JP2016183140A - Compound for electroluminescence devices, and electroluminescence device prepared therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a long-life electroluminescence device, and a compound for electroluminescence devices for achieving the same.SOLUTION: A compound for electroluminescence devices is represented by formula (1) or formula (2) (X is a substituted/unsubstituted aryl group; L is a linking group to represent a substituted/unsubstituted arylene group; i is 0 or 1).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a compound for an electroluminescent element and an electroluminescent element using the same.

  Electroluminescent devices have features such as self-emission and high-speed response, and are expected to be applied to flat panel displays. In particular, since a two-layered type (laminated type) in which a hole-transporting organic thin film (hole-transporting layer) and an electron-transporting organic thin film (electron-transporting layer) are reported has been reported, a low voltage of 10 V or less. It has attracted attention as a large-area light-emitting element that emits light with voltage. The laminated electroluminescent element is composed of a thin film having a basic structure of positive electrode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / negative electrode. Among these, the light emitting layer may have the function of the hole transport layer and the electron transport layer as in the case of the two-layer type. Further, since various colors can be emitted by selecting the type of the fluorescent organic compound, application to various light emitting elements, display elements and the like is expected.

  In such an electroluminescent device, materials having various structures for various colors have been proposed in order to realize a long-life and highly efficient device. Among them, the pyrene structure is used as a material having high stability. Among them, it is said that by using an asymmetric pyrene derivative having a pyrene structure disclosed in Patent Document 1 as a host material of a light emitting layer, a long-life electroluminescent element can be manufactured.

  However, since the asymmetric structure produces polarity in the molecule, it reacts with active species having high polarity such as holes and electrons generated in the electroluminescent element, causing decomposition of the material. Therefore, when the asymmetric pyrene derivative disclosed in Patent Document 1 is used as the host material for the light emitting layer, sufficient life characteristics have not been obtained.

  In addition, the pyrene derivative disclosed in Patent Document 2 can suppress the crystallization of the pyrene derivative and the formation of the excimer by using a bulky substituent, and by using this, a long-life electroluminescent device can be produced. It is said that.

  However, the bulkiness of the substituents possessed by the pyrene derivative disclosed in Patent Document 2 is not sufficient, and when the pyrene derivative disclosed in Patent Document 2 is used as a host material for the light-emitting layer, sufficient lifetime characteristics are obtained. It was not obtained.

Japanese Patent No. 4705914 JP 2002-63988 A

  Accordingly, an object of the present invention is to provide a long-life electroluminescent element and a compound for the electroluminescent element that realizes the electroluminescent element.

（一般式（１）または一般式（２）において、Ｘは置換または無置換のアリール基を表し、Ｌは連結基であり、置換または無置換のアリーレン基を表し、ｉは０または１を表す。）
一般式（１）または一般式（２）で表される化合物は嵩高いアントラセン部位が、ピレン環同士のスタッキングに起因する結晶化を抑制することで薄膜としての安定性を高めるため、長寿命な電界発光素子用の化合物となる。 In order to achieve the above object, the compound for an electroluminescent device of the present invention is preferably represented by the following general formula (1) or general formula (2).

(In General Formula (1) or General Formula (2), X represents a substituted or unsubstituted aryl group, L represents a linking group, represents a substituted or unsubstituted arylene group, and i represents 0 or 1 .)
The compound represented by the general formula (1) or the general formula (2) has a long life because the bulky anthracene portion enhances the stability as a thin film by suppressing crystallization caused by stacking of pyrene rings. It becomes the compound for electroluminescent elements.

The electroluminescent device according to the present invention is an electroluminescent device in which at least one organic layer is sandwiched between a pair of electrodes composed of an anode and a cathode. It is preferable to contain the compound for electroluminescent elements represented by (1) or General formula (2) individually or as a component of a mixture. By using the above compound for an electroluminescent element, a long-life electroluminescent element can be provided.

  In addition, the electroluminescent device according to the present invention is an organic electroluminescent device in which a plurality of organic layers including a hole injection layer are sandwiched between a pair of electrodes composed of an anode and a cathode. It is preferably composed of a mixed layer of the compound represented by the general formula (1) or the general formula (2) and the electron acceptor compound. By reducing the work function of the compound using an electron acceptor, the compound can be used as a hole injection layer. In particular, since the above compound has a pyrene structure with a low ionization potential, holes generated by doping with an electron acceptor become stable, and an electroluminescent device having a long lifetime can be provided.

  The organic layer further includes at least one light emitting layer and a hole transport layer, and the light emitting layer and the hole transport layer are for the electroluminescent device represented by the general formula (1) or the general formula (2). It preferably consists of a compound. By using the compound for an electroluminescent element represented by the general formula (1) or the general formula (2) from the hole injection layer to the light emitting layer, the carrier injection barrier between different layers is reduced, which causes deterioration. Since accumulation of carriers is suppressed, a long-life electroluminescent element can be provided.

  ADVANTAGE OF THE INVENTION According to this invention, the compound for electroluminescent elements and the electroluminescent element which implement | achieve it can be provided with a long life.

1 is an outline of an electroluminescent element of the present invention.

（一般式（１）または一般式（２）において、Ｘは置換または無置換のアリール基を表し、Ｌは連結基であり、置換または無置換のアリーレン基を表し、ｉは０または１を表す。） The present embodiment is a compound for an electroluminescent element represented by the following general formula (1) or general formula (2).

(In General Formula (1) or General Formula (2), X represents a substituted or unsubstituted aryl group, L represents a linking group, represents a substituted or unsubstituted arylene group, and i represents 0 or 1 .)

  Since the compound represented by the general formula (1) or the general formula (2) has a symmetric structure, the transition dipole moment does not decrease, so that a decrease in quantum efficiency can be suppressed. In addition, since the pyrene ring has a strong stacking force between the pyrene rings, the two pyrene rings form an excimer in the electroluminescent element, thereby reducing the light emission efficiency. However, in the compound represented by the general formula (1) or the general formula (2), two bulky anthracene sites can prevent the formation of excimer by suppressing the stacking of the pyrene rings. Can be prevented. Further, the bulky anthracene moiety suppresses crystallization due to stacking of pyrene rings, thereby improving the stability as a thin film. Such an increase in the stability of the thin film is considered to increase the lifetime of the electroluminescent device as a result.

  L is a linking group, and each is a substituted or unsubstituted arylene group. A low molecular weight arylene group such as a phenylene group, a biphenylene group, or a naphthylene group is preferable because it can be easily synthesized. Moreover, a phenylene group is more preferable as an arylene group from the viewpoint of preventing excimer formation of the pyrene ring due to the bulk of the anthracene ring. These linking groups are usually preferably unsubstituted, but may be further substituted, in which case an aryl group having no polarity is preferred.

  X is a substituted or unsubstituted aryl group, and a low molecular weight aryl group such as a phenyl group, a biphenyl group, a terphenyl group, or a naphthyl group is preferable in terms of easy synthesis. These substituents may be further substituted, but aryl groups having no polarity are preferred.

  The molecular weight of the compound is not particularly limited, but is preferably 1000 or less in consideration of the film forming process. When the molecular weight exceeds 1000, synthesis becomes difficult due to a decrease in solubility, and the coating process for application to a device becomes difficult. In addition, even when a device is produced by a vapor deposition process, the vapor deposition temperature is often a high temperature of 400 ° C. or more, and the material may be decomposed.

  Although the specific example of the compound of this embodiment represented by General formula (1) or General formula (2) below is shown, this embodiment is not limited to these.

  Moreover, this embodiment is an electroluminescent element characterized by including the compound of the said General formula (1) or General formula (2). An electroluminescent device according to an embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the electroluminescent device 1 includes an anode 3, a hole injection layer 4, a hole transport layer 5, a light emitting layer 6, an electron transport layer 7, an electron injection layer 8, and a cathode 9 on a substrate 2. Have sequentially.

  The substrate 2 is preferably formed of a transparent or translucent material, such as a glass plate, a transparent plastic sheet, a translucent plastic sheet, quartz, transparent ceramics, or a composite sheet combining these. The substrate 2 may be formed from an opaque material. In this case, the electroluminescent element 1 should just reverse the lamination | stacking order shown by FIG. Furthermore, the emission color may be controlled by combining the substrate 2 with, for example, a color filter film, a color conversion film, a dielectric reflection film, or the like.

  The anode 3 preferably uses a metal, an alloy or an electrically conductive compound having a relatively large work function as an electrode material. Examples of the electrode material used for the anode 3 include gold, platinum, silver, copper, cobalt, nickel, palladium, vanadium, tungsten, tin oxide, zinc oxide, ITO (Indium Tin Oxide), polythiophene, and polypyrrole. These electrode materials may be used alone or in combination. The anode 3 can form these electrode materials on the substrate 2 by, for example, a vapor phase growth method such as a vapor deposition method or a sputtering method. Further, the anode 3 may have a single layer structure or a multilayer structure.

  The hole injection layer 4 is a layer containing a compound having a function of facilitating injection of holes from the anode 3. In addition, adhesion with the anode 3 is also an important factor when selecting a material. Specifically, it can be formed using at least one phthalocyanine derivative, triarylmethane derivative, triarylamine derivative, or the like. Since the compound represented by the general formula (1) or the general formula (2) of the present embodiment has a work function larger than that of the anode 3, the compound is usually not suitable for the hole injection layer 4. However, when holes are forcibly generated using an electron acceptor such as antimony chloride, iron chloride, or molybdenum oxide, hole injection from the anode 3 is facilitated, so that the general formula ( The compound represented by 1) or general formula (2) can also be used as the hole injection layer 4. In particular, since the compound represented by the general formula (1) or the general formula (2) has a pyrene structure with a low ionization potential, holes generated by doping of the electron acceptor are stabilized, and a long-life electroluminescent device can be provided.

  The hole transport layer 5 is a layer containing a compound having a function of transporting injected holes to the light emitting layer 6 and a function of preventing electrons in the light emitting layer 6 from being injected into the hole transport layer 5. is there. The hole transport layer 5 includes at least one hydrocarbon compound such as a triarylmethane derivative, a triarylamine derivative, a stilbene derivative, a polysilane derivative, polyphenylenevinylene and a derivative thereof, polythiophene and a derivative thereof, a carbazole derivative, or an anthracene derivative. Can be formed. Further, the compound represented by the general formula (1) or the general formula (2) of the present embodiment can also be used as the hole transport layer 5.

  In addition, if it is a material which has the function of the positive hole injection layer 4 and the positive hole transport layer 5, as a positive hole injection transport layer, it can fulfill the function for two layers by a single layer. On the other hand, the hole injection layer 4 and the hole transport layer 5 can be further functionally separated into a plurality of layers.

  The light emitting layer 6 is a layer containing a compound having a function of transporting injected holes and electrons and a function of generating excitons by recombination of holes and electrons. Hydrocarbon compounds such as naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, pyrene derivatives, fluoranthene derivatives, and naphthacene derivatives are preferably used. The compound represented by the general formula (1) or the general formula (2) in the present embodiment is preferably used for the light emitting layer 6, and is usually used as a host material, thereby providing a long-life electroluminescent device.

  In addition to the host material, the light emitting layer 6 may contain another fluorescent substance as a light emitting doping material. Examples of fluorescent substances include compounds such as quinacridone, rubrene, and styryl dyes, quinoline derivatives such as metal complex dyes having 8-quinolinol or a derivative thereof such as tris (8-quinolinolato) aluminum as a ligand, tetraphenyl, and the like. Examples thereof include butadiene, anthracene, fluoranthene, pyrene, perylene, coronene, 12-phthaloperinone derivatives, phenylanthracene derivatives, tetraarylethene derivatives, aromatic amine derivatives, and the like. In particular, aromatic amine derivatives such as aminonaphthalene derivatives, aminopyrene derivatives, aminophenanthrene derivatives, aminofluorene derivatives, aminochrysene derivatives, aminoanthracene derivatives, and aminoperylene derivatives are very preferable materials.

  The light emitting layer 6 may contain other compounds in addition to the host material and the light emitting doping material. It can be used by adjusting the transport of carriers by mixing other compounds, or by changing the emission color by mixing fluorescent dyes. Examples of compounds that regulate carrier transport include electron transport such as 8-quinolinol such as tris (8-quinolinolato) aluminum or its derivatives, quinoxaline derivatives, pyridine derivatives, pyrimidine derivatives, imidazopyridine derivatives, imidazopyrimidine derivatives, phenanthroline derivatives, and the like. Or a hole transporting compound such as a triarylamine derivative can be preferably used.

  The electron transport layer 7 has a function of transporting injected electrons and a function of preventing holes from being injected from the light emitting layer 6. The electron transport layer 7 is composed of an organometallic complex having an 8-quinolinol-like derivative such as tris (8-quinolinolato) aluminum as a ligand, an oxadiazole derivative, a triazole derivative, a triazine derivative, a quinoline derivative, a quinoxaline derivative, diphenyl At least one quinone derivative, nitro-substituted fluorenone derivative, thiopyrandioxide derivative, pyridine derivative, pyrimidine derivative, imidazopyridine derivative, imidazopyrimidine derivative, heterocyclic compound such as phenanthroline derivative, hydrocarbon derivative such as anthracene derivative or fluoranthene derivative, etc. It can be formed using seeds. In addition, the compound represented by the general formula (1) or the general formula (2) of the present embodiment can also be used as the electron transport layer, and particularly represented by the general formula (1) or the general formula (2) in the light emitting layer. When a compound is used, it is preferable to use the same material for the electron transport layer.

  The electron injection layer 8 has a function of facilitating injection of electrons from the cathode 9 and a function of improving adhesion with the cathode 9. The electron injection layer 8 is composed of an organometallic complex having an 8-quinolinol or its derivative such as tris (8-quinolinolato) aluminum as a ligand, oxadiazole derivative, triazole derivative, triazine derivative, quinoline derivative, quinoxaline derivative, diphenyl A quinone derivative, a nitro-substituted fluorenone derivative, a thiopyrandioxide derivative, a pyridine derivative, a pyrimidine derivative, an imidazopyridine derivative, an imidazopyrimidine derivative, a phenanthroline derivative, or the like can be used. The compound represented by the general formula (1) or the general formula (2) of the present embodiment is usually not suitable for the electron injection layer 8, but when the cathode 9 having excellent injectability is used, an alkali metal or an alkali The electron injection layer 8 can be used by doping a metal having a relatively small work function such as an earth metal and a salt thereof.

  For the cathode 9, a metal having a relatively small work function and a salt thereof, an alloy, or an electrically conductive compound can be used as an electrode constituent material. For example, lithium, sodium, calcium, magnesium, indium, ruthenium, titanium, manganese, yttrium, aluminum as metal, lithium oxide, sodium oxide, calcium oxide, magnesium oxide as oxide, lithium fluoride, fluoride as fluoride Sodium, calcium fluoride, magnesium fluoride, alloys include lithium-indium alloy, sodium-potassium alloy, magnesium-silver alloy, magnesium-indium alloy, aluminum-lithium alloy, aluminum-calcium alloy, aluminum-magnesium alloy, electrical conduction Examples of the functional compound include a graphite thin film.

  These electrode constituent materials may be used alone or in combination. The cathode 9 can be formed of these electrode materials on the electron injection layer 8 by a method such as vapor deposition, sputtering, ionized vapor deposition, ion plating, or cluster ion beam. Further, the cathode 9 may have a single layer structure or a multilayer structure. In order to efficiently extract light emitted from the electroluminescent element, it is preferable that at least one of the anode 3 and the cathode 9 is transparent or translucent, and generally has a light transmittance of 80% or more. It is more preferable to set the material and thickness of the anode 3 or the cathode 9.

  The electroluminescent element is often formed by a vapor deposition process. However, the compound represented by the general formula (1) or the general formula (2) in the present embodiment has a pyrene ring stacking depending on the bulk of the anthracene ring. Since it is suppressed, the solubility is high, and a film can be sufficiently formed even by a coating process. Therefore, the cost of the process can be reduced by using the compound of the present invention. As the coating solvent, a hydrocarbon solvent such as toluene or xylene, or a halogen solvent such as dichloroethane can be used. As a film forming method, a spin coating method, various printing methods such as gravure printing, an ink jet method, or the like can be used. In the case of the spin coating method, a thin film of about 50 nm to 200 nm can be formed by using a solution having a concentration of about 1 to 3%.

  Hereafter, the specific synthesis example of the compound of this embodiment is shown, and this embodiment is demonstrated further in detail.

１３．６ｇ（４０．８ｍｍｏｌ）の９−ブロモ−１０−フェニルアントラセンを脱水テトラヒドロフランに溶解し、−７８℃に冷却した。ここに２８．３ｍｌ（４５ｍｍｏｌ）のｎブチルリチウムのｎヘキサン溶液を滴下し、更に１時間後に１１．７ｇ（８０ｍｍｏｌ）のホウ酸トリエチルを加えた。４時間反応を行った後に希塩酸溶液を加えた。次いで分離した有機層を用いて再結晶を行い、８．９ｇ（２９．９ｍｍｏｌ）の１０−フェニルアントラセン−９−ボロン酸を得た。収率は７３．３％であった。

13.6 g (40.8 mmol) of 9-bromo-10-phenylanthracene was dissolved in dehydrated tetrahydrofuran and cooled to -78 ° C. To this, 28.3 ml (45 mmol) of n-butyllithium in n-hexane was added dropwise, and 1 hour later, 11.7 g (80 mmol) of triethyl borate was added. After reacting for 4 hours, a diluted hydrochloric acid solution was added. The separated organic layer was then recrystallized to obtain 8.9 g (29.9 mmol) of 10-phenylanthracene-9-boronic acid. The yield was 73.3%.

１．４９ｇ（５．０ｍｍｏｌ）の１０−フェニルアントラセン−９−ボロン酸と０．７２ｇ（２．０ｍｍｏｌ）の１，６−ジブロモピレン、触媒としてのテトラキストリフェニルホスフィンパラジウム２３１ｍｇをトルエン４０ｍｌ、エタノール１０ｍｌの混合溶媒に溶解した。ここに２Ｍの炭酸ナトリウム水溶液１０ｍｌを加え１２０℃にて２日間反応した。反応終了後に有機層を分離し、カラムクロマトグラフィーによる精製を行い、１．１８ｇ（４．１９ｍｍｏｌ）の例示化合物Ｈ４を得た。収率は８３．８％であった。得られた固体のＡＰＣＩ−ＭＳを測定したところ、Ｃ５６Ｈ３４＝７０７に対し、ｍ／ｚ＝７０７が得られたことから、この化合物をＨ４と同定した。 (Synthesis Example 1) ... Synthesis of Exemplified Compound H4

1.49 g (5.0 mmol) of 10-phenylanthracene-9-boronic acid, 0.72 g (2.0 mmol) of 1,6-dibromopyrene, 231 mg of tetrakistriphenylphosphine palladium as a catalyst, 40 ml of toluene and 10 ml of ethanol In a mixed solvent. To this was added 10 ml of 2M aqueous sodium carbonate solution and reacted at 120 ° C. for 2 days. After completion of the reaction, the organic layer was separated and purified by column chromatography to obtain 1.18 g (4.19 mmol) of exemplified compound H4. The yield was 83.8%. When APCI-MS of the obtained solid was measured, m / z = 707 was obtained with respect to C56H34 = 707. Thus, this compound was identified as H4.

４．４７２ｇ（１５．０ｍｍｏｌ）の１０−フェニルアントラセン−９−ボロン酸と１８．８７３ｇ（７５．０ｍｍｏｌ）の１，３−ジブロモベンゼン、触媒としてのテトラキストリフェニルホスフィンパラジウム８６７ｍｇをトルエン１５０ｍｌ、エタノール５０ｍｌの混合溶媒に溶解した。ここに２Ｍの炭酸ナトリウム水溶液７５ｍｌを加え１００℃にて５時間反応した。反応終了後に有機層を分離し、カラムクロマトグラフィーによる精製を行い、４．３１７ｇ（１０．５ｍｍｏｌ）の９−（３−ブロモフェニル）−１０−フェニルアントラセンを得た。収率は７０．３％であった。

4.472 g (15.0 mmol) of 10-phenylanthracene-9-boronic acid, 18.873 g (75.0 mmol) of 1,3-dibromobenzene, 867 mg of tetrakistriphenylphosphine palladium as a catalyst, 150 ml of toluene and 50 ml of ethanol In a mixed solvent. To this, 75 ml of 2M aqueous sodium carbonate solution was added and reacted at 100 ° C. for 5 hours. After completion of the reaction, the organic layer was separated and purified by column chromatography to obtain 4.317 g (10.5 mmol) of 9- (3-bromophenyl) -10-phenylanthracene. The yield was 70.3%.

２．１ｇ（５ｍｍｏｌ）の９−（３−ブロモフェニル）−１０−フェニルアントラセンを脱水テトラヒドロフランに溶解し、−７８℃に冷却した。ここに３．４４ｍｌ（５．５ｍｍｏｌ）のｎブチルリチウムのｎヘキサン溶液を滴下し、更に１時間後に１．０２ｍＬ（６ｍｍｏｌ）のホウ酸トリエチルを加えた。１２時間反応を行った後に希塩酸溶液を加えた。次いで分離した有機層を用いて再結晶を行い、１．８ｇ（４．９ｍｍｏｌ）の３−（９−フェニルアントラセンー１０−イル）フェニルボロン酸を得た。収率は９７．５％であった。

2.1 g (5 mmol) of 9- (3-bromophenyl) -10-phenylanthracene was dissolved in dehydrated tetrahydrofuran and cooled to -78 ° C. To this, 3.44 ml (5.5 mmol) of n-butyllithium in n-hexane was added dropwise, and 1.02 mL (6 mmol) of triethyl borate was further added after 1 hour. After reacting for 12 hours, a diluted hydrochloric acid solution was added. The separated organic layer was then recrystallized to obtain 1.8 g (4.9 mmol) of 3- (9-phenylanthracen-10-yl) phenylboronic acid. The yield was 97.5%.

１．８ｇ（４．８ｍｍｏｌ）の３−（９−フェニルアントラセンー１０−イル）フェニルボロン酸と０．７２ｇ（２．０ｍｍｏｌ）の１，６−ジブロモピレン、触媒としてのテトラキストリフェニルホスフィンパラジウム２３１ｍｇをトルエン４０ｍｌ、エタノール１０ｍｌの混合溶媒に溶解した。ここに２Ｍの炭酸ナトリウム水溶液１０ｍｌを加え１２０℃にて２日間反応した。反応終了後に有機層を分離し、カラムクロマトグラフィーによる精製を行い、１．１８ｇ（４．１９ｍｍｏｌ）の例示化合物Ｈ６を得た。収率は８３．８％であった。得られた固体のＡＰＣＩ−ＭＳを測定したところ、Ｃ６８Ｈ４０＝８５９に対し、ｍ／ｚ＝８５９が得られたことから、この化合物をＨ６と同定した。 Synthesis Example 2 Synthesis of Exemplified Compound H6

1.8 g (4.8 mmol) 3- (9-phenylanthracen-10-yl) phenylboronic acid and 0.72 g (2.0 mmol) 1,6-dibromopyrene, 231 mg tetrakistriphenylphosphine palladium as catalyst Was dissolved in a mixed solvent of 40 ml of toluene and 10 ml of ethanol. To this was added 10 ml of 2M aqueous sodium carbonate solution and reacted at 120 ° C. for 2 days. After completion of the reaction, the organic layer was separated and purified by column chromatography to obtain 1.18 g (4.19 mmol) of exemplified compound H6. The yield was 83.8%. When APCI-MS of the obtained solid was measured, m / z = 859 was obtained with respect to C68H40 = 859. Therefore, this compound was identified as H6.

  Hereinafter, specific examples of the present embodiment will be shown together with comparative examples, and the present embodiment will be described in more detail.

Example 1
An ITO transparent electrode thin film having a thickness of 100 nm was formed on a glass substrate by RF sputtering and patterned. This glass substrate with an ITO transparent electrode was subjected to ultrasonic cleaning using a neutral detergent, acetone and ethanol, and then pulled up from boiling ethanol and dried. After the surface of the transparent electrode was washed with UV / O _3, it was fixed to a substrate holder of a vacuum deposition apparatus, and the inside of the tank was depressurized to 1 × 10 ⁻⁴ Pa or less.

  Next, while maintaining the reduced pressure state, Chemical Formula 11 having the following structure was deposited to a film thickness of 50 nm at a deposition rate of 0.1 nm / sec to form a hole injection layer.

  Next, chemical compound 12 having the following structure was deposited at a deposition rate of 0.1 nm / sec to a thickness of 10 nm to form a hole transport layer.

  Further, while maintaining the reduced pressure state, the compound H1 of the present embodiment as a host material and the chemical structure 13 of the following structure as a light-emitting dopant with a volume ratio of 97: 3 and a total deposition rate of 0.1 nm / sec and a thickness of 40 nm It vapor-deposited to make a light emitting layer.

  Next, while maintaining the reduced pressure state, the compound H1 of this embodiment was deposited at a thickness of 10 nm, followed by tris (8-hydroxyquinoline) aluminum (Alq3) at a deposition rate of 5 nm and a deposition rate of 0.1 nm / sec. did.

  Next, LiF was deposited to a thickness of 0.5 nm at a deposition rate of 0.1 nm / sec to form an electron injection electrode, Al was deposited to 100 nm as a protective electrode, and finally glass sealed to obtain an electroluminescent device.

When a direct current voltage was applied to the electroluminescent element, blue light emission derived from a light emitting dopant having an initial luminance of 480 cd / m ² and a luminance half life of 1410 hours at a current density of 10 mA / cm ² was obtained.

(Examples 2-22, Comparative Examples 1-2)
An electroluminescent device was produced in the same manner as in Example 1 except that the compounds listed in Table 1 were used instead of the compound (H1). Table 1 shows the test results of the initial luminance and the luminance half time of these elements. The compound shown in the comparative example has the following structure.

As shown in Table 1, when the pyrene derivative shown in this embodiment is used for a light emitting layer, two anthracene rings suppress the formation of excimer, and thus a high-brightness organic electroluminescent element can be obtained. Moreover, a long-life organic electroluminescent element is obtained by suppressing crystallization.

(Example 23)
An ITO transparent electrode thin film having a thickness of 100 nm was formed on a glass substrate by RF sputtering and patterned. This glass substrate with an ITO transparent electrode was subjected to ultrasonic cleaning using a neutral detergent, acetone and ethanol, and then pulled up from boiling ethanol and dried. After the surface of the transparent electrode was washed with UV / O _3, it was fixed to a substrate holder of a vacuum deposition apparatus, and the inside of the tank was depressurized to 1 × 10 ⁻⁴ Pa or less.

  Next, while maintaining the reduced pressure state, the compound H1 of the present embodiment and molybdenum oxide were vapor-deposited at a volume ratio of 95: 5 to a film thickness of 50 nm at an overall vapor deposition rate of 0.1 nm / sec. It was.

  Subsequently, the compound H1 of this embodiment was vapor-deposited at a vapor deposition rate of 0.1 nm / sec to a thickness of 10 nm to form a hole transport layer.

  Further, while maintaining the reduced pressure state, the compound H1 of this embodiment and the chemical compound 13 as a host material were vapor-deposited at a volume ratio of 97: 3 at a total vapor deposition rate of 0.1 nm / sec to a thickness of 40 nm. It was.

  Next, while maintaining the reduced pressure state, the compound H1 of this embodiment was deposited at a thickness of 10 nm, followed by tris (8-hydroxyquinoline) aluminum (Alq3) at a deposition rate of 5 nm and a deposition rate of 0.1 nm / sec. did.

  Next, LiF was deposited to a thickness of 0.5 nm at a deposition rate of 0.1 nm / sec to form an electron injection electrode, Al was deposited to 100 nm as a protective electrode, and finally glass sealed to obtain an electroluminescent device.

When a direct current voltage was applied to the electroluminescent element, blue light emission derived from a light emitting dopant having an initial luminance of 480 cd / m ² and a luminance half life of 1470 hours was obtained at a current density of 10 mA / cm ² .

(Examples 24-44, Comparative Examples 4-5)
An electroluminescent device was produced in the same manner as in Example 23 except that the compounds listed in Table 1 were used instead of the compound (H1). Table 3 shows the test results of the initial luminance and the luminance half time of these elements.

As shown in Table 2, when the pyrene derivative shown in this embodiment is used for the hole injection layer, the hole transport layer, and the light emitting layer, the two anthracene rings suppress the formation of the excimer. An electroluminescent element is obtained. In addition, radical cations generated by the electron acceptor doping are stabilized, and a long-life organic electroluminescence device can be obtained.

  As described above, the compound for an electroluminescent device according to the present invention is useful as a compound for realizing an electroluminescent device having high luminance and a long lifetime. An electroluminescent element utilizing this can be applied to a light emitting device such as a display or illumination.

DESCRIPTION OF SYMBOLS 1 Electroluminescent element 2 Substrate 3 Anode 4 Hole injection layer 5 Hole transport layer 6 Light emitting layer 7 Electron transport layer 8 Electron injection layer 9 Cathode

Claims (4)

The compound for electroluminescent elements represented by the following general formula (1) or general formula (2).

(In the general formula (1) or the general formula (2), X represents a substituted or unsubstituted aryl group, L represents a linking group, a substituted or unsubstituted arylene group, and i represents 0 or 1 Represents.) In an electroluminescent device in which at least one organic layer is sandwiched between a pair of electrodes consisting of an anode and a cathode,
At least one layer of the organic layer contains the compound for an electroluminescent device according to claim 1 alone or as a component of a mixture. In an organic electroluminescence device in which a plurality of organic layers including a hole injection layer are sandwiched between a pair of electrodes consisting of an anode and a cathode,
2. The electroluminescence according to claim 1, wherein the hole injection layer is composed of a mixed layer of a compound for an electroluminescent element represented by the general formula (1) or the general formula (2) and an electron acceptor compound. element. The organic layer further includes at least one light emitting layer and a hole transport layer,
The electroluminescent device according to claim 3, wherein the light emitting layer and the hole transport layer are composed of the compound for electroluminescent device represented by the general formula (1) or the general formula (2).

Images