JP2005310766A - Organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent element having excellent luminous efficiency. <P>SOLUTION: This organic electroluminescent element includes at least one organic compound layer including a luminescent layer between a pair of electrodes. The organic electroluminescent element contains a fluorescent compound which emits fluorescent light upon the application of a voltage, wherein light emission upon the application of the voltage is mainly derived from the fluorescent compound; and the element further contains a compound (herein after called an amplifying agent) having a function of increasing the number of singlet excitons formed upon the application of the voltage thereby amplifying luminescent intensity upon the application of the voltage. In the organic electroluminescent element, the fluorescent compound has a substituted group capable of decreasing the efficiency of Dexter energy transfer from a triplet exciton of the amplifying agent to a triplet exciton of the fluorescent compound. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light-emitting element that can emit light by converting electric energy into light, and particularly relates to an organic electroluminescent element (hereinafter also referred to as “light-emitting element” or “EL element”).

  An organic electroluminescence (EL) element has attracted attention as a promising display element because it can emit light with high luminance at a low voltage. An important characteristic value of this organic electroluminescence device is external quantum efficiency. The external quantum efficiency is calculated by “external quantum efficiency φ = number of photons emitted from the device / number of electrons injected into the device”, and the larger this value, the more advantageous the device in terms of power consumption.

  The external quantum efficiency of the organic electroluminescence device is determined by “external quantum efficiency φ = internal quantum efficiency × light extraction efficiency”. In an organic EL device using fluorescence emission from an organic compound, the limit value of the internal quantum efficiency is 25%, and the light extraction efficiency is approximately 20%. Therefore, the limit value of the external quantum efficiency is approximately 5%. Has been.

As a method for improving the internal quantum efficiency of an organic electroluminescent device and improving the external quantum efficiency of the device, a device using a triplet light emitting material (phosphorescent material) has been reported (for example, see Patent Document 1). ). This device can improve the external quantum efficiency as compared with a conventional device using fluorescent light emission (singlet light emitting device), and the maximum value of the external quantum efficiency is 8% (external quantum at 100 cd / m ^2). The efficiency has reached 7.5%), but since the phosphorescence emission from the heavy atom metal complex is used, the response of the emission is slow, and improvement in durability is desired.

As a method for improving this problem, a singlet light emitting device using energy transfer from a triplet exciton to a singlet exciton has been reported (for example, see Patent Document 2). However, the device described in this document has been required to be further improved in terms of durability.
International Publication No. 00/70655 Pamphlet International Publication No. 01/08230 Pamphlet

  An object of the present invention is to provide a light emitting device having good device durability.

The object has been achieved by the following means.
<1> An organic electroluminescent device having at least one organic compound layer including a light emitting layer between a pair of electrodes, containing a fluorescent light emitting compound that emits fluorescence when a voltage is applied, and mainly emits light when a voltage is applied. Contains a compound (hereinafter referred to as “amplifier”) derived from light emitted from a fluorescent compound and having a function of amplifying the number of singlet excitons generated when a voltage is applied to amplify the emission intensity when a voltage is applied. And the fluorescent compound has a substituent that reduces the Dexter-type energy transfer efficiency from the triplet exciton of the amplifying agent to the triplet exciton of the fluorescent compound. element.

<2> An organic electroluminescent element having at least one organic compound layer including a light emitting layer between a pair of electrodes, containing a fluorescent light emitting compound that emits fluorescence when a voltage is applied, Contains a compound (hereinafter referred to as “amplifier”) derived from light emitted from a fluorescent compound and having a function of amplifying the number of singlet excitons generated when a voltage is applied to amplify the emission intensity when a voltage is applied. And the organic electroluminescent element characterized by the said fluorescent-luminescent compound mother nucleus being covered three-dimensionally by the substituent.

<3> In an organic electroluminescent device having at least one organic compound layer including a light emitting layer between a pair of electrodes, the organic electroluminescent element contains a fluorescent light emitting compound that emits fluorescence when a voltage is applied. Contains a compound (hereinafter referred to as “amplifier”) derived from light emitted from a fluorescent compound and having a function of amplifying the number of singlet excitons generated when a voltage is applied to amplify the emission intensity when a voltage is applied. The organic electroluminescent device is characterized in that the fluorescent compound has a substituent that reduces the efficiency of electron transfer from the adjacent molecule to the fluorescent compound.

<4> The substituent that decreases the Dexter-type energy transfer efficiency is selected from the group consisting of an alkyl group, an aryl group, a heterocyclic group, an alkoxy group, an aryloxy group, a heterocyclic oxy group, a silyl group, a siloxy group, and an amino group. The organic electroluminescence device according to <1>, wherein the organic electroluminescence device is one or more substituents.

<5> The organic electroluminescent element according to any one of <1> to <4>, wherein the concentration of the fluorescent light-emitting compound in the light-emitting layer is 0.1% or more and 10% or less.

<6> The organic electroluminescent element according to any one of <1> to <5>, wherein the fluorescent quantum yield of the fluorescent light-emitting compound in the light-emitting layer is 70% or more.

<7> The organic electroluminescent element according to any one of <1> to <6>, wherein an emission spectrum of the amplifying agent and an absorption spectrum of the fluorescent light-emitting compound are at least partially overlapped.

<8> The organic electroluminescence device according to any one of <1> to <7>, wherein the amplification agent has a phosphorescence quantum yield of 20% or more.

<9> The organic electroluminescence device according to any one of <1> to <8>, wherein the amplification agent has a phosphorescence lifetime of 10 μs or less.

<10> The T ₁ level (energy level of the lowest excited triplet state) of the layer adjacent to the cathode side of the light emitting layer is 209.2 KJ / mol or more (50 Kcal / mol or more), 377.1 KJ / mol. The organic electroluminescent element according to any one of the above <1> to <9>, wherein the organic electroluminescent element is the following (90 Kcal / mol or less).

<11> The T ₁ level (energy level of the lowest excited triplet state) of the layer adjacent to the anode side of the light emitting layer is 209.2 KJ / mol or more (50 Kcal / mol or more), 377.1 KJ / mol. The organic electroluminescent element according to any one of <1> to <10>, wherein the organic electroluminescent element is the following (90 Kcal / mol or less).

<12> The organic electroluminescent element as described in any one of <1> to <11> above, wherein the fluorescent compound is a compound represented by the general formula (1).

(In the formula, Ar ¹¹ represents an aryl group or a heteroaryl group, R ¹¹ represents a substituent, n ¹¹ represents an integer of 1 or more, m ¹¹ represents an integer of 2 or more, and L represents a linking group. Or represents a single bond.)

<13> The organic electroluminescent element according to any one of <1> to <12>, wherein the fluorescent light-emitting compound is a compound represented by the following general formula (2).

(In the formula, Ar ²¹ represents an aryl group or a heteroaryl group, Ar ²² represents an aryl linking group or a heteroaryl linking group, R ²¹ and R ²² each represent a substituent, and n ²¹ represents 1; (The above represents an integer, n ²² represents an integer of 0 or more, and m ²¹ represents an integer of 2 or more.)

<14> The organic electroluminescence device according to any one of the above <2> to <13>, wherein the total carbon number of the substituent that lowers the Dexter-type energy transfer efficiency is 8 or more and 100 or less .

<15> The organic electroluminescent element according to any one of the above <2> to <14>, wherein the number of substituents that reduce the Dexter-type energy transfer efficiency is 3 or more and 20 or less.

<16> The above-described <2> to <15>, wherein the substituent that decreases the Dexter-type energy transfer efficiency is a group containing a tertiary and / or quaternary carbon atom. Organic electroluminescent element.

<17> The organic electroluminescence device according to any one of the above <2> to <16>, wherein the substituent that decreases the Dexter type energy transfer efficiency is an alkyl group containing a quaternary carbon atom. .

<18> The organic material according to any one of <1> to <17>, wherein the organic compound layer has an electron transport layer, and the electron transport layer contains a nitrogen-containing heterocyclic compound. Electroluminescent device.

<19> The total number of tertiary and quaternary carbon atoms in the fluorescent compound is 2 or more and 30 or less, according to any one of the above items <1> to <18> Organic electroluminescent device.
<20> The total number of tertiary and quaternary carbon atoms in the fluorescent compound is 4 or more and 20 or less, according to any one of the above items <1> to <19> Organic electroluminescent device.
<21> The tertiary and quaternary carbon atoms in the fluorescent compound are 6 or more and 15 or less in total, wherein any one of the above items <1> to <20> Organic electroluminescent device.

<22> The organic electroluminescent element according to any one of <1> to <21>, wherein the total number of quaternary carbon atoms in the fluorescent compound is 2 or more and 30 or less. .
<23> The organic electroluminescence device according to any one of <1> to <22>, wherein the total number of quaternary carbon atoms in the fluorescent compound is 4 or more and 20 or less. .
<24> The organic electroluminescent element as described in any one of <1> to <23> above, wherein the total number of quaternary carbon atoms in the fluorescent compound is 6 or more and 15 or less. .

<25> The organic electroluminescent device as described in any one of <1> to <24> above, wherein the total number of sp ³ carbon atoms in the fluorescent light-emitting compound is 8 or more and 100 or less. .
<26> The organic electroluminescent device according to any one of <1> to <25>, wherein sp ³ carbon atoms in the fluorescent compound are 17 to 70 in total. .
<27> The organic electroluminescent device as described in any one of <1> to <26> above, wherein the total number of sp ³ carbon atoms in the fluorescent compound is 20 or more and 60 or less. .

<28> The fluorescent compound is a condensed aromatic compound, a distyrylarylene derivative, an oligoarylene derivative, an aromatic nitrogen-containing heterocyclic compound, a sulfur-containing heterocyclic compound, a metal complex, an oxo-substituted heterocyclic compound, The organic electroluminescent element according to any one of <1> to <27>, wherein the organic electroluminescent element is at least one selected from the group consisting of an organosilicon compound and a triarylamine derivative.

  ADVANTAGE OF THE INVENTION According to this invention, the light emitting element which can be highly efficient and highly durable light emission can be provided.

  The organic electroluminescent device of the present invention is an organic electroluminescent device having at least one organic compound layer including a light emitting layer between a pair of electrodes, and contains a compound that emits fluorescence when a voltage is applied. Contains a compound (hereinafter referred to as an amplifying agent) that has the function of amplifying the number of singlet excitons generated when a voltage is applied and amplifying the light emission intensity when the voltage is applied, mainly derived from light emission from a fluorescent compound In addition, the fluorescent light-emitting compound has a substituent that reduces the Dexter-type energy transfer efficiency from the triplet exciton of the amplifying agent to the triplet exciton of the fluorescent light-emitting compound.

  Furthermore, the organic electroluminescent device of the present invention comprises a fluorescent compound that emits fluorescence when a voltage is applied in an organic electroluminescent device having at least one organic compound layer including a luminescent layer between a pair of electrodes. Luminescence at the time of application is mainly derived from light emission from the fluorescent light-emitting compound, and a compound having a function of amplifying the emission intensity at the time of voltage application by amplifying the number of singlet excitons generated at the time of voltage application (hereinafter referred to as “ The fluorescent light-emitting compound mother nucleus is substantially three-dimensionally covered with a substituent.

  Furthermore, the organic electroluminescent device of the present invention comprises a fluorescent compound that emits fluorescence when a voltage is applied in an organic electroluminescent device having at least one organic compound layer including a luminescent layer between a pair of electrodes. Luminescence at the time of application is mainly derived from light emission from the fluorescent light-emitting compound, and a compound having a function of amplifying the emission intensity at the time of voltage application by amplifying the number of singlet excitons generated at the time of voltage application (hereinafter referred to as “ And the fluorescent compound has a substituent that reduces the efficiency of electron transfer from the adjacent molecule to the fluorescent compound.

The organic electroluminescence device of the present invention is a device in which a light emitting layer or a plurality of organic compound layers including a light emitting layer is formed between a pair of electrodes, and the organic compound layer is a hole injection in addition to the light emitting layer. A layer, a hole transport layer, an electron injection layer, an electron transport layer, a protective layer, and the like may be disposed, and each of these layers may have other functions.
The light emitting layer includes the fluorescent compound and the amplifying agent, and various materials can be used for forming the layer and other layers.

  The above-mentioned “substituent that lowers the Dexter-type energy transfer efficiency from the triplet exciton of the amplifying agent to the triplet exciton of the fluorescent compound” is amplified by introducing the substituent into the nucleus of the fluorescent compound. This is a substituent having a function of reducing the Dexter-type energy transfer efficiency from the triplet exciton of the agent to the triplet exciton of the fluorescent luminescent compound as compared with the fluorescent luminescent compound comprising the fluorescent luminescent compound mother nucleus itself.

  A process in which a Dexter-type energy transfer from a triplet exciton of an amplifying agent to a triplet exciton of a fluorescent compound occurs when a triplet exciton of the amplifying agent is generated in a light emitting device including a fluorescent light emitting compound and an amplifying agent. There is a process in which Forster energy transfer occurs from the triplet exciton of the amplifying agent to the singlet exciton of the fluorescent compound. Decreasing the Dexter energy transfer efficiency from the triplet exciton of the amplifying agent to the triplet exciton of the fluorescent compound decreases the Forster energy transfer from the triplet exciton of the amplifying agent to the singlet exciton of the fluorescent compound. Can be raised efficiently.

  In other words, suppressing the Dexter type energy transfer from the triplet exciton of the amplifying agent to the triplet exciton of the fluorescent compound suppresses the triplet exciton formation of the non-luminescent fluorescent compound, and can emit light. This is useful in terms of improving the generation of singlet excitons of a fluorescent compound, that is, improving the efficiency of the light-emitting element.

  The Dexter-type energy transfer efficiency from the triplet exciton of the amplifying agent to the triplet exciton of the fluorescent luminescent compound can be determined by photochemical measurement of the film or solution containing the amplifying agent and the fluorescent luminescent compound. it can. The principle will be briefly described.

  The amplifying agent is photoexcited with respect to the film containing the amplifying agent and the fluorescent light-emitting compound to generate singlet excitons of the amplifying agent. Since the amplifying agent in the present invention is generally a compound having a heavy atom, the singlet exciton of the amplifying agent is quickly converted to a triplet exciton. When Dexter-type energy transfer from the triplet exciton of the amplifying agent to the triplet exciton of the fluorescent compound occurs, the phosphorescent emission of the amplifying agent is quenched by the fluorescent compound and the exciton lifetime of the amplifying agent is shortened Is observed. Further, since triplet excitons of the fluorescent compound are generated, fluorescence emission from the fluorescent compound cannot be obtained.

  On the other hand, when the Forster energy transfer from the triplet exciton of the amplifying agent to the singlet exciton of the fluorescent luminescent compound occurs, the triplet exciton of the amplifying agent is quenched by the fluorescent luminescent compound, and the exciton lifetime of the amplifying agent The phenomenon that becomes short is observed. Moreover, since singlet excitons are generated in the fluorescent light emitting compound, fluorescent light emission from the fluorescent light emitting compound is obtained.

  That is, the Dexter-type energy transfer efficiency from the triplet exciton of the amplifying agent to the triplet exciton of the fluorescent luminescent compound is obtained by photoexciting the amplifying agent and the amplifying agent in the film containing the fluorescent luminescent compound. It can obtain | require by measuring the emitted light intensity.

  For example, if these measurements are performed on a fluorescent light emitting compound skeleton into which a substituent (one or a plurality) is introduced, and the fluorescence intensity increases with respect to a compound to which the substituent is not introduced, the substituent becomes an amplifying agent. The triplet exciton is considered to be a substituent that suppresses the Dexter-type energy transfer from the triplet exciton of the fluorescent compound to the triplet exciton. In addition, since the fluorescence quantum yield of the fluorescent compound may be changed by introducing a substituent, in that case, it can be obtained by converting the data based on the change value of the fluorescence quantum yield. .

The substituent that lowers the Dexter-type energy transfer efficiency from the amplifying agent to the fluorescent compound is not particularly limited, and examples thereof include a substituent described in R ¹¹ described later. An alkyl group, an aryl group, a heterocyclic group, and the like. , An alkoxy group, an aryloxy group, a heterocyclic oxy group, a silyl group, a siloxy group, and an amino group are preferable, and an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a silyl group, and a siloxy group are more preferable, an alkyl group, an alkoxy group Group and silyloxy group are more preferable, and an alkyl group is particularly preferable.

  The substituent that lowers the Dexter-type energy transfer efficiency from the amplifying agent to the fluorescent light-emitting compound is preferably a group having a branched chain from the viewpoint of suppressing overlapping of molecular orbitals, and tertiary and / or quaternary carbon atoms. Is more preferable, a group having a quaternary carbon atom is more preferable, and an alkyl group having a quaternary carbon atom is particularly preferable. In addition, the substituent that lowers the Dexter-type energy transfer efficiency from the amplifying agent to the fluorescent light-emitting compound is preferably a group having 2 or more and 10 or less quaternary carbon atoms, each preferably having a quaternary carbon atom. A group having 2 or more and 10 or less is more preferable.

  The total number of carbon atoms of the substituent that decreases the Dexter-type energy transfer efficiency from the amplifying agent to the fluorescent compound is preferably 8 or more and 100 or less, more preferably 12 or more and 80 or less, in view of suppressing overlapping of molecular orbitals. It is more preferably 70 or less and particularly preferably 20 or more and 60 or less.

  The number of substituents that reduce the Dexter type energy transfer efficiency from the amplifying agent to the fluorescent compound (the number of substituents substituted on the fluorescent compound parent) is preferably 3 or more and 20 or less. The number is preferably 15 or more and more preferably 5 or more and 10 or less.

  The total number of tertiary and quaternary carbon atoms in the fluorescent compound is preferably 2 or more and 30 or less, more preferably 4 or more and 20 or less, and 6 or more and 15 or less. More preferably.

  The total number of quaternary carbon atoms in the fluorescent compound is preferably 2 or more and 30 or less, more preferably 4 or more and 20 or less, and 6 or more and 15 or less. Further preferred.

The number of sp ³ carbon atoms in the fluorescent compound is preferably 8 or more and 100 or less, more preferably 17 or more and 70 or less, and still more preferably 20 or more and 60 or less.

  The fluorescent compound is a condensed ring aromatic compound, distyrylarylene derivative, oligoarylene derivative, aromatic nitrogen-containing heterocyclic compound, sulfur-containing heterocyclic compound, metal complex, oxo-substituted heterocyclic compound, organosilicon compound And at least one selected from the group consisting of triarylamine derivatives.

  The above-mentioned “fluorescent light emitting compound mother nucleus is substantially three-dimensionally covered with a substituent” means that the contact between adjacent molecules and the fluorescent mother nucleus is hindered by the substituent introduced into the fluorescent light emitting compound mother nucleus. It is that you are. Here, “contact” means that the π orbit in the mother nucleus of the fluorescent compound and the π orbit in the amplifying agent have an interaction. “Having an interaction” means being able to exchange π electrons.

  Examples of the substituent that covers the fluorescent light-emitting compound mother nucleus three-dimensionally include the group described in the substituent that reduces the Dexter-type energy transfer efficiency from the triplet exciton of the amplifying agent to the triplet exciton of the fluorescent light-emitting compound. The preferred ranges are also the same.

  For example, when an alkyl group having a branched chain is introduced into rubrene, the alkyl group covers the rubrene atom as the number of substituents, the number of branched chains, and the number of carbon atoms are increased. The fact that the rubrene atom is substantially covered can be determined, for example, by examining the concentration dependence of the emission spectrum. For example, when the fluorescence spectrum of a 0.001 mol% alkyl-substituted rubrene solution is compared with the fluorescence spectrum of a 0.1 mol% alkyl-substituted rubrene solution, the difference in the maximum emission wavelength is within the range of ± 2 nm. It can be judged that the substituents covered the rubrene skeleton three-dimensionally.

  When the fluorescent light emitting compound mother nucleus is substantially three-dimensionally covered with the substituent, as a result, Dexter type energy transfer from the amplifying agent to the fluorescent light emitting material tends to be suppressed. Moreover, it is preferable at the point which the decomposition | disassembly by interaction with an adjacent molecule is suppressed.

  A substituent that reduces the efficiency of electron transfer from an adjacent molecule to a fluorescent light-emitting compound by a fluorescent light-emitting compound is compared with a fluorescent material that consists of the fluorescent core itself by introducing the substituent into the fluorescent light-emitting compound mother core. , A substituent that reduces electron transfer from an adjacent molecule (eg, host material, amplification agent, etc.) to the fluorescent compound.

  As a substituent that the fluorescent compound reduces the electron transfer efficiency from the adjacent molecule to the fluorescent compound, the Dexter type energy transfer efficiency from the triplet exciton of the amplifying agent to the triplet exciton of the fluorescent compound is reduced. And the preferred range is also the same.

  When the electron transfer efficiency from the adjacent molecule to the fluorescent compound decreases, the charge recombination efficiency in the fluorescent compound decreases, and accordingly, the triplet exciton generation efficiency of the fluorescent compound decreases. A reduction in triplet exciton generation efficiency of a non-luminescent fluorescent compound is preferable in that the EL element efficiency is improved.

  The degree of electron transfer to the fluorescent light-emitting compound can be determined by, for example, quantifying the amount of radical ions generated in the fluorescent light-emitting compound in the EL element by an absorption spectrum, ESR, or the like.

The fact that the light emission when the voltage is applied is mainly derived from the light emission from the fluorescent light-emitting compound, in other words, 51% or more of the light-emitting component obtained from the light-emitting element is light emission (fluorescence) from singlet excitons. The remaining 49% or less is light emission (phosphorescence) from triplet excitons, and preferably 70% or more of the light-emitting component obtained from the light-emitting element is fluorescence and 30% or less is phosphorescence, More preferably, 80% or more of the light-emitting component obtained from the light-emitting element is fluorescence, 20% or less is phosphorescence, and more preferably 90% or more is fluorescence, and 10% or less is phosphorescence. Fluorescence emission is mainly preferable in that the light emission response and durability are improved, and the efficiency reduction at high luminance (for example, 1000 cd / m ² or more) is small.

The phosphorescent maximum wavelength of the amplifying agent is preferably 380 nm or more and 650 nm or less, more preferably 400 nm or more and 630 nm or less, further preferably 410 nm or more and 620 nm or less, and particularly preferably 420 nm or more and 610 nm or less. preferable.
The phosphorescence emission spectrum of the amplifying agent preferably has the phosphorescence emission maximum wavelength, and is at least partially overlapped with the absorption spectrum of the fluorescent emission compound from the viewpoint of transfer of Forster-type excitation energy. More preferred.

As a condition for measuring the phosphorescence of the amplification agent, for example, a solution containing the amplification agent (for example, 1 × 10 ⁻⁵ mol / l toluene solution) is freeze-degassed, and the absorption maximum wavelength is photoexcited at 20 ° C. A technique for measuring the emission spectrum is mentioned.

  The phosphorescent lifetime of the amplifying agent is preferably 10 μs or less, more preferably 7 μs or less, and more preferably 5 μs or less from the viewpoint of reducing the number of singlet excitons, that is, preventing the conversion of excitation energy to thermal energy. Particularly preferred.

The phosphorescent quantum yield of the amplifying agent is preferably 20% or more, more preferably 40% or more, further preferably 50% or more, and particularly preferably 60% or more. The phosphorescent quantum yield of the amplifying agent can be measured at 20 ° C. after freeze-degassing a solution containing the amplifying agent (for example, 1 × 10 ⁻⁵ mol / l toluene solution).

  The emission maximum wavelength from the fluorescent compound is preferably 350 nm or more and 680 nm or less, more preferably 410 nm or more and 670 nm or less, further preferably 420 nm or more and 660 nm or less, and particularly preferably 430 nm or more and 650 nm or less. preferable.

  The light emitting device of the present invention preferably contains at least one host material in the light emitting layer. The host material may be contained in the layer containing the fluorescent compound in the light emitting layer, or may be contained in the layer containing the amplifying agent. It is preferably contained in both the layer containing the fluorescent compound and the layer containing the amplification agent.

The T ₁ level (energy level of the lowest excited triplet state) of the host material contained in the light-emitting element of the present invention is 209.2 KJ / mol or more (50 Kcal / mol or more), 377.1 KJ / mol or less ( 90 Kcal / mol or less), preferably 217.6 KJ / mol or more (52 Kcal / mol or more), 335.2 KJ / mol or less (80 Kcal / mol or less), more preferably 230.1 KJ / Mol or more (55 Kcal / mol or more), 293.3 KJ / mol or less (70 Kcal / mol or less).

In the light-emitting element of the present invention, the T ₁ level (energy level of the lowest excited triplet state) of a layer adjacent to the cathode side of the light-emitting layer (for example, an electron transport layer, a hole block layer, an exciton block layer) is 209. It is preferably 2 KJ / mol or more (50 Kcal / mol or more), 377.1 KJ / mol or less (90 Kcal / mol or less), 217.6 KJ / mol or more (52 Kcal / mol or more), 335.2 More preferably, it is KJ / mol or less (80 Kcal / mol or less), more preferably 230.1 KJ / mol or more (55 Kcal / mol or more), 293.3 KJ / mol or less (70 Kcal / mol or less). .

In the light-emitting element of the present invention, the layer adjacent to the light-emitting layer on the anode side (for example, a hole transport layer) has a T ₁ level (lowest excited triplet state energy level) of 209.2 KJ / mol or more (50 Kcal / mol). mol) or more, preferably 377.1 KJ / mol or less (90 Kcal / mol or less), 217.6 KJ / mol or more (52 Kcal / mol or more), 335.2 KJ / mol or less (80 Kcal / mol or less). ), More preferably 230.1 KJ / mol or more (55 Kcal / mol or more), 293.3 KJ / mol or less (70 Kcal / mol or less).

  The fluorescent compound used in the present invention is preferably a compound represented by the general formula (1), more preferably a compound represented by the general formula (2), and a compound represented by the following general formula (3). Is more preferable.

The general formula (1) will be described.
Ar ¹¹ represents an aryl group or a heteroaryl group, and an aryl group is preferred.
Examples of the aryl group include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a pyrenyl group, a perylenyl group, a triphenylenyl group, and the like, and a phenyl group, a naphthyl group, an anthryl group, and a pyrenyl group are preferable, and a pyrenyl group, a naphthyl group Is more preferable, and a phenyl group is more preferable.

  Examples of the heteroaryl group include pyridyl group, pyrazyl group, pyrimidyl group, triazyl group, imidazolyl group, pyrazolyl group, oxazolyl group, benzoimidazolyl group, benzooxazolyl group, oxadiazolyl group, and the like. Group, a benzoxazolyl group is preferable, a pyridyl group and a benzoimidazolyl group are more preferable, and a pyridyl group is more preferable.

R ¹¹ represents a substituent, and examples of the substituent include an alkyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms such as methyl, And ethyl, iso-propyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 30 carbon atoms, more preferably carbon 2 to 20, particularly preferably 2 to 10 carbon atoms such as vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), alkynyl group (preferably having 2 to 30 carbon atoms, more preferably carbon 2 to 20 and particularly preferably 2 to 10 carbon atoms, such as propargyl and 3-pentynyl). A reel group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenyl, p-methylphenyl, naphthyl, anthranyl, etc.), amino Group (preferably having 0 to 30 carbon atoms, more preferably 0 to 20 carbon atoms, particularly preferably 0 to 10 carbon atoms, such as amino, methylamino, dimethylamino, diethylamino, dibenzylamino, diphenylamino, ditolylamino, etc. An alkoxy group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms, such as methoxy, ethoxy, butoxy, 2-ethylhexyloxy, etc. An aryloxy group (preferably having 6 to 30 carbon atoms, more preferably carbon 6 to 20, particularly preferably 6 to 12 carbon atoms, such as phenyloxy, 1-naphthyloxy, 2-naphthyloxy, and the like, and heterocyclic oxy groups (preferably having 1 to 30 carbon atoms, more preferably Has 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include pyridyloxy, pyrazyloxy, pyrimidyloxy, quinolyloxy, and the like, and acyl groups (preferably having 1 to 30 carbon atoms, more preferably carbon numbers). 1 to 20, particularly preferably 1 to 12 carbon atoms, such as acetyl, benzoyl, formyl, pivaloyl, etc.), alkoxycarbonyl groups (preferably 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms). Particularly preferably having 2 to 12 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, etc. Is mentioned. ), An aryloxycarbonyl group (preferably having a carbon number of 7 to 30, more preferably a carbon number of 7 to 20, particularly preferably a carbon number of 7 to 12, such as phenyloxycarbonyl), an acyloxy group (preferably Has 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetoxy and benzoyloxy.), An acylamino group (preferably 2 to 30 carbon atoms, More preferably, it has 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetylamino, benzoylamino and the like, and an alkoxycarbonylamino group (preferably 2 to 30 carbon atoms, more preferably carbon atoms). 2 to 20, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino An aryloxycarbonylamino group (preferably having 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, and particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino). A sulfonylamino group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfonylamino and benzenesulfonylamino), a sulfamoyl group (Preferably having 0 to 30 carbon atoms, more preferably 0 to 20 carbon atoms, and particularly preferably 0 to 12 carbon atoms. Examples thereof include sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, and phenylsulfamoyl. ), A carbamoyl group (preferably having 1 to 30 carbon atoms, more preferably A prime number of 1-20, particularly preferably a carbon number of 1-12, such as carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl, etc., an alkylthio group (preferably having a carbon number of 1-30, more preferably a carbon number). 1 to 20, particularly preferably 1 to 12 carbon atoms, for example, methylthio, ethylthio, etc.), arylthio groups (preferably 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably carbon atoms). And a heterocyclic thio group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 12 carbon atoms). Pyridylthio, 2-benzimidazolylthio, 2-benzoxazolylthio, 2-benzthiazolylthio Etc. ), A sulfonyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms such as mesyl and tosyl), a sulfinyl group (preferably carbon). 1 to 30, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfinyl, benzenesulfinyl, etc.), ureido group (preferably 1 to 30 carbon atoms, more Preferably it is C1-C20, Most preferably, it is C1-C12, for example, ureido, methylureido, phenylureido etc. are mentioned), phosphoric acid amide group (preferably C1-C30, more preferably It has 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms. Examples thereof include diethyl phosphoric acid amide and phenyl phosphoric acid amide. Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group Group, heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom and a sulfur atom, specifically, for example, imidazolyl, pyridyl and quinolyl. , Furyl, thienyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, carbazolyl group, azepinyl group, etc.), silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms). Particularly preferably having 3 to 24 carbon atoms, such as trimethylsilyl, ), Silyloxy groups (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, and particularly preferably 3 to 24 carbon atoms, such as trimethylsilyloxy, triphenylsilyloxy, etc. And the like. These substituents may be further substituted.

At least one of R ¹¹ is a substituent that lowers the Dexter-type energy transfer efficiency from the amplifying agent to the fluorescent compound, a substituent that substantially covers the fluorescent compound host nucleus three-dimensionally, or fluorescent from an adjacent molecule. It is a substituent having a function of reducing the efficiency of electron transfer to the light emitting material.

R ¹¹ is preferably an alkyl group, an aryl group, a heterocyclic group, an alkoxy group, an aryloxy group, a heterocyclic oxy group, a silyl group, a siloxy group, or an amino group, and an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a silyl group Group, a siloxy group are more preferable, an alkyl group, an alkoxy group, and a silyloxy group are more preferable, and an alkyl group is particularly preferable.

R ¹¹ is preferably a group having a branched chain, more preferably a group having a tertiary and / or quaternary carbon atom, still more preferably a group having a quaternary carbon atom, particularly preferably an alkyl group having a quaternary carbon atom. preferable. Further, the substituent that lowers the Dexter-type energy transfer efficiency from the amplifying agent to the fluorescent light-emitting compound is preferably a group having 2 to 10 quaternary carbon atoms, and preferably has 2 to 10 quaternary carbon atoms. A group having from 10 to 10 is more preferred.

  The total carbon number of the substituent that lowers the Dexter-type energy transfer efficiency from the amplifying agent to the fluorescent compound is preferably 8 or more and 100 or less, more preferably 12 or more and 80 or less, further preferably 17 or more and 70 or less, and more preferably 20 or more and 60 The following are particularly preferred:

The number of substituents that reduce the Dexter-type energy transfer efficiency from the amplification agent to the fluorescent compound (the number of substituents substituted on the fluorescent compound parent) is preferably 3 or more and 20 or less, and preferably 4 or more and 15 or less. Is more preferably 5 or more and 10 or less.

n ¹¹ represents an integer of 1 or more. When n ¹¹ is 2 or more, the plurality of R ¹¹ may be the same or different. n ¹¹ is preferably 1 to 4, more preferably 1 to 3, more preferably 1,2.

  L represents a linking group or a single bond. You may have a substituent further on a coupling group. The linking group is not particularly limited, but is preferably an aryl linking group, a heteroaryl linking group, an alkyl linking group, an amino linking group, or a silicon linking group, more preferably an aryl linking group or a heteroaryl linking group, and an aryl linking group further. A condensed aryl linking group having three or more rings (anthracene linking group, tetracene linking group, pentacene linking group, phenanthrene linking group, pyrene linking group, perylene linking group, etc.) is particularly preferable.

m ¹¹ represents an integer of 2 or more. m ¹¹ is preferably 2 to 10, more preferably 3 to 8, and still more preferably 4 to 6.

The general formula (2) will be described.
Ar ²¹ has the same meaning as Ar ¹¹ , and the preferred range is also the same.

Ar ²² represents an aryl linking group or a heteroaryl linking group, preferably an aryl linking group, and three or more condensed ring aryl linking groups (anthracene linking group, tetracene linking group, pentacene linking group, phenanthrene linking group, pyrene linking group). Group, perylene linking group, etc.) are particularly preferred.

R ²¹ and R ²² each represent a substituent. Examples and preferred ranges of the substituents represented by R ²¹ and R ²² are the same as R ¹¹ described above.

n ²¹ has the same meaning as n ¹¹ , and the preferred range is also the same. n ²² represents an integer of 0 or more, preferably 0-10, more preferably 0-8, 2-6 is more preferable. When n ²² is 2 or more, the plurality of R ²² may be the same or different. m ²¹ has the same meaning as m ¹¹ , and the preferred range is also the same.

The general formula (3) will be described.
R ^{31 to} R ³⁶ each represent a substituent. Examples of the substituent include the substituents mentioned in the above R ¹¹ , and preferred ranges are also the same.

n ³¹ and n ³⁴ each represent an integer of 0 to 4, preferably 1 or 2, and more preferably 1.

n ³² , n ³³ , n ³⁵ , and n ³⁶ each represent an integer of 0 to 5, preferably 1, 2, 3, more preferably 1, 2, and even more preferably 1.

The concentration of the fluorescent light emitting compound in the light emitting layer is preferably 0.1% by mass or more and 20% by mass or less, and preferably 0.2% by mass or more and 15% by mass with respect to the total mass of the light emitting layer, from the viewpoint of light emission efficiency. % Or less, more preferably 0.5% by mass or more and 10% by mass or less.
The light emitting device of the present invention may contain a fluorescent compound in the light emitting layer alone or in combination of two or more. Two types of light may be emitted in different colors, for example, white light may be emitted.

  The amplifying agent used in the present invention is a compound having a function of amplifying the number of singlet excitons generated when a voltage is applied and amplifying the emission intensity of the compound that emits fluorescence when a voltage is applied. The amplifying agent is not particularly limited as long as it is a compound that amplifies the number of singlet excitons generated when a voltage is applied. For example, triplet excitons generated in a light-emitting element can be converted into a single compound or host material that emits fluorescence. Examples thereof include compounds having a function of transferring energy to term excitons. Examples of compounds that satisfy these functions include compounds that emit phosphorescence at 0 to 50 ° C., such as transition metal complexes and rare earth elements.

  As the amplifying agent, an iridium complex, a platinum complex, a rhenium complex, a ruthenium complex, a palladium complex, a rhodium complex, a copper complex, or a rare earth complex, which is a transition metal complex, is more preferable, and an iridium complex or a platinum complex is more preferable.

  Examples of the transition metal complex in the present invention include, for example, JP 2001-181617 A, JP 2001-247859 A, JP 2001-345183 A, JP 2002-1117078 A, and JP 2002-170684 A. JP, 2002-173684, JP, 2002-235076, JP, 2002-241751, JP, 2002-302671, JP, 2003-123982, JP, 2003-133074, etc. Can be used.

  The light emitting device of the present invention preferably has an electron transport layer, and the electron transport layer is preferably a non-complex compound. Although it does not specifically limit as a non-complex compound, A nitrogen-containing heterocyclic compound is preferable.

  The nitrogen-containing heterocyclic compound is not particularly limited, but a 6-membered aromatic nitrogen-containing heterocyclic compound or a 5-membered aromatic nitrogen-containing heterocyclic compound is preferable, and pyridine, pyrazine, pyrimidine, triazine, quinoxaline, quinoline. , Pyrrole, pyrazole, imidazole, oxazole, thiazole, oxadiazole, thiadiazole, and derivatives thereof (for example, tetraphenylpyridine, benzimidazole, imidazopyridine, etc.) are more preferable, and imidazole derivatives and imidazopyridine derivatives are more preferable, Particularly preferred are imidazopyridine derivatives.

The external quantum efficiency of the light-emitting device of the present invention is preferably 5% or more, more preferably 10% or more, and even more preferably 13% or more from the viewpoint of reducing power consumption and driving durability. The value of the external quantum efficiency should be the maximum value of the external quantum efficiency when the device is driven at 20 ° C. or the value of the external quantum efficiency near 100 to 300 cd / m ² when the device is driven at 20 ° C. Can do.

The internal quantum efficiency of the light emitting device of the present invention is preferably 30% or more, more preferably 50% or more, and further preferably 70% or more in terms of power consumption and durability. The internal quantum efficiency of the light emitting element is calculated by “internal quantum efficiency = external quantum efficiency / light extraction efficiency”. In a normal organic EL element, the light extraction efficiency is about 20%. However, the shape of the substrate, the shape of the electrode, the thickness of the organic layer, the thickness of the inorganic layer, the refractive index of the organic layer, the refractive index of the inorganic layer, etc. By devising it, it is possible to increase the light extraction efficiency to 20% or more. The value of the light extraction efficiency can be calculated by 1 / 2n ² where n is the refractive index of the light emitting layer.

  The concentration of the amplification agent in the film is not particularly limited, but is preferably 0.1% or more and 9% or less, more preferably 1% or more and 8% or less, further preferably 2% or more and 7% or less, and 3% or more and 6% or less. Is particularly preferred. It is preferable that the concentration is within these values in that the efficiency and durability of the light emitting element can be improved.

The fluorescence quantum yield of the fluorescent compound in the present invention is preferably 70% or more, more preferably 80% or more, further preferably 90% or more, and particularly preferably 95% or more. preferable. Here, the fluorescence quantum yield is represented by “fluorescence quantum yield (%) = (number of photons of fluorescence / number of absorbed photons) × 100”. As the fluorescence quantum yield, a value measured at 20 ° C. in a solid film or in a solution can be used. For example, the fluorescence quantum yield can be measured by comparing the emission intensity with a substance having a known value (fluorescein, anthracene, rhodamine, etc.).
The fluorescence quantum yield in the present invention is a value measured from the results of measurement of the absorption spectrum and emission spectrum of the fluorescent compound in the solution state.

  The light-emitting element of the present invention is preferably an element having at least three layers of a hole transport layer, a light-emitting layer, and an electron transport layer, and a hole block layer or an exciton block layer is provided between the light-emitting layer and the electron transport layer. An element that does not have is more preferable. Moreover, it is preferable that there is only one electron transport layer between the light emitting layer and the electrode.

  The hole blocking layer has a function of blocking holes injected from the anode, and the exciton blocking layer has a function of blocking excitons generated in the light emitting layer and limiting a light emitting region. Is.

  The ionization potential of the host material contained in the light emitting layer in the present invention is preferably 5.8 eV or more and 6.3 eV or less in terms of driving voltage and efficiency, and is 5.95 eV or more and 6.25 eV or less. Is more preferably 6.0 eV or more and 6.2 eV or less.

The electron mobility of the host material contained in the light emitting layer in the light emitting device of the present invention is 1 × 10 ⁻⁶ cm ² / Vs or more and 1 × 10 ⁻¹ cm ² / Vs or less in terms of driving voltage and efficiency. It is preferably 5 × 10 ⁻⁶ cm ² / Vs to 1 × 10 ⁻² cm ² / Vs, more preferably 1 × 10 ⁻⁵ cm ² / Vs to 1 × 10 ⁻² cm ² / V. More preferably, it is Vs or less, and particularly preferably 5 × 10 ⁻⁵ cm ² / Vs or more and 1 × 10 ⁻² cm ² / Vs or less.

The hole mobility of the host material contained in the light emitting layer in the light emitting element of the present invention is 1 × 10 ⁻⁶ cm ² / Vs or more and 1 × 10 ⁻¹ cm ² / Vs or less in terms of driving voltage and efficiency. It is preferably 5 × 10 ⁻⁶ cm ² / Vs to 1 × 10 ⁻² cm ² / Vs, more preferably 1 × 10 ⁻⁵ cm ² / Vs to 1 × 10 ⁻² cm ² / Vs. It is more preferably Vs or less, and particularly preferably 5 × 10 ⁻⁵ cm ² / Vs or more and 1 × 10 ⁻² cm ² / Vs or less.

  The glass transition point of the host material, the electron transport layer, and the hole transport material contained in the light emitting layer in the present invention is preferably 90 ° C. or higher and 400 ° C. or lower, and 100 ° C. or higher and 380 ° C. or lower in terms of heat resistance. It is more preferable that it is 120 degreeC or more and 370 degrees C or less, and it is especially preferable that it is 140 degreeC or more and 360 degrees C or less.

  The light-emitting element of the present invention has at least a hole transport layer, a light-emitting layer, and an electron transport layer, and the light-emitting layer includes a layer having at least one compound that emits fluorescence when a voltage is applied, and a layer having at least one amplifying agent. It is preferable to have at least one alternate laminated structure, the light emitting layer is preferably composed of 4 or more layers, and the light emitting layer is more preferably composed of 12 or more layers. More preferably, the light emitting layer is composed of an alternating laminated structure of 16 layers or more.

  In the light emitting device having the alternate laminated film of the present invention, it is preferable to produce the alternate laminated film in a process including the following procedures (a) to (c). (A) Depositing a fluorescent compound or a mixture thereof. At that time, the vapor deposition of the amplification agent or a mixture thereof is blocked with a shutter installed in the vicinity of the vapor deposition source to suppress the vapor deposition of the amplification agent or the mixture thereof on the light emitting element being manufactured. (B) Amplifying agent or a mixture thereof is deposited. At that time, the vapor deposition of the fluorescent light emitting compound or a mixture thereof is blocked with a shutter installed in the vicinity of the vapor deposition source to suppress the vapor deposition of the fluorescent light emitting compound or the mixture thereof onto the light emitting element being manufactured. (C) The steps (a) and (b) are repeated. Each process is switched by opening and closing a shutter installed near the evaporation source. For example, the process described in Example 1 corresponds to this.

  Moreover, in the light emitting element which has an alternating laminated film of this invention, it is preferable to produce an alternating laminated film at the process including the procedure of following (a)-(c). (A) Amplifying agent or a mixture thereof is deposited. At that time, the vapor deposition source of the fluorescent light emitting compound or a mixture thereof is closed with a shutter installed in the vicinity of the vapor deposition source to suppress the vapor deposition of the fluorescent light emitting compound or the mixture thereof on the light emitting element being manufactured. (B) Depositing a fluorescent compound or a mixture thereof. At that time, vapor deposition of the amplification agent or a mixture thereof is blocked with a shutter installed in the vicinity of the vapor deposition source, and the amplification agent or the mixture thereof is prevented from being deposited on the light emitting element being manufactured. (C) The steps (a) and (b) are repeated. Each process is switched by opening and closing a shutter installed near the evaporation source.

  In the light emitting layer in the present invention, the plurality of layers in the laminated structure can emit light in different emission colors, and can emit white light.

  The compound (fluorescent light emitting compound or amplifying agent) in the present invention may be a low molecular compound, and an oligomer compound or a polymer compound (weight average molecular weight (polystyrene conversion) is preferably 1000 to 5000000, more preferably 2000. ˜1000000, more preferably 3000 to 100,000. The compound in the present invention is preferably a low molecular compound.

  Next, although the compound example in this invention is shown, this invention is not limited to this.

Next, the light emitting device containing the compound in the present invention will be described.
The light emitting device of the present invention is not particularly limited in terms of system, driving method, usage pattern, and the like. An organic EL (electroluminescence) element can be mentioned as a typical light emitting element.

  The light-emitting element of the present invention can improve the light extraction efficiency by various known devices. For example, by processing the substrate surface shape (for example, forming a fine concavo-convex pattern), controlling the refractive index of the substrate / ITO layer / organic layer, controlling the film thickness of the substrate / ITO layer / organic layer, etc. It is possible to improve light extraction efficiency and external quantum efficiency.

The light-emitting element of the present invention takes out light emission from the anode side, a so-called top emission method (Japanese Patent Laid-Open Nos. 2003-208109, 2003-248441, 2003-208109, and 2003-257651). Japanese Patent Laid-Open No. 2003-208109, Japanese Patent Laid-Open No. 2003-282261, Japanese Patent Laid-Open No. 2003-208109, etc.).

  The substrate used in the light-emitting device of the present invention is not particularly limited, but inorganic materials such as zirconia-stabilized yttrium and glass, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyethylene, polycarbonate, and polyethersulfone. High molecular weight materials such as polyarylate, allyl diglycol carbonate, polyimide, polycycloolefin, norbornene resin, poly (chlorotrifluoroethylene), Teflon (registered trademark), polytetrafluoroethylene-polyethylene copolymer good.

  The organic electroluminescent device of the present invention may contain a blue fluorescent light-emitting compound, or a blue light-emitting device containing a blue fluorescent light-emitting compound and the light-emitting device of the present invention can be used simultaneously to produce a multicolor light-emitting device or a full-color light-emitting device. A light emitting device may be manufactured.

  The light emitting layer of the organic electroluminescent element of the present invention may have at least one laminated structure. The number of stacked layers is preferably 2 or more and 50 or less, more preferably 4 or more and 30 or less, and still more preferably 6 or more and 20 or less.

  The thickness of each layer constituting the stacked structure is not particularly limited, but is preferably 0.2 nm or more and 20 nm or less, more preferably 0.4 nm or more and 15 nm or less, further preferably 0.5 nm or more and 10 nm or less, and more preferably 1 nm or more and 5 nm. The following are particularly preferred:

The light emitting layer of the organic electroluminescent element of the present invention may have a plurality of domain structures. The light emitting layer may have another domain structure. For example, the light emitting layer, and a region of approximately 1 nm ³ of a mixture of a host material A and a fluorescent material B, may be configured in the region of about 1 nm ³ of a mixture of a host material C and a fluorescent material D. The diameter of each domain is preferably from 0.2 nm to 10 nm, more preferably from 0.3 nm to 5 nm, still more preferably from 0.5 nm to 3 nm, and particularly preferably from 0.7 nm to 2 nm.

  The method for forming the organic compound layer of the light-emitting element containing the compound in the present invention is not particularly limited, but resistance heating vapor deposition, electron beam, sputtering, molecular lamination method, coating method (spray coating method, dip coating method) , Impregnation method, roll coat method, gravure coat method, reverse coat method, roll brush method, air knife coat method, curtain coat method, spin coat method, flow coat method, bar coat method, micro gravure coat method, air doctor coat, Blade coating method, squeeze coating method, transfer roll coating method, kiss coating method, cast coating method, extrusion coating method, wire bar coating method, screen coating method, etc.), inkjet method, printing method, LB method, transfer method, etc. In terms of characteristics and manufacturing Anti heating deposition, a coating method, a transfer method is preferable.

  The light-emitting device of the present invention is a device in which a light-emitting layer or a plurality of organic compound films including a light-emitting layer is formed between a pair of anode and cathode electrodes. In addition to the light-emitting layer, a hole injection layer, a hole transport layer, and an electron injection It may have a layer, an electron transport layer, a protective layer, etc., and each of these layers may have other functions. Various materials can be used for forming each layer.

  The anode in the present invention supplies holes to a hole injection layer, a hole transport layer, a light emitting layer, and the like, and a metal, an alloy, a metal oxide, an electrically conductive compound, or a mixture thereof can be used. Preferably, the material has a work function of 4 eV or more. Specific examples include conductive metal oxides such as tin oxide, zinc oxide, indium oxide and indium tin oxide (ITO), metals such as gold, silver, chromium and nickel, and these metals and conductive metal oxides. Inorganic conductive materials such as copper iodide and copper sulfide, organic conductive materials such as polyaniline, polythiophene, and polypyrrole, and laminates of these with ITO, preferably conductive metals It is an oxide, and ITO is particularly preferable from the viewpoint of productivity, high conductivity, transparency, and the like. The film thickness of the anode can be appropriately selected depending on the material, but from the viewpoint of driving voltage, a film thickness in the range of usually 10 nm to 5 μm is preferable, more preferably 50 nm to 1 μm, and still more preferably 100 nm to 500 nm.

As the anode, a layer formed on a soda-lime glass, non-alkali glass, a transparent resin substrate or the like is usually used. When glass is used, it is preferable to use non-alkali glass as the material in order to reduce ions eluted from the glass. Moreover, when using soda-lime glass, it is preferable to use what gave barrier coatings, such as a silica. The thickness of the substrate is not particularly limited as long as it is sufficient to maintain the mechanical strength, but when glass is used, a thickness of 0.2 mm or more, preferably 0.7 mm or more is usually used.
Various methods are used for producing the anode depending on the material. For example, in the case of ITO, an electron beam method, a sputtering method, a resistance heating vapor deposition method, a chemical reaction method (sol-gel method, etc.), a coating of a dispersion of indium tin oxide, etc. A film is formed by this method.
The anode can be subjected to cleaning or other processing to lower the driving voltage of the light emitting element or to increase the light emission efficiency. For example, in the case of ITO, UV-ozone treatment, plasma treatment, etc. are effective.

The cathode supplies electrons to the electron injection layer, the electron transport layer, the light emitting layer, etc., and the adhesion, ionization potential, stability, etc., between the negative electrode and the adjacent layer such as the electron injection layer, electron transport layer, light emitting layer, etc. In consideration of the material, the material is selected.
As a material for the cathode, a metal, an alloy, a metal halide, a metal oxide, an electrically conductive compound, or a mixture thereof can be used. Specific examples include an alkali metal (for example, Li, Na, K, etc.) and its fluoride. Or oxides, alkaline earth metals (eg Mg, Ca, etc.) and fluorides or oxides thereof, gold, silver, lead, aluminum, sodium-potassium alloys or their mixed metals, lithium-aluminum alloys or their mixtures Examples thereof include metals, magnesium-silver alloys or mixed metals thereof, rare earth metals such as indium and ytterbium, preferably materials having a work function of 4 eV or less, more preferably aluminum, lithium-aluminum alloys or mixed metals thereof. , Magnesium-silver alloys or mixed metals thereof. The cathode can take not only a single layer structure of the compound and the mixture but also a laminated structure including the compound and the mixture. For example, a laminated structure of aluminum / lithium fluoride and aluminum / lithium oxide is preferable. The film thickness of the cathode can be appropriately selected depending on the material, but is usually preferably in the range of 10 nm to 5 μm, more preferably 50 nm to 1 μm, still more preferably 100 nm to 1 μm.
For production of the cathode, methods such as an electron beam method, a sputtering method, a resistance heating vapor deposition method, a coating method, and a transfer method are used, and a metal can be vapor-deposited alone or two or more components can be vapor-deposited simultaneously. Furthermore, a plurality of metals can be vapor-deposited simultaneously to form an alloy electrode, or a previously prepared alloy may be vapor-deposited.
The sheet resistance of the anode and the cathode is preferably low, and is preferably several hundred Ω / □ or less.

The material of the light emitting layer is a function that can inject holes from the anode or hole injection layer, hole transport layer and cathode or electron injection layer, electron transport layer when an electric field is applied, Any compound can be used as long as it can form a layer having a function of transferring injected charges and a function of emitting light by providing a recombination field of holes and electrons. Oxazole, benzimidazole, benzothiazole, styrylbenzene, polyphenyl, diphenylbutadiene, tetraphenylbutadiene, naphthalimide, coumarin, perylene, perinone, oxadiazole, aldazine, pyralidine, cyclopentadiene, bisstyrylanthracene, quinacridone, pyrrolopyridine, Thiadiazolopyridine, cyclope Tadiene, styrylamine, aromatic dimethylidin compounds, various metal complexes represented by 8-quinolinol metal complexes and rare earth complexes, polymer compounds such as polythiophene, polyphenylene, polyphenylene vinylene, organic silanes, iridium trisphenylpyridine complexes, and platinum Examples include transition metal complexes represented by porphyrin complexes and derivatives thereof. Although the film thickness of a light emitting layer is not specifically limited, Usually, the thing of the range of 1 nm-5 micrometers is preferable, More preferably, it is 5 nm-1 micrometer, More preferably, it is 10 nm-500 nm.
The method for forming the light emitting layer is not particularly limited, but the same method as the method for forming the organic compound layer described above, resistance heating vapor deposition, electron beam, sputtering, molecular lamination method, coating method, ink jet method, printing method , LB method, transfer method and the like are used, preferably resistance heating vapor deposition and coating method.

The light emitting layer may be formed of a single compound or a plurality of compounds. Further, the light emitting layer may be one or plural, and each layer may emit light with different emission colors, for example, white light may be emitted. White light may be emitted from a single light emitting layer. When there are a plurality of light emitting layers, each light emitting layer may be formed of a single compound (material), or may be formed of a plurality of compounds (materials).

The material of the hole injection layer and the hole transport layer may be any one having a function of injecting holes from the anode, a function of transporting holes, or a function of blocking electrons injected from the cathode. Good.
Specific examples include carbazole, triazole, oxazole, oxadiazole, imidazole, polyarylalkane, pyrazoline, pyrazolone, phenylenediamine, arylamine, amino-substituted chalcone, styrylanthracene, fluorenone, hydrazone, stilbene, silazane, aromatic group Tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, porphyrin compounds, polysilane compounds, poly (N-vinylcarbazole), aniline copolymers, thiophene oligomers, conductive polymer oligomers such as polythiophene, organic Examples thereof include silane, carbon film, compounds in the present invention, and derivatives thereof.

  The film thicknesses of the hole injection layer and the hole transport layer are not particularly limited, but are usually preferably in the range of 1 nm to 5 μm, more preferably 5 nm to 1 μm, and still more preferably 10 nm to 500 nm. .

  The hole injection layer and the hole transport layer may have a single-layer structure composed of one or more of the materials described above, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

As a method for forming the hole injection layer and the hole transport layer, a vacuum deposition method, an LB method, a method in which the hole injection transport material is dissolved or dispersed in a solvent, a coating method, an ink jet method, a printing method, or a transfer method is used. It is done.
In the case of the coating method, it can be dissolved or dispersed together with the resin component. Examples of the resin component include polyvinyl chloride, polycarbonate, polystyrene, polymethyl methacrylate, polybutyl methacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, and poly (N -Vinyl carbazole), hydrocarbon resin, ketone resin, phenoxy resin, polyamide, ethyl cellulose, vinyl acetate, ABS resin, polyurethane, melamine resin, unsaturated polyester resin, alkyd resin, epoxy resin, silicone resin, and the like.

The material for the electron injection layer and the electron transport layer may be any material having any one of a function of injecting electrons from the cathode, a function of transporting electrons, and a function of blocking holes injected from the anode.
Specific examples include fragrances such as triazole, oxazole, oxadiazole, imidazole, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyrandioxide, carbodiimide, fluorenylidenemethane, distyrylpyrazine, naphthalene, and perylene. Various metal complexes represented by metal complexes of cyclic tetracarboxylic anhydride, phthalocyanine, 8-quinolinol, metal phthalocyanine, benzoxazole and benzothiazole as ligands, organic silanes, and derivatives thereof Can be mentioned.

Although the film thickness of an electron injection layer and an electron carrying layer is not specifically limited, The thing of the range of 1 nm-5 micrometers is preferable normally, More preferably, it is 5 nm-1 micrometer, More preferably, it is 10 nm-500 nm.

  The electron injection layer and the electron transport layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

As a method for forming the electron injection layer and the electron transport layer, a vacuum vapor deposition method, an LB method, a method in which the electron injection transport material is dissolved or dispersed in a solvent, a coating method, an ink jet method, a printing method, a transfer method, and the like are used.
In the case of the coating method, it can be dissolved or dispersed together with the resin component. As the resin component, for example, those exemplified in the case of the hole injection transport layer can be applied.

The protective layer in the present invention can be formed, for example, on a light emitting element, and the protective layer material has a function of preventing substances that promote deterioration of the light emitting element such as moisture and oxygen from entering the light emitting element. Anything can be used.
Specific examples thereof include metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti, and Ni, MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, and Fe ₂ O. ₃ , metal oxides such as Y ₂ O ₃ and TiO ₂ , metal fluorides such as MgF ₂ , LiF, AlF ₃ , and CaF ₂ , SiN _x , SiO _x N _y Such as nitride, polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, tetrafluoroethylene And a copolymer obtained by copolymerizing a monomer mixture containing at least one comonomer, a fluorine-containing copolymer having a cyclic structure in the copolymer main chain, a water-absorbing substance having a water absorption of 1% or more, a water absorption of 0 .1% or less of moisture-proof substances and the like.
There is no particular limitation on the method for forming the protective layer. For example, vacuum deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency excitation ions) Plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, printing method, and transfer method can be applied.

  The use of the light emitting device of the present invention is not particularly limited, but is suitable for the fields of display device, display, backlight, electrophotography, illumination light source, recording light source, exposure light source, reading light source, sign, signboard, interior, optical communication, etc. Can be used.

  Specific examples of the present invention will be described below, but the embodiments of the present invention are not limited thereto.

(Comparative Example 1) (Element described in Patent Document 2)
The cleaned ITO substrate was put into a vapor deposition apparatus, and TPD (N, N′-diphenyl-N, N′-di (m-tolyl) -benzidine) was vapor-deposited to 60 nm. On top of this, CBP and DCM2 were deposited 1 nm in a 99: 1 ratio (mass ratio), and CBP and Ir (ppy) ₃ were deposited 1 nm in a 90 to 10 ratio, and this process was repeated five times. A total of 10 layers of alternately laminated films having a total thickness of 10 nm were formed. On top of this, BCP was deposited by 20 nm, and Alq was deposited thereon by 30 nm. A patterned mask (a mask having a light emission area of 4 mm × 5 mm) was placed on the organic thin film, and magnesium and silver were deposited in a vapor deposition apparatus at a ratio of 25: 1 to 100 nm, and then silver was deposited to 50 nm. Using a source measure unit 2400 type manufactured by Toyo Technica, applying a DC constant voltage to the EL element to emit light, red light emission was obtained.

  The structures of the compounds used in Comparative Examples and Examples are shown below.

(Example 1)
In place of DCM2 of the light emitting device described in Comparative Example 1, the compound (1-1) in the present invention was used and the device was evaluated in the same manner as in Comparative Example 1. As a result, yellow light emission was obtained, and the device durability at 100 cd / m ² drive was about 8 times that of the device of Comparative Example 1.

(Example 2)
In place of DCM2 of the light emitting device described in Comparative Example 1, the compound (1-17) in the present invention was used, and the device was evaluated in the same manner as in Comparative Example 1. As a result, red light emission was obtained, and the element durability at 100 cd / m ² drive was about 5 times that of the element of Comparative Example 1.

(Example 3)
The compound (1-17) in the present invention was used in place of DCM2 of the light emitting device described in Comparative Example 1, and Compound A was deposited by 50 nm instead of the laminated structure of BCP and Alq. evaluated.
As a result, red light emission was obtained, and the element durability at 100 cd / m ² drive was about 5 times that of the element of Comparative Example 1.

Example 4
Instead of TPD (60 nm) of the light emitting element described in Example 1, 10 nm of copper phthalocyanine and 50 nm of α-NPD (N, N′-diphenyl-N, N′-di (α-naphthyl) -benzidine) were vapor-deposited. The device fabrication was evaluated in the same manner as in Example 1. As a result, yellow light emission was obtained, and the device durability at 100 cd / m ² drive was about 20 times that of the device of Comparative Example 1.

  Similar effects can be obtained with other elements using the fluorescent compound in the present invention.

Claims (9)

An organic electroluminescent device having at least one organic compound layer including a light emitting layer between a pair of electrodes, containing a fluorescent light emitting compound that emits fluorescence when a voltage is applied, and the light emission upon application of the voltage is mainly the fluorescent light emitting compound A compound having a function of amplifying the number of singlet excitons generated when a voltage is applied and amplifying the emission intensity when the voltage is applied (hereinafter referred to as “amplifying agent”), and An organic electroluminescence device, wherein the fluorescent light-emitting compound has a substituent that decreases the Dexter-type energy transfer efficiency from the triplet exciton of the amplifying agent to the triplet exciton of the fluorescent light-emitting compound. An organic electroluminescent device having at least one organic compound layer including a light emitting layer between a pair of electrodes, containing a fluorescent light emitting compound that emits fluorescence when a voltage is applied, and the light emission upon application of the voltage is mainly the fluorescent light emitting compound A compound having a function of amplifying the number of singlet excitons generated when a voltage is applied and amplifying the emission intensity when the voltage is applied (hereinafter referred to as “amplifying agent”), and An organic electroluminescent element characterized in that the fluorescent light emitting compound mother nucleus is substantially three-dimensionally covered with a substituent. An organic electroluminescent device having at least one organic compound layer including a light emitting layer between a pair of electrodes, containing a fluorescent light emitting compound that emits fluorescence when a voltage is applied, and the light emission upon application of the voltage is mainly the fluorescent light emitting compound A compound having a function of amplifying the number of singlet excitons generated when a voltage is applied and amplifying the emission intensity when the voltage is applied (hereinafter referred to as “amplifying agent”), and The organic electroluminescent device, wherein the fluorescent light-emitting compound has a substituent that reduces electron transfer efficiency from an adjacent molecule to the fluorescent light-emitting compound. The substituent that decreases the Dexter-type energy transfer efficiency is selected from the group consisting of an alkyl group, an aryl group, a heterocyclic group, an alkoxy group, an aryloxy group, a heterocyclic oxy group, a silyl group, a siloxy group, and an amino group The organic electroluminescence device according to claim 1, wherein the organic electroluminescence device is the above substituent. 5. The organic electroluminescent element according to claim 1, wherein the concentration of the fluorescent light emitting compound in the light emitting layer is 0.1% or more and 10% or less. The organic electroluminescent element according to claim 1, wherein the fluorescent quantum yield of the fluorescent light-emitting compound in the light-emitting layer is 70% or more. The organic electroluminescent element according to claim 1, wherein an emission spectrum of the amplifying agent and an absorption spectrum of the fluorescent light-emitting compound overlap at least partially. The organic electroluminescent element according to claim 1, wherein the phosphorescent quantum yield of the amplifying agent is 20% or more. The organic electroluminescent element according to claim 1, wherein the amplification agent has a phosphorescence lifetime of 10 μs or less.