JPH07292353A - Electroluminescent element - Google Patents

Abstract

PURPOSE:To obtain an organic electroluminescent element, containing a specific compound in an organic luminous layer, etc., and useful for a planar light source or a flat display, etc., having a high luminous intensity and good in durability. CONSTITUTION:This electroluminescent element is obtained by using a compound expressed by formula I or II (Rj is phenyl or an alkyl; R2 and R3 each is an alkyl, an alkoxy, an aralkyl, an aryl, an alkylamine, etc.; R1 to R3 each may further have a substituent group; X is an atomic group capable of condensing with pyrimidone ring and providing a polycyclic constitution; Y is O, S or NR4; R4 is H, an alkyl or an aryl) as a luminous substance of an organic luminous layer or in an electron injecting layer.

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, flat displays and the like.

[0002]

2. Description of the Related Art Conventionally, an organic electroluminescence element is composed of an organic light emitting layer and a pair of counter electrodes sandwiching the layer, and the light emission is from electrons injected from one electrode and the other electrode. Recombination occurs in the light emitting layer due to the injected holes, the light emitter is excited to a higher energy level, and the excited light emitter emits energy as light when returning to the original ground state. It is believed that. Since such a carrier injection type electroluminescence device has started to use a thin film made of an organic compound, a device having a high light 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. No. 295695 is a combination of a hole injection layer and an organic electron injection transport layer, Jpn.Journa.
L of Applied Phisycs, vol 127, No. 2, pp. 269-271, discloses a combination of a hole transfer layer, a light emitting layer and an electron transfer layer, respectively, and the emission intensity has been improved by these.

However, although the above-mentioned conventional electroluminescence device has been improved in light emission intensity, it has a problem in durability and has not yet reached a practical level of light emission intensity and durability. Therefore, there is a demand for the development of a practical level organic 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 thereof is to provide a practical level organic electroluminescence device having a larger emission intensity and a higher durability.

[0005]

As a result of intensive efforts made by the present inventors, a pair of counter electrodes and a compound of the general formula [1] or [2] sandwiched by these electrodes (Chemical Formula 1) It has been found that the above object can be achieved by an electroluminescent device having a layer containing).

When R _{1 of the} general formulas [1] and [2] is a phenyl group, examples of the substituent that may be possessed are an alkyl group (methyl group, butyl group, etc.), an alkoxy group (ethoxy group, propoxy group). Etc.), a substituted or unsubstituted amino group (amino group, dimethylamino group, di-t-butylamino group, etc.), nitro group, hydrogen atom, and halogen atom. R ₁ is preferably an alkyl group, and examples thereof include a substituted or unsubstituted alkyl group such as an ethyl group, a propyl group and a trifluoromethyl group.

R ₂ and R ₃ in the general formulas [1] and [2] are an alkyl group (eg ethyl group, butyl group), an alkoxy group (eg methoxy group, propoxy group), an aralkyl group (eg benzyl group), Aryl group (eg phenyl group, naphthyl group, biphenyl group), heterocyclic group (eg pyridyl group, triazolyl group, thiazolyl group, pyrrolyl group, furyl group, oxazolyl group, benzimidazolyl group, benzothiazolyl group), halogen atom, these May have a substituent.

Specific examples of the polycyclic structure formed by condensing X and a pyrimidone ring include a benzene ring, a naphthalene ring, an anthracene ring, a benzocarbazole ring, a benzofuran ring, a pyridine ring and a furan ring. it can.

Specific examples of the compounds represented by the general formulas [1] and [2] are shown below, but the invention is not limited thereto.

[0010]

[Chemical 2]

[0011]

[Chemical 3]

[0012]

[Chemical 4]

[0013]

[Chemical 5]

[0014]

[Chemical 6]

[0015]

[Chemical 7]

[0016]

[Chemical 8]

There are various modes of constitution of the organic electroluminescence element of the present invention, but basically, it is composed of a light emitting layer and a pair of counter electrodes sandwiching the layer, and for example, a substrate / anode / light emitting layer / Cathode, substrate / anode / hole injection layer / emission layer / cathode, substrate / anode / emission layer / electron injection layer / cathode, substrate / anode / hole injection layer / emission layer / electron injection layer / cathode, etc. However, the present invention is not limited to these, and the light emitting layer, the hole injection layer, and the electron injection layer may be provided in a plurality of layers, or the hole injection layer / light emitting layer and the light emitting layer / electron injection layer may be repeatedly laminated. A mixed layer of an electron injection material and a light emitting material is provided between the light emitting layer and the electron injection layer, or a mixed layer of a hole injection material and a light emitting material is provided between the hole injection layer and the light emitting layer, Other layers can also be provided.

The compound of the general formula [1] or [2] of the present invention is preferably used in the electron 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 the thickness thereof 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 200.
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.

As the substrate, glass plates of soda glass, non-fluorescent glass, phosphoric acid type glass, silicate type glass, etc .; quartz;
Acrylic resin, styrene resin, polycarbonate resin, epoxy resin, polyethylene, silicone resin and other plastic plates and plastic films; alumina and other metal plates and metal foils are used.

As the anode, those having a work function of more than 4 eV are preferable, and metals such as carbon, aluminum, vanadium, iron, cobalt, nickel, chromium, copper, zinc, tungsten, silver, tin, platinum, gold and the like, and these metals are used. Alloys, complex compounds such as tin oxide or indium tin oxide such as zinc oxide, indium oxide, ITO and NESA, compounds such as copper iodide, mixtures of oxides and metals such as ZnO: Al, SnO ₂ : Sb, For example, conductive polymers such as poly (3-methylthiophene), polypyrrole, and polyaniline are used. The film thickness is preferably 10 to 1000 nm, more preferably
10 to 200 nm.

As the cathode, one having a work function of more than 4 eV is preferable, and magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, ytterbium, ruthenium, manganese, aluminum, silver, tin, lead, etc. can be used. Metals and alloys thereof, aluminum / aluminum oxide composites and the like are used. The film thickness is preferably 10 to 1000 nm, more preferably 10 to 900 nm.

When light is taken out from the electrode, at least one of the anode and the cathode is transparent or semitransparent with a transmittance of 10% or more, and only the anode is transparent or semitransparent with a transmittance of 10% or more. The substrate is also preferably transparent or translucent.

As the light-emitting substance used in the light-emitting layer, in addition to the compound represented by the general formula of the present invention, oxinoid compounds (JP-A-63-295695, JP-A-2-15595 and JP-A-2-6687).
No. 3 etc.), perylene compounds (“Soluble Per
yren Fluorensent Dyes with Photostability, vol.115,
Pp. 2927 (1982), `` Jpn. Journal of Applied Phyisic
s, vol.27, No.2, L269 (1988) '', `` Bull.Chem.Soc.Jpn.Vo
L.25, L411 (1952) ", European Patent No. 553, 353A1952)",
JP-A-55-36849, JP-A-2-66873, etc.), coumarin compound (JP-A-57-51781, JP-A-2-66)
873, etc.), azacoumarin compounds (those described in JP-A-3-792, etc.), oxazole compounds (US Patent 3,257,203, those described in JP-A-3-93763, etc.), Oxadiazole compound (US Patent 3,
189,447, those described in JP-A-2-216791, etc.),
Perinone compounds (described in JP-A-2-88689 and JP-A-2-289676), pyrrolopyrrole compounds (JP-A-2-29
Naphthalene compounds described in 6891 etc.
57-51781, those described in JP-A-2-255789, etc.),
Anthracene compound (JP-A-56-46234, JP-A-2-6687
No. 3, etc.), fluorene compounds (JP-A-5
4-110837, those described in JP-A-3-162485),
Pyrene compounds (described in JP-A-57-51781 and JP-A-3-162485), coronene compounds (JP-A-3-162485)
No., etc.), a quinolone compound and an azaquinolone compound (those described in JP-A-3-162483, etc.),
Pyrazoline and pyrazolone derivatives (US Pat. No. 3,180,72
9, JP-A-55-88064, JP-A-2-220394, JP-A 3-16248
No. 6, etc.), stilbene compounds (US Pat. No. 4,356,429, JP-A-57-51781, JP-A-61-210363,
61-228451, 61-14642, 61-72255, 62-47
No. 646, No. 62-30255, No. 60-94462, No. 63-149652,
Those described in JP-A Nos. 1-173034 and 1-245087, etc.), diphenoquinone compounds (“Polymer Prerints Jap
an, vol.37, page 681 (1988) ", those described in JP-A-3-152184, etc., styryl compounds (JP-A-1-245087,
2-222484, etc.), butadiene compounds (described in US Pat. No. 4,356,429, JP-A-57-51781, etc.), anthracene compounds (described in JP-A-3-178942) ), A cyanine compound (JP-A-2-66873)
Described in Japanese Patent Publication No. 57-5).
1781), metal complexes of 8-hydroxyquinoline compounds (described in JP-A Nos. 2-8287 and 2-8290, etc.), complexes of Schiff salts with Group III metals (special Kaihei 1
-297490 etc.), oxine metal complex (described in JP-A-3-76993 etc.), rare earth complex (described in JP-A-1-256584 etc.) Can be used.

Specific examples of the hole injecting compound having a hole transporting ability used in the hole injecting layer include triazole compounds (described in US Pat. No. 3,112,197) and oxadiazole derivatives (US Pat. No. 3,189,447), imidazole derivative (Japanese Patent Publication No. 37-16096).
, Polyarylalkane derivatives (US Pat. No. 3,615,402, JP-B-45-555, JP-A-51-
93222, 56-36656, etc.), pyrazoline derivatives and pyrazolone derivatives (US Pat. No. 3,180,72).
9, those described in JP-A-55-88064 and JP-A-57-45545), phenylenediamine derivatives (US Pat. No. 3,615,
No. 404, JP-B No. 51-10105, JP-A No. 54-53435, etc.), arylamine derivatives (US Pat. No. 4,17).
5,961, JP-B-49-65702, JP-A-56-223437, West German Patent No. 1,110,518, etc.), oxazole derivatives (US Patent No. 3,257,203, etc.), styrylanthracene derivatives (JP-A-56-46234
, Etc.), fluorenone derivatives (JP
54-110837), hydrazone derivatives (US Pat. No. 3,717,462, JP-A-54-59143, JP-A-3).
-138654), stilbene derivatives (described in JP-A 61-210363, JP-A 1-200262, etc.), porphyrin compounds (JP-A 63-295695,
Those described in JP-A No. 2-1295), aromatic tertiary amine compounds and styrylamine compounds (US Pat. No. 4,12,12).
7,412, JP-A-53-27033, JP-A-63-295695, JP-A-1-
Nos. 274154 and 3-111485), butadiene compounds (those described in JP-A-3-111484, etc.),
Polystyrene derivatives (as described in JP-A-3-95291), hydrazone derivatives (as described in JP-A-3-137187), triphenylmethane derivatives and tetraphenylbenzidine derivatives (JP-A-3-54289) Etc.) etc. can be used. Particularly preferred are polyfin 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 include compounds represented by the general formula of the present invention, as well as nitro-substituted fluorene-derived thiopyrandioxide derivatives and diphenoquinone derivatives ( `` Polymer Preprints, Japan, vol.37, No.3, page 681 (198
8) ”, those described in JP-A-3-152184, etc.), perylene tetracarboxylic derivatives (“ Jpn. Journal of Appli
ed Physics, vol.27, No.2, L269 (1988) "` `Bull.Chem.So
c. Jpn., vol125, L411 (1952) "), anthraquinodimethane derivative (JP-A-57-149259, 63-63).
No. 104061), a fluoronylidene methane derivative (the one described in JP-A-60-69657, 61-148159, etc.), an anthrone derivative (JP-A-61-225151).
No. 61-233750), oxadiazole derivatives (those described in JP-A-3-79692), perinone derivatives (those described in JP-A-2-289676) A compound such as a quinoline complex derivative can be used.

[0027]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1 A substrate (NH) having a 150 nm ITO film formed on glass as an anode
After patterning on Techno-Glass NA-45),
Ultrasonic cleaning was performed and hot air drying was performed at 120 ° C.

Then, on the substrate, the following compound (A-1)
Tungsten board (SF 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 at the film formation rate of.

[0030]

[Chemical 9]

Next, while maintaining the vacuum state, the Exemplified Compound No. 58 of the present invention was put into a molybdenum board (SS-1-9 manufactured by Nippon Bucks Metal Co., Ltd.), and a vacuum condition of 8.0 × 10 ⁻⁷ Torr was applied. Then, an electron injection layer of about 60 nm was formed at a film formation rate of 0.2 nm / sec.

Further, while maintaining the vacuum state, 50 nm of Mg: Ag (alloy of 10: 1 atomic ratio) is vacuum-deposited on the electron injection layer,
A cathode was formed.

An external power source was connected to the electroluminescence device thus obtained, a DC voltage of 12 V was applied, and the maximum luminance at that time was measured. Further, continuous lighting was performed by applying a DC voltage of 12 V in a dry nitrogen gas atmosphere at a temperature of 23 ° C., and the time at which the brightness was reduced to half was measured. The results are shown in Table 1.

Examples 2 to 6 Electroluminescent devices were obtained in the same manner as in Example 1 except that the compounds shown in Table 1 were used in the electron injection layer. The results of evaluating them in the same manner are also shown in Table 1.

Comparative Example 1 An electroluminescent device was prepared and evaluated in the same manner as in Example 1 except that the following compound (B-1) was used in the electron injection layer. The results are shown in Table 1.

[0036]

[Chemical 10]

[0037]

[Table 1]

Examples 7 to 12 Electroluminescent devices were prepared in the same manner as in Example 1 except that the compound (A-2) shown below was used for the hole injection layer and the compounds shown in Table 2 were used for the electron injection layer. And evaluated. The results are shown in Table 2.

[0039]

[Chemical 11]

Comparative Example 2 An electroluminescent device was prepared and evaluated in the same manner as in Example 7 except that the following compound (B-2) was used in the electron injection layer. The results are also shown in Table 2.

[0041]

[Chemical 12]

[0042]

[Table 2]

Examples 13 to 23 As a positive electrode, a substrate (NH
After patterning on Techno-Glass NA-45),
Ultrasonic cleaning was performed and hot air drying was performed at 120 ° C.

Next, the compound (A
-2) 0.03 g, compound shown in Table 3 as electron injection material
0.045 g, 0.045 g of polymethacrylate that was purified twice by reprecipitation as a binder resin was added to 10 m of 1,2-dichloroethane.
It was dissolved in 1 to prepare a coating solution. This coating solution was applied to the above substrate with a spin coater (1H-D3 type manufactured by Mikasa Co., Ltd.)
Coating was performed under the conditions of 0 rpm / 15 sec to obtain a coating film of about 100 nm.

Further on this, Mg: Ag (10: 1 atomic ratio alloy)
Was vacuum-deposited with 50 nm to form a cathode.

An external power source was connected to the obtained electroluminescent device, a DC voltage of 12 V was applied, and the maximum luminance at that time was measured. Further, continuous lighting was carried out by applying a DC voltage of 12 V in a dry nitrogen gas atmosphere at a temperature of 23 ° C., and the time at which the brightness was reduced to half was measured. The results are shown in Table 3.

[0047]

[Table 3]

[0048]

As is apparent from the examples, by using the specific organic compound according to the present invention, it is possible to obtain an electroluminescence device which is excellent in light emission intensity and durability and can be sufficiently put to practical use.

Claims (4)

[Claims] 1. An electroluminescent device having a layer containing a compound represented by the following general formula [1] or general formula [2]. [Chemical 1] [In the formula, R ₁ represents a phenyl group or an alkyl group, and R ₂
And R ₃ each represents an alkyl group, an alkoxy group, an aralkyl group, an aryl group, an alkylamine group, a halogenated alkyl group, a hydrogen atom, a halogen atom, a nitro group or a cyano group. The groups represented by R _{1 to} R ₃ may further have a substituent. X represents an atomic group which is condensed with a pyrimidone ring to form a polycyclic ring. Y represents an oxygen atom, a sulfur atom or NR ₄ , and R ₄ represents a hydrogen atom, an alkyl group or an aryl group. ] 2. The electroluminescent device according to claim 1, wherein the layer containing the compound represented by the general formula [1] or [2] is sandwiched between a pair of opposing electrodes. 3. The electroluminescent device according to claim 1, wherein the compound represented by the general formula [1] or [2] is a light emitting substance. 4. The electroluminescent device according to claim 1, wherein the compound represented by the general formula [1] or [2] is an electron injecting compound.