JPH061973A - Organic electroluminescent element - Google Patents

Abstract

PURPOSE:To provide the subject element having high luminescent intensity and excellent durability and useful for a surface light source, a flat display, etc., by using a layer containing a specific organic compound. CONSTITUTION:The objective element has a layer containing an organic compound of formula I [A is group of formula II or formula III (R is H, halogen, etc.; (n) is 0-4); Ar1 and Ar2 are alkyl, aralkyl or aryl]. The element has a structure of e.g. substrate/anode/hole-injection layer/luminescent layer/cathode/ substrate/anode/luminescent layer/electron injection layer/cathode and the compound of formula I is usually used in the hole-injection layer or the luminescent layer. The thickness of the hole-injection layer is preferably 40-200nm and that of the luminescent layer is preferably 20-150nm.

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, and more particularly to an organic electroluminescence device used for flat light sources and flat displays.

[0002]

2. Description of the Related Art Organic electroluminescent devices are
It is composed of an organic light-emitting layer and a pair of counter electrodes sandwiching the layer, and its light emission is recombined in the light-emitting layer by electrons injected from one electrode and holes injected from the other electrode. It occurs when the luminescent material is excited to a higher energy level and emits energy as light when the excited luminescent material returns to the original ground state.
In such a carrier injection type electroluminescence device, since an organic compound thin film is used as a light emitting layer, a device having high emission intensity has been obtained. For example, U.S. Pat. No. 3,530,325 uses a single crystal anthracene or the like as a light emitter, and JP-A-59-194393 discloses a combination of a hole injection layer and an organic light-emitting layer.
63-295695 is a combination of a hole injecting and transporting layer and an organic electron injecting and transporting layer and Jpn. Journal of Applied Physic
s, vo127, No2, P269-271 discloses a combination of a hole transfer layer, a light emitting layer and an electron transfer layer, and these have improved the emission intensity.

However, in the conventional organic electroluminescence device having the above-mentioned structure, although the emission intensity has been improved, there is a problem in durability, and the emission intensity and durability of a practical level have not yet been reached. Therefore, it has been desired to develop an electroluminescence device having higher emission intensity and higher durability.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the invention is to provide a practical-level electroluminescence element having higher emission intensity and higher durability.

[0005]

DISCLOSURE OF THE INVENTION As a result of intensive research to achieve the above object, the present inventors have made up of a pair of counter electrodes and one or a plurality of organic compound layers sandwiched by these electrodes. In the electroluminescent element, the layer containing the organic compound represented by the general formula [1] which defines the constituent elements shown in the above "Chemical formula 1",
It has been found that this can be achieved by an organic electroluminescence device characterized in that at least one layer is provided.

In the general formula [1], the alkyl groups of Ar ₁ and Ar ₂ include methyl, ethyl, propyl and butyl, the aralkyl group includes benzyl, and the aryl groups include phenyl and naphthyl. Is mentioned.

Examples of the alkyl group of R include methyl, ethyl, propyl and butyl, examples of the alkoxy group include methoxy, ethoxy and propoxy, and examples of the halogen atom include fluorine atom, chlorine atom, bromine atom and iodine. Atoms.

Next, a specific example represented by the general formula [1] will be shown.

[0009]

[Chemical 2]

[0010]

[Chemical 3]

[0011]

[Chemical 4]

[0012]

[Chemical 5]

[0013]

[Chemical 6]

[0014]

[Chemical 7]

[0015]

[Chemical 8]

[0016]

[Chemical 9]

[0017]

[Chemical 10]

[0018]

[Chemical 11]

[0019]

[Chemical 12]

[0020]

[Chemical 13]

[0021]

[Chemical 14]

[0022]

[Chemical 15]

The organic thin film electroluminescent element of the present invention has various configurations, but basically, it is composed of a plurality of organic compound layers and a pair of counter electrodes sandwiching the layers, and specifically, , Substrate / anode / hole injection layer / emission layer / cathode (FIG. 1 (1)), substrate / anode / emission layer / electron injection layer / cathode (FIG. 1 (2)), substrate / anode / hole injection layer / Emission layer / electron injection layer / cathode (FIG. 1 (3)) and the like, but the present invention is not necessarily limited to this configuration, and a light emission layer, a hole injection layer, and an electron injection layer are respectively provided. A plurality of layers may be provided, or a hole injection layer / a light emitting layer, a light emitting layer / an electron injection layer, and a hole injection layer / a light emitting layer / an electron injection layer may be repeatedly laminated in each layer, or a light emitting layer and an electron injection layer may be formed. Between the mixed layer of electron injection material and light emitting material, hole injection layer and emission layer No problem be provided other layers in the mixed layer is provided or also each of the hole injecting material and a light emitting material between the layers.

The compound of the present invention (general formula [1]) is used in the hole injection layer or the light emitting layer.

The light emitting layer is formed by a vapor deposition method, a spin coating method, a casting method or the like, and its film thickness is preferably 10 to 1000 nm, more preferably 20 to 150 nm. The hole injection layer is formed by a vapor deposition method, a spin coating method, a casting method or the like, and its film thickness is preferably 10 to 1000 nm, more preferably 40 to 20 nm.
It is 0 nm. The electron injection layer is formed by a vapor deposition method, a spin coating method, a casting method or the like, and its film thickness is preferably 10 to 1000 nm, more preferably 30 to 200 nm.

The substrate 1 is made of soda glass, non-fluorescent glass,
Phosphate-based glass, boric acid-based glass, etc., quartz, acrylic resin, styrene-based resin, polycarbonate-based resin, epoxy-based resin, polyethylene, polyester, silicone-based resin, etc. plastic plate and plastic film, metal plate such as alumina And a metal foil or the like is used.

The anode 2 preferably has a work function larger than 4 eV, such as carbon, aluminum, vanadium,
Metals such as iron, cobalt, nickel, chromium, copper, zinc, tungsten, silver, tin, platinum and gold and alloys thereof, tin oxide such as zinc oxide, indium oxide, ITO and NESA or indium tin oxide-based composites Compounds, compounds such as copper iodide, mixtures of oxides and metals such as ZnO: Al, SnO ₂ : Sb, and conductive polymers such as poly (3-methylthiophene), polypyrrole, and polyaniline are used. The film thickness is preferably 10 to 1000 nm,
More preferably, it is 10 to 200 nm.

The cathode 3 preferably has a work function of less than 4 eV, such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, ytterbium, ruthenium, manganese, aluminum, silver, tin and lead. Metals and alloys thereof, aluminum / aluminum oxide composites and the like are used. The film thickness is preferably 10 to 1000 nm,
More preferably, it is 10 to 900 nm.

When light is extracted from the electrode, at least one of the anode 2 and the cathode 3 is transparent or semitransparent with a transmittance of 10% or more, and only the anode 2 is transparent or semitransparent with a transmittance of 10% or more. When it is transparent, the substrate 1 is also preferably transparent or semi-transparent.

Specific examples of the light-emitting substance used in the light-emitting layer 4 include oxinoid compounds (JP-A-63-295695 and JP-A-2-15595) in addition to the organic compound represented by the above general formula.
No. 2-66873, etc.), perylene compound (“Soluble Perylene Fluorescent Dyes with Photost
ability, vol.115, P2927 (1982), "Jpn. Journal of Ap
plied Physics, vol.27, No2, L269 (1988) "," Bull.Che
m.Soc.Jpn.vol.25, L411 (1952) ", European Patent 553,353A1
No. 55, No. 55-36849, No. 57-51781, No. 2-66873
Nos. 2-196885, 2-288188, 3-791, etc.) and coumarin compounds (JP-A-57-51781, JP-A-2-66873, 3-792, etc.). Described), azacoumarin compounds (described in JP-A-3-792, etc.), oxazole compounds (US Pat. No. 3,257,203, JP-A-3-93763).
No., No. 3-162482, No. 2-220396, etc.),
Oxadiazole compounds (described in US Pat. No. 3,189,447, JP-A-2-216791, etc.), perinone compounds (described in JP-A-2-88689, JP-A-2-289676, etc.), pyrrolopyrrole compounds (special Those described in Kaihei 2-296891), naphthalene compounds (JP-A-57-51781, JP-A-2-2)
55789, 3-162485, etc.), anthracene compounds (JP-A-56-46234, JP-A-57-51781, JP-A-5-51781)
2-66873, 3-162485, etc.), fluorene compounds (described in JP-A-54-110837, JP-A-3-162485, etc.), fluoranthene compounds (JP-A-3-16)
2485), a tetracene compound (JP
3-162485, etc.), pyrene compounds (JP
57-51781, JP-A-3-162485, JP-A-3-502333, etc.), coronene compound (JP-A-3-162485, etc.), quinolone compound, and azaquinolone compound (JP-A-3-261485). 162483, etc.), pyrazoline derivatives and pyrazolone derivatives (US Pat. No. 3,180,729;
4,278,746, JP-A-55-88064, 55-88065, 49-
105537, 55-51086, 56-80051, 56-88141
No. 57-45545, No. 54-112637, No. 55-74546, those described in JP-A-2-220394, 3-162486, etc.), rhodamine compounds (JP-A-2-66873, JP-A-2-66873, 3-188189 etc.), chrysene compounds (JP-A-57-51781,
JP-A-3-502333, etc.), phenanthrene compound (JP-A-57-51781, etc.), cyclopentadiene compound (JP-A-2-289675, etc.), stilbene compound ( U.S. Pat. No. 4,356,429, JP-A-57-51781, 61-210363, 61-228451, 61-1.
No. 4642, No. 61-72255, No. 62-47646, No. 62-36674,
62-10652, 62-30255, 60-934454, 60-94
No. 462, No. 60-174749, No. 60-175052, No. 63-149652
JP-A Nos. 1-173034, 1-200262, 1-245087, etc.), diphenylquinone compounds ("Polyme
r Preprints, Japan, vol.37, p681 (1988) ", JP-A-3-152
No. 184) and styryl compounds (JP-A 1-2
45087, 2-209988, 2-222484, 2-247278, etc.), butadiene compound (US Pat.
6,429, those described in JP-A-57-51781), dicyanomethylenepyran compounds (JP-A-2-66873, JP-A-3-162)
481), dicyanomethylene thiopyran compound (described in JP-A-2-66873, JP-A-3-162481, etc.), fluorescein compound (described in JP-A-2-66873, etc.), Pyrylium compound (JP-A-2-66873
, Etc.), thiapyrylium compounds (JP
2-66873 etc.), selenapyrylium compound (described in JP-A-2-66873 etc.), telluropyrylium compound (described in JP-A-2-66873 etc.),
Aromatic aldadien compounds (described in JP-A-2-220393, etc.), oligophenylene compounds (JP-A-3-62484)
, Etc.), thioxanthene compounds (JP
3-177486), anthracene compound (described in JP-A-3-178942), cyanine compound (described in JP-A-2-66873), acridine compound (JP-A-57). -51781), metal chain of 8-hydroxyquinoline compound (Japanese Patent Laid-Open No. 2-8287,
2-8290), metal chains of 2,2'-bipyridine compounds (such as those described in JP-A Nos. 2-8288 and 2-8289), Schiff salts and Group III metals Chain (Japanese Patent Laid-Open No. 1-29749
No. 0, etc.), oxine metal chain (Japanese Patent Laid-Open No. 3-1
76993, etc.), rare earth chain (Japanese Patent Laid-Open No. 1-256)
No. 584, No. 1-282291, etc.) can be used.

Specific examples of the hole injecting compound having a hole transporting ability used in the hole injecting layer 5 include triazole derivatives (described in US Pat. No. 3,112,197) and oxadiazole derivatives (US Pat. No. 3,189,447). Etc.), imidazole derivatives (those described in JP-B-37-16096, etc.), polyarylalkane derivatives (US Pat. Nos. 3,615,402, 3,820,989, 3,542,544, and JP-B-45-555, 51). -10983, JP-A-51-93224, 55-1
No. 7105, No. 56-4148, No. 55-108667, No. 56-36656,
55-156953), pyrazoline derivatives and pyrazolone derivatives (US Pat. Nos. 3,180,729 and 4,278,7).
46, JP-A-55-88064, 55-88065, 49-105537
No. 55, No. 55-51086, No. 56-80051, No. 56-88141, No. 57.
-45545, 54-112637, 55-74546, etc.), phenylenediamine derivatives (US Pat. No. 3,615,40)
No. 4, Japanese Patent Publication No. 51-10105, No. 46-3712, No. 47-25336,
JP-A-54-53435, JP-A-54-110536, JP-A-54-119925, etc.), arylamine derivatives (US Pat.
7,450, 3,180,703, 3,240,597, 3,658,520
No. 4,232,103, 4,175,961, 4,012,376, JP-B-49-35702, 39-27577, JP-A-55-144250,
56-223437, West German Patent 1,110,518, etc.), amino-substituted chalcone derivative (US Patent 3,526,50)
No. 1), oxazole derivatives (U.S. Pat. No. 3,257,203, etc.), styrylanthracene derivatives (such as those described in JP-A-56-46234), fluorenone derivatives (JP-A-54-110837). And the like), hydrazone derivatives (US Pat. No. 3,717,462, JP-A-54-59143, JP-A-55-52063, JP-A-55-52064, and JP-A-55-467).
No. 60, No. 55-8495, No. 57-148749, JP-A-3-136059
Nos. 3-138654, etc.), stilbene derivatives (JP-A-61-210363, 61-228451, 61-14642).
Issue 61-72255, Issue 62-47646, Issue 62-36674, Issue 62
-10652, 62-30255, 60-934454, 60-94462
No. 60, No. 60-174749, No. 60-175052, No. 63-149652,
Japanese Patent Laid-Open No. 1-173034, 1-200262, etc.),
Porphyrin compound (JP-A-63-295695, JP-A-2-127)
95, etc.), aromatic tertiary amine compounds and styrylamine compounds (US Pat. No. 4,127,412, JP-A-53-27033, JP-A-54-58445, JP-A-54-149634, JP-A-54-64).
No. 299, No. 55-79450, No. 55-144250, No. 56-119132
Nos. 61-295558, 61-98353, 63-295695, JP-A 1-274154, 1-243393, 3-111485, etc.), butadiene compounds (JP-A 3-111484, etc.), polystyrene derivatives (JP-A-3-95291)
, Etc.) and hydrazone derivatives (Japanese Patent Laid-Open No. 3-13
No. 7187), triphenylmethane derivative, tetraphenylbenzidine derivative (JP-A-3-54289).
No. etc.) can be used,
Particularly preferred are porphyrin compounds, aromatic tertiary amine compounds and styrylamine compounds.

Specific examples of the electron injecting compound having an electron transporting ability used in the electron injecting layer 6 include nitro-substituted fluorenone-derived thiopyrandioxide derivatives and diphenoquinone derivatives ("Polymer Preprints, Japan, vo1.37, No.
3, P681, (1988) ", JP-A-3-152184, etc.), perylene tetracarboxyl derivative (" Jpn. Jour.
nal of Applied Physics, vol.27, No2, L269 (1988), `` Bu
L1.Chem.Soc.Jpn., vol.25, L411 (1952) ", anthraquinodimethane derivative (JP-A-57-149259).
No. 58, No. 58-55450, No. 61-225151, No. 61-133750, No.
63-104061, etc.), fluorenylidene methane derivative (JP-A-60-69657, JP-A-61-143764, JP-A-61-143764)
148159, etc.), anthrone derivatives (such as those described in JP-A-61-225151 and 61-233750), oxadiazole derivatives (such as those described in JP-A-3-79692), Compounds such as a perinone derivative (described in JP-A-2-289676) and a quinoline complex derivative can be used.

[0033]

EXAMPLES The present invention will be described in detail with reference to examples.

Example 1 A substrate (P110E-H-PS manufactured by Nippon Sheet Glass Co., Ltd.) on which ITO was deposited to a thickness of 150 nm on a glass as an anode was patterned into a desired shape and then polished with water using an alumina abrasive. went. After washing with water, ultrasonic washing with water for 10 minutes twice, ultrasonic washing with acetone for 10 minutes twice, ultrasonic washing with isopropyl alcohol for 10 minutes twice, and further hot air drying at 90 ° C were performed.

Then, the compound (2) was added to the substrate by using a tungsten board (SF, manufactured by Nippon Bucks Metal Co., Ltd.).
208) and 0.2 nm / sec under a vacuum condition of 8.0 × 10 ^-7 Torr.
A hole injection layer having a thickness of about 80 nm was formed by vacuum evaporation at a film formation rate of.

Then, 8-hydroxyquinoline aluminum was placed in a molybdenum boat (SS-1-9 manufactured by Nippon Bucks Metal Co., Ltd.) without breaking vacuum conditions, and 8.0 × 10
Under vacuum conditions of ^-7 Torr, a light emitting layer of about 60 nm was laminated and deposited at a film forming rate of 0.2 nm / sec.

On top of this, without breaking vacuum conditions, M
g: Ag (10: 1 atomic ratio alloy) was vacuum-deposited at 500 nm to form a cathode.

An external power supply was connected to the thus obtained organic electroluminescence device, a direct current voltage of 18 V was applied, and the maximum luminance at that time was measured. Further, continuous lighting was carried out by applying a DC voltage of 18 V in a dry nitrogen gas atmosphere at a temperature of 23 ° C., and the time at which the luminance was reduced by half was measured.

The results are shown in Table 1.

Examples 2 to 7 Organic electroluminescent elements were obtained in the same manner as in Example 1 except that the compounds shown in Table 1 were used instead of the compounds used in the hole injection layer. The characteristics are shown in Table 1.

Comparative Example (1) A state was prepared in the same manner as in Example 1 except that the compound (A-1) shown in the following "Chemical Formula 16" was used for the hole injection layer.
The results are shown in Table 1.

[0042]

[Table 1]

Example 8 A substrate (P110E-H-PS manufactured by Nippon Sheet Glass Co., Ltd.) having a 150 nm ITO film formed on glass as an anode was patterned into a desired shape and then polished with water using an alumina abrasive. went. After washing with water, ultrasonic washing with water for 10 minutes twice, ultrasonic washing with acetone for 10 minutes twice, ultrasonic washing with isopropyl alcohol for 10 minutes twice, and further hot air drying at 90 ° C were performed.

Then, the compound (1) was added to the substrate by using a tungsten board (SF, manufactured by Nippon Bucks Metal Co., Ltd.).
208) and 0.2 nm / sec under a vacuum condition of 8.0 × 10 ^-7 Torr.
It was vacuum-deposited at a film forming speed of to form a light emitting layer of about 60 nm.

Next, the compound (A-2) shown below in "Chemical formula 16" was placed in a molybdenum boat (SS-1-9 manufactured by Nippon Bucks Metal Co., Ltd.) without breaking vacuum conditions,
Approximately 80n at a deposition rate of 0.2nm / sec under a vacuum of × 10 ^-7 Torr
An electron injection layer of m was laminated and vapor deposited.

On top of this, M
g: Ag (10: 1 atomic ratio alloy) was vacuum-deposited at 500 nm to form a cathode.

An external power supply was connected to the thus obtained organic electroluminescence device, a 18 V DC voltage was applied, and the maximum luminance at that time was measured. Further, continuous lighting was carried out by applying a DC voltage of 18 V in a dry nitrogen gas atmosphere at a temperature of 23 ° C., and the time at which the luminance was reduced by half was measured. The results are shown in Table 2.

Examples 9 to 14 Organic electroluminescent devices were obtained in the same manner as in Examples except that the compounds shown in Table 2 were used instead of the compounds used in the light emitting layer. The characteristics are shown in Table 2.

Comparative Example (2) A device was prepared in the same manner as in Example 8 except that the compound (A-3) shown in "Chemical Formula 16" below was used in the light emitting layer. The results are shown in Table 2.

[0050]

[Table 2]

[0051]

[Chemical 16]

[0052]

By using the specific organic compound according to the present invention, it is possible to obtain an organic electroluminescence device which is sufficiently practical for emission intensity and durability.

[Brief description of drawings]

FIG. 1 (1) to (3) are cross-sectional views of an organic electroluminescence element according to an embodiment of the present invention.

[Explanation of symbols]

 1 substrate 2 anode 3 cathode 4 light emitting layer 5 hole injection layer 6 electron injection layer

Claims (1)

[Claims] 1. An organic electroluminescence device comprising at least one layer containing an organic compound represented by the following general formula [1]. [Chemical 1] [In the general formula [1], Ar ₁ and Ar ₂ represent an alkyl group, an aralkyl group or an aryl group, and R represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group. n is an integer of 0-4. ]