restriction | limiting in particular in the formation method of this specific organic layer, For example, it can also form by any methods, such as a vapor deposition method and a wet film-forming method.

  In the present invention, the specific organic layer forming method includes a heating step in which the specific organic layer is stored under a predetermined condition and then heat-treated, so that, for example, the surface of the organic layer is formed in the film formation step or the storage step of the specific organic layer. It is possible to remove moisture and volatile organic substances adsorbed on the substrate. Therefore, the atmosphere control in the film formation process and storage process of the specific organic layer is simplified, and even if the characteristics of the specific organic layer are deteriorated, the characteristics of the specific organic layer are formed and stored in the heating process. In this case, it is possible to improve the atmosphere to the same level as when the atmosphere is controlled, and it is possible to manufacture an organic EL element having good element characteristics with a simple manufacturing system. That is, it is possible to manufacture an organic EL element having the same element characteristics as when the atmosphere control is performed without performing the atmosphere control or the like.

  Hereinafter, the specific organic layer formation method in the manufacturing method of the organic EL element of this invention is demonstrated, and the organic EL element manufactured by this invention is demonstrated after that.

1. Specific Organic Layer Forming Method The specific organic layer forming method is a method of forming at least one layer (specific organic layer) of the organic layers formed between the first electrode and the second electrode of the organic EL device manufactured according to the present invention. It is a method used when forming, a film forming step for forming a specific organic layer, a storage step for storing the specific organic layer for 30 minutes or more and 400 days or less after the film forming step, and after the storage step, And a heating step of heat-treating the organic layer.
In the specific organic layer forming method, in addition to the film forming step, the storage step, and the heating step, other steps may be appropriately included. Examples of other processes include a pretreatment process, a drying process, and a cooling process described below.

  The specific organic layer forming method can be applied when any organic layer is formed among the organic layers of the organic EL element produced by the present invention. In the present invention, only one of the organic layers may be formed by the specific organic layer forming method, or two or more layers may be formed by the specific organic layer forming method. From the viewpoint of simplifying the production system, it is preferable to form two or less of the organic layers by the specific organic layer forming method, and it is particularly preferable to form only one layer by the specific organic layer forming method.

In the present invention, the specific organic layer forming method may be any organic layer formed between the first electrode and the second electrode, but is generally preferably a chemically stable layer. As such a layer, it is preferable that the organic substance contained in the organic layer is generally excellent in redox durability and the glass transition temperature is 100 ° C. or higher.
Conventionally, it has been required to control the atmosphere particularly when forming an organic layer by a wet film forming method. However, by performing a heating step in the specific organic layer forming method, the atmosphere control during the wet film forming can be controlled. It becomes unnecessary. Therefore, from the viewpoint that the advantages of the present invention can be particularly utilized, it is preferable that the layer formed by the wet film forming method is the specific organic layer and is formed by the specific organic layer forming method.
Hereinafter, although each process in a specific organic layer formation method is demonstrated, a pre-processing process and a cooling process shall be performed as needed.

1-1. Pretreatment step Before the specific organic layer is formed, a pretreatment step of removing impurities adhering to the formation surface (for example, the first electrode) can be performed. Thereby, an ionization potential can be adjusted and the hole or electron injection property to a specific organic layer can be improved. As a pretreatment method, for example, when a specific organic layer is formed on the first electrode, the surface is cleaned with a solvent using alcohol or the like, ultraviolet (UV) / ozone treatment, oxygen plasma, An argon plasma treatment method is preferable.
In addition, the type of the layer to be the formation surface of the specific organic layer, that is, the layer formed adjacent to the specific organic layer is appropriately selected according to the structure of the organic EL element, and the formation method of this layer is not particularly limited. Absent. For example, it may be a layer formed by a vapor deposition method, or may be a layer formed by a wet film formation method.

1-2. Film-forming process The film-forming process can be carried out with any modification as long as the effects of the present invention are not significantly impaired. For example, a vacuum deposition method or a wet film-forming method can be used.
As a method of forming a specific organic layer by a vacuum deposition method, first, one or more of the materials forming the specific organic layer are put in a crucible installed in a vacuum vessel (when two or more materials are used). Then, the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with a suitable vacuum pump. After that, the crucible is heated (each crucible is heated when two or more materials are used), and the evaporation amount is controlled to evaporate (when two or more materials are used, the evaporation amount is independently controlled and evaporated). And a thin film of the material can be formed on a substrate placed facing the crucible. In addition, when using 2 or more types of materials, those mixtures can be put into a crucible, and it can heat and evaporate, and can also form the specific organic layer which consists of a mixture.

  On the other hand, when the specific organic layer is formed by a wet film-forming method, a composition containing the material of the specific organic layer and a solvent (hereinafter sometimes referred to as “coating composition” as appropriate) is formed into a film. A film is formed by coating and dried. Hereinafter, a solvent used when the specific organic layer is formed by a wet film forming method, a film forming method, film forming conditions (film forming humidity, oxygen concentration, number of particles, etc.), a drying method, and the like will be described.

(1-2-1) Solvent The solvent used in the coating composition is not limited as long as the effects of the present invention are not significantly impaired, and examples thereof include ether solvents and ester solvents.
Examples of ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole , Phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, aromatic ethers such as 2,4-dimethylanisole, and the like.

  Examples of the ester solvent include aliphatic esters such as ethyl acetate, n-butyl acetate, ethyl lactate, and n-butyl lactate; phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and benzoic acid. and aromatic esters such as n-butyl.

In addition to the ether solvents and ester solvents described above, examples of usable solvents include aromatic hydrocarbon solvents such as benzene, toluene and xylene; N, N-dimethylformamide, N, N-dimethylacetamide and the like. Amide solvents such as dimethyl sulfoxide and the like.
In addition, these solvents may use only 1 type and may use 2 or more types by arbitrary combinations and a ratio. Moreover, you may use 1 type, or 2 or more types of solvents other than an ether solvent and an ester solvent in combination with 1 type or 2 or more types among the above-mentioned ether solvent and ester solvent.

  However, among the solvents described above, a solvent having a high ability (solvent ability) to dissolve the material of the specific organic layer formed by the wet film forming method is preferable. This is because the concentration of the coating composition can be arbitrarily set to prepare a coating composition having a concentration excellent in the efficiency of the film forming process.

  The concentration of the material of the specific organic layer in the coating composition is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.01% by weight or more, preferably 0.1% by weight or more, Preferably it is 0.5 weight% or more. Moreover, it is 70 weight% or less normally, Preferably it is 60 weight% or less, More preferably, it is 50 weight% or less. If the concentration is too high, film thickness unevenness may occur. If the concentration is too low, defects may occur in the film.

  In addition, since the organic EL element is usually formed by laminating layers (organic layers) made of a large number of organic compounds, each layer is preferably a uniform layer. Here, when a layer is formed by a wet film formation method, if there is a certain amount or more of moisture in the composition for forming each organic layer, moisture is mixed into the coating film and the durability of the film is impaired. The water content in the solution is preferably as low as possible. In general, the organic EL element uses many materials such as a cathode whose function is remarkably deteriorated due to moisture, so that the presence of moisture is preferably as small as possible from the viewpoint of reducing the function of the element. For the above reasons, the amount of water contained in the coating composition is usually 1% by weight or less, preferably 0.1% by weight or less.

  Examples of methods for reducing the amount of water in the coating composition include techniques such as using a nitrogen gas seal, using a desiccant, dehydrating the solvent in advance, and using a solvent with low water solubility. . Among these, from the viewpoint of preventing the phenomenon that the coating film absorbs moisture in the air and whitens when applying the coating composition, it is preferable to use a solvent having low water solubility. Specifically, the coating composition contains a solvent having low water solubility, for example, a solvent having water solubility at 25 ° C. of 1 wt% or less, preferably 0.1 wt% or less, based on the entire coating composition. In general, it is preferably contained at a concentration of 10% by weight or more, especially 30% by weight or more, and particularly 50% by weight or more.

(1-2-2) Film Forming Method If the specific organic layer is formed by a wet film forming method, the effect of the present invention is significantly impaired as long as the method can be uniformly applied to a target region. There is no limit unless it is. For example, spin coating method, dip coating method, die coating method, bar coating method, blade coating method, roll coating method, spray coating method, capillary coating method, ink jet method, screen printing method, gravure printing method, flexographic printing method, etc. Can be mentioned.
Among these film forming methods, a spin coating method, a spray coating method, and an ink jet method are preferable. This is because the liquid property specific to the coating composition used in the organic EL element is met.

(1-2-3) Film formation conditions (Film formation temperature)
The film-forming temperature in the environment where the film-forming process is performed by the wet film-forming method is not limited as long as the effects of the present invention are not significantly impaired. Is more preferable, and 16 ° C. or higher is even more preferable. Moreover, 50 degrees C or less is preferable, 40 degrees C or less is more preferable, and 30 degrees C or less is further more preferable.

(Deposition humidity)
The relative humidity in the environment in which the film forming process is performed is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.01 ppm or more, preferably 0.05 ppm or more, more preferably 0.1 ppm or more, and usually 80%. Below, it is preferably 60% or less, more preferably 15% or less, still more preferably 1% or less, and particularly preferably 100 ppm or less. If the relative humidity is too low, it may be difficult to control film formation conditions during wet film formation. On the other hand, if it is too large, moisture adsorption on the organic layer may be easily affected.

(Oxygen concentration)
The volume concentration of oxygen in an environment in which a film forming process is performed by a wet film forming method is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 0.01 ppm or more, more preferably 0.05 ppm or more, and preferably It is 50% or less, more preferably 25% or less, further preferably 1% or less, and particularly preferably 100 ppm or less. An environment in which the oxygen concentration is too low is difficult to control, and if the oxygen concentration is too high, oxygen diffuses inside the specific organic layer, which may affect device characteristics.

(Number of particles)
The number of fine particles (that is, the number of particles) in the film forming environment is not limited as long as the effects of the present invention are not significantly impaired. From the viewpoint of reducing dark spots, particles having a particle size of 0.5 μm or more are usually per 1 m ^3. It is 10,000 or less, preferably 5000 or less. Particularly preferably, the number of particles having a particle diameter of 0.3 μm or more is 5000 or less per 1 m ³ . Although there is no restriction | limiting in a lower limit, from a viewpoint of industrial practical use, it can be considered that there are normally 100 particles having a particle size of 0.3 μm or more per 1 m ³ . If the number of particles is too large, dark spots may occur, and environmental control tends to become more difficult as the lower limit is exceeded.
The number of fine particles is detected by a light scattering method, and can be detected by, for example, a handheld particle counter KR (manufactured by Lion Co., Ltd.).

(1-2-4) Film thickness The film thickness of the specific organic layer formed in the film formation step is not limited as long as the effects of the present invention are not significantly impaired, but preferably 10 nm in that high film thickness accuracy is obtained. As mentioned above, More preferably, it is 15 nm or more, More preferably, it is 20 nm or more. Further, it is preferably 30 μm or less, more preferably 20 μm or less, and further preferably 15 μm or less.
The film thickness accuracy is defined as the ratio between the maximum value and the minimum value of the film thickness of the light emitting portion (the organic layer portion sandwiched between the anode and the cathode). The film thickness accuracy is measured with a contact film thickness meter or an interference film thickness meter.

(1-2-5) Drying Usually, after film formation by a wet film formation method, the specific organic layer is dried. The drying of the specific organic layer can be carried out with any change as long as the effects of the present invention are not significantly impaired. However, drying means a step of removing the solvent in the coating composition formed by the wet film forming method.

(Dry method)
The drying method at the time of drying is not limited as long as the effects of the present invention are not significantly impaired, and examples thereof include heat treatment, reduced pressure treatment, inert gas treatment, and sputtering treatment. Of these, heat treatment is preferred because it is easy to reduce the residual solvent in the film.
The above processing may be performed alone or in combination. When combining a plurality of processes, the processes may be performed in an arbitrary order, or all or a part of the processes may be performed in parallel. However, it is preferable to perform drying under conditions that reduce drying unevenness.

(Drying temperature)
The drying temperature at the time of drying is not limited as long as the effects of the present invention are not significantly impaired, but when heat treatment is performed, it is usually 50 ° C. or higher, preferably 80 ° C. or higher. Moreover, it is 300 degrees C or less normally, Preferably it is 250 degrees C or less. If the temperature is too high, the other layers may be affected. If the temperature is too low, the solvent may remain in the film.
The drying temperature means an environmental temperature in the case of an in-furnace baking method, a plate temperature in the case of a hot plate method, and an environmental temperature in the case of a method using a heater.

(Drying time)
The drying time at the time of drying is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 30 seconds or more, more preferably 1 minute or more, and further preferably 2 minutes or more. Further, it is preferably 5 hours or less, more preferably 2 hours or less, and further preferably 1 hour or less. If the drying time is too long, components of layers other than the specific organic layer tend to diffuse, and if it is too short, the film tends to be non-homogeneous.

(Relative humidity)
Although the relative humidity at the time of drying is not limited as long as the effect of the present invention is not significantly impaired, it is preferably 1% or more, more preferably 5% or more, and further preferably 10% or more. Further, it is preferably 80% or less, more preferably 50% or less, and further preferably 20% or less. If the relative humidity is too high, moisture tends to remain in the film.

(Degree of vacuum)
The degree of vacuum at the time of drying is not limited as long as the effect of the present invention is not significantly impaired. However, in the case of performing a decompression treatment, it is preferably 1 × 10 ⁻² Pa or less, more preferably 1 × 10 ⁻³ Pa or less. More preferably, it is 5 × 10 ⁻⁴ Pa or less. Moreover, although there is no restriction | limiting in a lower limit, it is 1 * 10 < ^-5 > Pa or more normally. If the degree of vacuum is too high, it takes time to increase the degree of vacuum, and environmental control tends to be difficult during that time. If it is too low, the solvent tends to remain in the film.

(Film thickness after drying)
The thickness of the specific organic layer after drying is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 10 nm or more, more preferably 15 nm or more, and further preferably 20 nm or more. Moreover, it is preferably 300 nm or less, more preferably 200 nm, and still more preferably 150 nm or less. If the lower limit value is not reached, defects may occur in the thin film, and if the upper limit value is exceeded, the drive voltage increases, and unevenness in light emission may occur due to uneven film thickness.

(Film thickness accuracy after drying)
The film thickness accuracy of the specific organic layer after drying is preferably 500% or less, more preferably 300% or less, and still more preferably 200% or less. Further, it is preferably 2% or more, more preferably 5% or more, and further preferably 8% or more. If the film thickness accuracy is too large, device characteristics such as uneven light emission tend to be unstable, and if it is too small, film defects tend to occur, and the film quality tends to be non-homogeneous. The method for measuring the film thickness accuracy is the same as the method described above.

1-3. Cooling step The specific organic layer is cooled, for example, when the specific organic layer is formed by a wet film formation method in the above film formation step and then subjected to a heat treatment during drying or when heated in another step. You may perform the process (cooling process) to make. The cooling step can be carried out with any change as long as the effects of the present invention are not significantly impaired. Specifically, it is preferable that at least one of the items described below is satisfied.

(1-3-1) Cooling method The cooling method in the cooling step is not limited as long as the effects of the present invention are not significantly impaired. For example, the temperature at which the dried coating composition film is desired to be cooled. Examples thereof include a method of making the range, a method of mounting a substrate on a plate (hot plate), and cooling a specific organic layer through the plate.

(1-3-2) Cooling temperature Although the cooling temperature in a cooling process is not limited unless the effect of this invention is impaired remarkably, Preferably the dried specific organic layer is 150 degrees C or less, More preferably, it is 120 degrees C or less, Furthermore, Preferably it is 100 degrees C or less, Especially preferably, it is 80 degrees C or less, and although there is no restriction | limiting in a minimum, it is normally cooled to 5 degrees C or more. If the cooling temperature is too high, the components of other layers may diffuse, and if it is too low, crystals may form in the specific organic layer.
The cooling temperature is the environmental temperature. In the case of the hot plate method, it means the plate temperature.

(1-3-3) Cooling rate The cooling rate in the cooling step is not limited as long as the effects of the present invention are not significantly impaired, but preferably 0.1 ° C / min or more, more preferably 0.5 ° C / min or more, More preferably, it is 0.8 degree C / min or more, Most preferably, it is 1 degree C / min or more. Further, it is preferably 50 ° C./min or less, more preferably 30 ° C./min or less, further preferably 20 ° C./min or less, particularly preferably 10 ° C./min or less. If the cooling rate is too low, the production cost may increase, and if it is too high, the film quality may deteriorate due to the difference in linear expansion between adjacent films.

(1-3-4) Humidity The relative humidity in the cooling step is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 0.01 ppm or more, more preferably 0.05 ppm or more, and further preferably 0.08 ppm or more. It is. Further, it is preferably 50% or less, more preferably 10% or less, and still more preferably 1% or less. If the relative humidity is too low, there is a tendency that it is difficult to control the environment to be constant, and there is a possibility that the device cannot be stably manufactured. Further, if the relative humidity is too high, moisture may be physically adsorbed on the surface of the specific organic layer.

(1-3-5) Cooling time The cooling time in the cooling step is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 5 hours or less, more preferably 3 hours or less, even more preferably 1 hour or less, particularly Preferably it is 30 minutes or less. Further, it is preferably 30 seconds or longer. If the cooling time is too short, film distortion tends to occur.

(1-3-6) Cooling environment Although the cooling environment in a cooling process is not limited unless the effect of this invention is impaired remarkably, For example, a vacuum environment and an inert gas environment are mentioned.
In the case of a vacuum environment, the degree of vacuum is preferably 1 × 10 ⁻² Pa or less, more preferably 1 × 10 ⁻³ Pa or less. Moreover, although there is no lower limit normally, 1 * 10 < ^-5 > Pa or more is preferable. If the degree of vacuum is too high, it takes time to increase the degree of vacuum, and environmental control during that time tends to be difficult.
Examples of the inert gas include nitrogen gas, noble gases, nonflammable gases, and the like. In addition, only 1 type may be used for an inert gas and it may use 2 or more types together by arbitrary combinations and a ratio.

(1-3-7) Film thickness difference before and after the cooling process The film thickness difference between the specific organic layers before and after the cooling process is not limited as long as the effects of the present invention are not significantly impaired, but the film thickness before the cooling process is 100%. Is preferably 50% or less, more preferably 30% or less, and still more preferably 20% or less. If the film thickness difference is too large, there is a possibility of film peeling due to film distortion. In addition, although a minimum is 0%, from a viewpoint of industrial availability, it is 1% or more normally.

1-4. Preservation process The preservation process can be carried out with any modification as long as the effects of the present invention are not significantly impaired. The term “storage” as used in the present invention refers to a specific organic layer that has been subjected to a cooling step or the like as necessary after film formation in the film formation step, and a new organic layer or electrode is formed on the specific organic layer. This refers to the state of holding until film formation, and includes not only storage in a stationary state but also storage in a transportation state such as transportation. In addition, storing the specific organic layer includes storing the entire substrate on which the specific organic layer is formed.

(1-4-1) Storage period The storage period in the storage process is not particularly limited as long as the effect of the present invention is not significantly impaired, but is usually 30 minutes or longer, preferably 45 minutes or longer, more preferably 1 hour or longer. . Moreover, it is 400 days or less normally, Preferably it is 200 days or less, More preferably, it is 100 days or less. If this upper limit is exceeded, the amount of moisture and volatile organic substances adsorbed on the specific organic layer will increase, and the heating time required for the heating process described later will increase, affecting the materials that make up the specific organic layer. May affect. Moreover, the effect of this invention is easy to be acquired when it is more than the said lower limit.

(1-4-2) Storage humidity The relative humidity in the storage step is not particularly limited as long as the effects of the present invention are not significantly impaired, but is usually 60% or less, preferably 55% or less. Moreover, it is 0.01 ppm or more normally, Preferably it is 0.05 ppm or more, More preferably, it is 0.1 ppm or more. When the above upper limit is exceeded, the amount of moisture adsorbed on the specific organic layer increases, so that the heating time required for the heating step described later becomes longer and affects the material constituting the specific organic layer. there is a possibility

(1-4-3) Storage environment The environment in the storage process is not particularly limited as long as the effects of the present invention are not significantly impaired, and the temperature during storage is usually 4 ° C or higher, preferably 10 ° C or higher, more preferably 15 It can be set to at least ° C. Moreover, it is 90 degrees C or less normally, Preferably it is 70 degrees C or less, More preferably, it is 40 degrees C or less. As a result, the device can be stored in a stable environment. The atmosphere is usually in the atmosphere, but may be a vacuum environment, an inert gas environment, a dry air environment, or the like.

(1-4-4) Storage angle of substrate In the present invention, an angle formed by a horizontal plane (surface parallel to the ground) and the surface of a specific organic layer formed by a wet film formation method in a storage process (film formation) The angle between the specific organic layer and the horizontal plane is 0 ° when the upper surface of the specific organic layer faces downward in parallel with the horizontal plane, as long as the effect of the present invention is not significantly impaired. Is usually 0 ° or more, preferably 3 ° or more, and more preferably 5 ° or more from the viewpoint of reducing the adhesion of particles. Moreover, it is 90 degrees or less normally, Preferably it is 85 degrees or less, More preferably, it is 80 degrees or less.

(1-4-5) Number of Particles The number of fine particles in the atmosphere (number of particles) in the storage step is not limited as long as the effect of the present invention is not significantly impaired. From the viewpoint of reducing dark spots, the particle size is 0.5 μm or more. The number of particles is usually 10,000 or less, preferably 5000 or less per 1 m ³ . Particularly preferably, the number of particles having a particle diameter of 0.3 μm or more is 5000 or less per 1 m ³ . From the viewpoint of industrial practicality, it can be considered that there are usually 100 particles having a particle size of 0.3 μm or more per 1 m ³ . If the number of particles is too large, dark spots may occur, and environmental control tends to become more difficult as the number falls below the above range.
The number of fine particles is detected by a light scattering method, and can be detected by, for example, a handheld particle counter KR (manufactured by Lion Co., Ltd.).

1-5. Heating Step The heating step in the present invention is a step of heat-treating the specific organic layer after the storage step and before forming a new organic layer or electrode on the specific organic layer. The heat treatment can be carried out by arbitrarily changing unless the effects of the present invention are impaired.

(1-5-1. Heating means)
As a specific method of the heating means, for example, a hot plate method in which a substrate on which a specific organic layer is formed on a plate (hot plate) is mounted and the specific organic layer is heated through the plate, an upper surface of the specific organic layer Examples include a method in which a heater is disposed on the side and / or the lower surface side (base material side), and the specific organic layer is heated by irradiating electromagnetic waves (for example, infrared rays) from the heater. Of these, the plate (hot plate) method is preferable. This is because the specific organic layer can be heated uniformly, and moisture adsorbed in the specific organic layer, volatile organic substances, and the like can be removed. One heating means may be used, or two or more heating means may be used in any combination and ratio.

(1-5-2) Heating surface The heating direction in the heating step is not limited as long as the effects of the present invention are not significantly impaired. For example, a specific organic layer is formed on a hot plate. By mounting the substrate and heating the specific organic layer through the hot plate, the specific organic layer is heated from the lower surface (base material) of the substrate, and the substrate is put into a clean oven. The method etc. which heat a specific organic layer from all the front and rear, right and left directions are mentioned.

(1-5-3) Heating temperature Although the heating temperature in a heating process is not restrict | limited unless the effect of this invention is impaired remarkably, it is 100 degreeC or more normally, Preferably it is 150 degreeC or more. Moreover, it is 350 degrees C or less normally, Preferably it is 300 degrees C or less. As a result, moisture and volatile organic substances on the surface of the specific organic layer can be removed in a short time. If the upper limit is exceeded, the specific organic layer and other layers than the specific organic layer may be affected. If the lower limit is not reached, moisture on the surface of the specific organic layer may not be sufficiently removed.

(1-5-4) Heating time The heat treatment time in the heating step is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 30 seconds or more, more preferably 1 minute or more, and further preferably 2 minutes or more. It is. Further, it is preferably 2 hours or less, more preferably 1 hour or less, and further preferably 30 minutes or less. When the upper limit is exceeded, components in other layers may diffuse into the specific organic layer, and when the upper limit is exceeded, moisture on the surface of the specific organic layer may not be sufficiently removed.

(1-5-5) Relationship between heating time and heating temperature Generally, the purpose of the heat treatment performed during the film formation step is to achieve a temperature equal to or higher than the boiling point of the solvent contained in the specific organic layer that has been wet-formed. The solvent is volatilized and removed by heating at. On the other hand, the main purpose of the heating step is to remove moisture adsorbed on the surface of the specific organic layer. Therefore, during the heat treatment in the film forming process, it is usually required to heat at a temperature equal to or higher than the boiling point of the solvent for a sufficient time until the solvent completely evaporates. The treatment may be performed at a temperature at which it can be desorbed for the time described above.

(1-5-6) Humidity The relative humidity in the heating step is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 1% or more, more preferably 5% or more, and further preferably 10% or more. Further, it is preferably 80% or less, more preferably 50% or less, and still more preferably 20% or less. If the relative humidity is too high, moisture remains in the specific organic layer, and the effects of the present invention may not be sufficiently obtained.

(1-5-7) Degree of vacuum The degree of vacuum in the heating step is not limited as long as the effects of the present invention are not significantly impaired. However, in the case of performing a decompression treatment, preferably 1 × 10 ⁻² Pa or less, more preferably 1 × 10 ⁻³ Pa or less, more preferably 5 × 10 ⁻⁴ Pa or less, and the lower limit is not limited, but is usually 1 × 10 ⁻⁵ Pa or more. If the degree of vacuum is too high, it takes time to increase the degree of vacuum, and environmental control tends to be difficult during that time. On the other hand, if it is too low, moisture or the like tends to remain in the specific organic layer. is there.

1-6. Other Steps In the specific organic layer forming method, steps other than the above may be included before and after each step or during the steps, as necessary.

2. Organic Electroluminescent Device Hereinafter, the organic EL device according to the present invention will be described. The organic EL device according to the present invention includes at least the specific organic layer forming method in the production process. As an organic EL device manufactured by such a method, a substrate is usually provided, a first electrode is formed on the substrate, one or more organic layers are formed thereon, and the organic layer is further formed on the organic layer. And having a stacked structure in which a second electrode is formed. Here, one of the first electrode and the second electrode is an anode, and the other is a cathode. One of the organic layers is usually a light emitting layer, and examples of other organic layers include a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and an electron blocking layer. Examples include layers such as layers.
In addition, for the purpose of further improving the efficiency of hole or electron injection and improving the adhesion between the whole organic layer and the first electrode, a known buffer layer or the like between the first electrode and the organic layer May be formed.

  Hereinafter, the case where the first electrode is an anode and the second electrode is a cathode will be described in the order of stacking from the substrate side. FIG. 1 is a cross-sectional view schematically showing an example of the structure of an organic EL device manufactured according to the present invention. An organic EL element 10a shown in FIG. 1 is configured by laminating an anode 2, a hole injection layer 3, a light emitting layer 5, an electron transport layer 7, an electron injection layer 8, and a cathode 9 in this order on a substrate 1. Is done. In the organic EL element having such a configuration, for example, the hole injection layer 3 and the light emitting layer 5 may be formed by the specific organic layer forming method. Hereinafter, each of these components will be described.

2-1. Substrate The substrate 1 serves as a support for the organic EL element 10a, and a quartz or glass plate, a metal plate or a metal foil, a plastic film, a sheet, or the like is used. In particular, it is preferable to use a transparent substrate made of a general-purpose material such as a glass plate, a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, or polysulfone.

  Examples of the material of the substrate 1 include various types of shot glass such as BK7, SF11, LaSFN9, BaK1, and F2, synthetic phased silica glass, optical crown glass, low expansion borosilicate glass, sapphire glass, soda glass, and alkali-free glass. Glass, TFT-formed glass, and polymer materials include acrylic resins such as polymethylmethacrylate and cross-linked acrylate, aromatic polycarbonate resins such as bisphenol A polycarbonate, polyester resins such as polyethylene terephthalate, and polycycloolefins. Examples thereof include crystalline polyolefin resins, epoxy resins, styrene resins such as polystyrene, polysulfone resins such as polyethersulfone, and synthetic resins such as polyetherimide resin. Moreover, 2 or more types of laminated bodies may be sufficient among these. Depending on the purpose and application, an optical film such as an antireflection film, a circularly polarizing film, or a retardation film may be formed on or bonded to these substrates.

  However, it is preferable to pay attention to gas barrier properties when using a synthetic resin substrate. This is because if the gas barrier property of the substrate 1 is too small, the performance of the organic EL element 10a may be deteriorated by the outside air that has passed through the substrate 1. For this reason, a method of providing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also a preferable method.

2-2. An anode 2 is provided on the anode substrate 1. The anode 2 plays a role of injecting holes into a layer (such as the hole injection layer 3 or the light emitting layer 5) on the light emitting layer 5 side.

  This anode 2 is usually made of a metal such as aluminum, gold, silver, nickel, palladium, or platinum; a metal oxide such as an oxide of indium and / or tin; a metal halide such as copper iodide; a carbon black, or It is composed of a conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline. In addition, only 1 type may be used for the material of the anode 2, and 2 or more types may be used together by arbitrary combinations and a ratio.

Although there is no restriction | limiting in the formation method of the anode 2, Usually, it carries out by sputtering method, a vapor deposition method, etc. In addition, when forming the anode 2 using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, and conductive polymer fine powder, an appropriate binder resin solution is used. The anode 2 can also be formed by dispersing them and applying them onto the substrate 1. Furthermore, in the case of a conductive polymer, a thin film can be directly formed on the substrate 1 by electrolytic polymerization, or the anode 2 can be formed by applying a conductive polymer on the substrate 1 (Appl. Phys. Lett. 60, 2711, 1992).
In addition, the anode 2 is usually a single layer structure, but may be a laminated structure made of a plurality of materials if desired.

  The thickness of the anode 2 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more. Also, it is usually 1000 nm or less, preferably 500 nm or less. On the other hand, when the anode 2 may be opaque, the thickness of the anode 2 is arbitrary, and the anode 2 may be the same as the substrate 1. Further, it is possible to laminate different conductive materials on the anode 2.

Further, for the purpose of removing impurities adhering to the anode 2 and adjusting the ionization potential to improve the hole injection property, the surface of the anode 2 is subjected to ultraviolet (UV) / ozone treatment, oxygen plasma, argon plasma. It is preferable to process.
Furthermore, as described above, a known anode is provided between the hole injection layer 3 and the anode 2 for the purpose of further improving the efficiency of hole injection and improving the adhesion of the whole organic layer to the anode. A buffer layer may be inserted.

2-3. Hole Injection Layer The hole injection layer 3 is a layer that transports holes from the anode 2 to the organic light emitting layer 5. Usually, this hole injection layer 3 is formed on the anode 2. Therefore, the hole injection layer 3 is preferably configured to contain a hole injection compound and an electron accepting compound. Furthermore, the hole injection layer 3 may contain other components without departing from the spirit of the present invention.

  Examples of the method for forming the hole injection layer 3 on the anode 2 include a wet film formation method and a vacuum deposition method. However, a uniform and defect-free thin film can be easily obtained, and the formation time is short. In view of this, the wet film forming method is preferable. ITO (Indium Tin Oxide) generally used as the anode 2 has a surface roughness (Ra) of about 10 nm in addition to its surface, and often has local protrusions. There was a problem that it was easy to produce. Forming the hole injection layer 3 on the anode 2 by the wet film formation method reduces the occurrence of device defects due to the unevenness of the surface of the anode 2 as compared with the case of forming by the vacuum deposition method. It also has advantages. In particular, the hole injection layer 3 is preferably formed by the specific organic layer forming method. Thereby, it is not necessary to control the atmosphere during the wet film formation, and it is possible to form with a simple manufacturing system.

(2-3-1) Hole-injecting compound Examples of the hole-injecting compound include aromatic amine compounds, among which compounds containing a triarylamine structure are preferred, but holes in conventional organic electroluminescent devices are preferred. You may select suitably from the compounds which have been utilized as a formation material of an injection layer. As an aromatic amine compound, the binaphthyl type compound represented by following General formula (1) is mentioned, for example.

In the general formula (1), Ar ^{a to} Ar ^d are each independently a 5- or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic monocyclic group or condensed ring group which may have a substituent. Ar ^a and Ar ^b , Ar ^c and Ar ^d may be bonded to each other to form a ring. W1 and W2 each represent an integer of 0 to 4, and W1 + W2 ≧ 1. X ¹ and X ² each independently represent a direct bond or a divalent linking group. Further, a naphthalene ring in the general formula ^(1), - (X 1 ^NAr a Ar ^b) and ^- in addition to the ^{(X 2 NAr c Ar d)} , may have an arbitrary substituent.

In the general formula (1), as the monocyclic group or condensed ring group of a 5- or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic ring which may have a substituent of Ar ^{a to} Ar ^d , respectively. Independently, for example, a 5- or 6-membered monocyclic ring or a 2-3 condensed ring, specifically, a group derived from an aromatic hydrocarbon ring such as a phenyl group, a naphthyl group, an anthryl group; a pyridyl group, a thienyl group A group derived from an aromatic heterocycle such as Any of these may have a substituent.

As the substituent that Ar ^{a to} Ar ^d may have, those described later as the substituent that Ar ^{e to} Ar ^l may have, and an arylamino group (that is,-(NAr ^e Ar ^f ) described later, -(Corresponding to NAr ^g Ar ^h )).

Ar ^a and Ar ^b and / or Ar ^c and Ar ^d may be bonded to each other to form a ring. In this case, specific examples of the ring to be formed include a carbazole ring, a phenoxazine ring, an iminostilbene ring, a phenothiazine ring, an acridone ring, an acridine ring, an iminodibenzyl ring and the like that may have a substituent. Of these, a carbazole ring is preferred.

  In the general formula (1), W1 and W2 each represent an integer of 0 to 4, and W1 + W2 ≧ 1. Particularly preferred are W1 = 1 and W2 = 1. The arylamino groups in the case where W1 and / or W2 is 2 or more may be the same or different.

X ¹ and X ² each independently represent a direct bond or a divalent linking group. Although there is no restriction | limiting in particular as a bivalent coupling group, For example, what is shown below etc. are mentioned. A direct bond is particularly preferable as X ¹ and X ² .

In addition to — (X ¹ NAr ^a Ar ^b ) and — (X ² NAr ^c Ar ^d ), the naphthalene ring in the general formula (1) has one or more arbitrary substituents at an arbitrary position. It may be. Preferred examples of such a substituent include a halogen atom, a hydroxyl group, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, and an alkenyl group which may have a substituent. , One or more substituents selected from the group consisting of optionally substituted alkoxycarbonyl groups. Of these, an alkyl group is particularly preferred.
As the binaphthyl compound represented by the general formula (1), a binaphthyl compound in which Ar ^a and Ar ^c are each further substituted with an arylamino group is preferable, as represented by the following general formula (1-1). .

(In the general formula (1-1), Ar ^{e to} Ar ¹ each independently represents a 5- or 6-membered aromatic hydrocarbon ring or aromatic monocyclic group which may have a substituent, or Represents a condensed ring group, Ar ^e and Ar ^f , Ar ^g and Ar ^h may be bonded to each other to form a ring, and W 1 and W 2 have the same meanings as in general formula (1), X ¹ and X ² has the same meaning as in general formula (1).)

The naphthalene ring in the general formula (1-1) includes substituents — (X ¹ NA Ar ⁱ Ar ^j NAr ^f Ar ^e ) and — (X ² NAr ^k Ar ^l NAr ^g ) each containing an arylamino group bonded to the naphthalene ring. In addition to Ar ^h ), it may have an arbitrary substituent. In addition, these substituents — (X ¹ NA ⁱ Ar ^j NAr ^f Ar ^e ) and — (X ² NAr ^k Ar ^l NAr ^g Ar ^h ) have a substituent at any substitution position of the naphthalene ring. Also good. Especially, the binaphthyl type compound substituted to 4-position and 4'-position of the naphthalene ring in General formula (1-1) respectively is more preferable.

  Moreover, as a high molecular compound which has a positive hole transport site | part in a molecule | numerator used as a hole injectable compound, the high molecular compound which contains an aromatic tertiary amino group in a main skeleton as a structural unit is mentioned, for example. Specific examples thereof include a hole injecting compound having a structure represented by the following general formula (2) as a repeating unit.

(In formula (2), Ar ^{44 to} Ar ⁴⁸ each independently represent a divalent aromatic ring group which may have a substituent, and R ^a31 and R ^a32 each independently represent a substituent. And Q is selected from a direct bond or the following linking group, wherein “aromatic ring group” means “derived from an aromatic hydrocarbon ring” Including "group" and "group derived from an aromatic heterocycle")

(In formula (3), Ar ⁴⁹ represents a divalent aromatic ring group which may have a substituent, and Ar ⁵⁰ represents a monovalent aromatic ring group which may have a substituent. .)

In the general formula (2), Ar ^{44 to} Ar ⁴⁸ are each preferably a group derived from a divalent benzene ring, naphthalene ring, anthracene ring or biphenyl group which may each independently have a substituent, A group derived from a benzene ring is preferred. Examples of the substituent include a halogen atom; a linear or branched alkyl group having 1 to 6 carbon atoms such as a methyl group and an ethyl group; an alkenyl group such as a vinyl group; and a C 2-7 such as a methoxycarbonyl group and an ethoxycarbonyl group. A linear or branched alkoxycarbonyl group of 1 to 6 carbon atoms such as a methoxy group or an ethoxy group; an aryloxy group of 6 to 12 carbon atoms such as a phenoxy group or a benzyloxy group; And a dialkylamino group having an alkyl chain having 1 to 6 carbon atoms such as a diisopropylamino group. Of these, an alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group is particularly preferable. The case where Ar ^{44 to} Ar ⁴⁸ are all unsubstituted aromatic ring groups is particularly preferable.

R ^a31 and R ^a32 are preferably each independently a phenyl group, naphthyl group, anthryl group, pyridyl group, triazyl group, pyrazyl group, quinoxalyl group, thienyl group, or biphenyl group, which may have a substituent. Preferably a phenyl group, a naphthyl group or a biphenyl group, more preferably a phenyl group. Examples of the substituent include a group in which an aromatic ring in Ar ⁴⁴ to Ar ⁴⁸ may have include the same groups as previously described.

In the general formula (3), Ar ⁴⁹ is a divalent aromatic ring group which may have a substituent, preferably an aromatic hydrocarbon ring group from the viewpoint of hole transportability. Includes a divalent benzene ring, naphthalene ring, anthracene ring-derived group, biphenylene group, and terphenylene group which may have a substituent. Further, examples of the substituent include a group in which an aromatic ring may have at Ar ⁴⁴ to Ar ^48, include the same groups as previously described. Of these, an alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group is particularly preferable.

Ar ⁵⁰ is an aromatic ring group which may have a substituent, preferably an aromatic hydrocarbon ring group from the viewpoint of hole transportability, and specifically, phenyl which may have a substituent. Group, naphthyl group, anthryl group, pyridyl group, triazyl group, pyrazyl group, quinoxalyl group, thienyl group, biphenyl group and the like. As this substituent, the group similar to the group mentioned above is mentioned as a group which the aromatic ring in Ar < ⁴⁴ > -Ar < ⁴⁸ > of General formula (2) may have.
In the general formula (3), it is particularly preferable that Ar ⁴⁹ and Ar ⁵⁰ are both unsubstituted aromatic ring groups.

  Examples of the hole injecting compound including an aromatic tertiary amino group as a side chain include compounds having a repeating unit having a structure represented by the following general formulas (4) and (5).

（式（４）中、Ａｒ^５１は置換基を有していてもよい２価の芳香族環基を示し、Ａｒ^５２〜Ａｒ^５３は、各々独立して置換基を有していてもよい１価の芳香族環基を示し、Ｒ^ａ３３〜Ｒ^ａ３５は、各々独立して水素原子、ハロゲン原子、アルキル基、アルコキシ基、置換基を有していてもよい１価の芳香族環基を示す。）

(In formula (4), Ar ⁵¹ represents a divalent aromatic ring group which may have a substituent, and Ar ^{52 to} Ar ⁵³ may each independently have a substituent 1. R ^{a33 to} R ^a35 each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a monovalent aromatic ring group which may have a substituent. .)

(In the formula (5), Ar ^{54 to} Ar ⁵⁸ each independently represent a divalent aromatic ring group which may have a substituent, and R ³⁶ and R ³⁷ each independently represent a substituent. And Y is selected from a direct bond or the following linking group.)

In the general formula (4), Ar ⁵¹ is preferably a divalent benzene ring, a naphthalene ring, a group derived from an anthracene ring, or a biphenylene group each optionally having a substituent. For example, examples of the group that the aromatic ring in Ar ^{44 to} Ar ⁴⁸ in the general formula (2) described above may have include the same groups as those described above, and preferred groups are also the same.

Ar ⁵² and Ar ⁵³ are preferably each independently a phenyl group, a naphthyl group, an anthryl group, a pyridyl group, a triazyl group, a pyrazyl group, a quinoxalyl group, a thienyl group, and a biphenyl group. May have. Examples of the substituent include the same groups as those described above as the group that the aromatic ring in Ar ^{44 to} Ar ⁴⁸ of the general formula (2) may have, and preferred groups are also the same.

R ^{a33 to} R ^a35 are preferably each independently a hydrogen atom; a halogen atom; a linear or branched alkyl group having 1 to 6 carbon atoms such as a methyl group or an ethyl group; a carbon such as a methoxy group or an ethoxy group; A linear or branched alkoxy group of 1 to 6; a phenyl group; or a tolyl group.

In the general formula (5), Ar ^{54 to} Ar ⁵⁸ are preferably a divalent benzene ring, a naphthalene ring, a group derived from an anthracene ring, or a biphenylene group, each of which may have a substituent. A group derived from a benzene ring. Examples of the substituent include the same groups as those described above as the groups that the aromatic ring in Ar ^{44 to} Ar ⁴⁸ of formula (2) may have, and preferred groups are also the same.

R ³⁶ and R ³⁷ are each preferably a phenyl group, a naphthyl group, an anthryl group, a pyridyl group, a triazyl group, a pyrazyl group, a quinoxalyl group, a thienyl group, or a biphenyl group, each of which may have a substituent. . Examples of the substituent include the same groups as those described above as the groups that the aromatic ring in Ar ^{44 to} Ar ⁴⁸ of formula (2) may have, and preferred groups are also the same.

  Preferred examples of the structures represented by the general formulas (2) to (5) are shown below, but are not limited thereto.

  The hole injecting compound which is a polymer compound having a hole transporting site in the molecule is particularly preferably a homopolymer having a structure represented by any one of the general formulas (2) to (5). It may be a copolymer (copolymer) with any monomer. When it is a copolymer, it is preferable to contain 50 mol% or more, especially 70 mol% or more of the structural units represented by the general formulas (2) to (5). In addition, the hole injectable material which is a high molecular compound may contain multiple types of structures represented by the general formulas (2) to (5) in one compound. Moreover, you may use in combination of multiple types of the compound containing the structure represented by General formula (2)-(5). Of the general formulas (2) to (5), a homopolymer composed of a repeating unit represented by the general formula (2) is particularly preferable.

  Examples of the hole injecting material made of a polymer compound further include conjugated polymers. For this purpose, polyfluorene, polypyrrole, polyaniline, polythiophene, polyparaphenylene vinylene are preferred.

(2-3-2) Electron-accepting compound The type of electron-accepting compound used as the material for the hole injection layer is arbitrary as long as the effects of the present invention are not significantly impaired. Examples thereof include onium salts substituted with an organic group such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pendafluorophenyl) borate and triphenylsulfonium tetrafluoroborate; No. 251067), high-valence inorganic compounds such as ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene; aromatic boron compounds such as tris (pendafluorophenyl) borane (JP-A-2003-31365); fullerene derivatives ; Iodine etc. are mentioned. Of the above compounds, an onium salt substituted with an organic group is preferable in terms of having strong oxidizing power, and an inorganic compound having a high valence is preferable, and an onium salt substituted with an organic group in terms of being soluble in various solvents, A cyano compound and an aromatic boron compound are preferable. Furthermore, an onium salt substituted with an organic group is particularly preferred from the viewpoint of achieving both strong oxidizing power and high solubility, and particularly preferred are compounds represented by the following formulas (II-1) to (II-3). .

(In the above formulas (II-1) to (II-3), R ¹¹ , R ²¹ and R ³¹ each independently represents an organic group bonded to A ^{1 to} A ³ via a carbon atom. R ¹² , R ²² , R ²³ and R ^{32 to} R ³⁴ each independently represents an arbitrary group, and two or more adjacent groups of R ^{11 to} R ³⁴ may be bonded to each other to form a ring. A ^{1 to} A ³ are all elements of the long period type periodic table (hereinafter, unless otherwise specified, the term “periodic table” refers to the long period type periodic table). there are, a ¹ represents an element belonging to group 17 of the periodic table, a ² represents an element belonging to group 16 of the periodic table, a ³ is .Z ₁ representing an element belonging to group 15 of the periodic table ^n1- to Z ₃ ^n3- each independently, _.n 1 ~n ₃ which represents a counter anion, each independently, vs. Ani It represents the ion value of the emissions.)

In the above formulas (II-1) to (II-3), R ¹¹ , R ²¹ and R ³¹ each independently represents an organic group bonded to A ^{1 to} A ³ via a carbon atom. Therefore, the type of R ¹¹ , R ²¹ and R ³¹ is not particularly limited as long as it is an organic group having a carbon atom at the bonding portion with A ^{1 to} A ³ as long as it is not contrary to the gist of the present invention.
The molecular weights of R ¹¹ , R ²¹ and R ³¹ are each a value including the substituent, and are usually 1000 or less, preferably 500 or less.

Preferable examples of R ¹¹ , R ²¹ and R ³¹ include an alkyl group, an alkenyl group, an alkynyl group, an aromatic hydrocarbon group, and an aromatic heterocyclic group from the viewpoint of delocalizing a positive charge. Among them, an aromatic hydrocarbon group or an aromatic heterocyclic group is preferable because it delocalizes positive charges and is thermally stable.

The alkyl group includes, for example, a linear, branched or cyclic alkyl group having a carbon number of usually 1 or more and usually 12 or less, preferably 6 or less. Specific examples include methyl group, ethyl group, n-propyl group, 2-propyl group, n-butyl group, isobutyl group, tert-butyl group, cyclohexyl group and the like.
Examples of the alkenyl group include those having usually 2 or more, usually 12 or less, preferably 6 or less carbon atoms. Specific examples include a vinyl group, an allyl group, and a 1-butenyl group.

Examples of the alkynyl group include those having usually 2 or more, usually 12 or less, preferably 6 or less. Specific examples include ethynyl group and propargyl group.
Examples of the aromatic hydrocarbon group include a monovalent group derived from a 5- or 6-membered monocyclic ring or a 2 to 5 condensed ring, and a group in which a positive charge is delocalized on the group. . Specific examples thereof include a monovalent group derived from a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluorene ring, and the like. Can be mentioned.

  Examples of the aromatic heterocyclic group include a monovalent group derived from a 5- or 6-membered monocyclic ring or a 2-4 condensed ring, and a group in which a positive charge is delocalized on the group. . Specific examples thereof include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, triazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, Pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline And monovalent groups derived from a ring, an isoquinoline ring, a sinoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, an azulene ring, and the like.

In the above formulas (II-1) to (II-3), R ¹² , R ²² , R ²³ and R ^{32 to} R ³⁴ each independently represents an arbitrary substituent. Therefore, the types of R ¹² , R ²² , R ²³ and R ^{32 to} R ³⁴ are not particularly limited as long as they are not contrary to the spirit of the present invention.
The molecular weights of R ¹² , R ²² , R ²³ and R ^{32 to} R ³⁴ are values including the substituents, and are usually 1000 or less, preferably 500 or less.

Examples of R ¹² , R ²² , R ²³ and R ^{32 to} R ³⁴ include an alkyl group, an alkenyl group, an alkynyl group, an aromatic hydrocarbon group, an aromatic heterocyclic group, an amino group, an alkylamino group, and an arylamino group. , Acylamino group, alkoxy group, aryloxy group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylcarbonyloxy group, alkylthio group, arylthio group, sulfonyl group, alkylsulfonyl group, arylsulfonyl group, sulfonyloxy group, cyano Group, hydroxyl group, thiol group, silyl group and the like. Among them, like R ¹¹ , R ^21, and R ³¹ , an organic group having a carbon atom in the bonding portion with A ^{1 to} A ³ is preferable from the viewpoint of high electron acceptability. Examples include an alkyl group, an alkenyl group, Alkynyl groups, aromatic hydrocarbon groups, and aromatic heterocyclic groups are preferred. In particular, an aromatic hydrocarbon group or an aromatic heterocyclic group is preferable because it has a large electron accepting property and is thermally stable.
Examples of the alkyl group, alkenyl group, alkynyl group, aromatic hydrocarbon group and aromatic heterocyclic group are the same as those described above for R ¹¹ , R ²¹ and R ³¹ .

As described above, the groups exemplified as R ¹¹ , R ²¹ , R ³¹ , R ¹² , R ²² , R ²³ , and R ^{32 to} R ³⁴ are further substituted with other substituents unless they are contrary to the spirit of the present invention. It may be. The type of the substituent is not particularly limited, and examples thereof include a halogen atom in addition to the groups exemplified as R ¹¹ , R ²¹ , R ³¹ , R ¹² , R ²² , R ²³ , and R ^{32 to} R ³⁴ . A cyano group, a thiocyano group, a nitro group, etc. are mentioned. Among these, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryloxy group, an aromatic hydrocarbon group, and an aromatic heterocyclic group are preferable from the viewpoint of not hindering heat resistance and electron accepting property. In addition, the substituent to be further substituted may be substituted with only one, or two or more may be substituted with any combination and ratio.
In the formulas (II-1) to (II-3), two or more adjacent groups out of R ^{11 to} R ³⁴ may be bonded to each other to form a ring.

In formulas (II-1) to (II-3), A ^{1 to} A ³ are all elements after the third period (third to sixth periods) of the periodic table, and A ¹ is a long period type An element belonging to Group 17 of the periodic table is represented, A ² represents an element belonging to Group 16 and A ³ represents an element belonging to Group 15.
Among these, from the viewpoint of electron acceptability and availability, elements before the fifth period (third to fifth periods) of the periodic table are preferable. That is, A ¹ is preferably any ^one of an iodine atom, a bromine atom, and a chlorine atom, A ² is preferably any one of a tellurium atom, a selenium atom, and a sulfur atom, and A ³ is preferably an antimony atom, an arsenic atom, Any of the phosphorus atoms is preferred.

In particular, from the viewpoints of electron acceptability and compound stability, a compound in which A ¹ in formula (II-1) is a bromine atom or an iodine atom, or A ² in formula (II-2) is a selenium atom or a sulfur atom. Of these, a compound in which A ¹ in Formula (II-1) is an iodine atom is particularly preferable.

In formulas (II-1) to (II-3), Z ₁ ^{n1 to} Z ₃ ⁿ³ each independently represent a counter anion. The type of the counter anion is not particularly limited, and may be a monoatomic ion or a complex ion. However, the larger the size of the counter anion, the more the negative charge is delocalized, and the positive charge is also delocalized thereby increasing the electron accepting ability. Therefore, the complex ion is preferable to the monoatomic ion.

In formulas (II-1) to (II-3), n _{1 to} n ₃ are each independently any positive integer corresponding to the ionic value of the counter anion Z ₁ ^{n1 to} Z ₃ ⁿ³ . The values of n _{1 to} n ₃ are not particularly limited, but all are preferably 1 or 2, and particularly preferably 1.

Specific examples of Z ₁ ^{n1- to} Z ₃ ^n3- include hydroxide ions, fluoride ions, chloride ions, bromide ions, iodide ions, cyanide ions, nitrate ions, nitrite ions, sulfate ions, sulfite. Ion, perchlorate ion, perbromate ion, periodate ion, chlorate ion, chlorite ion, hypochlorite ion, phosphate ion, phosphite ion, hypophosphite ion, borate ion , Isocyanate ion, hydrosulfide ion, tetrafluoroborate ion, hexafluorophosphate ion, hexachloroantimonate ion; carboxylate ion such as acetate ion, trifluoroacetate ion, benzoate ion; methanesulfonate ion, trifluoro Sulfonate ions such as methane sulfonate ion; methoxy ions, t-butoxy ions, etc. Kokishiion and the like.

In particular, the counter anions Z ₁ ^{n1 to} Z ₃ ⁿ³ are preferably complex ions represented by the following formulas (II-4) to (II-6) from the viewpoint of stability of the compound and solubility in a solvent. In view of the large size, the negative charge is delocalized, and the positive charge is also delocalized to increase the electron accepting ability. Therefore, a complex ion represented by the following formula (II-6) is more preferable.

In formulas (II-4) and (II-6), E ¹ and E ³ each independently represent an element belonging to Group 13 of the long-period periodic table. Of these, a boron atom, an aluminum atom, and a gallium atom are preferable, and a boron atom is preferable from the viewpoint of stability of the compound and ease of synthesis and purification.
In formula (II-5), E ² represents an element belonging to Group 15 of the long-period periodic table. Among these, a phosphorus atom, an arsenic atom and an antimony atom are preferable, and a phosphorus atom is preferable from the viewpoint of stability of the compound, ease of synthesis and purification, and toxicity.

  In the formulas (II-4) and (II-5), X represents a halogen atom such as a fluorine atom, a chlorine atom, or a bromine atom, and is a fluorine atom in terms of stability of the compound, ease of synthesis and purification, A chlorine atom is preferable, and a fluorine atom is particularly preferable.

In the formula (II-6), Ar ^{61 to} Ar ⁶⁴ each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group. Examples of the aromatic hydrocarbon group and aromatic heterocyclic group are the same as those exemplified above for R ¹¹ , R ²¹ and R ³¹ , derived from a 5- or 6-membered monocyclic ring or a 2-4 condensed ring. A monovalent group is mentioned. Among these, a monovalent group derived from a benzene ring, a naphthalene ring, a pyridine ring, a pyrazine ring, a pyridazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, or an isoquinoline ring is preferable from the viewpoint of stability and heat resistance of the compound.

The aromatic hydrocarbon group and aromatic heterocyclic group exemplified as Ar ^{61 to} Ar ⁶⁴ may be further substituted with another substituent as long as not departing from the gist of the present invention. The type of the substituent is not particularly limited, and any substituent can be applied, but an electron-withdrawing group is preferable.

Illustrative examples of preferred electron-withdrawing groups as the substituent that Ar ^{61 to} Ar ⁶⁴ may have include halogen atoms such as fluorine atom, chlorine atom and bromine atom; cyano group; thiocyano group; nitro group; mesyl group Alkylsulfonyl groups such as tosyl group; arylsulfonyl groups such as tosyl group; acyl groups such as formyl group, acetyl group, benzoyl group and the like, usually having 1 or more, usually 12 or less, preferably 6 or less; methoxycarbonyl group, ethoxycarbonyl An alkoxycarbonyl group having 2 or more carbon atoms, usually 10 or less, preferably 7 or less; a phenoxycarbonyl group, a pyridyloxycarbonyl group or the like, and usually having 3 or more carbon atoms, preferably 4 or more and usually 25 or less. Preferably an aryloxycarbonyl group having 15 or less aromatic hydrocarbon groups or aromatic heterocyclic groups; Carbonyl group; aminosulfonyl group; fluorine atom in a linear, branched or cyclic alkyl group having usually 1 or more, usually 10 or less, preferably 6 or less, such as trifluoromethyl group or pentafluoroethyl group And a haloalkyl group substituted with a halogen atom such as a chlorine atom.

Especially, it is more preferable that at least one group out of Ar ^{61 to} Ar ⁶⁴ has one or two or more fluorine atoms or chlorine atoms as a substituent. In particular, it is particularly a perfluoroaryl group in which all the hydrogen atoms of Ar ^{61 to} Ar ⁶⁴ are substituted with fluorine atoms from the viewpoint of efficiently delocalizing negative charges and having an appropriate sublimation property. preferable. Specific examples of the perfluoroaryl group include a pentafluorophenyl group, a heptafluoro-2-naphthyl group, and a tetrafluoro-4-pyridyl group.
In addition, as for the said substituent, only one may be substituted and two or more may be substituted by arbitrary combinations and ratios.

  The formula amount of the complex ions represented by the formulas (II-4) to (II-6) is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 100 or more, preferably 300 or more, more preferably 400 or more. Moreover, it is usually 5000 or less, preferably 3000 or less, more preferably 2000 or less. If the formula amount of the complex ion is too small, delocalization of the positive charge and the negative charge is insufficient, so that the electron accepting ability may be decreased, and if the formula amount of the complex ion is too large, The compound itself may interfere with charge transport.

  As the material for the hole injection layer, any one of the various electron-accepting compounds described above may be used alone, or two or more may be used in any combination and ratio. When two or more kinds of electron-accepting compounds are used, two or more kinds of electron-accepting compounds corresponding to any one of the formulas (II-1) to (II-3) may be combined. Two or more electron-accepting compounds corresponding to different formulas may be combined.

  The content of the electron-accepting compound in the hole injection layer 3 and the composition for hole injection layer is arbitrary as long as the effects of the present invention are not significantly impaired. The value relative to the pore-transporting compound is usually 0.1% by weight or more, preferably 1% by weight or more, and usually 100% by weight or less, preferably 60% by weight or less, more preferably 50% by weight or less. A larger amount of the electron-accepting compound is preferable because it is easier to insolubilize, and the heating time can be insolubilized in a short time. In addition, when using together 2 or more types of electron-accepting compounds, it is made for the total content of these to be contained in the said range.

  In addition, when the hole injection layer 3 is formed or after the formation, the above hole transporting polymer or the following hole transporting compound reacts with the electron accepting compound, so that the hole injection after the formation is performed. In the layer 3, a cation radical and an ionic compound of a hole transporting polymer or a hole transporting compound may be generated.

(Low molecular weight hole transport compound)
As a material for the hole injection layer, it is preferable to use a low molecular weight hole transporting compound as necessary. The low molecular weight hole transporting compound can be appropriately selected from various compounds conventionally used as a hole injection / transport thin film purification material in an organic EL device. Among them, those having high solvent solubility are preferable.
Preferable examples of the low molecular weight hole transporting compound include aromatic amine compounds. Of these, aromatic tertiary amine compounds are particularly preferred.

The molecular weight of the low molecular weight hole transporting compound is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 200 or more, preferably 400 or more, more preferably 600 or more, and usually 5000 or less, preferably Is not more than 3000, more preferably not more than 2000, still more preferably not more than 1700, particularly preferably not more than 1400. If the molecular weight is too small, the heat resistance tends to be low, whereas if the molecular weight of the low molecular weight hole transporting compound is too large, synthesis and purification tend to be difficult.
In addition, a low molecular weight hole transportable compound may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

(Other ingredients)
As a material for the hole injection layer, in addition to the above-described polymer having a hole transporting property, an electron-accepting compound and a hole-transporting compound, as long as the effects of the present invention are not significantly impaired, it further contains other components. You may let them. Examples of other components include various light emitting materials, electron transporting compounds, binder resins, coatability improving agents, and the like. In addition, only 1 type may be used for another component and it may use 2 or more types together by arbitrary combinations and ratios.

(Formation of hole injection layer)
When the hole injection layer 3 is formed by a wet film formation method, the above-described material is dissolved in an appropriate solvent to prepare a coating composition, and a film is formed using it. Moreover, when forming by a specific organic layer formation method, it forms by passing through a preservation | save process and a heating process after a film-forming process. These details are the same as the contents explained in the section of “1. Specific organic layer forming method” above. In addition, when forming another organic layer by a specific organic layer formation method, you may use another method for formation of the positive hole injection layer 3. FIG. Hereinafter, the case where it forms with a specific organic layer formation method is demonstrated. The film formation method of the hole injection layer 3 is a wet film formation method below, but is not particularly limited to the wet film formation method, and may be a vacuum deposition method or the like.

  As the hole injection layer solvent to be contained in the composition for hole injection layer, any solvent can be used as long as the hole injection layer 3 can be formed. However, among the aforementioned polymers, electron-accepting compounds, and low-molecular-weight hole-transporting compounds, those capable of dissolving at least one, particularly two or more, and particularly all three are preferable. Specifically, the solubility of the polymer is usually 0.005% by weight or more, particularly 0.5% by weight or more, particularly 1% by weight or more at room temperature and normal pressure. It is preferable to dissolve 0.001% by weight or more, especially 0.1% by weight or more, particularly 0.2% by weight or more.

In addition, as the solvent for the hole injection layer, a polymer, an electron-accepting compound, a low-molecular-weight hole-transporting compound, and an inactive substance that can deactivate a free carrier (cation radical) generated from a mixture thereof, or A solvent that does not contain a substance that generates a deactivating substance is preferred.
Suitable examples of the solvent for the hole injection layer are the same as those described in “1. Specific organic layer forming method”. However, aromatic hydrocarbon solvents such as benzene, toluene, and xylene have a low ability to dissolve the oxidant and the polymer, and are therefore preferably used in a mixture with an ether solvent and an ester solvent.

  The ratio of the hole injection layer solvent to the hole injection layer composition is arbitrary as long as the effects of the present invention are not significantly impaired, but is usually 10% by weight or more, preferably 30% by weight or more, more preferably 50%. It is in the range of not less than weight, usually not more than 99.999% by weight, preferably not more than 99.99% by weight, and more preferably not more than 99.9% by weight. In addition, when mixing and using 2 or more types of solvents as a solvent for positive hole injection layers, it is made for the sum total of these solvents to satisfy | fill this range.

  After the application / film formation of the composition for hole injection layer, the obtained coating film is dried, and the hole injection layer 3 is formed by removing the solvent for hole injection layer. Further thereafter, the hole injection layer 3 is stored for a certain period of time and subjected to heat treatment. The wet film formation method, the drying method, the storage method, and the heat treatment method are not limited as long as the effects of the present invention are not significantly impaired, and any of those described in the section of “1. Specific organic layer formation method” A scheme can also be used.

  The thickness of the hole injection layer 3 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less.

2-4. Light-Emitting Layer A light-emitting layer 5 is provided on the hole injection layer 3. The light emitting layer 5 is excited by recombination of holes injected from the anode 2 through the hole injection layer 3 and electrons injected from the cathode 9 through the electron injection layer 8 between the electrodes to which an electric field is applied. , Which is the main light-emitting layer.

(2-4-1) Light-Emitting Layer Material The light-emitting layer 5 contains at least a material having a light-emitting property (light-emitting material) as a constituent material, and preferably a compound having a hole-transporting property ( A hole transporting compound) or a compound having an electron transporting property (electron transporting compound). There is no particular limitation on the light-emitting substance, and a substance that emits light at a desired emission wavelength and has high emission efficiency may be used. Moreover, it is preferable to contain two or more charge transport compounds. Furthermore, the light emitting layer 5 may contain other components as long as the effects of the present invention are not significantly impaired. In addition, when forming the light emitting layer 5 by the specific organic layer formation method, it is preferable to use a low molecular compound in any case. In addition, a low molecular compound means the compound whose weight average molecular weight is 6000 or less normally, Preferably it is 5000 or less, More preferably, it is 1500 or less.

(2-4-2) Light-Emitting Material Any known material can be applied as the light-emitting material. For example, a fluorescent material or a phosphorescent material may be used, but a phosphorescent material is preferable from the viewpoint of internal quantum efficiency.
For the purpose of improving the solubility in a solvent, it is preferable to reduce the symmetry and rigidity of the molecules of the luminescent material, or to introduce a lipophilic substituent such as an alkyl group.
Hereinafter, although the example of a fluorescent dye is mentioned among light emitting materials, a fluorescent dye is not limited to the following illustrations.

Examples of the fluorescent dye that gives blue light emission (blue fluorescent dye) include perylene, pyrene, anthracene, coumarin, p-bis (2-phenylethenyl) benzene, and derivatives thereof.
Examples of fluorescent dyes that give green light emission (green fluorescent dyes) include quinacridone derivatives and coumarin derivatives.
Examples of fluorescent dyes that give yellow light (yellow fluorescent dyes) include rubrene and perimidone derivatives.

  Examples of fluorescent dyes that give red luminescence (red fluorescent dyes) include DCM (4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran) compounds, benzopyran derivatives, rhodamine derivatives, benzoates. Examples thereof include thioxanthene derivatives and azabenzothioxanthene.

Next, phosphorescent materials among the light emitting materials will be described. Examples of the phosphorescent material include an organometallic complex containing a metal selected from Groups 7 to 11 of the periodic table.
Preferred examples of the metal selected from Groups 7 to 11 of the periodic table contained in the phosphorescent organometallic complex include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. . Preferred examples of these organometallic complexes include compounds represented by the following formula (V) or formula (VI).

｛式（Ｖ）中、Ｍは金属を表わし、ｑは上記金属の価数を表わす。また、Ｌ及びＬ’は二座配位子を表わす。ｊは０、１又は２の数を表わす。｝

{In Formula (V), M represents a metal, and q represents the valence of the metal. L and L ′ represent bidentate ligands. j represents a number of 0, 1 or 2. }

｛式（VI）中、Ｍ^７は金属を表わし、Ｔは炭素原子又は窒素原子を表わす。Ｒ^９２〜Ｒ^９５は、それぞれ独立に置換基を表わす。但し、Ｔが窒素原子の場合は、Ｒ^９４及びＲ^９５は無い。｝

{In Formula (VI), M ⁷ represents a metal, and T represents a carbon atom or a nitrogen atom. R ^{92 to} R ⁹⁵ each independently represents a substituent. However, when T is a nitrogen atom, R ⁹⁴ and R ⁹⁵ are absent. }

Hereinafter, the compound represented by the formula (V) will be described first.
In formula (V), M represents an arbitrary metal, and specific examples of preferable ones include the metals described above as metals selected from Groups 7 to 11 of the periodic table.
In the formula (V), the bidentate ligand L represents a ligand having the following partial structure.

In the partial structure of L, ring A1 ″ represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.
Examples of the aromatic hydrocarbon group constituting the ring A1 ″ include a 5- or 6-membered monocyclic ring or a 2-5 condensed ring. Specific examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene. And a monovalent group derived from a ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring.

Examples of the aromatic heterocyclic group constituting the ring A1 ″ include a 5- or 6-membered monocyclic ring or a 2-4 condensed ring. Specific examples thereof include a furan ring, a benzofuran ring, a thiophene ring, and a benzoic ring. Thiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring , Benzoisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, cinnoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring , Perimidine ring, key Gelsolin ring, quinazolinone ring, and a monovalent group derived from azulene ring.
In the partial structure of L, ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

  Examples of the nitrogen-containing aromatic heterocyclic group constituting the ring A2 include a 5- or 6-membered monocyclic ring or a 2-4 condensed ring. Specific examples thereof include pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, furopyrrole ring, thienofuran ring, benzoisoxazole Ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, And monovalent group derived from a quinazolinone ring.

Examples of the substituent that each ring A1 ″ or ring A2 may have include: a halogen atom such as a fluorine atom; an alkyl group such as a methyl group and an ethyl group; an alkenyl group such as a vinyl group; a methoxycarbonyl group and an ethoxy group Alkoxycarbonyl groups such as carbonyl groups; alkoxy groups such as methoxy groups and ethoxy groups; aryloxy groups such as phenoxy groups and benzyloxy groups; dialkylamino groups such as dimethylamino groups and diethylamino groups; diarylamino groups such as diphenylamino groups Carbazolyl group; acyl group such as acetyl group; haloalkyl group such as trifluoromethyl group; cyano group; aromatic hydrocarbon group such as phenyl group, naphthyl group, phenanthyl group and the like.
In addition, as for the said substituent, only 1 may be substituted and 2 or more may be substituted by arbitrary combinations and ratios.

  In formula (V), bidentate ligand L ′ represents a ligand having at least one of the following partial structures. In the following formulae, “Ph” represents a phenyl group.

  Among these, as L ′, the following ligands are preferable from the viewpoint of the stability of the complex.

  More preferred examples of the compound represented by the formula (V) include compounds represented by at least one of the following formulas (Va), (Vb) and (Vc).

｛式（Ｖａ）中、Ｍ^４は、Ｍと同様の金属を表わし、ｗは、上記金属の価数を表わし、環Ａ１”は、置換基を有していてもよい芳香族炭化水素基を表わし、環Ａ２は、置換基を有していてもよい含窒素芳香族複素環基を表わす。｝

{In Formula (Va), M ⁴ represents the same metal as M, w represents the valence of the metal, and ring A1 ″ represents an aromatic hydrocarbon group which may have a substituent. Ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.}

{In Formula (Vb), M ⁵ represents the same metal as M, w represents the valence of the metal, and ring A1 ″ represents an aromatic hydrocarbon group which may have a substituent or Represents an aromatic heterocyclic group, and ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.}

{In Formula (Vc), M ⁶ represents the same metal as M, w represents the valence of the metal, j represents 0, 1 or 2, ring A1 "and ring A1 'represent Each independently represents an optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group, and ring A2 and ring A2 ′ are each independently a nitrogen-containing optionally substituted group. Represents an aromatic heterocyclic group.}

  In the above formulas (Va), (Vb) and (Vc), preferred examples of the ring A1 ″ and the ring A1 ′ include a phenyl group, a biphenyl group, a naphthyl group, an anthryl group, a thienyl group, a furyl group, a benzothienyl group, A benzofuryl group, a pyridyl group, a quinolyl group, an isoquinolyl group, a carbazolyl group, and the like can be given.

  In the above formulas (Va), (Vb) and (Vc), preferred examples of ring A2 and ring A2 ′ include pyridyl group, pyrimidyl group, pyrazyl group, triazyl group, benzothiazole group, benzoxazole group, and benzimidazole group. Quinolyl group, isoquinolyl group, quinoxalyl group, phenanthridyl group and the like.

  Examples of the substituent that the compound represented by any one of the formulas (Va), (Vb), and (Vc) may have include a halogen atom such as a fluorine atom; an alkyl group such as a methyl group and an ethyl group Alkenyl groups such as vinyl groups; alkoxycarbonyl groups such as methoxycarbonyl groups and ethoxycarbonyl groups; alkoxy groups such as methoxy groups and ethoxy groups; aryloxy groups such as phenoxy groups and benzyloxy groups; dimethylamino groups and diethylamino groups A diarylamino group such as a diphenylamino group; a carbazolyl group; an acyl group such as an acetyl group; a haloalkyl group such as a trifluoromethyl group; a cyano group and the like.

  The carbon number of the substituent is arbitrary as long as the effects of the present invention are not significantly impaired. However, when the substituent is an alkyl group, the carbon number is usually 1 or more and 6 or less. When the substituent is an alkenyl group, the carbon number is usually 2 or more and 6 or less. When the substituent is an alkoxycarbonyl group, the carbon number is usually 2 or more and 6 or less. Moreover, when a substituent is an alkoxy group, the carbon number is 1 or more and 6 or less normally. Moreover, when a substituent is an aryloxy group, the carbon number is 6 or more and 14 or less normally. Moreover, when a substituent is a dialkylamino group, the carbon number is 2 or more and 24 or less normally. Moreover, when a substituent is a diarylamino group, the carbon number is 12 or more and 28 or less normally. When the substituent is an acyl group, the carbon number is usually 1 or more and 14 or less. Moreover, when a substituent is a haloalkyl group, the carbon number is 1 or more and 12 or less normally.

  The above substituents may be linked to each other to form a ring. As a specific example, whether the substituent of the ring A1 ″ and the substituent of the ring A2 are bonded, or the substituent of the ring A1 ′ and the substituent of the ring A2 ′ are bonded, One condensed ring may be formed, and examples of such a condensed ring include a 7,8-benzoquinoline group.

  Among the above-described substituents, the substituents of ring A1 ″, ring A1 ′, ring A2 and ring A2 ′ are more preferably alkyl groups, alkoxy groups, aromatic hydrocarbon groups, cyano groups, halogen atoms, haloalkyl groups. , Diarylamino group and carbazolyl group. In addition, as for the substituents of ring A1 ″, ring A1 ′, ring A2 and ring A2 ′, only one may be substituted or two or more may be in any combination. And may be substituted by a ratio.

In addition, preferable examples of M ^{4 to} M ⁶ in the formulas (Va), (Vb), and (Vc) include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, or gold.
Specific examples of the organometallic complex represented by any one of the above formulas (V), (Va), (Vb) and (Vc) are shown below. However, it is not limited to the following compounds.

Further, among the organometallic complexes represented by the above formula (V), in particular, as the ligand L and / or L ′, a 2-arylpyridine-based ligand (that is, 2-arylpyridine, an arbitrary substituent group) And a compound having an arbitrary group condensed thereto) are preferable.
The compounds described in International Publication No. 2005/019373 pamphlet can also be used as the light emitting material.

Next, the compound represented by formula (VI) will be described.
In the formula (VI), M ⁷ represents a metal. Specific examples include the metals described above as the metal selected from Groups 7 to 11 of the periodic table. Among these, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold is preferable, and divalent metals such as platinum and palladium are particularly preferable.

In the formula (VI), R ⁹² and R ⁹³ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, a carboxyl group, It represents at least one selected from the group consisting of an alkoxy group, an alkylamino group, an aralkylamino group, a haloalkyl group, a hydroxyl group, an aryloxy group, an aromatic hydrocarbon group, and an aromatic heterocyclic group. Each R ⁹² and R ⁹³ may be the same or different.

Further, when T is a carbon atom in the formula (VI), R ⁹⁴ and R ⁹⁵ each independently represent a substituent represented by the same examples as R ⁹² and R ⁹³ . Further, in the formula (VI), when T is a nitrogen atom, R ⁹⁴ and R ⁹⁵ are absent. Each T may be the same or different.

In the formula (VI), R ^{92 to} R ⁹⁵ may further have a substituent. When it has a substituent, there is no restriction | limiting in particular in the kind, Arbitrary groups can be made into a substituent. Moreover, as for the substituent, only 1 may be substituted and 2 or more may be substituted by arbitrary combinations and ratios.

Furthermore, in the formula (VI), any two or more groups out of R ^{92 to} R ⁹⁵ may be connected to each other to form a ring.

  Specific examples (T-1 to T-7) of the organometallic complex represented by the formula (VI) are shown below. However, it is not limited to the following examples. In the following chemical formulae, Me represents a methyl group, and Et represents an ethyl group.

  The molecular weight of the compound used as the light emitting material is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 10,000 or less, preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less, and usually 100 or more, Preferably it is 200 or more, More preferably, it is 300 or more, More preferably, it is the range of 400 or more. If the molecular weight is too small, the heat resistance is remarkably reduced, gas generation is caused, the quality of the layer is lowered when the layer is formed, or the morphology of the organic EL element is changed due to migration or the like. Sometimes. On the other hand, if the molecular weight is too large, it tends to be difficult to purify the organic compound, or it may take time to dissolve in the solvent.

In addition, any 1 type may be used for the luminescent material mentioned above, and 2 or more types may be used together by arbitrary combinations and a ratio.

  The ratio of the light emitting material in the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.05% by weight or more, preferably 0.3% by weight or more, more preferably 0.5% by weight or more. In addition, it is usually 35% by weight or less, preferably 25% by weight or less, and more preferably 20% by weight or less. If the amount of the light emitting material is too small, uneven light emission may occur. If the amount is too large, the light emission efficiency may be reduced. In addition, when using together 2 or more types of luminescent material, it is made for the total content of these to be contained in the said range.

(Hole transporting compound)
Further, the light emitting layer 5 may contain a hole transporting compound as a constituent material. Here, among the hole transporting compounds, examples of the low molecular weight hole transporting compound include, in addition to the various compounds exemplified in the above-mentioned column of (Low molecular weight hole transporting compound), for example, 4 , 4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl, which includes two or more tertiary amines and two or more condensed aromatic rings substituted with nitrogen atoms Aromatic amine compounds having a starburst structure such as diamine (Japanese Patent Laid-Open No. 5-234811), 4,4 ′, 4 ″ -tris (1-naphthylphenylamino) triphenylamine (Journal of Luminescence, 1997, Vol. 72-74, pp. 985), aromatic amine compounds consisting of tetramers of triphenylamine (Chemical Communications, 19). 6 years, pp. 2175), spiro compounds such as 2,2 ′, 7,7′-tetrakis- (diphenylamino) -9,9′-spirobifluorene (Synthetic Metals, 1997, Vol. 91, pp. 9 209) etc. In addition, in the light emitting layer 5, only 1 type may be used for a positive hole transport compound, and it may use 2 or more types together by arbitrary combinations and a ratio.

  The ratio of the hole transporting compound in the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.1% by weight or more, preferably 0.5% by weight or more, more preferably 1% by weight. In addition, it is usually 99% by weight or less, preferably 95% by weight or less, and more preferably 90% by weight or less. If the amount of the hole transporting compound is too small, it may be easily affected by a short circuit, and if it is too large, the film thickness may be uneven. In addition, when using together 2 or more types of hole transportable compounds, it is made for the total content of these to be contained in the said range.

(Electron transporting compound)
The light emitting layer 5 may contain an electron transporting compound as a constituent material. Here, among the electron transporting compounds, examples of low molecular weight electron transporting compounds include 2,5-bis (1-naphthyl) -1,3,4-oxadiazole (BND), 2,5, -Bis (6 '-(2', 2 "-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy), bathophenanthroline (BPhen), 2,9-dimethyl-4,7 -Diphenyl-1,10-phenanthroline (BCP, bathocuproin), 2- (4-biphenylyl) -5- (p-tertiarybutylphenyl) -1,3,4-oxadiazole (tBu-PBD), 4 , 4′-bis (9-carbazole) -biphenyl (CBP), etc. In the light emitting layer 5, only one type of electron transporting compound may be used, or two or more types may be combined arbitrarily. It may be used in combination with not proportion.

  The ratio of the electron transporting compound in the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.1% by weight or more, preferably 0.5% by weight or more, more preferably 1% by weight or more. In addition, it is usually 99% by weight or less, preferably 95% by weight or less, and more preferably 90% by weight or less. If the amount of the electron transporting compound is too small, it may be easily affected by a short circuit, and if it is too large, the film thickness may be uneven. In addition, when using together 2 or more types of electron transport compounds, it is made for the total content of these to be contained in the said range.

(Formation of light emitting layer)
When forming the light emitting layer 5 by the wet film-forming method, it forms by coating the composition mentioned above by dissolving the above-mentioned material in a suitable solvent, and forming into a film using it. In addition, when forming a light emitting layer by the specific organic layer formation method, it forms by passing through a preservation | save process and a heating process after the film-forming process. These details are the same as the contents explained in the section of “1. Specific organic layer forming method” above. In addition, when forming another organic layer by the specific organic layer formation method, you may use another method for formation of the light emitting layer 5. FIG. Hereinafter, the case where it forms with a specific organic layer formation method is demonstrated. In addition, as a film-forming method of the light emitting layer 5, a wet film-forming method will be described below.

  As the light emitting layer solvent to be contained in the coating composition for producing the light emitting layer 5, any solvent can be used as long as the light emitting layer 5 can be formed. However, those capable of dissolving the light-emitting material, the hole transporting compound, and the electron transporting compound described above are preferable. Specifically, the solubility of the light emitting material, the hole transporting compound, or the electron transporting compound is usually 0.01% by weight or more, particularly 0.05% by weight or more, and particularly preferably 0.00% at room temperature and normal pressure. It is preferable to dissolve 1% by weight or more.

Suitable examples of the solvent for the light emitting layer are the same as those described in “1. Specific organic layer forming method”.
The ratio of the solvent for the light emitting layer to the coating composition for producing the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.01% by weight or more, preferably 0.1% by weight. Above, more preferably 0.5% by weight or more, and usually 70% by weight or less, preferably 60% by weight or less, more preferably 50% by weight or less. In addition, when mixing and using 2 or more types of solvents as a solvent for light emitting layers, it is made for the sum total of these solvents to satisfy | fill this range.

After the coating composition for producing the light emitting layer 5 is applied and formed, the obtained coating film is dried and the light emitting layer solvent is removed to form the light emitting layer 5. The method of the wet film forming method is not limited as long as the effects of the present invention are not significantly impaired, and any method described in the section of “1. Specific organic layer forming method” can be used.
Further, the storage method and the heat treatment method are not limited as long as they are similar to the method described in “1. Specific organic layer forming method”.

  The thickness of the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 3 nm or more, preferably 5 nm or more, and usually 200 nm or less, preferably 100 nm or less. If the thickness of the light emitting layer 5 is too thin, defects may occur in the light emitting layer, and if it is too thick, the driving voltage of the organic EL element may increase.

2-5. Electron Transport Layer An electron transport layer 7 can be formed on the light emitting layer 5. The electron transport layer 7 is provided for the purpose of further improving the light emission efficiency of the device, and efficiently transports electrons injected from the cathode 9 between the electrodes to which an electric field is applied in the direction of the light emitting layer 5. Formed from a compound capable of

  As an electron transporting compound used for the electron transport layer 7, usually, the electron injection efficiency from the cathode 9 or the electron injection layer 8 is high, and the injected electrons having high electron mobility are efficiently transported. The compound which can be used is used. Examples of the compound satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, oxadiazole derivatives , Distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compounds ( JP-A-6-207169), phenanthroline derivative (JP-A-5-331459), 2-t-butyl-9,10-N, N'-dicyanoanthraquinonediimine, n-type hydrogenated amorphous silicon carbide , N-type zinc sulfide, n-type zinc Such as emissions of zinc, and the like. In addition, the material of the electron carrying layer 7 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

There is no restriction | limiting in the formation method of the electron carrying layer 7. FIG. Therefore, the above-described material can be formed by the method described in the above-mentioned “1. Specific organic layer forming method” or other methods.
The thickness of the electron transport layer 7 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.

2-6. Electron Injection Layer The electron injection layer 8 serves to efficiently inject electrons injected from the cathode 9 into the light emitting layer 5. In order to perform electron injection efficiently, the material for forming the electron injection layer 8 is preferably a metal having a low work function. Examples include alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium. The film thickness is usually preferably from 0.1 nm to 5 nm.

Furthermore, an organic electron transport compound represented by a metal complex such as a nitrogen-containing heterocyclic compound such as bathophenanthroline or an aluminum complex of 8-hydroxyquinoline is doped with an alkali metal such as sodium, potassium, cesium, lithium or rubidium ( (As described in JP-A-10-270171, JP-A-2002-1000047, JP-A-2002-1000048, etc.), it is possible to improve the electron injection / transport properties and achieve excellent film quality. preferable. In this case, the film thickness is usually 5 nm or more, preferably 10 nm or more, and is usually 200 nm or less, preferably 100 nm or less.
In addition, the material of the electron injection layer 8 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  There is no restriction | limiting in the formation method of the electron injection layer 8. FIG. Therefore, it can be formed by laminating the above material on the electron transport layer 7 by the method described in the above-mentioned “1. Specific organic layer forming method” or other methods.

2-7. Cathode The cathode 9 plays a role of injecting electrons into a layer (such as the electron injection layer 8 or the light emitting layer 5) on the light emitting layer 5 side.
As the material of the cathode 9, the material used for the anode 2 can be used. However, a metal having a low work function is preferable for efficient electron injection. For example, tin, magnesium, indium, A suitable metal such as calcium, aluminum, silver, or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy. In addition, the material of the cathode 9 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The film thickness of the cathode 9 is usually the same as that of the anode 2.

  Further, for the purpose of protecting the cathode 9 made of a low work function metal, it is preferable to further stack a metal layer having a high work function and stable to the atmosphere because the stability of the device is increased. For this purpose, for example, metals such as aluminum, silver, copper, nickel, chromium, gold and platinum are used. In addition, these materials may be used only by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

2-8. Other Layers The organic EL element having the layer configuration shown in FIG. 1 has been described above. However, the organic EL element according to the present invention may have another configuration without departing from the gist thereof. . For example, as long as the performance is not impaired, an arbitrary layer may be provided between the anode 2 and the cathode 9 in addition to the layers described above, and an arbitrary layer may be omitted. .
FIG. 2 is a cross-sectional view schematically showing another example of the structure of the organic EL element of the present invention. 2, the same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The organic EL element 10b shown in FIG. 2 has a hole blocking layer 6 between the light emitting layer 5 and the electron transport layer 7 in addition to the same configuration as the organic EL element 10a of FIG. A hole transport layer 4 is provided between the hole injection layer 3 and the light emitting layer 5.

(2-8-1) Hole Transport Layer The material for forming the hole transport layer 4 is the same as the compound exemplified as the hole transport compound that may be used by mixing with the hole injection layer 3. Can be mentioned. In addition, for example, polymer materials such as polyarylene ether sulfone containing polyvinyl carbazole, polyvinyl triphenylamine, and tetraphenylbenzidine can be used. In addition, the material of the positive hole transport layer 4 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  The hole transport layer 4 can be formed by a specific organic layer forming method. In addition, when forming another organic layer by a specific organic layer formation method, you may use another method for formation of the positive hole transport layer 4. FIG. Hereinafter, the case where the hole transport layer 4 is formed by the specific organic layer forming method will be described. The film forming method of the hole transport layer 4 is a wet film forming method below, but is not particularly limited to the wet film forming method, and may be a vacuum vapor deposition method or the like.

  When the hole transport layer 4 is formed by a wet film forming method, the above-described material is dissolved in an appropriate solvent to prepare a coating composition. As the hole transport layer solvent to be contained in the coating composition for producing the hole transport layer 4, any solvent can be used as long as the hole injection layer 3 can be formed. However, those capable of dissolving the above-described hole transporting compound and polymer material are preferable.

  Moreover, as a solvent for hole transport layers, a deactivated substance or a deactivated substance that may deactivate a polymer, an electron accepting compound, a hole transporting compound, and a free carrier (cation radical) generated from a mixture thereof. Solvents that do not contain those that generate are preferred.

  After coating / deposition of the coating composition for producing the hole transport layer 4, the obtained coating film is dried and the hole transport layer solvent is removed, whereby the hole transport layer 4 is formed. The Thereafter, a storage process and a heating process are performed. The wet film forming method, drying method, storage method, and heating method are not limited as long as the effects of the present invention are not significantly impaired, and any method described in the section of “1. Specific organic layer forming method” is used. be able to.

  The film thickness of the hole transport layer 4 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 10 nm or more, preferably 30 nm or more, and usually 300 nm or less, preferably 100 nm or less.

(2-8-2) Hole blocking layer The hole blocking layer 6 is a layer laminated on the light emitting layer 5 so as to be in contact with the interface of the light emitting layer 5 on the cathode 9 side. The hole blocking layer 6 has a role of blocking holes moving from the anode 2 from reaching the cathode 9 and a role of efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5. Have

  The physical properties required for the material constituting the hole blocking layer 6 include high electron mobility, low hole mobility, a large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high. As a material for the hole blocking layer satisfying such conditions, for example, bis (2-methyl-8-quinolinolato), (phenolato) aluminum, bis (2-methyl-8-quinolinolato), (triphenylsilanolato) Mixed ligand complexes such as aluminum, metal complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinato) aluminum binuclear metal complexes, distyrylbiphenyl derivatives Styryl compounds such as JP-A-11-242996 and triazole derivatives such as 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole Kaihei 7-41759) and phenanthroline derivatives such as bathocuproine (Japanese Patent Laid-Open No. 10-79297). It is. Further, a compound having at least one pyridine ring substituted at the 2,4,6-position described in International Publication No. 2005-022962 is also preferable as the material for the hole blocking layer 6. In addition, the material of the hole-blocking layer 6 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

There is no restriction | limiting in the formation method of the hole-blocking layer 6. FIG. Therefore, the above-described material can be formed by the method described in the above-mentioned “1. Specific organic layer forming method” or other methods.
The thickness of the hole blocking layer 6 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

(2-8-3) Electron blocking layer An electron blocking layer is provided between the hole injection layer 3 (the hole transport layer 4 when the hole transport layer 4 is formed) and the light emitting layer 5. Also good. The electron blocking layer was generated by increasing the recombination probability of holes and electrons in the light emitting layer 5 by blocking electrons moving from the light emitting layer 5 from reaching the hole injection layer 3 side. There are a role of confining excitons in the light emitting layer 5 and a role of efficiently transporting holes injected from the hole injection layer 3 in the direction of the light emitting layer 5. In particular, it is effective when a phosphorescent material or a blue light emitting material is used as the light emitting material.

The characteristics required for the electron blocking layer include high hole transportability, a large energy gap (difference between HOMO and LUMO), and a high excited triplet level (T1). Furthermore, in the present invention, when the light emitting layer 5 is formed as an organic layer according to the present invention by a wet film formation method, the electron blocking layer is also required to be compatible with the wet film formation. Examples of the material used for such an electron blocking layer include a copolymer of dioctylfluorene and triphenylamine typified by F8-TFB (described in International Publication No. 2004/084260). In addition, the material of an electron blocking layer may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
There is no restriction | limiting in the formation method of an electron blocking layer. Therefore, it can be formed by laminating the above material on the hole injection layer 3 or the like by the method described in the above-mentioned “1. Specific organic layer forming method” or other methods.

(2-8-4) Others For example, lithium fluoride (LiF), magnesium fluoride (MgF ₂ ), lithium oxide (Li ₂ O), cesium carbonate at the interface between the cathode 9 and the light emitting layer 5 or the electron transport layer 7. (II) Inserting a very thin insulating film (0.1 to 5 nm) formed of (CsCO ₃ ) or the like is also an effective method for improving the efficiency of the device (Applied Physics Letters, 1997, Vol. 70, pp.152; JP-A-10-74586; see IEEE Transactions on Electron Devices, 1997, Vol.44, pp.1245; SID 04 Digest, pp.154 etc.).

Moreover, in the layer structure demonstrated above, it is also possible to laminate | stack components other than a board | substrate in reverse order. For example, in the layer configuration of FIG. 1, the cathode 9, the electron injection layer 8, the electron transport layer 7, the light emitting layer 5, the hole injection layer 3, and the anode 2 are provided on the substrate 1 in this order.
Furthermore, the organic EL element of the present invention can be configured by laminating components other than the substrate between two substrates, at least one of which is transparent.

In addition, a structure in which a plurality of components (light emitting units) other than the substrate are stacked in a plurality of layers (a structure in which a plurality of light emitting units are stacked) may be employed. In that case, instead of the interface layer between the steps (between the light emitting units) (in the case where the anode is ITO and the cathode is Al, these two layers), for example, a charge made of vanadium pentoxide (V ₂ O ₅ ) or the like. When a generation layer (Carrier Generation Layer: CGL) is provided, a barrier between steps is reduced, which is more preferable from the viewpoint of light emission efficiency and driving voltage.

Furthermore, the organic EL element of the present invention may be configured as a single organic EL element, or may be applied to a configuration in which a plurality of organic EL elements are arranged in an array, and the anode and cathode are X- You may apply to the structure arrange | positioned at Y matrix form.
Each layer described above may contain components other than those described as materials unless the effects of the present invention are significantly impaired.

  The organic electroluminescent element obtained by the production method of the present invention can be used as an organic electroluminescent element in an organic electroluminescence display. The organic electroluminescence display has at least a transparent support substrate and an organic electroluminescent element laminated on the transparent support substrate. The organic electroluminescent element obtained by the present invention is, for example, as described in “Organic EL display” (Ohm, August 20, 2004, written by Shizushi Tokito, Chiba Adachi, Hideyuki Murata). An organic electroluminescent display can be formed.

The present invention will be described more specifically with reference to examples. However, the present invention is not limited to the description of the following examples without departing from the gist thereof.

[Example 1]
An organic electroluminescent device having the structure shown in FIG. 1 was prepared by the following method.
(Production of ITO substrate)
An indium tin oxide (ITO) transparent conductive film deposited to a thickness of 150 nm on a glass substrate 1 (sputtered film product; sheet resistance 15 Ω) is 2 mm wide stripes using normal photolithography and hydrochloric acid etching. The anode 2 was formed by patterning.

(Preprocessing)
The patterned ITO substrate was cleaned in the order of ultrasonic cleaning with a surfactant, water with pure water, and ultrasonic cleaning with isopropyl alcohol, dried with compressed air, and finally subjected to ultraviolet ozone cleaning for 1 minute.

(Hole injection layer deposition)
Next, the hole injection layer 3 was formed by a wet film formation method as follows. The material of the hole injection layer 3 is 2% by weight of a polymer having a repeating structure represented by the following formula (1-2) (weight average molecular mass 29400, number average molecular weight 12600, glass transition temperature 160 ° C.), and 4- A composition in which 0.8% by weight of isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate was dissolved in ethyl benzoate was prepared, and this composition was spin-coated on the ITO substrate. A film was formed.
As spin coating conditions, spinner rotation speed was 500 rpm, 2 seconds, and 1500 rpm, 30 seconds. As a drying condition, a thin film having a thickness of 30 nm could be formed by heating for 15 minutes in a clean oven at 230 ° C.

(Preservation process)
The device formed up to the hole injection layer 3 was stored in the atmosphere (room temperature 23 ° C. ± 1.5 ° C.) for 24 hours.
(Heating process)
After the storage step, heat treatment was performed for 15 minutes in a clean oven at 230 ° C. under a humidity of 2% or less in dry air.

(Light-emitting layer deposition)
The PPD shown below was laminated on the hole injection layer 3 by the vacuum evaporation method on the ITO substrate having the hole injection layer 3 that had undergone the heating step, thereby forming the light emitting layer 5 having a film thickness of 45 nm.

(Deposition of electron transport layer)
An ITO substrate having a hole injection layer 3 formed by a wet film formation method and a light emitting layer 5 formed by a vacuum deposition method is coated with an aluminum 8-hydroxyquinoline complex ET-1 shown below as an electron transport layer 7 in a film thickness of 60 nm. It laminated | stacked so that it might become.

(Electron injection layer and cathode film formation and sealing)
Here, the element that has been vapor-deposited up to the electron transport layer 7 is once taken out from the vacuum vapor deposition apparatus into the atmosphere, and is used as a cathode vapor deposition mask with a 2 mm width in a shape orthogonal to the ITO stripe as the anode. A stripe shadow mask is brought into close contact with the element, placed in another vacuum vapor deposition apparatus, and lithium fluoride (LiF) is formed to a thickness of 0.5 nm as the electron injection layer 8 by the same vacuum vapor deposition method as the electron transport layer 7. Subsequently, aluminum was laminated as the cathode 9 so as to have a film thickness of 80.0 nm.

Subsequently, in order to prevent the element from being deteriorated by moisture in the atmosphere during storage, a sealing process was performed by the method described below.
In a nitrogen glove box connected to a vacuum deposition apparatus, a photocurable resin was applied to the outer periphery of a 23 mm × 23 mm size glass plate with a width of about 1 mm, and a moisture getter sheet was installed in the center. On this, the board | substrate which complete | finished cathode formation was bonded together so that the vapor-deposited surface might oppose a desiccant sheet. Then, only the area | region where the photocurable resin was apply | coated was irradiated with ultraviolet light, and resin was hardened. Thereby, the organic electroluminescent element which has a light emission area part of 2 mm x 2 mm size was obtained.

[Comparative Example 1]
In Example 1, an organic electroluminescent element was produced in the same manner as in Example 1 except that the storage step and the heating step were not performed.

[result]
Table 1 below shows the luminance half-time measured by the following method and the driving voltage at the time of 21 mA / cm ² constant current driving for the organic electroluminescent elements obtained in Example 1 and Comparative Example 1, respectively.

[Measuring method]
<Luminance half-life>
The luminance half-life is measured by observing a change in luminance with a photodiode when a constant direct current with a current value of 21 mA / cm ² is applied to the manufactured organic EL element. The time (brightness half-life) until it became half of the test start was determined. The energization test was performed in a room where the room temperature was controlled to 23 ± 1.5 ° C. by air conditioning.
<Drive voltage>
The drive voltage was measured by driving the produced organic EL element with a constant current of 21 mA / cm ² to obtain a voltage increase.

表１から明らかなように、大気中での保存工程後、加熱工程を行なった実施例１の有機電界発光素子では、加熱工程を行なわなかった比較例１の有機電界発光素子と比較して、ほぼ同等の駆動電圧、及び通電時の輝度を有することがわかる。
以上より、長期間保存した素子に対しても、加熱処理を行なうことにより、長期保存することによる駆動寿命の低下、及び駆動電圧の上昇を改善可能であることが明らかであった。

As is clear from Table 1, the organic electroluminescence device of Example 1 that performed the heating step after the storage step in the atmosphere was compared with the organic electroluminescence device of Comparative Example 1 that did not perform the heating step. It can be seen that it has substantially the same drive voltage and brightness when energized.
From the above, it was clear that a decrease in driving life and an increase in driving voltage due to long-term storage can be improved by performing heat treatment even on an element stored for a long time.

[Example 2]
An electroluminescent device having the structure shown in FIG. 3 was produced by the following method. The process up to formation of the hole injection layer 3 was performed in the same manner as in Example 1.
(Formation of hole transport layer)
Next, the hole transport layer 4 was formed by a wet film formation method as follows. As a material for the hole injection layer, a composition in which 0.4% by weight of a polymer having a repeating structure of the following formula (HT-1) was dissolved in dehydrated toluene was prepared, and this composition was used as the hole injection layer 3. A film was formed thereon by spin coating.
As spin coating conditions, spinner rotation speed was 500 rpm, 2 seconds, and 1500 rpm, 30 seconds. The drying condition was performed in a clean oven at 230 ° C. for 1 hour, whereby a thin film having a thickness of 20.9 nm could be formed.

(Preservation process)
The element formed up to the hole transport layer 4 was stored in the atmosphere (room temperature 23 ° C. ± 1.5 ° C.) for 93 hours.
(Heating process)
After the storage step, heat treatment was performed for 30 minutes in a clean oven at 260 ° C.

(Formation of light emitting layer)
Subsequently, the light emitting layer 5 was formed by the wet film-forming method as follows. The material of the light emitting layer was prepared by mixing materials H-1 and D-1 shown below at a ratio of 100 to 10, and preparing a composition in which 2.3% by weight of this mixture was dissolved in cyclohexylbenzene. A film was formed on the hole transport layer 4 by spin coating.
As spin coating conditions, spinner rotation speed was 500 rpm, 2 seconds, and 1000 rpm, 30 seconds. Then, the light emitting layer 5 with a film thickness of 43.3 nm was formed by drying at 130 degreeC for 1 hour.

(Formation of electron transport layer)
On the obtained light emitting layer 5, the 8-hydroxyquinoline complex ET-1 of aluminum shown below as the electron carrying layer 7 was sequentially laminated | stacked by the vacuum evaporation method so that it might become a film thickness of 30 nm, respectively.

(Formation and sealing of electron injection layer and cathode)
The element on which the electron transport layer 7 has been deposited is once taken out from the vacuum deposition apparatus into the atmosphere, and a 2 mm wide stripe shadow mask having a shape perpendicular to the ITO stripe as the anode is used as a mask for cathode deposition. The device is in close contact with the device, and is placed in another vacuum deposition apparatus. By the same vacuum deposition method as that for the organic layer, lithium fluoride (LiF) is formed as the electron injection layer 7 with a film thickness of 0.48 nm, and then the cathode 8 is formed with aluminum. The layers were stacked so as to have a film thickness of 80.0 nm.
Subsequently, in order to prevent the element from being deteriorated by moisture in the atmosphere during storage, a sealing process was performed by the method described below.
In a nitrogen glove box connected to a vacuum deposition apparatus, a photocurable resin was applied to the outer periphery of a 23 mm × 23 mm size glass plate with a width of about 1 mm, and a moisture getter sheet was installed in the center. On this, the board | substrate which complete | finished cathode formation was bonded together so that the vapor-deposited surface might oppose a desiccant sheet. Then, only the area | region where the photocurable resin was apply | coated was irradiated with ultraviolet light, and resin was hardened.
By the above procedure, an organic electroluminescent element having a light emitting area portion having a size of 2 mm × 2 mm was finally obtained by glass sealing.

[Comparative Example 2]
In Example 2, the organic electroluminescence device was obtained in the same manner as in Example 2 except that the storage process time after the formation of the hole transport layer 4 was changed from 96 hours to 24 hours and the heating process was not performed. Got.

[result]
Table 1 below shows the luminance half-life measured by the following method and the driving voltage at 1000 nit driving for the organic electroluminescent elements obtained in Example 2 and Comparative Example 2, respectively.

[Measuring method]
<Luminance half-life>
The luminance half-life is measured by observing the change in luminance when a voltage of 1000 nit when applying a constant DC current is applied to the manufactured organic EL element, using a photodiode. Is the half of the start of the test, that is, the time until it reaches 500 nit (luminance half-life). The energization test was performed in a room where the room temperature was controlled to 23 ± 1.5 ° C. by air conditioning.

<Drive voltage>
The driving voltage was measured by measuring the voltage at which the luminance was 1000 nit when a constant direct current was first applied to the manufactured organic EL element.

以上の結果より、長期間保存した素子に対して加熱工程を行うことにより、長期保存することによる駆動電圧の上昇を改善することが明らかとなった。

From the above results, it has been clarified that an increase in driving voltage due to long-term storage can be improved by performing a heating process on a device stored for a long time.

  The present invention relates to various fields where an organic EL optical element is used, for example, a light source (for example, a light source of a copying machine, a flat panel display (for example, for an OA computer or a wall-mounted television) or a surface light emitter). It can be suitably used in the fields of liquid crystal displays and backlights of instruments), display panels, indicator lamps and the like.

It is sectional drawing which shows typically an example of the structure of the organic electroluminescent element of this invention. It is sectional drawing which shows typically the other example of the structure of the organic electroluminescent element of this invention. It is sectional drawing which shows typically the other example of the structure of the organic electroluminescent element of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Electron injection layer 9 Cathode

Claims (6)

A method for producing an organic electroluminescent device having a first electrode, an organic layer, and a second electrode in this order,
A storage step of storing the organic layer for 30 minutes to 400 days after forming the organic layer;
A method for producing an organic electroluminescent element, comprising: a heating step of heat-treating the organic layer. The method of manufacturing an organic electroluminescent element according to claim 1, wherein the organic layer is a hole injection layer. The method for producing an organic electroluminescent element according to claim 1, wherein the organic layer is a hole transport layer. The method for producing an organic electroluminescent element according to any one of claims 1 to 3, wherein the temperature of the heat treatment in the heating step is 100 ° C or higher and 400 ° C or lower. An organic electroluminescent device manufactured by the method for manufacturing an organic electroluminescent device according to claim 1. It has an organic electroluminescent element manufactured by the manufacturing method of the organic electroluminescent element as described in any one of Claims 1-4, The organic electroluminescent display characterized by the above-mentioned.

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