KR20050100643A - Material for hole injection layer, organic el element and organic el display - Google Patents

Abstract

It is intended to provide a highly reliable organic EL element, etc. capable of achieving a comparable luminance at a lower voltage, suffering from little leak current at a negative bias and showing favorable diode characteristics. An organic EL element having an organic film layer containing at least a hole injection layer between a positive electrode and a negative electrode wherein the hole injection layer contains a perfluoropolyether compound. In a preferable embodiment, the perfluoropolyether compound is represented by one of the following structural formulae (1) and (2). R1-Rf-R 2 Structural formula (1) Rf-R3Structural formula (2) In the structural formulae (1) and (2), R1, R2 and R3 represent each hydrogen, fluorine or a substituent; and Rf represents a perfluoropolyether skeleton represented by the following structural formula (3). Structural formula (3) In the structural formula (3), R4 and R5 represents -CpF2p+1 (wherein p is an integer of 0 or above); n and m are each an integer of 0 or above; and x and y are each an integer of 1 or above.

Description

Material for hole injection layer, organic EL element and organic EL display {MATERIAL FOR HOLE INJECTION LAYER, ORGANIC EL ELEMENT AND ORGANIC EL DISPLAY}

The present invention provides a hole injection layer material capable of improving the hole injection amount, an organic EL device capable of realizing the same brightness at a lower voltage, having a low leakage current at a sub-bias, and high reliability, and a high performance organic EL device using the organic EL device. Relates to a display.

The organic EL device has characteristics such as self-luminous and high-speed response, and is expected to be applied to a flat panel display. In particular, an organic EL device has a two-layer type in which a hole transporting organic thin film (hole transporting layer) and an electron transporting organic thin film (electron transporting layer) are laminated. Since the (stacked type) has been reported (for example, refer to the following nonpatent literature 1), it has attracted attention as a large area light emitting element which emits light at a low voltage of 10 V or less. The laminated organic EL device has a basic configuration of a positive electrode / hole transporting layer / light emitting layer / electron transporting layer / negative electrode, and the light emitting layer may be provided with the hole transporting layer or the electron transporting layer as in the case of the two-layer type. .

Conventionally, the positive electrode in the said organic electroluminescent element is formed with the transparent compound which has electroconductivity, and indium tin oxide (ITO) has been widely used as such a compound. By the way, in the organic electroluminescent element obtained by directly forming a light emitting layer on the positive electrode formed from ITO etc., there existed a problem that a hole injection amount was inadequate and it did not operate at low voltage.

For this reason, attempts are made to improve the hole injection amount by oxidizing the surface of the positive electrode by UV irradiation in oxygen or oxygen plasma, and to operate the organic EL element at low voltage. In addition, a hole injection layer formed of a copper phthalocyanine (CuPc) layer or the like is provided between the hole transport layer and the positive electrode to improve the hole injection amount and to operate the organic EL element at a low voltage. See Patent Document 1). Moreover, the proposal of the multilayer electrode which has a conductive layer and a fluorocarbon layer as a hole injection layer in this order as a positive electrode in the said organic electroluminescent element is also made | formed (for example, refer patent document 2 below).

However, in this case, there is a problem that the effect of improving the hole injection amount is still insufficient, and when a negative voltage is applied, leakage current flows, diode characteristics are insufficient, and reliability is insufficient. There is also a problem such as insufficient wettability with adjacent layers. The hole injection amount can be further improved, the operation can be performed at low voltage, the leakage current is small when the negative voltage is applied, the diode characteristics are good, the adhesion with the adjacent layer is good, and the interlayer separation does not occur, and the reliability is achieved. It is a reality that this high organic EL element has not been provided yet.

This invention makes it a subject to solve the conventional problem and to achieve the following objectives. That is, the present invention provides a hole injection layer material capable of improving the hole injection amount, an organic EL device capable of realizing the same luminance at a lower voltage, less leakage current at a sub-bias, good diode characteristics, and high reliability; And it aims at providing the high performance organic electroluminescent display which used this organic electroluminescent element.

Non-Patent Document 1

C.W.Tang and S.A.VanSlyke, Applied Physics Letters vo1.51, 913 (1987)

<Patent Document 1>

Japanese Patent Laid-Open No. 2000-30867

<Patent Document 2>

Japanese Patent Publication No. 11-219790

1A shows a circuit diagram of a crosstalk model in an organic EL panel, and FIG. 1B shows an equivalent circuit thereof.

2 is a schematic explanatory diagram for explaining an example of the layer structure in the organic EL device of the present invention.

3 is a schematic explanatory diagram for illustrating an example of the structure of an organic EL display (passive matrix panel) of a passive matrix system.

FIG. 4 is a schematic explanatory diagram for explaining a circuit in the organic EL display (passive matrix panel) of the passive matrix system shown in FIG. 3.

5 is a schematic explanatory diagram for illustrating an example of the structure of an organic EL display (active matrix panel) of an active matrix system.

FIG. 6 is a schematic explanatory diagram for explaining a circuit in an organic EL display (active matrix panel) of an active matrix system shown in FIG. 5.

7 is a graph showing the relationship between the film thickness of the hole injection layer and the ionization potential.

It is a schematic diagram which shows an example of the relationship of the ionization potential in each layer of the organic electroluminescent element of this invention.

9 is a schematic explanatory diagram for illustrating an example of the layer structure in the organic EL device of Comparative Example 1. FIG.

10 is a graph showing the relationship between the voltage and the luminescence brightness in each organic EL device of Example 1 and Comparative Example 1. FIG.

11 is a graph showing the amount of current with respect to a constant voltage in each of the organic EL devices of Example 1 and Comparative Example 1. FIG.

12 is a graph showing the amount of current to negative voltage in each of the organic EL elements of Example 1 and Comparative Example 1. FIG.

(Material for hole injection layer)

The material for the hole injection layer of the present invention contains a perfluoropolyether compound, and may further contain other components appropriately selected as necessary.

Perfluoropolyether compound

There is no restriction | limiting in particular as said perfluoro polyether compound, According to the objective, it can select suitably, For example, what has a perfluoro polyether skeleton is mentioned, It is represented by any one or more of following formula (1) and (2). It is mentioned preferably.

However, in Formulas 1 and 2, R ¹ , R ^2, and R ³ may be the same or different from each other, and represent a hydrogen atom, a fluorine atom, or a substituent.

Rf represents the perfluoropolyether skeleton represented by the following general formula (3), and is preferably partially hydrogenated. For example, a part (50% or less) of the fluorine atom in Rf may be substituted with a hydrogen atom.

In Formula 3, R ⁴ and R ⁵ may be the same or different, represent the formula C _P F _{2p + 1} (stage, p represents an integer of 0 or more, also among them is preferably from 0 to 10).

n and m may be the same or different from each other, represent an integer of 0 or more, and preferably 0 to 10.

x and y may be same or different, and represent an integer of 1 or more, and 1-200 are preferable.

Specific examples of the perfluoropolyether skeleton represented by the above Rf include those listed in Table 1 below. In addition, in Table 1, p, q, l, m, and n represent the integer of 1 or more.

When R ¹ to R ³ in Formulas 1 and 2 are the substituents, the substituents are not particularly limited and may be appropriately selected according to the purpose, for example, an alkyl group, an aralkyl group, an alkenyl group, an aryl group, and a cyano group. , An amino group, an acyl group, an alkoxycarbonyl group, a carboxyl group, an alkoxy group, an alkylsulfonyl group, a hydroxyl group, an amide group, an aryloxy group, an aromatic hydrocarbon ring group, an aromatic heterocyclic group, and the group represented by the following formula (4) are preferable. These substituents may also be substituted with the above substituents.

As said alkyl group, for example, an alkyl group having 1 to 25 carbon atoms is preferable, and specifically, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group and neopentyl group , Hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, C ₁₂ H ₂₅ , C ₁₄ H ₂₉ , C ₁₆ H ₃₃ , C ₁₈ H ₃₇ , C ₂₄ H ₄₉ , and the like.

As said aryl group, a phenyl group, tolyl group, xylyl group, biphenylyl group, naphthyl group, anthryl group, phenanthryl group, etc. are mentioned, for example.

As said aralkyl group, a benzyl group, a phenylethyl group, a phenylpropyl group, etc. are mentioned, for example.

Examples of the alkenyl group include vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group, octenyl group and the like.

In said Formula (4), R <^6> represents a hydrocarbon group, for example, an alkyl group, an aralkyl group, an alkenyl group, an aryl group, etc. are mentioned. In these groups, some or all of the hydrogen atoms may be substituted with halogen atoms such as fluorine, bromine and chlorine.

a represents an integer greater than or equal to 0, for example, 0-10 are preferable and 0-5 are more preferable.

R ⁷ To R ¹⁰ may be the same as or different from each other, and represent a hydrogen atom, a fluorine atom or a hydrocarbon group. Moreover, as said hydrocarbon group, an alkyl group, an aryl group, an aralkyl group, an alkenyl group, etc. are mentioned, for example. Some or all of the hydrogen atoms in these groups may be substituted with halogen atoms such as fluorine, bromine and chlorine, cyano group, hydroxyl group, amino group, aminoalkyl group, phosphono group and the like.

As a specific example of the substituent represented by the said General formula (4), what is shown to following Table 2 is mentioned preferably.

As said perfluoropolyether compound, the amine salt compound of the perfluoropolyether which is a reaction product of the said perfluoro polyether compound and an amine, etc. are mentioned preferably, for example.

There is no restriction | limiting in particular as said amine, According to the objective, it can select suitably, For example, any of a primary amine, a secondary amine, and a tertiary amine may be sufficient, and a quaternary ammonium salt may be sufficient as the It is preferable to have an alkyl group among these, it is more preferable to have a C6 or more alkyl group, and it is still more preferable to have a C10 or more alkyl group.

There is no restriction | limiting in particular as said primary amine, According to the objective, it can select suitably, For example, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, t-butylamine , n-pentylamine, cyclopentylamine, isopentylamine, n-hexylamine, cyclohexylamine, n-octylamine, n-decylamine, 1-phenylethylamine, 2-phenylethylamine, allylamine, 2- Dimethylaminoethylamine, 2-methoxyethylamine, etc. are mentioned.

There is no restriction | limiting in particular as said secondary amine, According to the objective, it can select suitably, For example, dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, pyrroli Dine, piperidine, hexamethyleneamine, piperazine, morpholine and the like.

There is no restriction | limiting in particular as said tertiary amine, According to the objective, it can select suitably, For example, trialkylamine, such as triethylamine, tributylamine, trihexylamine, and triamylamine, triethanolamine, dimethylaminoethanol, etc. Aliphatic or non-aromatic cyclic amines such as alkanolamine, triethylenediamine, dimethylphenylamine, dimethylbenzylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, dimethylaniline And aromatic amines such as pyridine and picoline, and alicyclic amines such as 1,8-diazabicyclo (5.4.0) undecene-1 and the like.

There is no restriction | limiting in particular as said quaternary ammonium salt, It can select suitably according to the objective, For example, tetraalkylammonium halide (for example, tetra C1, such as tetramethylammonium chloride, tetraethylammonium chloride, tetrabutylammonium bromide, etc.). TriC1-6 alkyl- such as ˜6 (which represents 1 to 6 carbon atoms) alkylammonium halide), trialkylaralkylammonium halide (for example, trimethylbenzylammonium chloride, triethylbenzylammonium chloride, tripropylbenzylammonium chloride) C7-10 aralkyl ammonium halide), N-alkylpyridinium halide (for example, N-methylpyridinium chloride, etc.) etc. are mentioned.

As a specific example of the amine salt compound of the said perfluoropolyether, the reaction compound of the following perfluoropolyether (henceforth polyfunctional perfluoropolyether) which has a carboxyl group in both terminals, and an amine, and a carboxyl group in only one terminal is mentioned. The reaction compound of the following perfluoro polyether (henceforth monofunctional perfluoro polyether), and an amine etc. which have is mentioned.

(Wherein Rf represents a perfluoropolyether chain. R ¹ , R ² , R ² and R ⁴ each represent hydrogen or a hydrocarbon group.)

(Wherein Rf represents a perfluoropolyether chain. R ¹ , R ² , R ³ , and R ⁴ each represent hydrogen or a hydrocarbon group.)

In the amine salt compound of the perfluoropolyether, the perfluoropolyether skeleton may be partially hydrogenated. For example, a part (50% or less) of a fluorine atom in the perfluoropolyether skeleton is hydrogen. It may be substituted by an atom.

The amine salt compound of the said perfluoropolyether can be synthesize | combined easily by the following method using the said perfluoropolyether and an amine or a diamine. That is, a monofunctional perfluoropolyether or a polyfunctional perfluoropolyether and an amine or diamine are mixed and at a temperature above the melting point of the amine or diamine used (60 ° C. when stearylamine is used as the amine). It can synthesize | combine by heating.

There is no restriction | limiting in particular as a weight average molecular weight of the said perfluoropolyether compound, Although it can select suitably according to the objective, For example, 500-10000 are preferable and 1000-6000 are more preferable.

When the said weight average molecular weight is less than 500, the effect of the increase of a hole injection amount may not fully be acquired, and when it exceeds 10000, solubility to an organic solvent may fall and film formation may fall. ·

As said perfluoropolyether compound, what was synthesize | combined suitably can also be used, A commercial item can also be used, As this commercial item, for example, Audimont Corporation make, brand names Z-dol 1000, Z-dol 2000, Z- dol 4000 etc. are mentioned preferably.

The hole injection layer material of the present invention can be suitably used in various fields, and can be preferably used in LEDs (light emitting diodes), organic EL devices, and the like, and particularly preferably in the hole injection layers in the organic EL device of the present invention. Can be used.

(Organic EL device)

The organic EL device of the present invention has an organic thin film layer including at least a hole injection layer between the positive electrode and the negative electrode, and the hole injection layer contains the perfluoropolyether compound.

The organic thin film layer is not particularly limited except having at least the hole injection layer, and may be appropriately selected according to the purpose. For example, the organic thin film layer may have a hole transport layer, a hole blocking layer, a light emitting layer, an electron transport layer, an electron injection layer, or the like. .

There is no restriction | limiting in particular as a layer structure in the organic electroluminescent element of this invention, According to the objective, it can select suitably, For example, the following (1)-(13), ie, (1) positive electrode / hole injection layer / hole transport layer / Light emitting layer / electron transport layer / electron injection layer / negative electrode, (2) positive electrode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / negative electrode, (3) positive electrode / hole transport layer / light emitting layer / electron transport layer / electron injection layer / negative electrode, (4) positive electrode / hole transport layer / light emitting layer / electron transport layer / negative electrode, (5) positive electrode / hole injection layer / hole transport layer / light emitting layer and electron transport layer / electron injection layer / negative electrode, (6) positive electrode / hole injection layer / hole transport layer / Light emitting layer and electron transporting layer / negative electrode, (7) positive electrode / hole transporting layer / light emitting layer and electron transporting layer / electron injection layer / negative electrode, (8) positive electrode / hole transporting layer / light emitting layer and electron transporting layer / negative electrode, (9) positive electrode / hole injection layer / Hole transporting layer and light emitting layer / electron transporting layer / electron injection layer / negative electrode, (10) positive electrode / hole injection layer / hole transporting layer and light emitting layer / Self-transporting layer / negative electrode, (11) positive electrode / hole transporting layer and light emitting layer / electron transporting layer / electron injection layer / negative electrode, (12) positive electrode / hole transporting layer and light emitting layer / electron transporting layer / negative electrode, (13) positive electrode / hole transporting layer, light emitting layer and electron A transport layer / negative electrode etc. are mentioned preferably. Moreover, when the said organic electroluminescent element has the said hole blocking layer, the layer structure in which the said hole blocking layer is arrange | positioned between the said light emitting layer and the said electron carrying layer in said (1)-(13) is mentioned preferably. .

Among these layer configurations, the form of the above (6) positive electrode / hole injection layer / hole transport layer / light emitting layer and electron transport layer / negative electrode is as shown in FIG. 2, and the organic EL element 10 is formed on the glass substrate 12. The positive electrode 14 (e.g., ITO electrode), the hole injection layer 16, the hole transporting layer 18, the electron transporting layer and the light emitting layer 20, and the negative electrode 22 (e.g., Al-Li electrode) are in this order. It is a laminated constitution formed by lamination. In addition, the positive electrode 14 (for example, ITO electrode) and the negative electrode 22 (for example, Al-Li electrode) are connected to each other via a power supply. The organic thin film layer is formed of the hole injection layer 16, the hole transport layer 18, and the electron transport layer and the light emitting layer 20.

Positive electrode

There is no restriction | limiting in particular as said positive electrode, It can select suitably according to the objective, It is preferable that a hole (carrier) can be supplied to the said hole injection layer.

There is no restriction | limiting in particular as a material of the said positive electrode, According to the objective, it can select suitably, For example, a metal, an alloy, a metal oxide, an electrically conductive compound, a mixture thereof, etc. are mentioned, Among these, a work function is 4 eV or more. Material is preferred.

Specific examples of the material of the positive electrode include conductive metal oxides such as tin oxide, zinc oxide, indium oxide and indium tin oxide (ITO), metals such as gold, silver chromium and nickel, mixtures or laminates of these metals and conductive metal oxides, Inorganic conductive materials such as copper iodide and copper sulfide, organic conductive materials such as polyaniline, polythiophene and polypyrrole, and laminates of these and ITO. These may be used individually by 1 type and may use 2 or more types together. Among these, conductive metal oxides are preferable, and ITO is particularly preferable in terms of productivity, high conductivity, transparency, and the like.

There is no restriction | limiting in particular as thickness of the said positive electrode, Although it can select suitably according to a material etc., 1-5000 nm is preferable and 20-200 nm is more preferable.

The said positive electrode is normally formed on substrates, such as glass, such as a soda-lime glass and an alkali free glass, and a transparent resin.

When using the said glass as said board | substrate, the said soda-lime glass provided with the barrier coating, such as the said alkali free glass and a silica, is preferable at the point which reduces the elution ion from the said glass.

The thickness of the substrate is not particularly limited as long as it is sufficient to maintain mechanical strength. However, when glass is used as the substrate, the thickness is usually 0.2 mm or more, and 0.7 mm or more is preferable.

The positive electrode may be, for example, a vapor deposition method, a wet film formation method, an electron beam method, a sputtering method, a reactive sputtering method, a molecular beam epitaxial method, a cluster ion beam method, an ion plating method, a plasma polymerization method (high frequency excitation ion plating method), It can form suitably by the above-mentioned methods, such as the method of apply | coating the dispersion of the said ITO by molecular lamination | stacking method, LB method, the printing method, the transfer method, the chemical reaction method (sol-gel method), etc.

By cleaning and other processes, the positive electrode may lower the driving voltage of the organic EL element or increase the luminous efficiency. As said other treatment, when the raw material of the said positive electrode is ITO, UV-ozone treatment, a plasma treatment, etc. are mentioned preferably, for example.

Hole injection layer

The hole injection layer has a function of injecting holes from the positive electrode when the electric field is applied and transporting the holes to the hole transport layer.

As an ionization potential in the said hole injection layer, as shown in FIG. 7, it is located between the ionization potential in the said positive electrode and the ionization potential in HOMO (highest frequency molecular orbital) of the said hole transport layer, ie, the said positive electrode It is preferably smaller than the potential at and larger than the ionization potential of HOMO (highest wave molecular orbital) in the hole transport layer. In this case, it is advantageous in that the energy barrier when injecting the holes from the holes into the organic thin film layer is small, the current to the constant voltage flows well, and the luminous efficiency is improved. In addition, the ionization potential means a value indicating the energy required to separate one electron infinitely far from the ground state of an atom or molecule, that is, ionization energy in units of electron volts.

The specific value of the ionization potential in the hole injection layer is not generally defined depending on the thickness of the hole injection layer, but is preferably about 4.8 to 5.6 eV.

In addition, the said ionization potential can be measured using a well-known ionization potential measuring apparatus.

It is preferable that the said hole injection layer contains the said perfluoro polyether compound, and is formed from the material for the said hole injection layer of this invention.

When the hole injection layer is formed of the material for the hole injection layer of the present invention, the ionization potential of the hole injection layer can be easily controlled within the preferred range as described above, and the adjacent layer with the hole injection layer (the It is advantageous in that wettability with the positive electrode and the hole transport layer) is abundant and adhesiveness is good.

The hole injection layer may be, for example, a vapor deposition method, a wet film formation method, an electron beam method, a sputtering method, a reactive sputtering method, a molecular beam epitaxial method, a cluster ion beam method, an ion plating method, a plasma polymerization method (high frequency excitation ion plating method). ), And may be preferably formed by a method such as a molecular lamination method, an LB method, a printing method, or a transfer method.

There is no restriction | limiting in particular as said vapor deposition method, According to the objective, it can select from a well-known thing suitably, For example, a vacuum vapor deposition method, resistance heating vapor deposition, chemical vapor deposition method, physical vapor deposition method, etc. are mentioned. As said chemical vapor deposition method, a plasma CVD method, a laser CVD method, a thermal CVD method, a gas source CVD method, etc. are mentioned, for example.

There is no restriction | limiting in particular as said wet film formation method, According to the objective, it can select suitably from a well-known thing, For example, the inkjet method, a spin coating method, the kneader coating method, the bar coating method, the blade coating method, the casting method, Dipping method, curtain coating method, etc. are mentioned.

In the wet film forming method, a solution obtained by dissolving or dispersing the material of the hole injection layer together with the resin component can be used (coating or the like). Examples of the resin component include polyvinylcarbazole and polycarbide. Carbonate, polyvinyl chloride, polystyrene, polymethylmethacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, hydrocarbon resin, ketone resin, phenoxy resin, polyamide, ethylcellulose, vinyl acetate, ABS resin And polyurethanes, melamine resins, unsaturated polyester resins, alkyd resins, epoxy resins, silicone resins and the like.

The formation of the hole injection layer by the wet film formation method is preferable by applying, drying, etc., using, for example, a solution (coating solution) in which the hole injection layer material and the resin material used as necessary are dissolved in a solvent. I can do it.

Moreover, there is no restriction | limiting in particular as said solvent, It can select suitably from a well-known thing, A commercial item can be used preferably, For example, FC77 (made by 3M company), Vertrel XF (made by Dupont company), etc. Can be mentioned.

There is no restriction | limiting in particular as thickness of the said hole injection layer, Although it can select suitably according to the objective, For example, 10 nm or less is preferable and 0.1-10 nm is more preferable.

When the thickness of the hole injection layer exceeds 10 nm, holes may not smoothly flow through the light emitting layer.

Hole Transport Layer

There is no restriction | limiting in particular as said hole transport layer, Although it can select suitably according to the objective, For example, it is preferable to have a function which transports the hole from the said hole injection layer at the time of an electric field application.

There is no restriction | limiting in particular as a material of the said hole transport layer, According to the objective, it can select suitably, For example, an aromatic amine compound, carbazole, imidazole, triazole, oxazole, oxadiazole, polyaryl alkane, pyrazoline, Pyrazolone, phenylenediamine, arylamine, amino substituted chalcone, styrylanthracene, fluorenone, hydrazone, stilbene, silazane, styrylamine, aromatic dimethylidine compound, porphyrin-based compound, polysilane-based compound, poly ( N-vinylcarbazole), aniline copolymers, thiophene oligomers and polymers, conductive polymer oligomers and polymers such as polythiophene, and carbon films. In addition, when the material of these hole transport layers is mixed with the material of the light emitting layer to form a film, the hole transporting layer and the light emitting layer can be formed.

These may be used individually by 1 type, and may use 2 or more types together, Especially, an aromatic amine compound is preferable, Specifically, TPD (N, N'-diphenyl-N, N'- represented by a following formula) Bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine, NPD represented by the following formula (N, N'-dinaphthyl-N, N'-diphenyl- [ 1,1'-biphenyl] -4,4'-diamine) etc. are more preferable.

There is no restriction | limiting in particular as thickness of the said hole transport layer, Although it can select suitably according to the objective, Usually, it is 1-500 nm, and 10-100 nm is preferable.

The hole transport layer is, for example, vapor deposition method, wet film formation method, electron beam method, sputtering method, reactive sputtering method, MBE (molecular beam epitaxial) method, cluster ion beam method, ion plating method, plasma polymerization method (high frequency excitation ion plating method) Can be preferably formed by the above-described methods such as molecular lamination, LB, printing, and transfer.

Light emitting layer

The emission layer may inject holes from the positive electrode, the hole injection layer, the hole transport layer, and the like when an electric field is applied, and inject electrons from the negative electrode, the electron injection layer, the electron transport layer, and the like. It provides a recombination place between the holes and the electrons, and contains a luminescent material that develops a predetermined emission color by recombination energy generated during the recombination.

There is no restriction | limiting in particular as said light emitting material, According to the objective, it can select suitably from a well-known thing, A green light emitting material, a blue light emitting material, a yellow light emitting material, a red light emitting material, etc. are mentioned.

The green light emitting material is not particularly limited as long as it can emit green light, and examples thereof include an aluminoquinolinium complex, a benzoquinolinol Be complex, and the like.

The blue light emitting material is not particularly limited as long as it can emit blue light, and examples thereof include benzoxazole Zn complexes and quinolinol complexes.

The yellow luminescent material is not particularly limited as long as it can emit yellow light, and examples thereof include a 4-coordinate complex with 8-quinolinol with Zn.

The red luminescent material is not particularly limited as long as it can emit red light, and examples thereof include DCM pigments (CWTang, SAVanSlyke, and CHChen, Applied Physics Letters vo1.65, 3610 (1989)), and red fluorescence. Porphine compound or porphyrin compound having a compound (Japanese Patent Laid-Open No. 9-13024, Japanese Patent Laid-Open No. 9-296166, Japanese Patent Laid-Open No. 11-251061, Japanese Patent Laid-Open 11-251062, International Publication No. WO98 / 00474, and the bisantrene compound having red fluorescence (Japanese Patent Laid-Open No. Hei 11-144868).

The light emitting layer can be formed according to a known method, for example, by a deposition method, a wet film formation method, a molecular beam epitaxial (MBE) method, a cluster ion beam method, a molecular lamination method, an LB method, a printing method, a transfer method, or the like. Can be formed.

As thickness of the said light emitting layer, 1-50 nm is preferable and 3-20 nm is more preferable.

If the thickness of the light emitting layer is in the above preferable numerical range, it is advantageous in that the light emission efficiency, light emission luminance, and color purity of the light emitted by the organic EL element are sufficient.

The light emitting layer may be designed as a light emitting layer and an electron transporting layer, a light emitting layer and a hole transporting layer, etc. having both functions of the hole transporting layer, the electron transporting layer and the like.

The light emitting layer or the light emitting layer, the electron transporting layer, the light emitting layer, and the hole transporting layer contains the light emitting material as a guest material, and in addition to the guest material, the light emitting wavelength further contains a host material having a light emission wavelength near the light absorption wavelength of the guest material. desirable. The host material is usually contained in the light emitting layer, but may also be contained in the hole transport layer, the electron transport layer, or the like.

In the case of using the guest material and the host material together, the host material is first excited when organic EL light emission occurs. In addition, since the emission wavelength of the host material and the absorption wavelength of the guest material overlap, excitation energy is efficiently transferred from the host material to the guest material, and the host material does not emit light and returns to the ground state. Since only the said guest material which became the state emits excitation energy as light, it is excellent in luminous efficiency, color purity, etc.

In general, when light emitting molecules are present alone or in high concentrations in a thin film, interaction between light emitting molecules occurs by accessing light emitting molecules, and a phenomenon in which light emission efficiency is called "concentration quenching" occurs. When using a material together with the said host material, since the said guest compound is disperse | distributed in the said host compound at comparatively low concentration, it is advantageous at the said "concentration quenching" being suppressed effectively and the luminous efficiency is excellent. In the case where the guest material and the host material are used together in the light emitting layer, the host material is generally excellent in film formation, which is advantageous in that the film formation is excellent while maintaining light emission characteristics.

There is no restriction | limiting in particular as said host material, Although it can select suitably according to the objective, It is preferable that the light emission wavelength is near the light absorption wavelength of the said guest material, For example, a low molecular weight host material, a polymeric host material, etc. are mentioned. Can be.

There is no restriction | limiting in particular as said low molecular weight host material, According to the objective, it can select suitably, For example, 4,4'-bis (2,2'- diphenylvinyl) -1,1'-biphenyl (DPVBi) , p-sexyphenyl (p-SP), 1,3,6,8-tetraphenylpyrene (tppy), N, N'-dinaphthyl-N, N'-diphenyl- [1,1'-ratio Phenyl] -4,4'-diamine (NPD), an auxin complex and a carbazole derivative, preferably an aromatic amine derivative represented by the following formula (5), a carbazole derivative represented by the following formula (7), The auxin complex represented, the 1,3.6,8-tetraphenylpyrene compound represented by the following general formula (11), and the 4,4'-bis (2,2'-diphenylvinyl) -1,1'- represented by the following general formula (13) Biphenyl (DPVBi) (Main emission wavelength = 470 nm), p-Sexyphenyl represented by Formula 14 (Main emission wavelength = 400 nm), 9,9'-Bianthryl (main emission wavelength = 460 nm) represented by Formula 15 ) And the like are preferable.

In said Formula (5), n represents the integer of 2 or 3. Ar represents a bivalent or trivalent aromatic group or a heterocyclic aromatic group. R ¹¹ and R ¹² may be the same as or different from each other, and represent a monovalent aromatic group or a heterocyclic aromatic group. The monovalent aromatic group or the heterocyclic aromatic group can be appropriately selected depending on the purpose without particular limitation.

Among the aromatic amine derivatives represented by Formula 5, N, N'-dinaphthyl-N, N'-diphenyl- [1,1'-biphenyl] -4,4'- Diamine (NPD) (main emission wavelength = 430 nm) and derivatives thereof are preferred.

In said Formula (7), Ar represents the bivalent or trivalent group containing the aromatic ring shown below, or the bivalent or trivalent group containing a heterocyclic aromatic ring.

These may be substituted by nonconjugated group, R represents a coupling group, For example, the following are mentioned preferably.

In Formula 7, R ¹³ and R ¹⁴ are each independently a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an aryl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, a carboxyl group, an alkoxy group, an alkylsulfonyl group , A hydroxyl group, an amide group, an aryloxy group, an aromatic hydrocarbon ring group, or an aromatic heterocyclic group, and these may be further substituted with a substituent.

In said Formula (7), n represents an integer and 2 or 3 is mentioned preferably.

Among the aromatic amine derivatives represented by Formula 7, Ar is an aromatic group in which two benzene rings are linked via a single bond, R ¹³ and R ¹⁴ are hydrogen atoms, n is 2, that is, represented by the following Formula 8 The one selected from 4,4'-bis (9-carbazolyl) -biphenyl (CBP) (main emission wavelength = 380 nm) and derivatives thereof is preferable in view of particularly excellent luminous efficiency.

However, in said Formula (9), R <^15> represents a hydrogen atom or a monovalent hydrocarbon group.

Among the auxin complexes represented by the above formula (9), an aluminum quinoline complex (Alq) represented by the following formula (10) (main emission wavelength = 530 nm) is preferable.

         Alq

However, in Formula 11, R ¹⁶ to R ¹⁹ may be the same as or different from each other, and represent a hydrogen atom or a substituent. As said substituent, an alkyl group, a cycloalkyl group, or an aryl group is mentioned preferably, for example, These may further be substituted by a substituent.

Among the 1,3,6,8-tetraphenylpyrenes represented by Formula 11, R ¹⁶ to R ¹⁹ are hydrogen atoms, that is, 1,3,6,8-tetraphenylpyrene represented by the following Formula 12 (main emission wavelength = 440 nm) is preferable in that the luminous efficiency is particularly excellent.

1,3,6,8-tetraphenylpyrene

p-sexyphenyl

9,9'-Biantril

As the polymer host material, polyparaphenylene vinylene (PPV), polythiophene (PAT), polyparaphenylene (PPP), polyvinylcarbazole (PVCz), and polyfluorene (PF) represented by the following chemical formulas And polyacetylene (PA) and derivatives thereof, and among these, polyvinylcarbazole (PVCz) represented by the following general formula (16) is preferable.

PPV Inductor

PAT derivative

PPP derivative

PVCz Inductor

PF derivative

PA derivative

Provided that R represents a hydrogen atom, a halogen atom, an alkoxy group, an amino group, an alkyl group, a cycloalkyl group, an aryl group which may contain a nitrogen atom or a sulfur atom, or an aryloxy group, which may be further substituted with a substituent. x represents an integer.

In the above formula (16), R ²⁰ and R ²¹ each represent a plurality of substituents provided at arbitrary positions of the cyclic structure, and may be the same or different from each other, a hydrogen atom, a halogen atom, an alkoxy group, an amino group, an alkyl group, A cycloalkyl group, the aryl group which may contain the nitrogen atom, or the sulfur atom, and the aryloxy group are shown, and these may be further substituted by the substituent. R ²⁰ and R ²¹ may be connected to each other to form an aromatic ring which may include a nitrogen atom, a sulfur atom, and an oxygen atom, which may be further substituted with a substituent. x represents an integer.

Hole blocking layer

There is no restriction | limiting in particular as said hole blocking layer, Although it can select suitably according to the objective, For example, it is preferable to have a function which barriers the hole injected from the said positive electrode.

There is no restriction | limiting in particular as a material of the said hole blocking layer, According to the objective, it can select suitably.

When the organic EL element has the hole blocking layer, holes transported from the positive electrode side are blocked in the hole blocking layer, and electrons transported from the negative electrode pass through the hole blocking layer to reach the light emitting layer, thereby emitting the light emitting layer. Since recombination of electrons and holes occurs efficiently at, the recombination of the holes and the electrons in the organic thin film layer other than the light emitting layer can be prevented, and light emission from the target light emitting material can be efficiently obtained. It is advantageous in terms of color purity and the like.

The hole blocking layer is preferably disposed between the light emitting layer and the electron transport layer.

There is no restriction | limiting in particular as thickness of the said hole blocking layer, According to the objective, it can select suitably, For example, it is about 1-500 nm normally, and 10-50 nm is preferable.

The hole blocking layer may have a single layer structure or a laminated structure.

The hole blocking layer may be, for example, a vapor deposition method, a wet film formation method, an electron beam method, a sputtering method, a reactive sputtering method, a molecular beam epitaxial method, a cluster ion beam method, an ion plating method, a plasma polymerization method (high frequency excitation ion plating method). ), A molecular lamination method, an LB method, a printing method, and a transfer method, and the like can be preferably formed.

Electron transport layer

There is no restriction | limiting in particular as said electron carrying layer, Although it can select suitably according to the objective, For example, it is preferable to have any one of the function of transporting the electron from the said negative electrode, and the function of blocking the hole injected from the said positive electrode. .

There is no restriction | limiting in particular as a material of the said electron carrying layer, According to the objective, it can select suitably, For example, quinoline derivatives, an oxadiazole derivative, a triazole derivative, a phenanthroline derivative, a phenol, such as said aluminum quinoline complex (Alq) And a ylene derivative, a pyridine derivative, a pyrimidine derivative, a quinoxaline derivative, a diphenylquinone derivative, a nitro substituted fluorene derivative, and the like. In addition, when the material of these electron transporting layers is mixed with the material of the light emitting layer to form a film, an electron transporting layer and a light emitting layer can be formed, and when the material of the hole transporting layer is also mixed to form a film, an electron transporting layer and a hole transporting layer and a light emitting layer are formed. In this case, polymers, such as polyvinylcarbazole and polycarbonate, can be used.

There is no restriction | limiting in particular as thickness of the said electron carrying layer, According to the objective, it can select suitably, For example, it is about 1-500 nm normally, and 10-50 nm is preferable.

The electron transport layer may have a single layer structure or a laminated structure.

In this case, as the electron transporting material used for the electron transporting layer adjacent to the light emitting layer, the use of an electron transporting material having a shorter wavelength of light absorption means than the induced light material limits the light emitting region in the organic EL element to the light emitting layer. It is preferable at the point which prevents unnecessary light emission from the said electron carrying layer. Examples of the electron transporting material include phenanthroline derivatives, oxadiazole derivatives, triazole derivatives, and the like, and 2,9-dimethyl-4,7-diphenyl-1,10 represented by the following general formula (17): -Phenanthroline (BCP), the compound shown below, etc. are mentioned preferably.

2- (4-tert-butylphenyl) -5- (4-biphenylyl) -1,3,4-oxadiazole

3-phenyl-4- (1-naphthyl) -5-phenyl-1,2,4-triazole

3- (4-tert-butylphenyl) -4-phenyl-5- (4'-biphenylyl) -1,2,4-triazole

The electron transport layer is, for example, vapor deposition method, wet film formation method, electron beam method, sputtering method, reactive sputtering method, MBE (molecular beam epitaxial) method, cluster ion beam method, ion plating method, plasma polymerization method (high frequency excitation ion plating method) Can be preferably formed by the above-described methods such as molecular lamination, LB, printing, and transfer.

Electron injection layer

There is no restriction | limiting in particular as said electron injection layer, Although it can select suitably according to the objective, For example, it is preferable to have a function which injects the electron from the said negative electrode, and transports it to an electron carrying layer.

There is no restriction | limiting in particular as a material of the said electron injection layer, According to the objective, it can select suitably, For example, alkali-metal fluorides, such as lithium fluoride, alkaline-earth metal fluorides, such as strontium fluoride, etc. are mentioned.

There is no restriction | limiting in particular as thickness of the said electron injection layer, According to the objective, it can select suitably, For example, it is about 0.1-10 nm normally, and 0.5-2 nm is preferable.

The electron injection layer is, for example, vapor deposition method, wet film formation method, electron beam method, sputtering method, reactive sputtering method, MBE (molecular beam epitaxial) method, cluster ion beam method, ion plating method, plasma polymerization method (high frequency excitation ion plating method). ), A molecular lamination method, an LB method, a printing method, and a transfer method, and the like can be preferably formed.

Negative electrode

There is no restriction | limiting in particular as said negative electrode, According to the objective, it can select suitably, Specifically, when the said organic thin film layer has only the said light emitting layer, The said organic thin film layer has the said electron carrying layer further in the said light emitting layer In the case where the electron transport layer has an electron injection layer between the organic thin film layer and the negative electrode, it is preferable that electrons can be supplied to the electron injection layer.

There is no restriction | limiting in particular as a material of the said negative electrode, According to adhesiveness, ionization potential, stability, etc. with layers adjacent to the said negative electrode, such as the said electron carrying layer and the said light emitting layer, a molecule | numerator, stability, etc. can be selected suitably, For example, a metal, an alloy, a metal Oxides, electrically conductive compounds, mixtures thereof, and the like.

Specific examples of the material of the negative electrode include alkali metals (eg, Li, Na, K, Cs, etc.), alkaline earth metals (eg, Mg, Ca, etc.), gold, silver, lead, aluminum, sodium-potassium alloys, or these Mixed metals, lithium-aluminum alloys or mixed metals thereof, magnesium-silver alloys or mixed metals thereof, rare earth metals such as indium and ytterbium, and alloys thereof.

These may be used individually by 1 type and may use 2 or more types together. Among these, materials having a work function of 4 eV or less are preferable, and aluminum, lithium-aluminum alloy or mixed metals thereof, magnesium-silver alloy or mixed metals thereof and the like are more preferable.

There is no restriction | limiting in particular as thickness of the said negative electrode, Although it can select suitably according to the material of the said negative electrode, 1-10000 nm is preferable and 20-200 nm is more preferable.

The negative electrode may be, for example, a vapor deposition method, a wet film formation method, an electron beam method, a sputtering method, a reactive sputtering method, a molecular beam epitaxial method, a cluster ion beam method, an ion plating method, a plasma polymerization method (high frequency excitation ion plating method), It can form suitably by the above-mentioned methods, such as a molecular lamination method, the LB method, the printing method, and the transfer method.

When using 2 or more types together as said negative electrode material, the said 2 or more types of material may be deposited simultaneously, an alloy electrode etc. may be formed, and the alloy electrode etc. may be formed by depositing the alloy manufactured previously.

As a resistance value of the said positive electrode and the said negative electrode, the lower one is preferable and it is preferable that it is several hundred ohm / square or less.

-Other layers-

The organic EL element of this invention may have the other layer suitably selected according to the objective, and as said other layer, a protective layer etc. are mentioned preferably, for example.

There is no restriction | limiting in particular as said protective layer, According to the objective, it can select suitably, For example, it is preferable that the molecule | numerator or substance which promotes deterioration of organic electroluminescent element, such as water and oxygen, can be suppressed to intrude in an organic electroluminescent element. Do.

As the material of the protective layer, for example, metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti, Ni, MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO , Metal oxides such as Fe ₂ O ₃ , Y ₂ O ₃ , TiO ₂ , nitrides such as SiN, SiN _x O _y , metal fluorides such as MgF ₂ , LiF, AlF ₃ , CaF ₂ , polyethylene, polypropylene, polymethyl Methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, copolymers of chlorotrifluoroethylene and dichlorodifluoroethylene, tetrafluoroethylene The copolymer obtained by copolymerizing the monomer mixture containing 1 or more types of comonomers, the fluorine-containing copolymer which has a cyclic structure in a copolymer main chain, the absorptive substance of 1% or more of water absorption, the moisture-proof substance of 0.1% or less of water absorption, etc. are mentioned.

The protective layer is, for example, a vapor deposition method, a wet film formation method, a sputtering method, a reactive sputtering method, a molecular beam epitaxial (MBE) method, a cluster ion beam method, an ion plating method, a plasma polymerization method (high frequency excitation ion plating method), or a printing method. It can form preferably by the above-mentioned methods, such as the transfer method.

As luminous efficiency of the organic electroluminescent element of this invention, it is preferable to emit light at voltage 10V or less, It is more preferable to emit light at 7V or less, It is further more preferable to emit light at 5V or less.

The light emission luminance of the organic EL device of the present invention is preferably 100 cd / m 2 or more at an applied voltage of 10 V, more preferably 500 cd / m 2 or more, and particularly preferably 1000 cd / m 2 or more.

Examples of the organic EL device of the present invention include a computer, a vehicle-mounted display device, an outdoor display device, a household device, a commercial device, a home appliance, a traffic display device, a clock display device, a calendar display device, a luminescent screen, an audio device, and the like. Although it can use preferably in various fields including these, it can use especially for the organic electroluminescent display of the following this invention.

(Organic EL display)

There is no restriction | limiting in particular except the organic electroluminescent display of this invention using the organic electroluminescent element of the said invention, A well-known structure can be used suitably.

The organic EL display may be monochromatic, multicolor, or full-color.

As a method of making the organic EL display in full color form, for example, as described in "Monthly Display", September 2000, pp. 33 to 37, three primary colors of color (blue (B)) Three-color emission method in which an organic EL device that emits light corresponding to green (G) and red (R)) is disposed on a substrate, and white light emission by the organic EL device for white light emission is determined through a color filter. BACKGROUND ART White conversion into primary colors and color conversion methods for converting blue light emission by an organic EL device for blue light emission into red (R) and green (G) through fluorescent sublayers are known.

In the case of producing a full color organic EL display by the three-color emission method, an organic EL element for blue light emission, an organic EL element for red light emission, and an organic EL element for green light emission are required.

There is no restriction | limiting in particular as said organic electroluminescent element for red luminescence, It can select from a well-known thing suitably, For example, DCJTB 1% aluminum quinoline complex (layer structure represented by ITO (positive electrode) / said NPD / following formula) ( Alq) / said Alq / Al-Li (negative electrode) etc. are mentioned preferably. The DCJTB is 4-dicyanomethylene-6-cp-zulolidinostyryl-2-tert-butyl-4H-pyran. In addition, Alq is as above-mentioned.

DCJTB

4-dicyanomethylene-6-cp-zoloridinostyryl-2-tert-butyl-4H-pyran

There is no restriction | limiting in particular as said organic electroluminescent element for green light emission, Although it can select suitably from a well-known thing, For example, a layer structure is ITO (positive electrode) / the said NPD / dimethylquinacridone 1% the said Alq / the said Alq / Al-Li (negative electrode) etc. are mentioned preferably.

There is no restriction | limiting in particular as said organic electroluminescent element for blue light emission, Although it can select suitably from a well-known thing, For example, a layer structure is ITO (positive electrode) / said NPD / said DPVBi / said Alq / Al-Li (negative electrode) The thing etc. are mentioned preferably.

There is no restriction | limiting in particular as a form of the said organic electroluminescent display, According to the objective, it can select suitably, For example, it describes in "Nikei Electronics", No. 765, March 13, 2000, pages 55-62. Passive matrix panels, active matrix panels, and the like as mentioned above are preferable.

For example, as shown in FIG. 3, the passive matrix panel has a band-shaped positive electrode 14 (for example, an ITO electrode) disposed parallel to each other on the glass substrate 12, and on the positive electrode 14. It has a strip-shaped organic thin film layer 24 for blue light emission, the organic thin film layer 26 for green light emission, and the organic thin film layer 28 for red light emission arrange | positioned so that it may become parallel to each other in order orthogonal to the positive electrode 14, and On the organic thin film layer 24 for blue light emission, the organic thin film layer 26 for green light emission, and the organic thin film layer 28 for red light emission.

In the passive matrix panel, for example, as shown in FIG. 4, the positive electrode line 30 including the plurality of positive electrodes 14 and the negative electrode line 32 including the plurality of negative electrodes 22 are substantially disposed on each other. A circuit is formed by crossing in a straight direction. Each of the organic thin film layers 24, 26, and 28 for blue light emission, green light emission, and red light emission located at each intersection function as a pixel, and a plurality of organic EL elements 34 exist in correspondence with each pixel. Doing. In the passive matrix panel, if a current is applied by the constant current source 36 to one positive electrode 14 in the positive electrode line 30 and one negative electrode 22 in the negative electrode line 32, then, at that time, An electric current is applied to the organic thin film layer located at the intersection, and the organic EL thin film layer at that position emits light. By controlling the light emission in the pixel unit, it is possible to easily form a full color image.

In the active matrix panel, for example, as shown in FIG. 5, scan lines, data lines, and current supply lines are formed on the glass substrate 12 in the form of checker boards, and are connected to scan lines or the like forming the checker boards. It has a positive electrode 14 (for example, an ITO electrode) which can be driven by the TFT circuit 40 and the TFT circuit 40 arranged in the eye and arranged in each of the grids, and is in order on each other on the positive electrode 14. The organic thin film layer 24 for stripping blue light, the organic thin film layer 26 for emitting green light, and the organic thin film layer 28 for emitting red light, and the organic thin film layer 24 for emitting blue light, green It has the negative electrode 22 arrange | positioned so that all may be covered on the organic thin film layer 26 for light emission, and the organic thin film layer 28 for red light emission. The organic thin film layer 24 for blue light emission, the organic thin film layer 26 for green light emission, and the organic thin film layer 28 for red light emission each have the hole transport layer 16, the light emitting layer 18, and the electron carrying layer 20, respectively. .

In the active matrix panel, for example, as shown in FIG. 6, checker boards are formed so that the scanning lines 46 arranged in parallel, the data lines 42 arranged in parallel, and the current supply line 44 are perpendicular to each other. In each board, the switching TFT 48 and the driving TFT 50 are connected to form a circuit. When a current is applied from the drive circuit 38, the switching TFT 48 and the driving TFT 50 can be driven for each board. In addition, in each of the checkerboards, the organic thin film elements 24, 26, and 28 for blue light emission, green light emission, and red light emission function as pixels, and are arranged in the horizontal direction in the active matrix panel. When a current is applied from the drive circuit 38 to one of the scanned lines 46 and the current supply line 44 arranged in the longitudinal direction, the switching TFT 48 located at the intersection point at that time is driven, thereby The driving TFT 50 is driven, and the organic EL element 52 at the position emits light. By controlling the light emission in units of pixels, a full color image can be easily formed.

The organic EL display of the present invention is, for example, a computer, an on-vehicle indicator, an outdoor indicator, a household appliance indicator, a work appliance indicator, a household appliance indicator, a traffic relation indicator, a clock indicator, a calendar indicator, a luminescent screen, an acoustic It can be used preferably in various fields, such as an apparatus.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, the present inventors earnestly examined and found the following. That is, when the hole injection layer containing the perfluoropolyether (PFPE) compound is formed on the positive electrode, the hole injection amount can be further improved, the operation can be performed at a low voltage, and leakage current is difficult to flow even in the reverse voltage. It is discovery that the organic electroluminescent element which exhibits a diode characteristic and can suppress generation | occurrence | production of crosstalk effectively can be obtained.

The present invention is based on the above findings by the present inventors.

The material for a hole injection layer of the present invention contains a perfluoropolyether compound. Therefore, in the hole injection layer formed using the hole injection layer material, the hole injection amount is improved compared to the conventional hole injection layer formed using the other material, and the leakage current at the sub-bias is good, resulting in good diode characteristics. Indicates.

The organic EL device of the present invention has an organic thin film layer including at least a hole injection layer between the positive electrode and the negative electrode, and the hole injection layer contains a perfluoropolyether compound. Therefore, in the organic EL device, since the hole injection layer is rich in wettability with the positive electrode and the hole transporting layer, which are adjacent layers thereof, adhesion is good and interlayer peeling does not occur. Since the hole injection amount is larger than that of the hole injection layer in the conventional organic EL device, the same luminance can be realized at a lower voltage. In addition, since the surface of the positive electrode with raised unevenness is smoothed by the hole injection layer, the leakage current at the sub-bias is small, showing good diode characteristics, and electrical short between the positive electrode and the negative electrode is effectively alleviated. As a result, no crosstalk is generated in the organic EL display formed using the organic EL element.

Here, generation of crosstalk in the organic EL display will be described. When only element A emits light in Fig. 1A, which is a circuit diagram in the passive matrix of the organic EL display, element B does not emit light. As can be seen from the circuit equivalent to the circuit shown in Fig. 1A, as shown in Fig. 1B, when the element A emits light, current flows in the path of dotted and dashed lines. At this time, since the direction in which current flows only in the element B is reversed in the path of the dashed-dotted line (no current flows with respect to the voltage in the negative direction), the element B functions as a diode so that no current flows. In addition, the device B does not emit light. However, if the diode characteristic of the device B is insufficient (low) and the leakage current at the negative voltage is large, current flows not only in the path of the dotted line but also in the path of the dashed line, so that the device B emits light. The phenomenon in which not only the element A but also the element B emits light is called cross talk. When this cross talk occurs, the light emission luminance is lowered, and a problem arises in that a clear image cannot be obtained.

Since the generation of the crosstalk is effectively suppressed in the organic EL device of the present invention, the same brightness is obtained at a lower voltage, the light emission brightness is excellent, and the reliability is high.

The organic EL display of the present invention is made using the organic EL element of the present invention. Therefore, in the organic EL display, since the generation of the crosstalk is effectively suppressed, the same brightness is obtained at a lower voltage, the light emission brightness is excellent, and the reliability is high.

Hereinafter, although the Example of this invention is described, this invention is not limited to these Examples in any way.

(Example 1)

Production of Organic EL Devices

As the positive electrode, a glass substrate with an ITO electrode was used, which was ultrasonically cleaned with water, acetone and isopropyl alcohol, and subjected to UV ozone treatment.

As the material for the hole injection layer, an amine salt compound (manufactured by Sony, weight average molecular weight: 4000) of a perfluoropolyether (PFPE) represented by the following chemical formula was used, which was added to a solvent (FC77 (manufactured by 3M Corporation)) of 0.023. The positive electrode was immersed in the coating liquid for hole transport layer formed by dissolving at a mass% concentration, and pulled up at a pulling rate of 100 mm / min, thereby forming a hole injection layer having a thickness of 0.8 nm on the ITO by dip coating. .

R ^1- (CF ₂ -O) _x (C ₂ F ₄ -O) _y -R ²

In said formula, x = -20, y = -20, y / x is 1. R ¹ and R ² are represented by the following formula.

In said formula, s is 5.

Next, α-NPD (N, N'-di (1-naphthyl) -N, N'-diphenyl- [1,1'-biphenyl] -4,4'-diamine) was used as the hole transport material. Using a vacuum vapor deposition apparatus (vacuum degree = 1 × 10 ^-6 torr (1.3 × 10 ^-4 Pa), substrate temperature = room temperature), the deposition rate was 0.1 nm / s on the hole injection layer. Was deposited on the hole injection layer so as to be 50 nm to form the hole transport layer.

Subsequently, tris (8-hydroxyquinolinio) aluminum (Alq ₃ ) was deposited on the hole transport layer to have a thickness of 50 nm under a deposition rate of 0.1 nm / s to form the light emitting layer and the electron transporting layer.

Further, an Al-Li alloy (content of Li = 0.5 mass%) was deposited on the light emitting layer and the electron transporting layer so as to have a thickness of 50 nm under a deposition rate of 0.2 nm / s to form the negative electrode.

As mentioned above, the laminated organic electroluminescent element as shown in FIG. 2 was manufactured.

Here, in the organic EL device of Example 1, the thickness of the hole injection layer formed of the amine salt compound of perfluoropolyether (PFPE) is changed, and the ionization potential of the ionization potential measuring device (AC-1, Ritsch Gageki) Company). The results are shown in FIG.

7 shows that the ionization potential value of the hole injection layer varies depending on the thickness of the hole injection layer, but is within the range of about 5.23 eV to 5.44 eV.

In addition, the said positive electrode, the said hole injection layer, the said hole transporting layer, the said light emitting layer and the electron carrying layer, and the said, were used for the organic electroluminescent element of Example 1 using the ionization potential measuring apparatus (AC-1, manufactured by Riken Corporation). The value of each ionization potential in the negative electrode was measured. The results are shown in FIG.

From the results in FIG. 8, it can be seen that the ionization potential in the hole injection layer (PFPE layer) is located between the ionization potential in the positive electrode and the ionization potential in HOMO (highest wave molecular orbital) of the hole transport layer. .

(Comparative Example 1)

In Example 1, except having not provided a hole injection layer, it carried out similarly to Example 1, and manufactured the laminated organic EL element as shown in FIG.

Measurement of Luminance Luminance

As a result of applying a voltage between the ITO electrode (positive electrode) and the Al-Li alloy (negative electrode) to each organic EL device in Example 1 and Comparative Example 1, as shown in FIG. 10, Example 1 and Comparative Example In each organic EL element of 1, green light emission was observed at a voltage of 4 V or more, but in the organic EL element of Example 1, the luminance of light emitted at the same voltage was higher than that of the organic EL element of Comparative Example 1, especially 4 It has been found that it has good luminescence brightness at low voltages of -8V. This is presumably because in the organic EL device of Example 1, since the energy barrier when holes are injected from the holes into the organic thin film layer is small, the current to the constant voltage flows well and the luminous efficiency is improved.

Evaluation of diode characteristics

As a result of investigating the relationship between the applied voltage and the current value flowing in each organic EL element in Example 1 and Comparative Example 1, the following results were obtained. That is, in the case of the organic EL element of Example 1, as shown in Fig. 11, it was found that at a constant voltage, a large amount of current flows and excellent hole transportability is achieved compared to the organic EL element of Comparative Example 1. Moreover, as shown in FIG. 12, it turned out that current does not flow at a negative voltage, and it has favorable diode characteristics. On the other hand, in the case of the organic EL device of Comparative Example 1, as shown in Fig. 11, although the current flows at the constant voltage, it was found to be smaller than the organic EL device of Example 1, and the hole transportability was inferior. Moreover, as shown in FIG. 12, it turned out that an electric current flows also in a negative voltage and a diode characteristic falls.

Evaluation of Cross Torque Generation

As a result of manufacturing the organic EL display using the organic EL device of Example 1, no crosstalk was generated and a clear image was obtained. On the other hand, as a result of producing an organic EL display (organic EL panel) using the organic EL element of Comparative Example 1, cross talk occurred and a clear image was not obtained. It is assumed that this is because the organic EL device of Example 1 has excellent diode characteristics.

According to the present invention, the conventional problem can be solved, and the hole injection layer material capable of improving the hole injection amount can realize the same luminance at a lower voltage, and the leakage current at the sub-bias shows good diode characteristics and reliability. A high organic EL element and a high performance organic EL display using the organic EL element can be provided.

Claims (17)

An organic EL device comprising an organic thin film layer including at least a hole injection layer between a positive electrode and a negative electrode, wherein said hole injection layer contains a perfluoropolyether compound. The organic EL device according to claim 1, wherein the perfluoropolyether skeleton in the perfluoropolyether compound is partially hydrogenated. The organic EL device according to claim 1 or 2, wherein the perfluoropolyether compound is an amine salt compound of perfluoropolyether. The organic EL device according to any one of claims 1 to 3, wherein the perfluoropolyether compound is represented by any one or more of the following general formulas (1) and (2). <Formula 1> <Formula 2> However, in Formulas 1 and 2, R ¹ , R ^2, and R ³ may be the same as or different from each other, and represent a hydrogen atom, a fluorine atom, or a substituent, and Rf represents a perfluoropolyether skeleton represented by the following Formula 3 Indicates. <Formula 3> However, in Chemical Formula 3, R ⁴ and R ⁵ may be the same as or different from each other, and Chemical Formula: -C _p F _{2p + 1} (where p represents an integer of 0 or more), and n and m are the same as each other. Or may be different, and represent an integer of 0 or more, and x and y may be the same or different from each other, and represent an integer of 1 or more. The compound according to claim 4, wherein R ¹ to R ³ in Formulas 1 and 2 represent an alkyl group, an aralkyl group, an alkenyl group, an aryl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, a carboxyl group, an alkoxy group, an alkylsulfonyl group, a hydroxyl group, An organic EL device selected from amide groups, aryloxy groups, aromatic hydrocarbon ring groups, aromatic heterocyclic groups, and groups represented by the following general formula (4). <Formula 4> In the formula (4), R ⁶ represents a hydrocarbon group, a represents an integer of 0 or more, and R ⁷ to R ¹⁰ may be the same or different from each other, and represent a hydrogen atom, a fluorine atom, or a hydrocarbon group. The organic EL device according to any one of claims 1 to 5, wherein the weight average molecular weight of the perfluoropolyether compound is 500 to 10,000. The organic EL device according to any one of claims 1 to 6, wherein the hole injection layer has a thickness of 10 nm or less. 8. The organic thin film layer according to any one of claims 1 to 7, wherein the organic thin film layer has a hole injection layer, a hole transport layer, and a light emitting layer in this order from the positive electrode side, and the ionization potential in the hole injection layer is ionized in the positive electrode. An organic EL device which is smaller than the potential and larger than the ionization potential of HOMO (highest frequency molecular orbital) in the hole transport layer. The organic EL device according to claim 8, wherein the ionization potential in the hole injection layer is 4.8 to 5.6 eV. A material for a hole injection layer, which contains at least a perfluoropolyether compound. A material for a hole injection layer, wherein the perfluoropolyether compound is an amine salt compound of perfluoropolyether. The material for a hole injection layer according to claim 10 or 11, wherein the perfluoropolyether skeleton in the perfluoropolyether compound is partially hydrogenated. The material for a hole injection layer according to any one of claims 10 to 12, wherein the perfluoropolyether compound is represented by any one or more of the following formulas (1) and (2). <Formula 1> <Formula 2> However, in Formulas 1 and 2, R ¹ , R ^2, and R ³ may be the same as or different from each other, and represent a hydrogen atom, a fluorine atom, or a substituent, and Rf represents a perfluoropolyether skeleton represented by the following Formula 3 Indicates. <Formula 3> However, in Chemical Formula 3, R ⁴ and R ⁵ may be the same as or different from each other, and Chemical Formula: -C _p F _{2p + 1} (where p represents an integer of 0 or more), and n and m are the same as each other. Or may be different, and represent an integer of 0 or more, and x and y may be the same or different from each other, and represent an integer of 1 or more. The compound according to claim 13, wherein R ¹ to R ³ in Chemical Formulas 1 and 2 represent an alkyl group, an aralkyl group, an alkenyl group, an aryl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, a carboxyl group, an alkoxy group, an alkylsulfonyl group, and a hydroxyl group. A material for a hole injection layer selected from amide groups, aryloxy groups, aromatic hydrocarbon ring groups, aromatic heterocyclic groups, and groups represented by the following general formula (4). <Formula 4> In the above formula (4), R ⁶ represents a hydrocarbon group, a represents an integer of 0 or more, and R ⁷ to R ¹⁰ may be the same or different from each other, and represent a hydrogen atom, a fluorine atom, or a hydrocarbon group. The material for a hole injection layer according to any one of claims 10 to 14, wherein the weight average molecular weight of the perfluoropolyether compound is 500 to 10000. The organic electroluminescent display of any one of Claims 1-9 was used. The organic EL display according to claim 16, which is either one of a passive matrix panel and an active matrix panel.