JP2003226870A - Light emitting device material, and light emitting device and device using the same - Google Patents

Abstract

(57) [Summary] (Problems corrected) [PROBLEMS] To provide a light emitting element material using an organic compound having a sufficient electron transporting ability, a light emitting element using the same, and a light emitting element material that is less likely to deteriorate the element and using the same A light emitting device is provided. A light-emitting element material is a compound represented by the following general formula (1) or a compound containing a compound represented by the following general formula (1) as a repeating unit. (Where A is a group of the formula (2) or the formula (4),
B is a tricyclic fused ring group, and n represents an integer of 1 or 2. ) (In the formula, at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ is an electron withdrawing group, and the others represent a hydrogen atom or a substituent.) (In the formula, R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ represent a hydrogen atom or a substituent.)

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a light emitting element material, a light emitting element using the same, and an apparatus using the light emitting element.

[0002]

2. Description of the Related Art In recent years, with the diversification of information equipment, CR
There is an increasing need for a flat display element that consumes less power than T. In particular, the electroluminescence element is a self-luminous type, and has attracted attention because of its clear display and wide viewing angle. In particular, the organic electroluminescence element is
Charges (holes and electrons) injected from both the anode and cathode electrodes recombine in the light emitter to generate excitons, which excite molecules of the light emitting material to emit light, so-called injection type light emitting device. Therefore, it can be driven at a low voltage. Moreover, since the light-emitting material is an organic compound, the molecular structure of the light-emitting material can be easily changed, and thus an arbitrary emission color can be obtained.

As an organic electroluminescence device, first, an organic thin film is formed into a two-layer structure of a thin film made of a hole transporting material and a thin film made of an electron transporting material, and holes injected from the respective electrodes into the organic thin film. A device structure that emits light when electrons recombine has been developed (Ap
plied Physics Letters, 51, 1987, P.913.).

As an electron transporting material used in such a layered device, a tris (8-quinolinolato) aluminum complex (hereinafter
Alq) is used. After that, electron transport materials centering on organometallic complexes such as beryllium benzoquinoline and gallium complexes have been developed.

On the other hand, electron transport materials using organic compounds have been developed. Examples of the electron transport material using an organic compound include 2- (4-biphenylyl) -5- (4-
Examples include oxadiazol derivatives such as t-butylphenyl) -1,3,4-oxadiazol (PBD) and π-electron deficient aromatic compounds such as triazole derivatives. This is because the heterocycle has a π-electron deficiency and thus has excellent electron affinity.

However, when the organometallic complex is used as an electron transport material, the organometallic complex has a weak bond between the ligand and the central metal. Therefore, there is a problem that the cleavage of the coordination bond is likely to occur when the electrons are given and received, that is, when the redox reaction is performed, and the device is likely to deteriorate.

On the other hand, electron transport materials using organic compounds have the following problems. For example, a triazole derivative such as PBD has a problem that it is easily crystallized and cannot be put to practical use. Therefore, it has been attempted to suppress crystallization by dimerizing or introducing a bulky functional group. However, since these organic compounds do not have the effect of reducing the electron injection obstacle, the driving voltage becomes high, etc.
Only by utilizing the π-electron deficiency, the electron transport property is not sufficient.

[0008]

The present invention has been made in view of the above, and an object thereof is to provide a light emitting device material using an organic compound having a sufficient electron transporting ability and a light emitting device using the same. Especially. Another object of the present invention is to provide a light emitting element material in which the element does not easily deteriorate and a light emitting element using the same.

[0009]

In developing a new light emitting device, improving the luminous efficiency is one of the important points. To improve luminous efficiency,
This is done by developing a light emitting material with high quantum efficiency or by improving the probability of recombination of electrons and holes. In general, an organic material has a property in which electrons easily enter an empty orbital in a cation radical state, that is, an excellent hole transport property. On the other hand, as an organic material having an excellent electron transporting property, only a compound in which a π-electron-deficient heterocycle such as triazole or triazine is introduced is known. This is because the π-electron-deficient compound has an insufficient electron-transporting ability, so that holes are excessively present inside the light-emitting element and sufficient recombination of holes and electrons cannot be achieved.

In order for the organic compound to be an excellent electron-transporting material, 1) the molecule has a large electron affinity because electrons are easily injected from the cathode and is easily a radical anion. 2) The injected electron. Is a molecule having a high electron mobility in order to quickly move in the electron transport layer and reach the light emitting layer, and 3) holes are efficiently recombined with electrons in the light emitting layer. It is desired that the molecule be a molecule that is difficult to become a radical cation.

As a result of intensive studies on the above problems, the present inventors have completed the present invention by discovering an organic compound which is easy to inject electrons from the cathode and has high electron mobility. That is,
The present invention is as follows.

The light emitting device material of the present invention is characterized by being a compound represented by the following general formula (1) or a compound containing the compound represented by the following general formula (1) as a repeating unit.

[Chemical 6] (In the formula, A is an electron injecting group having a low LUMO level, B is a tricyclic condensed ring group, and n is an integer of 1 or 2.)

In the compound represented by the general formula (1), A may be p-phenylenedivinylene which may have a group represented by the following general formula (2) or a substituent. .

[Chemical 7] (In the formula, at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ is an electron-withdrawing group, and the others are hydrogen atoms or substituents.)

In the compound represented by the general formula (1), B may be a nitrogen-containing condensed three-ring heterocyclic group.

In the compound represented by the general formula (1), A may be silole which may have a group represented by the following general formula (4) or a substituent.

[Chemical 8] (In the formula, R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ represent a hydrogen atom or a substituent.)

The light emitting device material may be used as an electron transporting material.

The light emitting element material is a light emitting element in which at least an organic compound layer is provided between an anode and a cathode, and may be contained in the organic compound layer.

The organic compound layer may include at least a light emitting layer and an electron transport layer, and the electron transport layer may contain the light emitting element material.

A light emitting device in which at least an organic compound layer is provided between an anode and a cathode, wherein the organic compound layer includes at least a light emitting layer, and the light emitting layer contains the light emitting device material. Good.

The light emitting device material may be uniformly dispersed in the electron transport layer or in the organic light emitting layer.

On the other hand, when the light emitting element material is contained in the light emitting layer, the light emitting element material is dispersed in the light emitting layer with a concentration gradient in the thickness direction of the light emitting layer, and becomes closer to the cathode. You may have a gradient so that it may become high concentration.

The light emitting device may be one in which a hole transport layer and a light emitting layer are laminated in this order from the anode side.

The above light emitting element can be used as a display device and a lighting device. For example, an image signal output unit that generates an image signal, a driving unit that generates a current based on the image signal from the image signal output unit, and a light emitting unit that emits light based on the current generated from the driving unit are provided. The display device is characterized in that the light emitting section has at least one light emitting element, and the light emitting element is the above light emitting element.

Alternatively, there is provided a lighting device comprising a driving section for generating a current and a light emitting section for emitting light based on a current generated by the driving section, wherein the light emitting section has at least one light emitting element. The lighting device is characterized in that the light emitting element is the above light emitting element.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The light emitting device material of the present invention is a compound represented by the following general formula (1) or a general formula (1) below.
Is a compound containing the compound represented by as a repeating unit.

[Chemical 9] (In the formula, A is an electron injecting group having a low LUMO level, B is a three-ring condensed heterocyclic group, and n is 1 or 2
Represents the integer. )

The light emitting device material of the present invention has a portion A having an electron injecting function for easily injecting electrons from the cathode to form a radical anion, and an electron transporting function B for transporting the injected electrons to the light emitting material. It is a new electron transport material consisting of

First, the section A having an electron injection function will be described. The electron transport material is required to be a molecule that facilitates injection of electrons from the cathode. In the light emitting device, a metal having a small work function such as an alkali metal or an alkaline earth metal is generally used as a cathode material in order to facilitate injection of electrons into an organic material. The work function of alkali metals is in the range from 2.93 eV for Li to 1.95 eV for Cs. The work function of an alkaline earth metal is 3.66 eV of Mg to 2.52 e of Ba.
Up to V (Chemical Handbook, 4th revised edition, Maruzen, 1
993, Basic Edition II). That is, the electron-transporting material that is easily injected with electrons is a substance whose LUMO energy level of the molecule is in the range of 3.66 eV to 1.95 eV depending on the work function of the above-mentioned alkali metal or alkaline earth metal. . As a method of lowering the LUMO energy level of a molecule to the above range, there are a method of introducing an electron withdrawing group into a molecule and a method of using a molecule having a large electron affinity.

The method of introducing an electron withdrawing group into a molecule is a method of introducing a known electron withdrawing group such as a cyano group, a carbonyl group, an aldehyde group or a nitro group into a molecule. As the molecule into which the electron withdrawing group is introduced, p-phenylenedivinylene is preferable.

The present inventors attempted molecular orbital calculation of phenylenebiscyanodivinylene in which a cyano group was introduced into p-phenylenedivinylene. Calculations were performed using the Gaussian 98W program, an ab initio molecular orbital method. In the minimum base STO-3G, the LUMO level of phenylenebiscyanodivinylene decreased by 0.94 eV with the introduction of the cyano group. That is, it can be seen that p-phenylenedivinylene having a cyano group introduced therein has a large electron affinity and is likely to be a radical anion.

Examples of molecules having a high electron affinity include silole. Since silole has a remarkably low LUMO level due to the inter-orbital interaction between the σ * orbital of the silicon site and the π * orbital of the carbon diene site, it has a large electron affinity. As a result, silole receives electrons from the cathode and becomes a cyclic π-electron system having (4n + 2) π-electrons, and the anion state shows aromaticity. When the silole is stabilized in the anion state, electrons are filled in the light emitting element material, and hopping movement of electrons is promoted. As a result, the recombination probability of electrons and holes can be improved.

Next, the B section having an electron transporting function will be described. Part B is a tricyclic fused ring group. In order for the light emitting device material to have an excellent electron transporting ability, it is necessary that injected electrons move quickly through the electron transporting layer and reach the light emitting layer. Therefore, the light emitting device material of the present invention is required to be a molecule having a high electron mobility. In the present invention, the B portion having an electron transporting function is a three-ring condensed ring and has high flatness. That is, the three-ring condensed ring has a large overlap of π electron orbits between molecules. As a result, a π network is formed between molecules, and electrons can move through this π network, resulting in high electron mobility. Further, the hopping electrons are π electrons. Even considering the hopping movement of electrons, the electrons can move through the π network.
In this respect, when the aromatic ring or the heterocyclic ring is connected without forming a condensed ring, the rings are twisted and connected, so that the planarity is poor and the above effect cannot be obtained. Moreover, since the three-ring condensed ring is superior in planarity to the two-ring condensed ring, the electron mobility can be further increased.

Examples of the three-ring condensed ring used for the three-ring condensed ring group constituting the B part include three-ring condensed hydrocarbon rings such as biphenylene, indacene, acenaphthylene, fluorene, phenalene, phenanthrene and anthracene,
Known tricyclic condensed heterocycles such as carbazole, carboline, phenanthridine, acridine, phenanthroline, pericidine, benzoquinoline, benzocinnoline, phenotriazine, phenoxazine, phenothiazine, phenoxathiin and cyananthrene can be used. Preferred is a π-electron-deficient hetero-fused ring, which has an increased electron affinity and is easy to take in an electron. More preferably, it is a nitrogen-containing condensed 3-ring heterocycle. These three-ring condensed ring may have a substituent. If the substituent is a polymerizable group, it can be polymerized via the substituent.

That is, the light emitting device material represented by the general formula (1) of the present invention has a portion A having an electron injecting function in which electrons are easily injected from the cathode to form radical anions, and the injected electrons. It is a compound that is extremely stable in the anion radical state because it is composed of the B portion having an electron transporting function of transporting to the light emitting material. For this reason, the movement of electrons from the cathode to the light emitting layer is performed extremely smoothly.
As a result, since the driving voltage can be lowered, it is possible to suppress the chemical deterioration of the metal cations that have emitted electrons at the cathode and contribute to the long-term stabilization of the light emitting element.

Although n may be 1 or 2,
From the viewpoint of preventing crystallization, n is preferably 2.

The light emitting device material of the present invention may be a compound containing the compound represented by the general formula (1) as a repeating unit. That is, it may be an oligomer in which the compound represented by the general formula (1) is repeated about 2 to 20, and the weight average molecular weight thereof is 10,000 to 100,000.
It may be about 0 polymer.

One of the preferred embodiments of the compound represented by the above general formula (1) is a compound represented by the following general formula (3) in which A contains a group represented by the above general formula (2). .

[Chemical 10]

In the formula, at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ is an electron-withdrawing group, and the others are hydrogen atoms or substituents. R ¹ , R ² , R ³ , R ⁴ ,
Examples of the substituent represented by R ⁵ and R ⁶ include a methyl group,
Examples thereof include an alkyl group having 1 to 5 carbon atoms such as an ethyl group and a propyl group, an alkenyl group, and an aryl group such as a phenyl group. The electron-withdrawing group has the same meaning as the electron-withdrawing group described in the general formula (1). B has the same meaning as the three-ring condensed ring group described in the above general formula (1).

Another preferred embodiment of the compound represented by the general formula (1) is a compound represented by the following general formula (4).

[Chemical 11]

In the formula, R ⁷ , R ⁸ , R ⁹ and R ¹⁰ represent a hydrogen atom or a substituent. Examples of the substituent represented by R ⁵ , R ⁶ , R ⁷ and R ⁸ include an alkyl group having 1 to 5 carbon atoms such as a methyl group, an ethyl group and a propyl group, an alkenyl group,
An aryl group such as a phenyl group can be mentioned. B has the same meaning as the three-ring condensed ring group described in the above general formula (1).

The light emitting device of the present invention is a light emitting device in which at least an organic compound layer is provided between an anode and a cathode. The organic compound layer contains the above light emitting element material.

The light emitting device of the present invention may include a functional layer as the organic compound layer. Figure 1
It is a schematic diagram which shows an example of the light emitting element which can be used by this invention. For example, as shown in FIG. 1, an anode 2, a hole transport layer 3, a light emitting layer 4, an electron transport layer 5, and a cathode 6 may be laminated in this order on a transparent substrate 1. This structure is commonly called a DH structure.

Besides the above structure, the SH-A structure in which the light emitting layer 4 also has the function of the electron transport layer 5, the hole transport layer 3
The SH-B structure in which the light emitting layer 4 also has the above function, and the single-layer structure in which the light emitting layer 4 has both the functions of the hole transporting layer 3 and the electron transporting layer 5, both of which are the light emitting element of the present invention. Can be used as

In the present specification, the light emitting element means an element having at least a functional layer such as a light emitting layer between the hole transport electrode and the electron injecting electrode. In the functional layer, all the functional layers may be composed of a layer made of an organic material, or may be composed of a layer made of an inorganic material. For example, the electron transport layer may be a layer made of an organic material and the hole transport layer may be a layer made of an inorganic material. Alternatively, any one layer or a plurality of layers of the hole transport layer, the light emitting layer, and the electron transport layer may be a layer containing an inorganic material.

In one embodiment of the light emitting device of the present invention, as shown in FIG. 1, the electron transport layer 5 is a layer made of the light emitting device material of the present invention.

The light emitting device having the structure of FIG. 1 can be manufactured, for example, as follows. The transparent substrate 1 is not particularly limited as long as it has a proper strength, is not adversely affected by heat during vapor deposition, etc., in producing an element, and is transparent. As a material of the transparent substrate 1, for example, glass (for example, Corning 17
37) and transparent resins such as polyethylene, polypropylene, polyether sulfone, polycarbonate,
Examples thereof include polyether ether ketone. Not only the display element of this embodiment but also the display element according to the present invention can be formed by sequentially stacking on the transparent substrate 1.

Not only in the display element of this embodiment but also in the display elements according to the present invention in general, the anodes including the illustrated anode 2 are usually formed of a transparent conductive film.
As a material of such a transparent conductive film, it is preferable to use a conductive substance having a work function larger than about 4 eV. Such substances include carbon, aluminum, vanadium, iron, cobalt, nickel, copper, zinc, tungsten, silver, tin, gold, and other metals such as alloys thereof, as well as tin oxide, indium oxide, antimony oxide, zinc oxide, Metal oxides such as zirconium oxide and solid solutions or mixtures thereof (eg ITO (indium tin oxide))
A conductive compound such as a conductive metal compound can be exemplified.

When forming the anode 2, on the transparent substrate 1,
A desired light-transmitting property and conductivity are ensured by using a method such as vapor deposition, sputtering, or a sol-gel method or a method of applying such a substance by dispersing such a substance in a resin or the like by using the above-mentioned conductive substance. It may be formed as follows. In particular, the ITO film is formed by a method such as sputtering, electron beam evaporation, or ion plating for the purpose of improving its transparency or decreasing its resistivity.

The film thickness of the anode 2 is determined from the required sheet resistance value and visible light transmittance. In the case of a light emitting element, since the driving current density is relatively high, it is necessary to reduce the sheet resistance value. Therefore, the film thickness is often 100 nm or more.

Next, the hole transport layer 3 is formed on the anode 2. In the light emitting device according to the present invention, including the hole transport layer 3 shown in the figure, as the hole transport material that can be used for forming the hole transport layer, known materials can be used, but the light emission stability and durability are preferable. A derivative having triphenylamine as a basic skeleton, which is excellent in properties.

Specifically, the tetraphenylbenzidine compound, triphenylamine trimer and benzidine dimer described in JP-A-7-126615,
-48656, various tetraphenyldiamine derivatives described in JP-A-7-69558, N,
Examples thereof include N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-biphenyl-4,4'-diamine (MTPD (common name TPD)). The triphenylamine tetramer described in JP-A-10-228982 is more preferable. In addition, diphenylamino-α-phenylstilbene, diphenylaminophenyl-α-phenylstilbene and the like can be used.
Further, an inorganic material such as amorphous silicon forming the p layer may be used.

The thickness of the hole transport layer 3 is 10 nm to 10 nm.
It may be about 00 nm. The hole transport layer thickness is 10
When the thickness is less than nm, the light emission efficiency is good, but dielectric breakdown is likely to occur and the life of the device is shortened. On the other hand, when the thickness of the hole transport layer 3 is more than 1000 nm, it is necessary to increase the applied voltage in order to emit light with a predetermined brightness.
The luminous efficiency is poor and the element is easily deteriorated.

Next, the light emitting layer 4 is formed on the hole transport layer 3. The light emitting material used for the light emitting layer of the light emitting device according to FIG. 3 is not particularly limited, and in addition to Alq described above, its derivative tris (4-methyl-8-quinolinolato) aluminum, 4, Distyrylarylene derivatives such as 4′-bis (2,2-diphenylvinyl) biphenyl, porphyrin derivatives such as tetraphenylporphyrin, anthracene, pyrene, bisstyrylanthracene derivatives, tetraphenylbutadiene derivatives, coumarin derivatives, oxadiazole derivatives,
Known low-molecular light emitting materials such as pyrrolopyridine derivatives, perinone derivatives, cyclopentadiene derivatives, and thiadiazolopyridine derivatives, and poly (p-phenylene vinylene)
Known polymer light emitting materials such as polyphenylene vinylene derivatives, polythiophene derivatives, polyfluorene and the like can be mentioned. In addition, a light emitting material such as a laser dye, for the purpose of improving the light emitting efficiency or changing the light emitting color,
Dope rubrene, tris (2-phenylpyridine) iridium, 2,3,7,8,12,13,1
7,18-Octaethylporphyrin platinum (II)
You may use the phosphorescent heavy metal complex such as.

In order to improve the hole transporting ability and electron transporting ability in the light emitting layer, the light emitting layer may contain the above hole transporting material or the light emitting element material of the present invention in its layer structure. Further, an inorganic light emitting substance may be used as the light emitting substance. Further, the light emitting material may be dispersed in the polymer matrix.

The thickness of the light emitting layer 4 is 5 nm to 1000 nm.
It should be about. When the thickness of the light emitting layer is thinner than 5 nm, the light emitting efficiency is good, but dielectric breakdown is likely to occur, and the life of the device is shortened. On the other hand, the thickness of the light emitting layer is 1000 nm
If the thickness becomes thicker, it is necessary to increase the applied voltage in order to emit light with a predetermined brightness, and the luminous efficiency is poor, and
Deterioration of the element is likely to occur. Usually 5 nm to 100 nm
It is preferable that the film thickness is about the same.

The light emitting layer may be made of only a single material which emits each color such as red, green and blue independently, or a plurality of light emitting materials may be contained in the same layer to extract a mixed color.
Further, a structure in which red, green, and blue light emitting materials are separately coated for each subpixel may be used. Furthermore, a layered structure in which light emission colors are different for each layer may be stacked and the light emission colors from the respective layers may be stacked.

Next, the electron transport layer 5 is formed on the light emitting layer 4. The above-mentioned light-emitting device materials are used as the electron-transporting material that can be used for forming the electron-transporting layer in the light-emitting device according to the present invention including the illustrated electron-transporting layer 5.

The electron transport layer 5 has a thickness of 10 nm to 100.
It may be about 0 nm. The thickness of the electron transport layer is 10 nm
When the thickness is thinner, the luminous efficiency is good, but dielectric breakdown is likely to occur, and the life of the device is shortened. On the other hand, when the thickness of the electron transport layer is more than 1000 nm, it is necessary to increase the applied voltage in order to emit light with a predetermined brightness, the luminous efficiency is poor, and the element is likely to be deteriorated.

The hole transport layer 3 and the electron transport layer 5 are
Although each may be a single layer, it may be formed from a plurality of layers in consideration of ionization potential and the like.

Hole transport layer 3, light emitting layer 4, electron transport layer 5
May be formed by a vapor deposition method, or by using a solution in which the material forming these layers is dissolved or a solution in which the material forming these layers is dissolved with an appropriate resin, a dip coating method or a spin coating method. You may form by coating methods, such as. The Langmuir-Blodgett (LB) method may be used. A preferred film forming method is a vacuum vapor deposition method. This is because according to the vacuum vapor deposition method, a homogeneous layer in an amorphous state can be formed in each of the above layers.

The light emitting layer may contain an electron transporting substance. In this case, the electron transport material may be dispersed uniformly throughout the light emitting layer. Further, the electron transport material may be dispersed in the thickness direction of the light emitting layer from the cathode side to a range of about ½ of the light emitting layer. Further, in the light emitting layer, when the electron transporting substance in the light emitting layer has a concentration gradient, the light emitting layer having the concentration gradient can be formed by controlling the temperature and controlling the concentration. If the number of moles of the electron transporting substance contained in the light emitting layer is equal to or less than the number of moles of the light emitting substance,
Number of moles of electron-transporting substance: Number of moles of light-emitting substance = 1: 100
The light emitting layer may be formed in the range of 100: 1. In particular,
The light emitting device material of the present invention not only has excellent electron injection properties and electron transport properties, but also has good emission characteristics. Therefore, it functions effectively as an electron transporting light emitting layer.

Hole transport layer 3, light emitting layer 4, electron transport layer 5
May be formed individually, but it is preferable to form each layer continuously in a vacuum. If formed continuously, it is possible to prevent impurities from adhering to the interface of each layer,
It is possible to prevent a decrease in operating voltage and improve characteristics such as improved luminous efficiency and a longer life.

Hole transport layer 3, light emitting layer 4, electron transport layer 5
One of the layers contains a plurality of compounds,
When the layer is formed using a vacuum vapor deposition method, it is preferable to co-evaporate by controlling the temperature of a plurality of boats containing a single compound individually, but by vapor depositing a mixture of a plurality of compounds in advance. Is also good.

Although not shown, an electron injection layer for improving electron injection / transport characteristics may be formed on the electron transport layer 5. As the electron injecting material for forming the electron injecting layer, various conventionally known electron injecting materials can be used, but preferably, an alkali metal (lithium, sodium, etc.), an alkaline earth metal (beryllium, magnesium, etc.), or These salts and oxides can be used.

The electron injection layer can be formed by a method such as vapor deposition or sputtering. The thickness is 0.1 nm to 2
It is about 0 nm.

Next, the cathode 6 is formed on the electron transport layer 5. For the cathodes in the light emitting device according to the present invention, including the cathode 6 shown in FIG. 3, it is desirable to use an alloy of a metal having a low work function. When the electron injection layer is formed, a metal having a high work function such as aluminum or silver can be stacked. Further, even if the cathode is made of a transparent or translucent material, surface emission can be taken out.

When forming the cathode 6, the metal material as described above is used to form the cathode by a method such as vapor deposition and sputtering. The thickness of the cathode 6 is 10 nm to 500 n
m, more preferably in the range of 50 nm to 500 nm is preferable in terms of conductivity and manufacturing stability.

The light emitting device material of the present invention has excellent electron injecting property and electron transporting property. Therefore, the luminous efficiency can be improved regardless of whether the luminescent color of the luminescent material is red, green, or blue, so that a high-quality display device and a lighting device can be provided. In the display device, a plurality of light emitting elements of the present invention may be arranged in matrix over a substrate, and the light emitting element of the present invention is stacked on a substrate provided with a thin film transistor for driving control of the light emitting element. It may be formed. The lighting device can create a new lighting space as a new surface-emitting type light source. Further, in a display device such as a liquid crystal display, it can be used as a backlight for a white light source or a monochromatic light source, and thus can be applied to other optical applications.

[0068]

EXAMPLES The contents of the present invention will be specifically described below based on examples. (Example 1) In this example, an example of the element structure shown in FIG. 1 will be described. On the glass substrate on which ITO was formed, N,
A hole transport layer having a thickness of 50 nm and formed of N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine was formed. Next, tris (8-quinolinolato) aluminum was vapor deposited to form a light emitting layer having a film thickness of 30 nm. Next, the following chemical formula (5)

[Chemical 12] To form a 20 nm thick electron transport layer. Lithium was evaporated to a thickness of 1 nm on the electron transport layer. Next, a cathode of aluminum having a thickness of 100 nm is formed,
The light emitting device shown in FIG. 1 was manufactured.

A direct current voltage was applied to the present light emitting device to evaluate the characteristics of the light emitting device. The luminous efficiency was 4.5 cd / A, and stable green light emission was obtained with high luminous efficiency. When this device was subjected to a constant current lighting test at an initial luminance of 1000 cd / m ² , the luminance half-life was about 800 hours.

In this example, the electron-withdrawing group having a cyano group was used. However, even if the electron-withdrawing group having a carbonyl group, an aldehyde group or a nitro group is used, stable green light emission with high luminous efficiency can be obtained. It was The brightness half-life was also about 800 hours.

Example 2 In Example 1, the electron transporting material is replaced by the chemical formula (6) instead of the chemical formula (5).

[Chemical 13] A light emitting device of Example 2 was prepared in the same manner as in Example 1 except that was used.

A direct current voltage was applied to the present light emitting device to evaluate the characteristics of the light emitting device. The luminous efficiency was 4.3 cd / A, and stable green light emission was obtained with high luminous efficiency. When this element was subjected to a constant current lighting test at an initial luminance of 1000 cd / m ² , the luminance half-life was about 850 hours.

(Example 3) In Example 1, the electron transporting material was replaced by the chemical formula (7) instead of the chemical formula (5).

[Chemical 14] A light emitting device of Example 3 was prepared in the same manner as in Example 1 except that was used.

A direct current voltage was applied to the present light emitting device to evaluate the characteristics of the light emitting device. The luminous efficiency was 4.6 cd / A, and stable green light emission was obtained with high luminous efficiency. When this device was subjected to a constant current lighting test at an initial luminance of 1000 cd / m ² , the luminance half-life was about 700 hours.

(Example 4) In Example 1, the electron transporting material was replaced by the chemical formula (8) instead of the chemical formula (5).

[Chemical 15] A light emitting device of Example 4 was prepared in the same manner as in Example 1 except that was used.

A direct current voltage was applied to the present light emitting device to evaluate the characteristics of the light emitting device. The luminous efficiency was 4.3 cd / A, and stable green light emission was obtained with high luminous efficiency. When this device was subjected to a constant current lighting test at an initial luminance of 1000 cd / m ² , the luminance half-life was about 800 hours.

(Embodiment 5) In this example, an image signal output section for generating an image signal, a drive section having a scan electrode drive circuit and a signal drive circuit for generating an image signal from the image signal output section, and 100 × A display device including 100 light emitting portions having light emitting elements arranged in a matrix was manufactured. Each of the light emitting devices prepared in Examples 1 to 4 is 100
An electroluminescent display device arranged in a matrix of × 100 was prepared and a moving image was displayed. In each display device, a good image with high color purity was obtained. Further, even when the electroluminescent display device was repeatedly manufactured, there was no variation among the devices, and a device having excellent in-plane uniformity was obtained.

An illuminating device having a driving section for generating a current and a light emitting section having a light emitting element for emitting light based on the current generated by the driving section was prepared. Further, in this example, the lighting device was used as a backlight of the liquid crystal display panel. When the light-emitting devices produced in Examples 1 to 4 were produced on a film substrate and a voltage was applied to turn them on, a uniform surface-emission illumination device having a curved surface was obtained without using indirect illumination leading to a loss in brightness. It was

Comparative Example 1 In the light emitting device of Example 1, the electron transport layer was formed with a thickness of 30 nm of 2- (4-biphenyl) -5- (4-t-butylphenyl) 1,3,4-oxadiazo-. A light emitting device was produced in the same manner as in Example 1 except that the layer was made of a ruthenium.

A direct current voltage was applied to the present light emitting device to evaluate the characteristics of the light emitting device. The luminous efficiency was 2.8 cd / A. When this element was subjected to a constant current lighting test at an initial luminance of 1000 cd / m ² , the luminance half-life was about 350 hours.

[0081]

As described above, according to the present invention, it is possible to obtain a light emitting device material using an organic compound having a sufficient electron transporting ability and a light emitting device using the same. Further, it is possible to obtain a light emitting element material which does not easily deteriorate the element and a light emitting element using the same.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing one embodiment of a light emitting device of the present invention.

[Explanation of symbols]

1 transparent substrate 2 anode 3 hole transport layer 4 Light emitting layer 5 Electron transport layer 6 cathode

Continued front page    (72) Inventor Hisanori Sugiura             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 3K007 AB12 DB03

Claims (14)

[Claims] 1. A compound represented by the following general formula (1):
Alternatively, a light emitting device material is a compound containing a compound represented by the following general formula (1) as a repeating unit. [Chemical 1] (In the formula, A is an electron injecting group having a low LUMO level, B is a tricyclic condensed ring group, and n is an integer of 1 or 2.) 2. In the compound represented by the general formula (1), A is p-phenylenedivinylene which may have a group represented by the following general formula (2) or a substituent. The light emitting element material according to claim 1, wherein [Chemical 2] (In the formula, at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ is an electron-withdrawing group, and the others are hydrogen atoms or substituents.) 3. The light emitting device material according to claim 1, wherein in the compound represented by the general formula (1), B is a nitrogen-containing tricyclic condensed heterocyclic group. 4. In the compound represented by the general formula (1), A is p-phenylenedivinylene which may have a group represented by the following general formula (2) or a substituent, The light emitting element material according to claim 1, wherein B is a nitrogen-containing tricyclic condensed heterocyclic group. [Chemical 3] (In the formula, at least one of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ is an electron-withdrawing group, and the others are hydrogen atoms or substituents.) 5. The compound represented by the general formula (1), wherein A is silole which may have a group or a substituent represented by the following general formula (4). The light emitting device material according to claim 1. [Chemical 4] (In the formula, R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ represent a hydrogen atom or a substituent.) 6. In the compound represented by the general formula (1), A is silole optionally having a group represented by the following general formula (4) or a substituent, and B is a The light-emitting device material according to claim 1, which is a nitrogen tricyclic condensed heterocyclic group. [Chemical 5] (In the formula, R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ represent a hydrogen atom or a substituent.) 7. A light emitting device in which at least an organic compound layer is provided between an anode and a cathode, wherein the organic compound layer contains the light emitting device material according to any one of claims 1 to 6. A light-emitting element characterized in that. 8. The organic compound layer includes at least a light emitting layer and an electron transporting layer, and the electron transporting layer contains the light emitting element material according to any one of claims 1 to 6. Light emitting element. 9. A light-emitting device in which at least an organic compound layer is provided between an anode and a cathode, wherein the organic compound layer includes at least a light-emitting layer, and the light-emitting layer includes the light-emitting layer. 6. A light-emitting device containing the light-emitting device material according to item 6. 10. The light emitting device according to claim 8, wherein the light emitting device material is uniformly dispersed in the electron transport layer or in the organic light emitting layer. 11. The light emitting device material is dispersed in the light emitting layer with a concentration gradient in the thickness direction of the light emitting layer, and has a gradient such that the concentration becomes higher toward the cathode. The light emitting device according to claim 9, wherein the light emitting device is a light emitting device. 12. The light emitting device according to claim 7, wherein the light emitting device is formed by laminating a hole transport layer and a light emitting layer in this order from the anode side. 13. An image signal output section for generating an image signal, a drive section for generating a current based on the image signal from the image signal output section, and a light emitting section for emitting light based on the current generated by the drive section. 13. A display device comprising: and the light emitting section having at least one light emitting element, wherein the light emitting element is the light emitting element according to any one of claims 7 to 12. Display device. 14. A lighting device comprising: a drive unit that generates an electric current; and a light emitting unit that emits light based on a current generated by the drive unit, wherein the light emitting unit has at least one light emitting element. The light emitting device is a device according to any one of claims 7 to 12.
An illumination device comprising the light-emitting element according to any one of 1.