JP2003007475A - Organic electroluminescence element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescence element of high luminescence efficiency. SOLUTION: Concerning to the organic electroluminescence element, which is formed between both the electrodes of a positive electrode layer and a negative electrode layer, and has an electron hole transportation electronic block layer (electron hole transportation layer) and a luminescence layer electron hole transportation layer, the electron hole transportation electronic block layer is constituted from a polymer, which has a repetition unit expressed with a formula (1). In the formula (1), R shows either of hydrogen, fatty-series hydrocarbon group, ether group, or heterocyclic-ring group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence device capable of emitting light with high brightness.

[0002]

2. Description of the Related Art Conventionally, as an organic electroluminescence device having a multilayer laminated structure for the purpose of improving luminous efficiency, it is formed between both electrode layers of an anode layer and a cathode layer,
Those having a hole transport layer and a light emitting layer are known. In this, as a substance having a hole-transporting property and an electron-blocking property that constitutes the hole-transporting layer,

[0003]

[Chemical 2]

N, N'-diphenyl-shown in [Chemical Formula 2]
It is common to use a hole transporting low molecule such as N, N'-bis (3-methylphenyl) -1,1'-biphenyl-4,4'-diamine (hereinafter also referred to as TPD).

Further, as the light emitting method of the above-mentioned conventional organic electroluminescence device, if light emission from an excited triplet state, that is, phosphorescence is used, the quantum efficiency of light emission can be improved. The theoretical limit of internal quantum efficiency is 25% in the case of light emission by excited singlet state, that is, in the case of emitting light only by fluorescence, whereas in light emission by phosphorescence, excitation energy of triplet state contributes to light emission. Therefore, the theoretical limit of the internal quantum efficiency may be considered to be 100%. Therefore, it can be expected that the light emission efficiency defined by the light emission luminance with respect to the drive voltage is improved.

[0006]

At this time, in the case of light emission by phosphorescence,

[0007]

[Chemical 3]

N, N'-diphenyl-shown in [Chemical Formula 3]
A hole transporting low molecule such as N, N'-bis (1-naphthyl) -1,1'-biphenyl-4,4'-diamine (hereinafter also referred to as NPD), or

[0009]

[Chemical 4]

Holes such as poly (N-vinylcarbazole) (hereinafter also referred to as PVK) shown in [Chemical Formula 4] having a relatively high electric resistance value that correlates with hole mobility, such as a hole transporting polymer. Uses transportable substances.

Therefore, the NP shown in [Chemical Formula 3] above
When PVK represented by D or [Chemical Formula 4] is used as a hole-transporting substance and an organic electroluminescence device that emits light by phosphorescence is driven, a relatively high applied voltage is required, which is expected to improve the luminous efficiency. It becomes a factor to inhibit.

In view of the above problems, it is an object of the present invention to provide an organic electroluminescence device which can emit light with high brightness when driven at a low voltage, that is, has high luminous efficiency.

[0013]

In order to solve the above problems, the present invention provides an organic electroluminescence device having a hole transport layer and a light emitting layer, which is formed between both electrode layers of an anode layer and a cathode layer. The hole transport layer is composed of a polymer having a repeating unit represented by [Chemical Formula 1].
Since such a polymer is a conductive polymer, it has a high hole mobility, and therefore holes can surely move from the hole transport layer to the light emitting layer.

In this case, R in the repeating unit represented by the above [Chemical formula 1] is preferably an alkyl group having 10 or less carbon atoms.

Further, R in the repeating unit represented by the above [Chemical formula 1] is preferably an alkoxyl group having 10 or less carbon atoms.

Further, R in the repeating unit represented by the above [Chemical formula 1] preferably comprises a substituent having an aryl group.

Further, in these cases, if the polymer is constituted so as to have an electron affinity lower than that of the host agent in the light emitting layer, the electron injection barrier of the hole transporting layer is increased, so that the hole transporting layer is formed. The electron blocking effect is surely provided to function as a hole transporting electron blocking layer. For this reason,
Further, high-luminance light emission can be obtained.

Further, in these cases, it is desirable that the light emitting layer has a dopant emitting phosphorescence. By doing so, it becomes possible to form an organic electroluminescence element capable of emitting light by phosphorescence.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a basic structure of an organic electroluminescence device having a device structure laminated in multiple layers for the purpose of improving luminous efficiency. The element structure of the organic electroluminescence element is such that each of the hole transport layer 20, the electron block layer 30, the light emitting layer 40, the hole block layer 50, and the electron transport layer 60 is formed on the anode layer 10 formed on a substrate (not shown). The thin film layer has a multi-layered structure in which the anode layer 10 and the cathode layer 70 are sequentially laminated between both electrode layers, and the light emitting layer 40 includes a light emitting layer doping agent 41 and a light emitting layer host agent 42. Has been done.

In the element structure shown in FIG. 1, for the anode layer 10, a transparent conductive substance formed on a transparent insulating support such as a glass substrate is used, and the material thereof is tin oxide or oxide. Indium, indium tin oxide (I
Conductive oxides such as TO) or metals such as gold, silver and chromium, inorganic conductive substances such as copper iodide and copper sulfide,
Conductive polymers such as polythiophene, polypyrrole, and polyaniline can be used.

When the cathode layer 70 is made of a transparent material, the anode layer 10 may be made of an opaque material.

In the device structure shown in FIG. 1,
The cathode layer 70 includes niobium, lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, boron, aluminum,
A simple substance such as copper, silver or gold or an alloy can be used. Further, these may be laminated and used. It can also be formed by a wet process using tetrahydroaluminate. In this case, examples of the tetrahydroaluminate used for the cathode layer 70 include lithium aluminum hydride, potassium aluminum hydride, magnesium aluminum hydride, and aluminum calcium hydride. Among these, lithium aluminum hydride is particularly excellent in the electron injection property into the electron transport layer.

The hole transport layer 20 is a layer for transporting holes injected from the anode layer 10, and is an organic layer containing a hole transporting organic substance. As an example of the hole transport layer organic material, a polyfluorene compound having a repeating unit represented by [Chemical Formula 1], for example,

[0024]

[Chemical 5]

Di-normal butyl polyfluorene represented by [Chemical formula 5],

[0026]

[Chemical 6]

A dinormal butylfluorene / anthracene copolymer compound represented by [Chemical Formula 6], PVK represented by [Chemical Formula 4],

[0028]

[Chemical 7]

It is preferably composed of a polymer such as poly (para-phenylene vinylene) shown in [Chemical Formula 7]. Alternatively, TPD shown in [Chemical Formula 2], NPD shown in [Chemical Formula 3],

[0030]

[Chemical 8]

Carbazole biphenyl (hereinafter also referred to as CBP) shown in [Chemical Formula 8],

[0032]

[Chemical 9]

4,4'-bis (10-phenothiazinyl) biphenyl shown in [Chemical Formula 9],

[0034]

[Chemical 10]

The copper phthalocyanine shown in [Chemical Formula 10] and the electron blocking layer 30 block electrons in order to prevent the electrons injected from the cathode layer 70 to the light emitting layer 40 from directly passing to the anode layer 10. And is composed of an electron blocking substance. Examples of the electron blocking substance include compounds represented by [Chemical Formula 2] to [Chemical Formula 9],

[0036]

[Chemical 11]

2,4,6-triphenyl-1,3,5-triazole shown in [Chemical Formula 11],

[0038]

[Chemical 12]

Examples thereof include Florene shown in [Chemical Formula 12].

Further, the light emitting layer 40 has a doping agent 41 and a host agent 42, and in order to disperse the doping agent 41 and the host agent 42 uniformly, it is possible to add a binder polymer. In the host agent 42, holes and electrons injected from the anode layer 10 and the cathode layer 70, respectively, are emitted from the light emitting layer 4.
Is a substance that is activated when recombining at 0 and acts as an exciton, and is a polyfluorene compound represented by [Chemical Formula 1], for example,

[0041]

[Chemical 13]

Dinormal butoxypolyfluorene represented by [Chemical Formula 13], PVK represented by [Chemical Formula 4], CBP represented by [Chemical Formula 8],

[0043]

[Chemical 14]

1,3,5-tri (5-
(4-tert-butylphenyl) -1,3,4-oxadiazole) phenyl (hereinafter also referred to as OXD-1),

[0045]

[Chemical 15]

1,3-di (5-
(4-tert-butylphenyl) -1,3,4-oxadiazole) phenyl (hereinafter also referred to as OXD-7),

[0047]

[Chemical 16]

2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1, shown in [Chemical Formula 16],
3,4-oxadiazole, (hereinafter also referred to as PBD),

[0049]

[Chemical 17]

3,4,5-tri (1-naphthyl) -1,2,4-triazole represented by [Chemical Formula 17]

[0051]

[Chemical 18]

N-phenylcarbazole represented by [Chemical Formula 18],

[0053]

[Chemical 19]

N-methylcarbazole represented by [Chemical Formula 19],

[0055]

[Chemical 20]

N-phenyl polycarbazole represented by [Chemical Formula 20]

[0057]

[Chemical 21]

N-methylpolycarbazole represented by [Chemical Formula 21],

[0059]

[Chemical formula 22]

[0060]

[Chemical formula 23]

[0061]

[Chemical formula 24]

[0062]

[Chemical 25]

Oxadiazole-based polymer compounds represented by [Chemical Formula 22] to [Chemical Formula 25],

[0064]

[Chemical formula 26]

[0065]

[Chemical 27]

[0066]

[Chemical 28]

Triazole polymer compounds represented by [Chemical formula 26] to [Chemical formula 28]

[0068]

[Chemical 29]

Bathocuproine (hereinafter referred to as B)
Also called CP. ),

[0070]

[Chemical 30]

Examples include tris (8-hydroxyquinolinato) aluminum (hereinafter also referred to as Alq3) shown in [Chemical Formula 30].

On the other hand, the doping agent 41 of the light emitting layer 40 is a substance which emits phosphorescence by the excitation energy of the host agent 42 which is an exciton,

[0073]

[Chemical 31]

A tri (2phenylpyridine) iridium complex represented by [Chemical Formula 31] (hereinafter also referred to as Ir (ppy) ₃ ),

[0075]

[Chemical 32]

[0076]

[Chemical 33]

[0077]

[Chemical 34]

[0078]

[Chemical 35]

[0079]

[Chemical 36]

[0080]

[Chemical 37]

(In the chemical formula [Chemical Formula 37], acac is

[0082]

[Chemical 38]

The functional group represented by [Chemical Formula 38] is shown below. following
The same applies to the chemical formulas shown in [Chemical Formula 39] to [Chemical Formula 43]. )

[0084]

[Chemical Formula 39]

[0085]

[Chemical 40]

[0086]

[Chemical 41]

[0087]

[Chemical 42]

[0088]

[Chemical 43]

Iridium complex compounds represented by [Chemical Formula 32] to [Chemical Formula 37] and [Chemical Formula 39] to [Chemical Formula 43],

[0090]

[Chemical 44]

2, 3, 7, 8, 12, shown in [Chemical 44]
13,17,18-octaethyl-21H, 23H-platinum (II) porphine (hereinafter also referred to as PtOEP),

[0092]

[Chemical formula 45]

3- (2'-benzothiazolyl) -7-diethylaminocoumarin (hereinafter referred to as coumarin 6) shown in [Chemical Formula 45]
Also say. )

[0094]

[Chemical formula 46]

(2-Methyl-6- (2-
(2,3,6,7-Tetrahydro-1H, 5H-benzo (ij) quinolidine-9-yl) ethynyl) -4H-pyran-4-ylidene) propane-dinitrile (hereinafter DCM2
Also say. ), And so on.

Examples of binder polymers that can be added to the light emitting layer 40 include polystyrene, polyvinylbiphenyl, polyvinylphenanthrene, polyvinylanthracene, polyvinylperylene, poly (ethylene-co-vinylacetate), and polybutadienes cis and tran.
s, poly (2-vinylnaphthalene), polyvinylpyrrolidone, polystyrene, poly (methylmethacrylate),
Poly (vinyl acetate), poly (2-vinyl pyridine-co-styrene), polyacenaphthylene, poly (acrylonitrile-co-butadiene), poly (benzyl methacrylate), poly (vinyltoluene), poly (styrene-co-) Acrylonitrile), poly (4-vinylbiphenyl), polyethylene glycol and the like.

Further, the hole blocking layer 50 is the anode layer 10
The holes injected into the light emitting layer 40 from the cathode layer 70 as they are.
It is a layer for blocking holes in order to prevent the holes from passing through and is composed of a hole blocking substance. Examples of the hole blocking substance include OX shown in [Chemical Formula 14].
D-1, PBD shown in [Chemical 16], BC shown in [Chemical 29]
P, Alq3 shown in [Chemical Formula 30],

[0098]

[Chemical 47]

3- (4-biphenylyl) -5- (4-tert-butylphenyl) -4-phenyl-1,2,4-triazole (hereinafter also referred to as TAZ) shown in [Chemical Formula 47],

[0100]

[Chemical 48]

4,4'-bis (1,1 shown in [Chemical Formula 48]
-Diphenylethenyl) biphenyl (hereinafter DPVBi
Also called. ),

[0102]

[Chemical 49]

2,5-bis (1-naphthyl) -1.3.4-oxadiazole (hereinafter referred to as BND
Also called. )

[0104]

[Chemical 50]

4,4'-bis (1,1-bis (4-methylphenyl) ethenyl) biphenyl (hereinafter also referred to as DTVBi) shown in [Chemical Formula 50],

[0106]

[Chemical 51]

2,5-bis (4-) shown in [Chemical Formula 51]
Biphenylyl) -1,3,4-oxadiazole (hereinafter also referred to as BBD),

[0108]

[Chemical 52]

[0109]

[Chemical 53]

Oxadiazole-based polymer compounds represented by [Chemical Formula 52] and [Chemical Formula 53],

[0111]

[Chemical 54]

[0112]

[Chemical 55]

Examples thereof include triazole polymer compounds represented by [Chemical Formula 54] and [Chemical Formula 55].

The electron transport layer 60 is a layer for transporting electrons injected from the cathode layer 70 and contains an electron transport agent. The electron transport agent is composed of an electron transporting polymer,
Further, a structure containing a low molecule having an electron transport property is possible.

Here, as an example of the electron transporting low molecule,
OXD-7 shown in [Chemical Formula 15] and P shown in [Chemical Formula 16]
BD, BCP shown in [Chemical formula 29], Alq shown in [Chemical formula 30]
3, TAZ shown in [Chemical 47], DPV shown in [Chemical 48]
Bi, BND shown in [Chemical 49], DT shown in [Chemical 50]
VBi, the BBD shown in [Chemical 51],

[0116]

[Chemical 56]

2,5-diphenyl-represented by [Chemical Formula 56]
1,3,4-oxadiazole (hereinafter also referred to as PPD), and as an example of an electron-transporting polymer,
2] and oxadiazole-based polymer compounds represented by [Chemical Formula 53], and triazole-based polymer compounds represented by [Chemical Formula 54] and [Chemical Formula 55].

The element structure shown in FIG. 2 or FIG. 3 is possible by modifying the basic structure of the organic electroluminescence element shown in FIG. 1 in order to further improve the luminous efficiency and simplify the structure.

The element structure of the organic electroluminescent element shown in FIG. 2 shows the first embodiment of the organic electroluminescent element of the present invention. Although the electron blocking layer 30 and the hole blocking layer 50 in FIG. 1 are omitted, in FIG. 2, the hole transporting layer 20 is provided with an electron blocking effect to be formed as the hole transporting electron blocking layer 23. The electron transport layer 60 can have a hole blocking effect to maintain the luminous efficiency.

The element structure of the organic electroluminescent element shown in FIG. 3 is the same as the element structure shown in FIG.
The hole transporting layer 20 is provided with an electron blocking effect and is changed to a hole transporting electron blocking layer 23, the electron blocking layer 30 and the hole blocking layer 50 are omitted, and the anode layer 10 and the hole transporting electron blocking layer 23 are omitted. And a hole injecting layer 21 made of a hole injecting material is added between and.

Examples of the hole injecting substance include metal phthalocyanines such as copper phthalocyanine shown in [Chemical formula 10] and

[0122]

[Chemical 57]

Poly (3,4) ethylenedioxythiophene / polystyrene sulfonate (hereinafter also referred to as PEDT / PSS) represented by [Chemical Formula 57],

[0124]

[Chemical 58]

Examples include poly (3,4) ethylenedioxythiophene (hereinafter also referred to as PEDT) shown in [Chemical Formula 58].

Next, referring to FIG. 2 as the first embodiment of the present invention, a method for manufacturing an organic electroluminescence element will be described.

First, the anode layer 10 is formed by a vapor deposition method or a sputtering method on a transparent insulating support which will be a substrate (not shown), for example, a glass substrate.

Next, a first solution is prepared by dissolving or dispersing a hole transporting polymer or a hole transporting low molecule having an electron blocking effect in a solvent. Here, it is also possible to further dissolve or disperse the binder polymer in the first solution. Then, by a wet method using the first solution, the hole transport electron blocking layer 23 including the hole transport layer having the electron blocking effect is formed on the anode layer 10.

Further, a second solution is prepared by dissolving or dispersing the doping agent 41 and the host agent 42 of the light emitting layer 40 in a solvent. Here, it is also possible to further dissolve or disperse the binder polymer in the second solution. Then, the light emitting layer 40 is formed on the hole transport electron blocking layer 23 by a wet method using the second solution.

Further, a third solution is prepared by dissolving or dispersing the electron transporting polymer or the electron transporting low molecule in a solvent. Here, the binder polymer can be further dissolved or dispersed in the third solution. The electron transport layer 6 is formed on the light emitting layer 40 by a wet method using the third solution.
Form 0.

The solubility parameter of the solvent used in the second solution is determined by the substance contained in the hole transporting electron blocking layer 23 (high hole transporting property also having an electron blocking effect) at the film formation temperature of the light emitting layer 40. It has a value that is out of the soluble range for a molecule or a hole transporting small molecule). When the light emitting layer 40 is formed by the wet method using such a solvent, the organic substance contained in the lower hole transport electron blocking layer 23 is not dissolved.

Further, the solubility parameter of the solvent used in the third solution is set to the substances contained in the light emitting layer 40 (the dopant 41, the host agent 42, the binder polymer, etc.) at the film formation temperature of the electron transport layer 60. Has a value outside the soluble range. When the electron transport layer 60 is formed by the wet method using such a solvent, the organic substance contained in the lower light emitting layer 40 is not dissolved.

At this time, the solvent used for the above-mentioned first to third solutions is evaporated by natural drying to form the hole-transporting electron blocking layer 23, the light-emitting layer 40 and the electron-transporting layer 60. In this case, there is no need to perform treatments such as heating, polymerization by irradiation of ultraviolet rays, curing, etc. Therefore, the manufacturing process is simple and the production efficiency can be improved.

The wet method used in the present invention includes ordinary coating methods such as casting method, blade coating method, dip coating method, spin coating method, spray coating method, roll coating method and ink jet coating method. .

Finally, the cathode layer 70 is formed on the electron transport layer 60 by using the vapor deposition method or the like to obtain the organic electroluminescence device of the present invention.

The solubility parameter SP is defined by SP = {(ΔH-RT) / V} ^1/2 at the absolute temperature T of the liquid having a molar evaporation heat ΔH and a molar volume V. However, in the above formula, SP is a solubility parameter (unit: (cal / cm ³ ) ^1/2 ), ΔH is a heat of molar evaporation (unit: cal / mol), and R is a gas constant (unit: cal / mol). (Mol · K)), T is the absolute temperature (unit: K), and V is the molar volume (unit: cm ^3).
/ Mol).

FIG. 3 shows a second embodiment of the organic electroluminescence device of the present invention. During the manufacturing process of the device structure shown in FIG. 2, before forming the hole transport electron blocking layer 23, After forming a hole injecting substance such as PEDT represented by [Chemical Formula 58] on the anode layer 10 by a wet method to form the hole injecting layer 21, the hole injecting layer 21 is formed on the hole injecting layer 21 as shown in FIG. Similarly, the hole transport electron blocking layer 23, the light emitting layer 40, the electron transport layer 60, and the cathode layer 70 are sequentially formed, and the resultant is obtained.

[0138]

EXAMPLES [Example 1] A polystyrene-converted weight average amount (hereinafter referred to as molecular weight) measured by gel permeation chromatography of 60,000 [Chemical formula 5].
A solution 1 was prepared by dissolving 6 mg of a di-normal-butyl polyfluorene polymer (electron affinity: 2.15 eV) shown in 1 with 1 ml of 1,2-dichloroethane.

Solution 1 was placed on an ITO substrate that had been subjected to oxygen plasma treatment (commercial ITO, manufactured by Asahi Glass Co., Ltd .: 20 Ω / □ or less).
Was spin-coated at 1000 rpm for 1 second to obtain a hole-transporting electron blocking layer having a film thickness of 50 nm.

A vacuum degree of 10 ⁻³ Pa,
The CBP (electron affinity 2.33e) shown in [Chemical Formula 8] is formed on the hole transporting electron blocking layer at a vapor deposition rate of 1 nm / sec.
V) and Ir (ppy) ₃ shown in [Chemical Formula 31]
Co-evaporate so that (ppy) ₃ becomes 6.5% by weight and 2
A film having a thickness of 0 nm was formed as a light emitting layer, and OXD-1 represented by [Chemical Formula 14] was formed as a film having an electron transporting layer with a film thickness of 50 nm at a vapor deposition rate of 1 nm / sec.

Lithium was deposited at a film thickness of 0.5 nm at a vapor deposition rate of 0.01 nm / sec, and aluminum was further deposited at a vapor deposition rate of 1 nm / sec to a thickness of 50 nm to form a cathode. Formed. In this way, when the device structure shown in FIG. 2 was created, 4.7 V (driving voltage,
same as below. ) Green light emission of 630 cd / m ² (luminance, the same hereinafter) was obtained at 1 mA / cm ² (current density, the same hereinafter). [Comparative Example 1] [Examples] except that NPD (electron affinity 2.46 eV) shown in [Chemical Formula 3] was used instead of dinormal butyl polyfluorene shown in [Chemical Formula 5] to form a film by vapor deposition. 1], the device structure shown in FIG. 2 was prepared.
Deposition conditions are vacuum degree of 10 ^-3 Pa and deposition rate of 1 nm / sec.
Is. At this time, 400 cd / at 5 V and 1 mA / cm ^2.
A green emission of m ² was obtained. [Comparative Example 2] [Execution] The device structure shown in FIG. 2 was prepared in the same manner as in [Example 1]. At this time, 4.5
A green emission of 200 cd / m ² was obtained at V and 1 mA / cm ² . [Example 1], [Comparative Example 1] and [Comparative Example 2]
Comparing with, when the electron affinity of the hole transporting electron blocking substance is smaller than that of the light emitting layer host agent, 1 mA / cm
^It can be seen that the luminance at the current density of ² is improved.

Further, by comparing [Example 1] with [Comparative Example 1], it can be seen that the driving voltage at 1 mA / cm ² can be reduced by using a conductive polymer in the hole transport electron blocking layer. [Example 2] to [Example 9], [Comparative Example 3], [Comparative Example 4] In the repeating unit represented by [Chemical Formula 1] in place of the dinormal butyl polyfluorene represented by [Chemical Formula 5]. An element structure shown in FIG. 2 was prepared in the same manner as in [Example 1] except that a polymer produced by using the substituents shown in [Table 1] below was used as R of. The molecular weight of all these polymers is 6
When it was set to 10,000, light emission having the light emission efficiency shown in [Table 1] below was obtained.

[0143]

[Table 1]

Comparing [Comparative Example 3] with [Example 5] and [Comparative Example 4] with [Example 7],
When the number of carbon atoms in R is 10 or more, as the number of carbon atoms increases, the voltage increases and the brightness decreases. From this, the number of carbon atoms of the substituent used as R is preferably 10 or less. [Example 10] PEDT / PSS represented by [Chemical Formula 57] was spin-coated between the ITO substrate and the hole-transporting electron blocking layer for 10 seconds at a rotation speed of 4000 rpm to obtain 50 n.
An element structure shown in FIG. 3 was prepared in the same manner as in [Example 1] except that a hole injection layer having a thickness of m was formed. This time,
Green light emission of 580 cd / m ² was obtained at 4.2 V and 1 mA / cm ² . [Example 11] A copper phthalocyanine represented by [Chemical Formula 10] was vacuum-deposited between the ITO substrate and the hole-transporting electron blocking layer to form a vacuum degree of 10 ^-3 Pa and a deposition rate of 0.
An element structure shown in FIG. 3 was prepared in the same manner as in [Example 1] except that a hole injection layer having a film thickness of 2 nm was formed at 1 nm / sec. At this time, it is 570 at 4.4 V and 1 mA / cm ² .
Green light emission of cd / m ² was obtained. [Example 12] to [Example 17], [Comparative Example 5] [Example 5] was repeated except that the compound shown in the following [Table 2] was used instead of the CBP shown in [Chemical formula 8] used as the host agent for the light emitting layer. When the device structure shown in FIG. 2 was prepared in the same manner as in Example 1, emission with the emission efficiency shown in [Table 2] was obtained.

[0145]

[Table 2]

The electron affinity of BCP represented by [Chemical Formula 29] used as a host material for the light emitting layer in [Comparative Example 5] is
It is smaller than dinormal butyl polyfluorene (2.15 eV) represented by [Chemical Formula 5], and it is shown that the luminance at 1 mA / cm ² is reduced. [Example 18] to [Example 24] Same as [Example 1] except that the compound shown in [Table 3] below was used in the electron transport layer instead of OXD-1 shown in [Chemical formula 14]. When the device structure shown in FIG. 2 was created, light emission having the light emission efficiency shown in [Table 3] below was obtained. The BCP represented by [Chemical Formula 29] used in [Example 24] is formed to have a film thickness of 6 nm.

[0147]

[Table 3]

[Example 25] to [Example 30] The device structure shown in Fig. 2 was prepared in the same manner as in [Example 1] except that lithium was replaced with the compounds shown in [Table 4] below. As a result, light emission having the light emission efficiency shown in [Table 4] was obtained.

[0149]

[Table 4]

[Example 31] to [Example 42] [Example 1] except that the compound shown in [Table 5] below was used instead of Ir (ppy) ₃ shown in [Chemical Formula 31] as a light emitting layer doping agent. ], The device structure shown in FIG.
Luminescence having the luminous efficiency shown in [Table 5] was obtained.

[0151]

[Table 5]

[Example 43] A dinormal butyl polyfluorene polymer represented by [Chemical Formula 5] (molecular weight 60,000)
0, electron affinity: 2.15 eV) 6 mg as 1 ml
Solution 1 was prepared by dissolving with 1,2-dichloroethane.

2.5 mg as CBP (electron affinity 2.33 eV) shown in [Chemical formula 8] and I shown in [Chemical formula 31]
A solution 2 was prepared by dissolving 0.17 mg of r (ppy) ₃ and 2.5 mg of polyvinyl biphenyl (molecular weight 115,000) as a binder polymer in 1 ml of m-xylene.

Solution 1 was placed on an ITO substrate that had been subjected to oxygen plasma treatment (commercial ITO, manufactured by Asahi Glass Co., Ltd .: 20 Ω / □ or less).
Was spin-coated at 1000 rpm for 1 second to form a hole-transporting electron blocking layer having a thickness of 50 nm.

Solution 2 was spin-coated on the hole-transporting electron blocking layer at 1000 rpm for 1 second to form a light-emitting layer having a thickness of 20 nm.

An electron transporting layer having a film thickness of 50 nm was formed from OXD-1 represented by [Chemical Formula 14] at a vapor deposition rate of 1 nm / sec.

Lithium was formed into a film having a thickness of 0.5 nm at a deposition rate of 0.01 nm / sec, and aluminum was further formed thereon at a deposition rate of 1 nm / sec to a thickness of 50 nm to form a cathode. Formed.

When the device structure shown in FIG. 2 was prepared in this manner, it was 600 cd at 6.2 V and 1 mA / cm ² .
A green emission of / m ² was obtained. [Comparative Example 6] A solution 1 was prepared by using PVK (molecular weight: 1,100,000, electron affinity: 2.52 eV) shown in [Chemical formula 4] in place of the dinormal butyl polyfluorene shown in [Chemical formula 5]. The element structure shown in FIG. 2 was prepared in the same manner as in [Example 43] except for the above. At this time, 9.0V, 1m
Green luminescence of 400 cd / m ² was obtained at A / cm ² .
Comparing [Example 43] with [Comparative Example 6], when the electron affinity of the hole transport electron blocking substance is smaller than that of the light emitting layer host material, the brightness at a current density of 1 mA / cm ² is improved. I understand. In addition, by using a conductive polymer in the hole transporting electron blocking layer, 1 mA /
It can be seen that the driving voltage in cm ² can be reduced. [Example 44] to [Example 49] In place of the dinormal butyl polyfluorene represented by [Chemical formula 5], as the R in the repeating unit represented by [Chemical formula 1], a substituent represented by the following [Table 6] may be used. The device structure shown in FIG. 2 was prepared in the same manner as in [Example 43] except that the polymer produced by using the above was used. The molecular weights of the above polymers were all 60,000. At this time, light emission with the light emission efficiency shown in [Table 6] was obtained.

[0159]

[Table 6]

[Example 50] PEDT represented by [Chemical Formula 58] was spin-coated at a rotation speed of 4000 rpm for 10 seconds between the ITO substrate and the hole-transporting electron blocking layer to form a hole having a thickness of 50 nm. An element structure shown in FIG. 3 was prepared in the same manner as in [Example 43] except that the injection layer was formed. At this time, it is 580 at 5.9 V and 1 mA / cm ² .
Green light emission of cd / m ² was obtained. [Example 51] A copper phthalocyanine represented by [Chemical Formula 10] was vacuum-deposited between the ITO substrate and the hole-transporting electron blocking layer at a vacuum degree of 10 ^-3 Pa and a deposition rate of 0.1 nm / sec. An element structure shown in FIG. 3 was prepared in the same manner as in [Example 43] except that a hole injection layer having a film thickness of 2 nm was formed. At this time, green light emission of 570 cd / m ² was obtained at 6.1 V and 1 mA / cm ² . [Example 52] to [Example 57], [Comparative Example 7] [Example 7] except that the compound shown in [Table 7] below was used instead of the CBP shown in [Chemical formula 8] as the host agent for the light emitting layer. Four
When the device structure shown in FIG. 2 was created in the same manner as in [3], light emission with a light emission efficiency as shown in [Table 7] was obtained.

[0161]

[Table 7]

As shown in [Comparative Example 7], the electron affinity of the host agent for the light emitting layer is the electron affinity (2.15 eV) of the dinormal butyl polyfluorene represented by [Chemical Formula 5] used in [Example 43]. If it is smaller, the current density is 1 mA / c
The brightness decreases at m ² . [Example 58] to [Example 68] 5.0 mg as a polymer (molecular weight 60,000) shown as a compound in [Table 8] below and 0.17 mg as Ir (ppy) ₃ shown in [Chemical Formula 31]. Is dissolved in 1 ml of m-xylene to prepare solution 2
When the device structure shown in FIG. 2 was prepared in the same manner as in [Example 43] except that the above was prepared, light emission having the light emission efficiency shown in [Table 8] was obtained.

[0163]

[Table 8]

[Example 69] to [Example 75] [Chemical formula 1]
2] was prepared in the same manner as in [Example 43] except that the compound shown in [Table 9] below was used in the electron transport layer instead of OXD-1 shown in [Table 9]. ] The light emission of the luminous efficiency shown in was obtained. [Example 75]
The BCP represented by [Chemical Formula 29] used in [1] is formed to a film thickness of 6 nm.

[0165]

[Table 9]

[Example 76] to [Example 81] For the cathode,
When the device structure shown in FIG. 2 was prepared in the same manner as in [Example 43] except that the compound shown in [Table 10] below was used instead of lithium, luminescence with the emission efficiency shown in [Table 10] was obtained. It was

[0167]

[Table 10]

[Examples 82 to 93] [Examples] [Examples] except that the compound shown in [Table 11] below was used instead of Ir (ppy) ₃ shown in [Chemical Formula 31] as the light emitting layer doping agent. When the device structure shown in FIG. 2 was created in the same manner as in [43], light emission having the light emission efficiency shown in [Table 11] was obtained.

[0169]

[Table 11]

[Example 94] A dinormal butyl polyfluorene polymer represented by [Chemical Formula 5] (molecular weight 60,000) was used.
0, electron affinity: 2.15 eV) 6 mg as 1 ml
Solution 1 was prepared by dissolving with 1,2-dichloroethane. CBP (electron affinity 2.33e) shown in [Chemical Formula 8]
V) is 2.5 mg and Ir (pp
y) ₃ as 0.17mg and the binder polymer serving as polyvinyl biphenyl (molecular weight 115,000) was dissolved with 2.5mg to m- xylene 1 ml, were prepared solution 2.

2.5 as the PBD shown in [Chemical Formula 16]
mg and polystyrene as a binder polymer (molecular weight 50,
000) was dissolved in 1 ml of cyclohexane to prepare solution 3, and the solution 3 was prepared on the oxygen-plasma-treated ITO substrate (commercial ITO, manufactured by Asahi Glass Co., Ltd .: 20Ω / □).
Solution 1 was spin-coated at 1000 rpm for 1 second to form a hole-transporting electron blocking layer having a thickness of 50 nm.

Solution 2 was spin-coated on the hole-transporting electron blocking layer at a rotation speed of 1000 rpm for 1 second to form a light-emitting layer having a thickness of 20 nm. Solution 3 on the light emitting layer
Was spin-coated at 1000 rpm for 1 second to obtain an electron transport layer having a film thickness of 50 nm.

The evaporation rate of lithium was 0.01 by evaporation.
A film thickness of 0.5 nm is formed at a nm / sec, and aluminum is further deposited thereon at a vapor deposition rate of 1 nm / sec to a thickness of 50 nm.
A film was formed to a thickness to form a cathode. In this way, when the device structure shown in FIG. 2 was created, it was 8.5 V and 1 mA.
Green emission of 600 cd / m ² was obtained at / cm ² . [Comparative Example 8] A solution 1 was prepared by using PVK (molecular weight: 1,100,000, electron affinity: 2.52 eV) represented by [Chemical Formula 4] in place of the dinormal butyl polyfluorene represented by [Chemical Formula 5]. The element structure shown in FIG. 2 was prepared in the same manner as in [Example 94] except for the above. At this time, 12.0
A green emission of 400 cd / m ² was obtained at V and 1 mA / cm ² . Comparing [Example 94] with [Comparative Example 8], when a hole transport electron blocking substance having a lower electron affinity than the light emitting layer host material is used, 1 mA / cm ²
It can be seen that the brightness in In addition, when a conductive polymer is used for the hole transport electron blocking layer, 1 mA /
It can be seen that the driving voltage in cm ² can be reduced. [Example 95] to [Example 100] Substitutions shown in [Table 12] below as R in the repeating unit shown in [Chemical Formula 1] in place of the dinormal butyl polyfluorene shown in [Chemical Formula 5]. When the device structure shown in FIG. 2 was prepared in the same manner as in [Example 94] except that the polymer produced using a group was used, light emission having the light emission efficiency shown in [Table 12] was obtained. The molecular weights of the above polymers were all 60,000.

[0174]

[Table 12]

[Example 101] PEDT represented by [Chemical Formula 58] between the ITO substrate and the hole transport electron blocking layer.
Was spin-coated at a rotation speed of 4000 rpm for 10 seconds to form a hole injection layer having a thickness of 50 nm.
The device structure shown in FIG. 3 was prepared in the same manner as in [Example 94]. At this time, at 8.3 V, 1 mA / cm ² , 580 cd /
A green emission of m ² was obtained. [Example 102] Copper phthalocyanine represented by [Chemical Formula 10] was vacuum-deposited between the ITO substrate and the hole-transporting electron blocking layer to obtain a vacuum degree of 10 ^-3 Pa and a deposition rate of 0.
An element structure shown in FIG. 3 was prepared in the same manner as in [Example 94] except that the film was formed as a hole injection layer having a film thickness of 1 nm / se and a thickness of 2 nm. At this time, it is 570 at 8.4 V and 1 mA / cm ² .
Green light emission of cd / m ² was obtained. [Example 103] to [Example 108], [Comparative Example 9] Instead of the CBP shown in [Chemical Formula 8] as the host agent for the light emitting layer,
[Example 9 except that the compounds in the following [Table 13] were used
4] and the device structure shown in FIG.
Luminescence having the luminous efficiency shown in [Table 13] was obtained.

[0176]

[Table 13]

Comparing [Comparative Example 9] with [Example 94], the electron affinity of the light-emitting layer host agent is that of the hole transporting electron blocking substance (dinormal butyl polyfluorene represented by [Chemical Formula 5]). It can be seen that when the electron affinity is smaller than (2.15 eV), the brightness at 1 mA / cm ² is lowered. [Example 109] to [Example 119] 5.0 mg of the compound (molecular weight 60,000) shown below in [Table 14] and 0.17 mg of Ir (ppy) ₃ shown in [Chemical Formula 31] were added to 1 ml of m-xylene. When the device structure shown in FIG. 2 was prepared in the same manner as in [Example 94] except that the solution 2 was prepared by dissolving in Example 1 to obtain Solution 2, light emission with the emission efficiency shown in [Table 14] was obtained.

[0178]

[Table 14]

[Example 120] Same as [Example 94] except that 5.0 mg of the copolymer (molecular weight 50,000) represented by [Chemical Formula 22] was dissolved in 1 ml of cyclohexane to prepare solution 3. The device structure shown in FIG. At this time, 5.5V, at 1mA / cm ² 580cd / m ²
A green emission of was obtained. [Example 121] to [Example 126] A device structure shown in Fig. 2 was prepared in the same manner as in [Example 94] except that lithium was used as the cathode instead of the compounds shown in [Table 15] below. Luminous luminescence having the luminous efficiency shown in [Table 15] was obtained.

[0180]

[Table 15]

[Example 127] to [Example 138] Ir (ppy) ₃ shown in [Chemical Formula 31] as a light emitting layer doping agent.
2 was prepared in the same manner as in [Example 94] except that the compounds shown in [Table 16] below were used, and light emission with the emission efficiency shown in [Table 16] was obtained.

[0182]

[Table 16]

[Example 139] A dinormal butyl polyfluorene polymer represented by [Chemical Formula 5] (molecular weight 60,000)
0, electron affinity: 2.15 eV) 6 mg as 1 ml
Solution 1 was prepared by dissolving with 1,2-dichloroethane.

N-phenyl polycarbonate represented by [Chemical Formula 20]
Lubazole (electron affinity 2.25 eV, molecular weight 60,0
00) as 5.0 mg and Ir (pp
y) ₃0.17 mg as a solution in 1 ml of m-xylene
Solution 2 was prepared.

A solution 3 was prepared by dissolving 5.0 mg of the oxadiazole-based copolymer (molecular weight 50,000) represented by [Chemical Formula 22] in 1 ml of cyclohexane.

On an ITO substrate (commercial ITO, manufactured by Asahi Glass Co., Ltd .: 20 Ω / □ or less) subjected to oxygen plasma treatment, PEDT / PSS represented by [Chemical Formula 57] was rotated at a rotation speed of 4000.
50n by spin coating at rpm for 10 seconds
A hole injection layer having a thickness of m was formed.

Next, the solution 1 was rotated at 1000 rpm for 1 time.
A hole transport electron blocking layer having a thickness of 50 nm was formed by spin coating for 2 seconds.

Solution 2 was spin-coated on the hole-transporting electron blocking layer at a rotation speed of 1000 rpm for 1 second to form a light-emitting layer having a thickness of 20 nm.

Solution 3 was applied on the light emitting layer at a rotation speed of 1000 r.
An electron transport layer having a film thickness of 50 nm was formed by spin coating at pm for 1 second.

Cesium was deposited to a thickness of 0.5 nm at a deposition rate of 0.01 nm / sec, and aluminum was further deposited thereon at a deposition rate of 1 nm / sec to a thickness of 50 nm to form a cathode. In this way, the device structure shown in FIG. 3 was created.

At this time, 65 V at 3.5 V and 1 mA / cm ²
A green emission of 0 cd / m ² was obtained. [Example 140] 6 as a di-normal butyl polyfluorene polymer (molecular weight 60,000) represented by [Chemical formula 5]
Solution 1 was prepared by dissolving mg in 1 ml of 1,2-dichloroethane.

[Chemical formula 5] was formed on an ITO substrate that had been subjected to oxygen plasma treatment (commercial ITO, manufactured by Asahi Glass Co., Ltd .: 20Ω / □ or less).
7], the PEDT / PSS shown in FIG.
A hole injection layer having a film thickness of 50 nm was formed by spin coating at m for 10 seconds.

Next, the solution 1 was rotated at 1000 rpm for 1 time.
A hole transport electron blocking layer having a thickness of 50 nm was formed by spin coating for 2 seconds.

With a vacuum deposition apparatus at a vacuum degree of 10 ^-3 Pa,
Al represented by [Chemical Formula 30] on the hole transport electron blocking layer
q3 and coumarin 6 shown in [Chemical Formula 45] are co-evaporated at a vapor deposition rate of 1 nm / sec so that coumarin 6 is 1% by weight to form a light emitting layer having a thickness of 20 nm. An electron transport layer having a film thickness of 50 nm was formed from the Alq3 shown.

Lithium was vapor-deposited at a film thickness of 0.5 nm to form a film at a vapor deposition rate of 0.01 nm / sec, and aluminum was further vapor-deposited at a film thickness of 50 nm at a vapor deposition rate of 1 nm / sec to form a film. Formed as a cathode.

At this time, 160 at 5 V and 10 mA / cm ²
A green emission of 0 cd / m ² was obtained. [Comparative Example 10] [Example 5] NPD shown in [Chemical Formula 3] was used in place of the dinormal butyl polyfluorene shown in [Chemical Formula 5], and the hole transport electron blocking layer was formed by vapor deposition. 140], the device structure shown in FIG. 3 was prepared. Deposition conditions are vacuum degree of 10 ^-3 Pa and deposition rate of 1 nm.
/ Sec. At this time, green light emission of 1500 cd / m ² was obtained at 7 V and 10 mA / cm ² . Comparing [Example 140] with [Comparative Example 10], it can be seen that the driving voltage could be reduced by using the conductive polymer dinormal butyl polyfluorene. [Example 141] Except that DCM2 shown in [Chemical Formula 46] was used instead of coumarin 6 shown in [Chemical Formula 45].
A device structure shown in FIG. 3 was prepared in the same manner as in [Example 140]. At this time, 5V, at 10mA / cm ² 500cd / m ²
Red emission was obtained. [Example 142] to [Example 143], [Comparative Example 11]
~ [Comparative Example 12] R in the repeating unit represented by [Chemical Formula 1]
The solubility range of the solubility parameter display of the polyfluorene compound in which is a linear alkyl (-C _n H _{2n + 1} ) was measured.
The measuring method is the method shown as [Experiment 1] below.
The test piece was prepared by laminating a thin film having a predetermined film thickness on a substrate, and the dissolution range in a solvent having a predetermined solubility parameter was measured. [Experiment 1] 6 mg of a polymer, which is a material for a thin film layer such as a hole transport layer, an electron block layer, a light emitting layer, a hole block layer, an electron transport layer, and an electron injection layer, which constitutes an organic electroluminescence device, was added to trichloro Dissolve in 1 ml of methane to make a solution. Commercial IT with oxygen plasma treatment
This solution was spin-coated on an O substrate (manufactured by Asahi Glass Co., Ltd .: 20Ω / □ or less) at a rotation speed of 1500 rpm for 1 second,
A substrate with a thin film of 50 nm is prepared and used as a test piece.

[0197]

[Table 17]

Solvents having the solubility parameters shown in [Table 17] are prepared in the ascending order of the solubility parameter values, and as shown in FIGS. 4 (a) and 4 (b), the solvent 1
Beaker 2 filled with 1 test piece 3 each
It is dipped for 0 second, and then, as shown in FIG. 4C, the test piece 3 is taken out and it is visually confirmed whether or not the thin film is dissolved.

Of the solubility parameters of the solvent in which the thin film dissolves, the minimum value and the maximum value are defined as the dissolution range of the test piece.

The molecular weight of the polymer used at this time was 60,000.
It carried out with the thing of 0. The measurement results of the dissolution range are shown in [Table 1
8].

[0201]

[Table 18]

Here, in place of the dinormal butyl polyfluorene represented by [Chemical formula 5], R in the repeating unit represented by [Chemical formula 1] is produced as a straight-chain alkyl (—C _n H _{2n + 1} ). A device structure shown in FIG. 3 was prepared in the same manner as in [Example 139] except that a polymer having a molecular weight of 60,000 was used for the hole transport electron blocking layer. Was obtained.

[0203]

[Table 19]

In [Comparative Example 11], a device could not be prepared because the polymer was not dissolved in 1,2-dichloroethane.
In [Comparative Example 12], the device could not be prepared because the hole transport electron blocking layer was dissolved during the formation of the light emitting layer. [Example 144] to [Example 145], [Comparative Example 13]
Except that the solvent was changed to hexane to prepare solution 1, and the solvent was changed to toluene to prepare solution 2.
When the device structure shown in FIG. 3 was prepared in the same manner as in [Example 139], light emission having the light emission efficiency shown in [Table 20] below was obtained.

[0205]

[Table 20]

In [Comparative Example 13], an element could not be prepared because the hole transport electron blocking layer was dissolved during the formation of the light emitting layer. [Example 146] to [Example 147], [Comparative Example 14]
~ [Comparative Example 15] A device structure shown in Fig. 3 was prepared in the same manner as in [Example 139] except that the molecular weight of dinormal butyl polyfluorene represented by [Chemical Formula 5] was set as shown in [Table 21] below. When created, light emission having the light emission efficiency shown in [Table 21] was obtained. In addition, the solubility range by the solubility parameter display at each molecular weight is also described.

[0207]

[Table 21]

In [Comparative Example 14], the device could not be prepared because the hole transport electron blocking layer was dissolved during the formation of the light emitting layer. In [Comparative Example 15], an element could not be prepared because there was no solvent to dissolve. [Example 148] to [Example 155], [Comparative Example 16]
When the device structure shown in FIG. 3 was prepared in the same manner as in [Example 139] except that the solution 2 was prepared by dissolving in a solvent (1 ml each) shown in [Table 22] below, the luminous efficiency shown in [Table 22] was obtained. Luminescence was obtained.

[0209]

[Table 22]

In [Comparative Example 16], an element could not be prepared because N-phenylpolycarbazole represented by [Chemical Formula 20] was not dissolved in acetonitrile used as a solvent.

[0211]

As is apparent from the above description, the polyfluorene compound used in the present invention has a high hole mobility because it is a conductive polymer, so that the electric resistance value of the hole transport layer is reduced. It Further, since the polyfluorene compound has a relatively low electron affinity, the hole transport layer can have an electron blocking effect, and the emission brightness is improved. Therefore, the organic electroluminescent element of the present invention can emit light with high brightness by driving at a relatively low voltage, and thus can improve the light emission efficiency.

[Brief description of drawings]

FIG. 1 is a device structure of an organic electroluminescence device.

FIG. 2 is a first embodiment of the device structure of the present invention.

FIG. 3 is a second embodiment of the device structure of the present invention.

[FIG. 4] (a) to (c) Procedure for measuring the dissolution range of a sample piece by displaying solubility parameters

[Explanation of symbols]

10 Anode layer 23 Hole transport electron blocking layer (hole transport layer) 40 light emitting layer 41 Dope 42 Host agent 70 cathode layer

Claims (6)

[Claims] 1. In an organic electroluminescence device, which is formed between both electrode layers of an anode layer and a cathode layer and has a hole transport layer and a light emitting layer, the hole transport layer comprises: (In the chemical formula [Chemical Formula 1], R represents hydrogen, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, an ether group, or a heterocyclic group.) An organic electroluminescence device characterized in that 2. The organic electroluminescence device according to claim 1, wherein R in the repeating unit represented by [Chemical Formula 1] is an alkyl group having 10 or less carbon atoms. 3. The organic electroluminescent device according to claim 1, wherein R in the repeating unit represented by [Chemical Formula 1] is an alkoxyl group having 10 or less carbon atoms. 4. The organic electroluminescent device according to claim 1, wherein R in the repeating unit represented by [Chemical Formula 1] is a substituent having an aryl group. 5. The polymer has a smaller electron affinity than the host agent in the light emitting layer.
The organic electroluminescence element according to any one of 1. 6. The organic electroluminescence device according to claim 1, wherein the light emitting layer has a dopant that emits phosphorescence.