JP5497284B2 - White organic electroluminescence device - Google Patents

Description

    The present invention relates to a white organic electroluminescent element (hereinafter sometimes referred to as a white organic EL element) that can be effectively used for a surface light source such as a full color display, a backlight, and an illumination light source, and a light source array such as a printer.

  Today, research and development on various display elements are active. In particular, organic EL elements are attracting attention as promising display elements because they can emit light with high luminance at a low voltage.

  The organic EL element is composed of a light emitting layer or a plurality of organic layers including a light emitting layer and a counter electrode sandwiching the organic layer. In the organic EL element, electrons injected from the cathode and holes injected from the anode are recombined in the organic layer, emitted light from the generated excitons, and other molecules generated by energy transfer from the excitons. It is an element for obtaining light emission using at least one of light emission from the excitons.

  The light emitting layer of the organic EL element generally contains a light emitting material and a host material. As the light emitting material, fluorescent light emitting materials and phosphorescent light emitting materials are known. In particular, phosphorescent light-emitting materials are expected to have a higher quantum yield than fluorescent light-emitting materials, and thus search continues. For example, a tetradentate or higher multidentate platinum complex has been disclosed as a light emitting material having high luminous efficiency and excellent driving durability (for example, see Patent Document 1).

  Many organic compounds are known as host materials. For example, those having a carbazole skeleton, those having a diarylamine skeleton, those having a pyridine skeleton, those having a pyrazine skeleton, those having a triazine skeleton, and those having an arylsilane skeleton are known. Alternatively, an indole compound having a specific structure is disclosed as being excellent in durability and luminous efficiency (for example, see Patent Document 2).

On the other hand, the organic EL element is also characterized in that light emission of various emission colors is possible by mixing colors combining a plurality of emission colors.
Among the luminescent colors, the need for white light emission is particularly high. White light emission can be used as power saving in general lighting, an in-vehicle display, or a backlight. Furthermore, it can be divided into blue, green, and red pixels using a color filter, and a full-color display device is also possible.

  However, it has been pointed out that light emitting materials having different exciton energies may cause problems such as quenching or emission color change due to energy transfer due to interaction. Means for isolating the light emitting materials from each other have been proposed so that each light emitting material emits a predetermined light without mutual interaction.

For example, it has been proposed that two layers of a blue light emitting layer that emits short wavelength light and a red light emitting layer that emits long wavelength light are stacked to obtain white light emission as a mixed color of both light emitting layers ( For example, see Patent Document 3).
However, in the case of stacking two light emitting layers with different color development (different peak wavelengths), the balance of carrier transportability changes as the driving time of the element, that is, the light emission time or the applied voltage changes. For example, there is a problem that chromaticity change (color shift) and luminance decrease occur. Therefore, it was a big subject to improve durability and voltage dependency in the white light emitting organic EL element.
JP 2007-73620 A WO2008 / 066196 JP-A-7-142169

  An object of the present invention is to provide a white organic EL device having excellent durability.

The above object of the present invention is achieved by the following means.
<1> A white organic electroluminescent device having a pair of electrodes and at least one organic layer including a light emitting layer between the electrodes on a substrate, wherein the light emitting layer includes at least an aggregate light emitting material and a monomer light emitting material. And a host material, wherein a peak wavelength of light emission from the aggregate light-emitting material is longer than a peak wavelength of light emission from the monomer light-emitting material.
<2> The white organic electroluminescent element according to <1>, wherein the host material is an indole compound represented by the following general formula (1):

(In general formula (1), R ^{101 to} R ¹⁰⁵ represent a hydrogen atom or a substituent. R ¹⁰⁶ represents a secondary or tertiary alkyl group. R ¹⁰¹ and R ¹⁰⁶ are bonded to each other to form a ring. L ¹⁰¹ represents a linking group, and n ¹⁰¹ represents an integer of 2 or more.
<3> The white organic electroluminescent element as described in <1> or <2>, wherein the monomer luminescent material is a blue phosphorescent material having an emission peak wavelength of 420 nm or more and less than 500 nm.
<4> The white organic electroluminescent element according to any one of <1> to <3>, wherein the aggregate light emitting material is an aggregate of the monomer light emitting material.
<5> The white organic electroluminescent element according to <4>, wherein the monomer light-emitting material is a metal complex.
<6> The white organic electroluminescent element as described in <5>, wherein the metal complex is a tetradentate platinum complex.
<7> The light emitting layer further includes at least one of a green phosphorescent material having an emission peak wavelength of 500 nm or more and less than 570 nm and a red phosphorescent material having an emission peak wavelength of 570 nm or more and 650 nm or less < The white organic electroluminescent element according to any one of 1> to <6>.
<8> The first light-emitting layer in which the light-emitting layer includes the aggregate light-emitting material, the monomer light-emitting material, and the host material, the green phosphorescent light-emitting material having an emission peak wavelength of 500 nm or more and less than 570 nm, and the emission peak The white organic electroluminescent element according to <7>, further comprising a second light emitting layer containing at least one of red phosphorescent materials having a wavelength of 570 nm or more and 650 nm or less.
<9> The second light-emitting layer includes a green phosphorescent material having an emission peak wavelength of 500 nm to less than 570 nm and a red phosphorescent material having an emission peak wavelength of 570 nm to 650 nm < The white organic electroluminescent element according to 8>.
<10> The second light-emitting layer includes the first light-emitting layer including the aggregate light-emitting material, the monomer light-emitting material, and the host material, and the second phosphorescent light-emitting material including the green phosphorescent light-emitting material having an emission peak wavelength of 500 nm to less than 570 nm. The white organic electroluminescent element according to <7>, further comprising: a light emitting layer; and a third light emitting layer containing a red phosphorescent material having an emission peak wavelength of 570 nm to 650 nm.
<11> The white organic material according to any one of <1> to <10>, wherein a concentration of the light emitting material including the aggregate light emitting material and the monomer light emitting material of the light emitting layer is 25% by mass to 40% by mass. Electroluminescent device.
<12> The white organic electroluminescent element according to any one of <2> to <11>, wherein the indole compound is a compound represented by the general formula (2):

(In General Formula (2), R ^{201 to} R ²⁰⁵ represent a hydrogen atom or a substituent. R ²⁰⁶ represents a secondary or tertiary alkyl group. R ²⁰¹ and R ²⁰⁶ are bonded to each other to form a ring. R ²⁰⁷ represents a substituent, n ²⁰¹ represents an integer of 2 to 6, and n ²⁰² represents an integer of 0 to 4, provided that n ²⁰¹ + n ²⁰² ≦ 6.
<13> The white organic electroluminescent element according to any one of <2> to <12>, wherein the indole compound is a compound represented by the general formula (3):

(In General Formula (3), R ^{301 to} R ³⁰⁵ represent a hydrogen atom or a substituent. R ³⁰⁶ represents a secondary or tertiary alkyl group. R ³⁰¹ and R ³⁰⁶ are bonded to each other to form a ring. R ^{311 to} R ³¹⁵ each represent a hydrogen atom or a substituent, R ³¹⁶ represents an alkyl group having a secondary or tertiary carbon atom, and R ³¹¹ and R ³¹⁶ are bonded to each other to form a ring. R ^{321 to} R ³²⁴ each represents a hydrogen atom or a substituent.

According to the present invention, a white organic EL element having excellent durability is provided.
In the white organic EL device of the present invention, the light emitting material is composed of a monomer light emitting material and an aggregate light emitting material in which the monomer light emitting material is associated, and white light is obtained by color mixture of light emitted from them. The white light-emitting element using the associated light emission of the present invention has a simple light-emitting layer configuration, and has excellent driving durability and color due to deterioration as compared with a multicolor light-emitting element using light-emitting materials of different emission colors. The feature is that the shift and the luminance decrease hardly occur. Furthermore, by using a combination of a green phosphorescent light emitting material and a red phosphorescent light emitting material, it is possible to form a white element with higher color rendering properties.

Hereinafter, the white organic EL element will be described in detail.
The white organic EL device in the present invention has a cathode and an anode on a substrate, and an organic compound layer including an organic light emitting layer (hereinafter sometimes simply referred to as “light emitting layer”) between both electrodes. In view of the properties of the light emitting element, at least one of the anode and the cathode is preferably transparent.
The organic compound layer in the present invention may be either a single layer or a laminate. As an aspect in the case of lamination, an aspect in which a hole transport layer, a light emitting layer, and an electron transport layer are laminated in this order from the anode side is preferable. Further, a charge blocking layer or the like may be provided between the hole transport layer and the light-emitting layer, or between the light-emitting layer and the electron transport layer. A hole injection layer may be provided between the anode and the hole transport layer, and an electron injection layer may be provided between the cathode and the electron transport layer. Each layer may be divided into a plurality of secondary layers.

The white organic EL element in the present invention has a pair of electrodes and a white organic electroluminescent element having at least one organic layer including a light emitting layer between the electrodes (hereinafter referred to as “white organic EL element” as appropriate). The light emitting layer contains at least an aggregate light emitting material, a monomer light emitting material, and a host material, and a peak wavelength of light emission from the aggregate light emitting material is light emission from the monomer light emitting material. The wavelength is longer than the peak wavelength.
The monomer light emitting material in the present invention emits light different from light emitted from the monomer light emitting material by forming an aggregate. Preferably, the peak wavelength of light emission from the aggregate is 50 nm or more longer than the peak wavelength of light emission from the monomer light-emitting material, and more preferably 70 nm or more.
The content ratio of the monomer light emitting material and the aggregate light emitting material in the light emitting layer is preferably in the range of 1: 0.4, more preferably in the range of 1: 0.6, and still more preferably in terms of the ratio of the respective emission peak intensities. , 1: 0.8.

(1) Host material In particular, by using an indole compound as the host material, the association of the monomer luminescent materials is promoted, and a stable aggregate luminescent material can be obtained.

  The host material in the present invention is preferably an indole compound represented by the following general formula (1).

In the general formula ^{(1), R} 101 ~R ¹⁰⁵ represents a hydrogen atom or a substituent. R ¹⁰⁶ represents a secondary or tertiary alkyl group. R ¹⁰¹ and R ¹⁰⁶ may be bonded to each other to form a ring. L ¹⁰¹ represents a linking group, and n ¹⁰¹ represents an integer of 2 or more.
The indole compound is more preferably a compound represented by the general formula (2).

In the general formula ^{(2), R} 201 ~R ²⁰⁵ represents a hydrogen atom or a substituent. R ²⁰⁶ represents a secondary or tertiary alkyl group. R ²⁰¹ and R ²⁰⁶ may be bonded to each other to form a ring. R ²⁰⁷ represents a substituent. n ²⁰¹ represents an integer of 2 to 6, and n ²⁰² represents an integer of 0 to 4. ^However, it is ⁿ 201 ⁺ n ²⁰² ≦ 6.
The indole compound is preferably a compound represented by the general formula (3).

In the general formula ^{(3), R} 301 ~R ³⁰⁵ represents a hydrogen atom or a substituent. R ³⁰⁶ represents a secondary or tertiary alkyl group. R ³⁰¹ and R ³⁰⁶ may be bonded to each other to form a ring. R ^{311 to} R ³¹⁵ represent a hydrogen atom or a substituent. R ³¹⁶ represents an alkyl group having a secondary or tertiary carbon atom. R ³¹¹ and R ³¹⁶ may be bonded to each other to form a ring. R ^{321 to} R ³²⁴ represent a hydrogen atom or a substituent.

The indole compound in the present invention will be described in more detail.
First, the general formula (1) will be described.

R ^{101 to} R ¹⁰⁵ represent a hydrogen atom or a substituent.
Examples of the substituent include an alkyl 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 methyl, ethyl, iso-propyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), alkenyl group (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms). Yes, for example, vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), alkynyl group (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms). Yes, such as propargyl, 3-pentynyl, etc.), aryl group (preferably having 6 to 30 carbon atoms, more preferred) Has 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyl, p-methylphenyl, naphthyl, anthranyl and the like, and an amino group (preferably having 0 to 30 carbon atoms, more preferably The number of carbon atoms is 0 to 20, particularly preferably 0 to 10, and examples thereof include amino, methylamino, dimethylamino, diethylamino, dibenzylamino, diphenylamino, ditolylamino, and the like, and an alkoxy group (preferably having a carbon number). 1 to 30, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms, such as methoxy, ethoxy, butoxy, 2-ethylhexyloxy), aryloxy groups (preferably carbon A number 6 to 30, more preferably a number 6 to 20, and particularly preferably a number 6 to 12, For example, phenyloxy, 1-naphthyloxy, 2-naphthyloxy, etc.), a heterocyclic oxy group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 12 carbon atoms). And examples thereof include pyridyloxy, pyrazyloxy, pyrimidyloxy, quinolyloxy, and the like.

An acyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as acetyl, benzoyl, formyl, pivaloyl, etc.), an alkoxycarbonyl group ( Preferably it has 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 12 carbon atoms, and examples thereof include methoxycarbonyl, ethoxycarbonyl and the like, and an aryloxycarbonyl group (preferably having a carbon number). 7 to 30, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonyl, and acyloxy groups (preferably 2 to 30 carbon atoms, more preferably carbon atoms). 2 to 20, particularly preferably 2 to 10 carbon atoms, for example, acetoxy, benzoyloxy An acylamino group (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, and examples thereof include acetylamino and benzoylamino). An alkoxycarbonylamino group (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 12 carbon atoms such as methoxycarbonylamino), aryloxycarbonylamino group (Preferably 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino), sulfonylamino group (preferably 1 carbon atom) To 30, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, Methanesulfonylamino, benzenesulfonylamino, etc.), sulfamoyl groups (preferably having 0 to 30 carbon atoms, more preferably 0 to 20 carbon atoms, particularly preferably 0 to 12 carbon atoms, such as sulfamoyl, methyl Famoyl, dimethylsulfamoyl, phenylsulfamoyl, etc.),

A carbamoyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl and the like), alkylthio. A group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio and ethylthio), an arylthio group (preferably having 6 to 6 carbon atoms). 30, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio, and the like, and a heterocyclic thio group (preferably 1 to 30 carbon atoms, more preferably 1 carbon atom). -20, particularly preferably 1 to 12 carbon atoms, such as pyridylthio, 2-benzimidazolyl E, 2-benzoxazolylthio, 2-benzthiazolylthio, etc.), sulfonyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms). For example, mesyl, tosyl, etc.), sulfinyl groups (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfinyl, benzene And ureido groups (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 12 carbon atoms. Examples thereof include ureido, methylureido, and phenylureido. ),

A phosphoric acid amide group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as diethyl phosphoric acid amide and phenylphosphoric 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, heterocyclic ring A 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, quinolyl, furyl and thienyl. , Piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, carbazolyl , An azepinyl group, etc.), a silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, such as trimethylsilyl and triphenylsilyl). ), A silyloxy group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms, and examples thereof include trimethylsilyloxy and triphenylsilyloxy). Is mentioned. These substituents may be further substituted.

R ^{101 to} R ¹⁰⁵ are preferably a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group, more preferably a hydrogen atom, an alkyl group, or an aryl group, still more preferably a hydrogen atom or an alkyl group, and particularly preferably a hydrogen atom.

R ¹⁰⁶ represents a secondary or tertiary alkyl group. The secondary or tertiary alkyl group of R ¹⁰⁶ is preferably directly bonded to the indole ring (for example, t-butyl group, isopropyl group, isobutyl group, isopentyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, 2-phenyl- 2-propyl group, 2- (2-pyridyl) propyl group, etc.). R ¹⁰⁶ is preferably a tertiary alkyl group, more preferably an alkyl group in which a tertiary carbon atom is bonded to an indole ring, and further preferably a C 4-10 alkyl group in which a tertiary carbon atom is bonded to an indole ring. An alkyl group having 4 to 6 carbon atoms in which a carbon atom is bonded to an indole ring is particularly preferable (preferably a t-butyl group). Further, R ¹⁰¹ and R ¹⁰⁶ may be bonded to each other to form a ring. Examples of the ring formed by combining R ¹⁰¹ and R ¹⁰⁶ with each other include a cyclopentene ring, a cyclohexene ring, a 1,4-cyclohexadiene ring, a cycloheptene ring, and a cyclooctene ring.
R ¹⁰⁶ may have a substituent, and examples of the substituent include those exemplified as the substituents represented by R ^{101 to} R ¹⁰⁵ .

L ¹⁰¹ represents a linking group. As the linking group, a linking group comprising an atom selected from a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a silicon atom, and a phosphorus atom is preferable, and an alkyl linking group, an aryl linking group, a heteroaryl linking group is preferable. Are more preferable, an aryl linking group and a heteroaryl linking group are more preferable, and an aryl linking group is particularly preferable.
The linking group represented by L ¹⁰¹ may have a substituent, and examples of the substituent include those exemplified as the substituents represented by R ^{101 to} R ¹⁰⁵ .
Specific examples of the linking group represented by L ¹⁰¹ include the following.

n ¹⁰¹ represents an integer of 2 or more, an integer of 2 to 4 is preferable, 2, 3 is more preferable, and 2 is more preferable.
In addition, the structure of the some indole skeleton part in General formula (1) may be the same, or may mutually differ.

  The compound represented by the general formula (1) is preferably a compound represented by the general formula (2), and more preferably a compound represented by the general formula (3).

The general formula (2) will be described.
R ^{201 to} R ²⁰⁶ are synonymous with R ^{101 to} R ¹⁰⁶ , respectively, and the preferred range is also the same. Furthermore, R ²⁰¹ and R ²⁰⁶ may be bonded to each other to form a ring. Examples of the ring formed by combining R ²⁰¹ and R ²⁰⁶ with each other include a cyclopentene ring, a cyclohexene ring, a 1,4-cyclohexadiene ring, a cycloheptene ring, and a cyclooctene ring.
R ²⁰⁶ may have a substituent, and examples of the substituent include those exemplified as the substituents represented by R ^{101 to} R ¹⁰⁵ .

R ²⁰⁷ represents a substituent. Examples of the substituent include the substituents described for R ¹⁰¹ above, preferably an alkyl group, an aryl group, and a silyl group, more preferably an alkyl group and an aryl-substituted silyl group, and still more preferably an alkyl group and a triphenylsilyl group.

n ²⁰¹ represents an integer of 2 to 6, and n ²⁰² represents an integer of 0 to 4. ^However, it is ⁿ 201 ⁺ n ²⁰² ≦ 6. n ²⁰¹ is preferably an integer of 2 to 4, more preferably 2, 3, and still more preferably 2. n ²⁰² is preferably 0 to 3, more preferably 0 to 2, still more preferably 0 to 1, and particularly preferably 0. When n ²⁰¹ is an integer of 2 to 4, a plurality of R ²⁰⁷ may be the same or different from each other.
In addition, the structure of the some indole skeleton part in General formula (2) may be the same, or may mutually differ.

The general formula (3) will be described.
R ^{301 to} R ³⁰⁶ have the same meanings as R ^{101 to} R ¹⁰⁶ , respectively, and the preferred ranges are also the same. Further, R ³⁰¹ and R ³⁰⁶ may be bonded to each other to form a ring. Examples of the ring formed by combining R ³⁰¹ and R ³⁰⁶ include a cyclopentene ring, cyclohexene ring, 1,4-cyclohexadiene ring, cycloheptene ring, and cyclooctene ring.
R ³⁰⁶ may have a substituent, and examples of the substituent include those exemplified as the substituents represented by R ^{101 to} R ¹⁰⁵ .
R ^{311 to} R ³¹⁶ have the same meanings as R ^{101 to} R ¹⁰⁶ , respectively, and the preferred ranges are also the same. Furthermore, R ³¹¹ and R ³¹⁶ may be bonded to each other to form a ring. Examples of the ring formed by combining R ³¹¹ and R ³¹⁶ include a cyclopentene ring, a cyclohexene ring, a 1,4-cyclohexadiene ring, a cycloheptene ring, and a cyclooctene ring.
R ³¹⁶ may have a substituent, and examples of the substituent include those exemplified as the substituents represented by R ^{101 to} R ¹⁰⁵ .

R ^{321 to} R ³²⁴ represent a hydrogen atom or a substituent. Examples of the substituent include the substituents described for R ¹⁰¹ . R ³²¹ , R ³²² and R ³²⁴ are preferably a hydrogen atom, an alkyl group or an aryl group, more preferably a hydrogen atom or an alkyl group, and even more preferably a hydrogen atom. R ³²³ is preferably a hydrogen atom, an alkyl group, or an aryl group, more preferably a hydrogen atom, an alkyl group, or an aryl-substituted silyl group, and even more preferably a hydrogen atom or a triphenylsilyl group.

  The indole derivative used in the present invention may be a low molecular weight compound, or a high molecular weight compound in which a residue is connected to a polymer main chain (preferably a mass average molecular weight of 1,000 to 5,000,000, more preferably 5,000 to 2,000,000, more preferably Or a high molecular weight compound having an indole derivative structure of the present invention in the main chain (preferably a mass average molecular weight of 1,000 to 5,000,000, more preferably 5,000 to 2,000,000, more preferably 10,000 to 1,000,000). . In the case of a high molecular weight compound, it may be a homopolymer, may be a copolymer with another polymer, and if it is a copolymer, it may be a random copolymer or a block copolymer. There may be. Further, in the case of a copolymer, a compound having a light emitting function and / or a compound having a charge transport function may be included in the polymer.

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

(2) Aggregate luminescent material and monomer luminescent material The aggregate luminescent material and monomer luminescent material used in the present invention are preferably phosphorescent luminescent materials. More preferably, the aggregate luminescent material is an aggregate of the monomer luminescent material.
Preferably, both the aggregate luminescent material and the monomer luminescent material are metal complexes.
Preferably, the metal complex is a tetradentate platinum complex.

Examples of the phosphorescent material that can be used in the present invention include complexes containing transition metal atoms or lanthanoid atoms.
Although it does not specifically limit as a transition metal atom, Preferably, ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, and platinum are mentioned, More preferably, they are rhenium, iridium, and platinum.
Examples of lanthanoid atoms include lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Among these lanthanoid atoms, neodymium, europium, and gadolinium are preferable.

Examples of the ligand of the complex include G.I. Wilkinson et al., Comprehensive Coordination Chemistry, Pergamon Press, 1987, H.C. Examples include ligands described in Yersin's "Photochemistry and Photophysics of Coordination Compounds" published by Springer-Verlag 1987, Akio Yamamoto "Organic Metal Chemistry-Fundamentals and Applications-" .
Specific ligands are preferably halogen ligands (preferably chlorine ligands), nitrogen-containing heterocyclic ligands (eg, phenylpyridine, benzoquinoline, quinolinol, bipyridyl, phenanthroline, etc.), diketones Ligand (for example, acetylacetone), carboxylic acid ligand (for example, acetic acid ligand), carbon monoxide ligand, isonitrile ligand, cyano ligand, more preferably nitrogen-containing Heterocyclic ligand. The complex may have one transition metal atom in the compound, or may be a so-called binuclear complex having two or more. Different metal atoms may be contained at the same time.

  Among these, as specific examples of the light emitting material, for example, US6303238B1, US6097147, WO00 / 57676, WO00 / 70655, WO01 / 08230, WO01 / 39234A2, WO01 / 41512A1 Gazette, WO02 / 02714A2, WO02 / 15645A1, WO02 / 44189A1, JP2001-247859, JP2002-302671, JP2002-117978, JP2002-225352 Gazette, JP 2002-235076, JP 2003-123982, JP 2002-170684, EP 12111257, JP 2002-226495, JP 2002-23 No. 894, JP-A No. 2001-247859, JP-A No. 2001-298470, JP-A No. 2002-173684, JP-A No. 2002-203678, JP-A No. 2002-203679, JP-A No. 2004-357791 Examples thereof include phosphorescent compounds described in JP-A-2006-256999, JP-A-2007-19462, and the like.

In addition, as the phosphorescent light emitting material in the present invention, an electron transporting light emitting material or a hole transporting light emitting material is used.
The electron transporting light emitting material is preferably an electron transporting light emitting material having an electron affinity (Ea) of 2.5 eV or more and 3.5 eV or less and an ionization potential (Ip) of 5.7 eV or more and 7.0 eV or less. is there.
Materials that can be preferably used are ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, platinum, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, And lutesium complexes. More preferred are ruthenium, rhodium, palladium, or platinum complexes, and most preferred is a platinum complex.
Although the specific example of the platinum complex used for this invention is shown below, it is not limited to these.

<Hole transportable phosphorescent material>
As the phosphorescent material in the present invention, a hole-transporting phosphorescent material can be used. The hole transporting phosphorescent material preferably has an electron affinity (Ea) of 2.4 eV to 3.4 eV and an ionization potential (Ip) of 5.0 eV to 6.3 eV. It is a phosphorescent material.
Materials that can be preferably used are ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, platinum, lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, And lutesium complex, more preferably iridium complex.
Although the example of a specific iridium complex is illustrated below, this invention is not limited to these.

  Among these, examples of the blue phosphorescent light emitting material having an emission peak at 420 nm or more and less than 500 nm include, but are not limited to, the following.

  Examples of the green phosphorescent material having an emission peak at 500 nm or more and less than 570 nm include, but are not limited to, the following.

  Examples of the red phosphorescent light emitting material having an emission peak at 570 nm or more and 650 nm or less include, but are not limited to, the following.

1. Configuration of White Organic Electroluminescent Device The white organic electroluminescent device of the present invention is a white organic electroluminescent device having a pair of electrodes and at least one organic layer including a light emitting layer between the electrodes on the substrate, The light emitting layer contains at least an aggregate light emitting material, a monomer light emitting material, and a host material, and a peak wavelength of light emission from the aggregate light emitting material is longer than a peak wavelength of light emission from the monomer light emitting material. It is characterized by.
The layer configuration of the white organic electroluminescent element of the present invention will be described with reference to the drawings.
The configuration of the organic EL device of the present invention will be described with reference to the drawings.
FIG. 1 is a conceptual diagram showing a cross-sectional configuration of the organic EL element of the present invention. A substrate 1 has an anode 2, a hole injection layer 3, and a hole transport layer 4, and a light emitting layer 5, an electron transport layer 6, an electron injection layer 7, and a cathode 8 are formed thereon.

FIG. 2 is a conceptual diagram showing a cross-sectional configuration of another aspect of the organic EL element of the present invention.
On the substrate 1, the anode 2, the hole injection layer 3, and the hole transport layer 4 are provided. On the substrate 1, the first light emitting layer 15-1 and the second light emitting layer 15-2 are provided. The electron transport layer 6, the electron injection layer 7, and the cathode 8 are included. The first light-emitting layer 15-1 contains a blue light-emitting (B light-emitting) phosphorescent light-emitting material (may be referred to as “blue phosphorescent light-emitting material”) having a light emission peak at 420 nm or more and less than 500 nm. The light emitting layer 15-2 has a green light emitting (G light emitting) phosphorescent light emitting material having an emission peak at 500 nm or more and less than 570 nm (may be described as “green phosphorescent light emitting material”) and an emission peak at 570 nm or more and 650 nm or less. A phosphorescent material that emits red light (R light emission) (may be described as “green phosphorescent material”).
As the structure of the light emitting layer, the first light emitting layer 15-1 is a layer containing a green phosphorescent light emitting material and a red phosphorescent light emitting material, and the second light emitting layer 15-2 is a blue phosphorescent light emitting material. It may be a layer containing.
According to this configuration, the excitons generated from the blue phosphorescent material are prevented from coming into direct contact with the excitons generated from the green phosphorescent material or the red phosphorescent material. Inefficiency due to misalignment or quenching is prevented, and luminous efficiency is improved.

FIG. 3 is a conceptual diagram showing a cross-sectional configuration of an organic EL element according to another aspect of the present invention.
On the substrate 1, an anode 2, a hole injection layer 3, and a hole transport layer 4 are provided, and a first light-emitting layer 25-1, a second light-emitting layer 25-2, and a third light-emitting layer are formed thereon. The layer 25-3 is provided, and the electron transport layer 6, the electron injection layer 7, and the cathode 8 are provided thereon. The first light emitting layer 25-1 contains a blue phosphorescent light emitting material, the second light emitting layer 25-2 contains a green phosphorescent light emitting material, and the third light emitting layer 25-3 contains a red phosphorescent light emitting material. Containing.
As a structure of the light emitting layer, the first light emitting layer 25-1 is a layer containing a red phosphorescent light emitting material, and the second light emitting layer 25-2 is a layer containing a green phosphorescent light emitting material, The third light emitting layer 25-3 may be a layer containing a blue phosphorescent material.
Further, the first light emitting layer 25-1 is a layer containing a green phosphorescent light emitting material, and the second light emitting layer 25-2 is a layer containing a blue phosphorescent light emitting material, and the third light emitting layer. 25-3 may be a layer containing a red phosphorescent material.
Furthermore, the first light emitting layer 25-1 is a layer containing a red phosphorescent light emitting material, and the second light emitting layer 25-2 is a layer containing a blue phosphorescent light emitting material, and the third light emitting layer The layer 25-3 may be a layer containing a green phosphorescent material.
According to this configuration, the excitons generated from the blue phosphorescent material are further prevented from coming into direct contact with the excitons generated from the green phosphorescent material or the red phosphorescent material, such as by energy transfer between the excitons. Inefficiency due to color shift or quenching is prevented, and luminous efficiency is improved.

  Next, elements constituting the light emitting device of the present invention will be described in detail.

(substrate)
The substrate used in the present invention is preferably a substrate that does not scatter or attenuate light emitted from the organic compound layer. Specific examples include zirconia-stabilized yttrium (YSZ), inorganic materials such as glass, polyesters such as polyethylene terephthalate, polybutylene phthalate, and polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, and polycycloolefin. , Norbornene resins, and organic materials such as poly (chlorotrifluoroethylene).
For example, when glass is used as the substrate, alkali-free glass is preferably used 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. In the case of an organic material, it is preferable that it is excellent in heat resistance, dimensional stability, solvent resistance, electrical insulation, and workability.

  There is no restriction | limiting in particular about the shape of a board | substrate, a structure, a magnitude | size, It can select suitably according to the use, purpose, etc. of a light emitting element. In general, the shape of the substrate is preferably a plate shape. The structure of the substrate may be a single layer structure, a laminated structure, may be formed of a single member, or may be formed of two or more members.

  The substrate may be colorless and transparent or colored and transparent, but is preferably colorless and transparent in that it does not scatter or attenuate light emitted from the organic light emitting layer.

The substrate can be provided with a moisture permeation preventing layer (gas barrier layer) on the front surface or the back surface.
As a material for the moisture permeation preventive layer (gas barrier layer), inorganic materials such as silicon nitride and silicon oxide are preferably used. The moisture permeation preventing layer (gas barrier layer) can be formed by, for example, a high frequency sputtering method.
When a thermoplastic substrate is used, a hard coat layer, an undercoat layer, or the like may be further provided as necessary.

(anode)
The anode usually has a function as an electrode for supplying holes to the organic compound layer, and there is no particular limitation on the shape, structure, size, etc., depending on the use and purpose of the light-emitting element. , Can be appropriately selected from known electrode materials. As described above, the anode is usually provided as a transparent anode.

  Suitable examples of the material for the anode include metals, alloys, metal oxides, conductive compounds, and mixtures thereof. Specific examples of the anode material include conductive metals such as tin oxide doped with antimony and fluorine (ATO, FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO). Metals such as oxides, gold, silver, chromium, nickel, and mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, polyaniline, polythiophene, polypyrrole, etc. Organic conductive materials, and a laminate of these and ITO. Among these, conductive metal oxides are preferable, and ITO is particularly preferable from the viewpoints of productivity, high conductivity, transparency, and the like.

  The anode is composed of, for example, a wet method such as a printing method and a coating method, a physical method such as a vacuum deposition method, a sputtering method, and an ion plating method, and a chemical method such as a CVD and a plasma CVD method. It can be formed on the substrate according to a method appropriately selected in consideration of suitability with the material to be processed. For example, when ITO is selected as the anode material, the anode can be formed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like.

  In the organic electroluminescent element of the present invention, the formation position of the anode is not particularly limited and can be appropriately selected according to the use and purpose of the light emitting element. Is preferably formed on the substrate. In this case, the anode may be formed on the entire one surface of the substrate, or may be formed on a part thereof.

  The patterning for forming the anode may be performed by chemical etching such as photolithography, or may be performed by physical etching such as laser, or vacuum deposition or sputtering with a mask overlapped. It may be performed by a lift-off method or a printing method.

  The thickness of the anode can be appropriately selected depending on the material constituting the anode and cannot be generally defined, but is usually about 10 nm to 50 μm, and preferably 50 nm to 20 μm.

The resistance value of the anode is preferably 10 ³ Ω / □ or less, and more preferably 10 ² Ω / □ or less. When the anode is transparent, it may be colorless and transparent or colored and transparent. In order to take out light emission from the transparent anode side, the transmittance is preferably 60% or more, and more preferably 70% or more.

  The transparent anode is described in detail in the book “New Development of Transparent Electrode Films” published by CMC (1999), supervised by Yutaka Sawada, and the matters described here can be applied to the present invention. In the case of using a plastic substrate having low heat resistance, a transparent anode formed using ITO or IZO at a low temperature of 150 ° C. or lower is preferable.

(cathode)
The cathode usually has a function as an electrode for injecting electrons into the organic compound layer, and there is no particular limitation on the shape, structure, size, etc., depending on the use and purpose of the light-emitting element, It can select suitably from well-known electrode materials.

  Examples of the material constituting the cathode include metals, alloys, metal oxides, electrically conductive compounds, and mixtures thereof. Specific examples include alkali metals (eg, LI, Na, K, Cs, etc.), alkaline earth metals (eg, Mg, Ca, etc.), gold, silver, lead, aluminum, sodium-potassium alloys, lithium-aluminum alloys, magnesium. -Rare earth metals such as silver alloys, indium and ytterbium. These may be used alone, but two or more can be suitably used in combination from the viewpoint of achieving both stability and electron injection.

Among these, as a material constituting the cathode, an alkali metal or an alkaline earth metal is preferable from the viewpoint of electron injecting property, and a material mainly composed of aluminum is preferable from the viewpoint of excellent storage stability.
The material mainly composed of aluminum is aluminum alone, an alloy of aluminum and 0.01% by mass to 10% by mass of alkali metal or alkaline earth metal, or a mixture thereof (for example, lithium-aluminum alloy, magnesium-aluminum alloy). Etc.).

  The materials for the cathode are described in detail in JP-A-2-15595 and JP-A-5-121172, and the materials described in these public relations can also be applied in the present invention.

There is no restriction | limiting in particular about the formation method of a cathode, According to a well-known method, it can carry out.
For example, the cathode described above is configured from a wet method such as a printing method or a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a chemical method such as CVD or plasma CVD method. It can be formed according to a method appropriately selected in consideration of suitability with the material. For example, when a metal or the like is selected as the cathode material, one or more of them can be simultaneously or sequentially performed according to a sputtering method or the like.

  Patterning when forming the cathode may be performed by chemical etching such as photolithography, physical etching by laser, or the like, or by vacuum deposition or sputtering with the mask overlaid. It may be performed by a lift-off method or a printing method.

In the present invention, the cathode formation position is not particularly limited, and may be formed on the entire organic compound layer or a part thereof.
Further, a dielectric layer made of an alkali metal or alkaline earth metal fluoride or oxide may be inserted between the cathode and the organic compound layer with a thickness of 0.1 nm to 5 nm. This dielectric layer can also be regarded as a kind of electron injection layer. The dielectric layer can be formed by, for example, vacuum deposition, sputtering, or ion plating.

The thickness of the cathode can be appropriately selected depending on the material constituting the cathode and cannot be generally defined, but is usually about 10 nm to 5 μm, and preferably 50 nm to 1 μm.
Further, the cathode may be transparent or opaque. The transparent cathode can be formed by depositing a thin cathode material to a thickness of 1 nm to 10 nm and further laminating a transparent conductive material such as ITO or IZO.

(Organic compound layer)
The organic compound layer in the present invention will be described.
The organic EL device of the present invention has at least one organic compound layer including a light emitting layer, and the light emitting layer contains at least an aggregate light emitting material, a monomer light emitting material, and a host material. The peak wavelength of light emission from the aggregate light emitting material is longer than the peak wavelength of light emission from the monomer light emitting material.
Examples of the organic compound layer other than the light emitting layer include layers such as a hole transport layer, an electron transport layer, a charge blocking layer, a hole injection layer, and an electron injection layer as described above.

  In the organic EL device of the present invention, each layer constituting the organic compound layer is preferably formed by any of dry film forming methods such as vapor deposition and sputtering, wet coating methods, transfer methods, printing methods, and ink jet methods. Can do.

(Light emitting layer)
The organic light emitting layer receives holes from the anode, the hole injection layer, or the hole transport layer when an electric field is applied, receives electrons from the cathode, the electron injection layer, or the electron transport layer, and recombines holes and electrons. It is a layer having a function of providing a field to emit light.
The light emitting layer in the present invention contains at least an aggregate light emitting material and a monomer light emitting material as at least a light emitting material. Preferably, the aggregate luminescent material is an aggregate formed of the monomer luminescent material.
The aggregate luminescent material and monomer luminescent material in the present invention are preferably phosphorescent luminescent materials.

The light emitting layer in the present invention contains a host material.
The host material is a compound mainly responsible for charge injection and transport in the light-emitting layer, and is a compound that itself does not substantially emit light. In this specification, “substantially no light emission” means that the light emission amount from the substantially non-light emitting compound is preferably 5% or less, more preferably 3% or less of the total light emission amount of the entire device. More preferably, it means 1% or less.
The host material in the present invention preferably contains an indole compound represented by the general formula (1).
The host material in the present invention plays an important role for the monomer light emitting material to form an aggregate. It is not clear what specific structure the aggregate in the present invention has, but when it consists of a monomer light emitting material alone, it hardly forms an aggregate, and the specific host material in the present invention Therefore, it is presumed that the host material in the present invention stabilizes the monomer aggregate.

(Hole injection layer, hole transport layer)
The hole injection layer and the hole transport layer are layers having a function of receiving holes from the anode or the anode side and transporting them to the cathode side. As a material that can be used for the hole injection layer and the hole transport layer of the present invention, other hole injection materials and hole transport materials can be used in addition to the interlock type compound of the present invention. These hole injection material and hole transport material may be a low molecular compound or a high molecular compound.
Specifically, pyrrole derivatives, carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styryl Anthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, phthalocyanine compounds, porphyrin compounds, thiophene derivatives, organosilane derivatives, or carbon And the like.

  An electron-accepting dopant can be contained in the hole injection layer or the hole transport layer of the organic EL device of the present invention. As the electron-accepting dopant introduced into the hole-injecting layer or the hole-transporting layer, an inorganic compound or an organic compound can be used as long as it has an electron-accepting property and oxidizes an organic compound.

  Specifically, examples of the inorganic compound include metal halides such as ferric chloride, aluminum chloride, gallium chloride, indium chloride, and antimony pentachloride, metal oxides such as vanadium pentoxide, and molybdenum trioxide.

In the case of an organic compound, a compound having a nitro group, halogen, cyano group, trifluoromethyl group or the like as a substituent, a quinone compound, an acid anhydride compound, fullerene, or the like can be preferably used.
In addition, JP-A-6-212153, JP-A-11-111463, JP-A-11-251067, JP-A-2000-196140, JP-A-2000-286054, JP-A-2000-315580 JP, JP-A-2001-102175, JP-A-2001-160493, JP-A-2002-252085, JP-A-2002-56985, JP-A-2003-157981, JP-A-2003-217862 JP-A-2003-229278, JP-A-2004-342614, JP-A-2005-72012, JP-A-2005-166637, JP-A-2005-209643, and the like are preferably used. I can do it.

  These electron-accepting dopants may be used alone or in combination of two or more. Although the usage-amount of an electron-accepting dopant changes with kinds of material, it is preferable that it is 0.01 mass%-50 mass% with respect to hole transport layer material, and it is 0.05 mass%-20 mass%. It is further more preferable and it is especially preferable that it is 0.1 mass%-10 mass%.

The thicknesses of the hole injection layer and the hole transport layer are each preferably 500 nm or less from the viewpoint of lowering the driving voltage.
The thickness of the hole transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm. In addition, the thickness of the hole injection layer is preferably 0.1 nm to 200 nm, more preferably 0.5 nm to 100 nm, and still more preferably 1 nm to 100 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. .

(Electron injection layer, electron transport layer)
The electron injection layer and the electron transport layer are layers having a function of receiving electrons from the cathode or the cathode side and transporting them to the anode side.

An electron injection material and an electron transport material can be used for the electron transport layer in the present invention. These electron injection material and electron transport material may be a low molecular compound or a high molecular compound.
Specifically, pyridine derivatives, quinoline derivatives, pyrimidine derivatives, pyrazine derivatives, phthalazine derivatives, phenanthroline derivatives, triazine derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, fluorenone derivatives, anthraquinodimethane derivatives, anthrone Derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, naphthalene, perylene and other aromatic ring tetracarboxylic acid anhydrides, phthalocyanine derivatives, 8-quinolinol derivative metal complexes, Metal phthalocyanines, various metal complexes represented by metal complexes with benzoxazole and benzothiazole as ligands, organosilane derivatives represented by siloles Body, or the like is preferably a layer containing.

The thicknesses of the electron injection layer and the electron transport layer are each preferably 500 nm or less from the viewpoint of lowering the driving voltage.
The thickness of the electron transport layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm. In addition, the thickness of the electron injection layer is preferably 0.1 nm to 200 nm, more preferably 0.2 nm to 100 nm, and still more preferably 0.5 nm to 50 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.

(Hole blocking layer)
The hole blocking layer is a layer having a function of preventing holes transported from the anode side to the light emitting layer from passing through to the cathode side. In the present invention, a hole blocking layer can be provided as an organic compound layer adjacent to the light emitting layer on the cathode side.
Examples of the compound constituting the hole blocking layer include aluminum complexes such as BAlq, triazole derivatives, phenanthroline derivatives such as BCP, and the like.
The thickness of the hole blocking layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and still more preferably 10 nm to 100 nm.
The hole blocking 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.

(Electronic block layer)
The electron blocking layer is a layer having a function of preventing electrons transported from the cathode side to the light emitting layer from passing through to the anode side. In the present invention, an electron blocking layer can be provided as the organic compound layer adjacent to the light emitting layer on the anode side.
As examples of the compound constituting the electron blocking layer, for example, those mentioned as the hole transport material described above can be applied.
The thickness of the electron blocking layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and even more preferably 10 nm to 100 nm.
The hole blocking 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.

(Protective layer)
In the present invention, the entire organic EL element may be protected by a protective layer.
As a material contained in the protective layer, any material may be used as long as it has a function of preventing materials that promote device deterioration such as moisture and oxygen from entering the device.
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. Metal oxide such as O ₃ , Y ₂ O ₃ , or TiO ₂ , metal nitride such as SiN _x , SiN _x O _y , metal fluoride such as MgF ₂ , LiF, AlF ₃ , or CaF ₂ , polyethylene, polypropylene Polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, a copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, tetrafluoroethylene and at least one comonomer. Copolymer obtained by copolymerizing monomer mixture containing And 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, and a moisture-proof substance having a water absorption of 0.1% or less.

  The method for forming the protective layer is not particularly limited, and for example, vacuum deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency) Excited ion plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, printing method, or transfer method can be applied.

(Sealing)
Furthermore, the organic electroluminescent element of this invention may seal the whole element using a sealing container.
Further, a moisture absorbent or an inert liquid may be sealed in a space between the sealing container and the light emitting element. Although it does not specifically limit as a moisture absorber, For example, barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, calcium chloride, magnesium chloride, copper chloride Cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, magnesium oxide, and the like. The inert liquid is not particularly limited, and examples thereof include paraffins, liquid paraffins, fluorinated solvents such as perfluoroalkane, perfluoroamine, and perfluoroether, chlorinated solvents, and silicone oils. Can be mentioned.

(Drive)
The organic electroluminescence device of the present invention emits light by applying a direct current (which may include an alternating current component as necessary) voltage (usually 2 to 15 volts) or a direct current between the anode and the cathode. Can be obtained.
The driving method of the organic electroluminescence device of the present invention is described in JP-A-2-148687, JP-A-6-301355, JP-A-5-29080, JP-A-7-134558, JP-A-8-234585, The driving methods described in Japanese Patent No. 8-24047, Japanese Patent No. 2784615, US Pat. No. 5,828,429, Japanese Patent No. 6023308, and the like can be applied.

  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 may be a so-called top emission type in which light emission is extracted from the anode side.

(Use of the present invention)
The organic electroluminescence device of the present invention can be suitably used for display devices, displays, backlights, electrophotography, illumination light sources, recording light sources, exposure light sources, reading light sources, signs, signboards, interiors, optical communications, and the like.

The present invention will be specifically described using examples, but the present invention is not limited to these examples.
1. Production of organic EL element (production of elements 1 to 4 of the present invention)
A glass substrate having a thickness of 0.5 mm and a square of 2.5 cm was placed in a cleaning container, subjected to ultrasonic cleaning in 2-propanol, and then subjected to UV-ozone treatment for 30 minutes. The following layers were deposited on this transparent anode by vacuum deposition. The vapor deposition rate in the examples of the present invention is 0.2 nm / second unless otherwise specified. The deposition rate was measured using a quartz resonator. The film thicknesses described below were also measured using a crystal resonator.
-Anode: ITO (Indium Tin Oxide) was deposited on a glass substrate to a thickness of 100 nm.
Hole injection layer: 4,4 ′, 4 ″ -Tris (N- (2-naphthyl) -N-phenyl-amino) -triphenylamine (abbreviated as 2-TNATA) on the anode (ITO); 0.3% by mass of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (abbreviated as F4-TCNQ) was co-evaporated with respect to 2-TNATA. The thickness was vapor deposition at 160 nm.
-Hole transport layer: α-NPD (Bis [N- (1-naphthyl) -N-pheny] benzidine) was deposited on the hole injection layer to a thickness of 10 nm.
Second hole transport layer: Amine compound 1 was deposited to a thickness of 3 nm on the hole transport layer.
-Light emitting layer: Indole compound 1 and platinum complex 1 were co-deposited as a host material on the second hole transport layer. The co-evaporation ratio was changed, and the content of platinum complex 1 in the light emitting layer was changed as shown in Table 1. The thickness was 67 nm.
Electron transport layer: Bis- (2-methyl-8-quinolinolato) -4- (phenyl-phenolate) -aluminum (III) (abbreviated as BAlq) represented by the general formula (1) on the light emitting layer Vapor deposition was performed to a thickness of 40 nm.
Electron injection layer: LiF was deposited on the electron transport layer to a thickness of 1 nm.
Cathode: A patterned mask (a mask having a light emitting area of 2 mm × 2 mm) was placed on the electron transport layer, and metal aluminum was deposited to 100 nm to form a cathode.

The produced laminate was put in a glove box substituted with argon gas, and sealed with a stainless steel sealing can and an ultraviolet curable adhesive (XNR5516HV, manufactured by Nagase Ciba Co., Ltd.).
In this way, the elements 1-4 of this invention were produced.

  The structure of the material used in the examples is shown below.

Production of Comparative Elements 1 to 3 Comparative elements 1 to 3 were produced in the same manner as the element 1 of the present invention except that the following light emitting layer was used as the light emitting layer in the production of the element 1 of the present invention.
Light emitting layer: N, N′-di-carbazoly-3,5-benzene (abbreviated as mCP) and platinum complex 1 were co-evaporated. The co-evaporation ratio was changed, and the content of platinum complex 1 in the light emitting layer was changed as shown in Table 1. The thickness was 67 nm.

(Performance evaluation)
With respect to the obtained element of the present invention and the comparative element, the emission color and driving durability were examined according to the following.
1) Luminescent color-Sensory evaluation of the luminescent color was made by visual recognition.
In addition, emission spectrum was measured by spectrophotometric form, and the peak wavelength of emission was obtained. The peak wavelength of light emission by the monomer was observed at 456 nm, and the peak wavelength of light emission by the aggregate was observed at 570 nm. From this, the ratio of the peak intensity of light emission by the aggregate to the peak intensity of light emission by the monomer was determined.

2) Driving durability Using a source measure unit 2400 manufactured by Toyo Technica Co., Ltd., a DC voltage was applied to each element to emit light with a luminance of 1000 cd / m ² . It was made to emit light so that. The light emission was continued under the current-voltage condition, and the time for the luminance to decrease to 500 cd / m ² was measured to determine the driving durability.
The obtained results are shown in Table 1.

From the results of Table 1, all of the elements of the present invention emitted white light, and as the platinum complex 1 content increased from 20% by mass to 40% by mass, the emission intensity due to aggregate light emission was 0.3 to 0.3%. Increased to 0.7, driving durability improved.
On the other hand, in the comparative device, even when the content of platinum complex 1 is increased from 20% by mass to 40% by mass, the intensity ratio of the aggregates is increased only from 0.05 to 0.12, and the emission color is the monomer. It was blue due to light emission. In addition, the driving durability decreased as the content of the platinum complex 1 increased.
Therefore, the formation of aggregates at an unexpectedly high ratio in the device of the present invention, and the improvement in driving durability due to the formation of aggregates are completely unexpected effects.

Example 2
1. Fabrication of organic EL elements

(Preparation of element 10 of the present invention)
In the production of the element 1 of the present invention, the element 10 of the present invention was produced in the same manner as the element 1 of the present invention except that the following light emitting layer was used as the light emitting layer.
Luminescent layer: ternary co-evaporation of indole compound 1 and 40% by mass of platinum complex 1 and 1% by mass of platinum complex 2 with respect to indole compound 1 was performed. The thickness was 67 nm.

(Preparation of element 11 of the present invention)
In the production of the element 1 of the present invention, the element 11 of the present invention was produced in the same manner as the element 1 of the present invention, except that the following light emitting layer was used as the light emitting layer.
Luminescent layer: ternary co-evaporation of indole compound 1 and 40% by mass of platinum complex 1 and 1% by mass of Ir (ppy) ₃ with respect to indole compound 1 was performed. The thickness was 67 nm.

(Preparation of element 12 of the present invention)
In preparation of the element 1 of this invention, the element 12 of this invention was produced like the organic EL element 1 of this invention except having used the following light emitting layer as a light emitting layer.
Luminescent layer: ternary co-evaporation of indole compound 1 and 30% by mass of platinum complex 1 and 1% by mass of Ir (piq) ₃ with respect to indole compound 1 was performed. The thickness was 67 nm.

(Preparation of element 13 of the present invention)
In the production of the element 1 of the present invention, the element 13 of the present invention was produced in the same manner as the element 1 of the present invention except that the following light emitting layer was used as the light emitting layer.
Light emitting layer: ternary co-evaporation of indole compound 1 and 40% by mass of platinum complex 1 and 1% by mass of Ir (piq) ₃ with respect to indole compound 1 was performed. The thickness was 67 nm.

2. Performance Evaluation With respect to the obtained device of the present invention and comparative device, the emission color and driving durability were examined in the same manner as in Example 1. Further, the emission color was quantified by the CIE XYZ color system. The color system is based on the RGB additive method, in which an xy chromaticity diagram is created and colors are expressed by chromaticity coordinates (x, y) (edited by the Japan Photographic Society, "Basics of Photographic Engineering-Silver Salt"). Photo edition ", see pages 603 to 606, published in 1998).
As a result, in addition to the emission spectrum of the platinum complex 1 monomer and aggregate, light emission from the additional light-emitting material was added, and abundant color rendering white light emission was obtained.
For example, in the element 10 of the present invention, white light emission of (x, y) = (0.31, 0.34) was obtained in the CIE chromaticity coordinates.
In the element 11 of the present invention, white light emission of (x, y) = (0.26, 0.36) was obtained in the CIE chromaticity coordinates.
In the element 12 of the present invention, white light emission of (x, y) = (0.34, 0.31) was obtained in the CIE chromaticity coordinates.
In the element 13 of the present invention, white light emission of (x, y) = (0.34, 0.32) was obtained in the CIE chromaticity coordinates.

Example 3
1. Fabrication of organic EL elements

(Preparation of element 20 of the present invention)
In the production of the organic EL element 1 of the present invention of Example 1, the present invention was performed in the same manner as the organic EL element 1 of the present invention except that the following light emitting layer was used as the light emitting layer. An organic EL element 20 was produced.
1st light emitting layer: 30 mass% platinum complex 1 with respect to indole compound 1 and indole compound 1 was co-evaporated. The thickness was 57 nm.
Second light emitting layer: 15% by mass of platinum complex 2 with respect to mCP was co-deposited on the first light emitting layer. The thickness was 10 nm.

(Preparation of element 21 of the present invention)
In the production of the organic EL element 1 of the present invention of Example 1, the present invention was performed in the same manner as the organic EL element 1 of the present invention except that the following light emitting layer was used as the light emitting layer. An organic EL element 20 was produced.
1st light emitting layer: 30 mass% platinum complex 1 with respect to indole compound 1 and indole compound 1 was co-evaporated. The thickness was 57 nm.
Second light-emitting layer: mCP and 5% by mass of Ir (piq) ₃ with respect to the indole compound 1 were co-evaporated on the first light-emitting layer. The thickness was 10 nm.

2. Performance Evaluation With respect to the obtained device of the present invention and comparative device, the emission color and driving durability were examined in the same manner as in Example 1. Further, as in Example 2, the emission color was quantified by the CIE XYZ color system.
As a result, in addition to the emission spectrum of the platinum complex 1 monomer and aggregate, light emission from the additional light-emitting material was added, and abundant color rendering white light emission was obtained.
For example, in the element 20 of the present invention, white light emission of (x, y) = (0.26, 0.36) was obtained in the CIE chromaticity coordinates.
In the element 21 of the present invention, white light emission of (x, y) = (0.34, 0.32) was obtained in the CIE chromaticity coordinates.

It is a conceptual diagram which shows the cross-sectional structure of the organic EL element of this invention. It is a conceptual diagram which shows the cross-sectional structure of another aspect of the organic EL element of this invention. It is a conceptual diagram which shows the cross-sectional structure of another aspect of the organic EL element of this invention.

Claims (10)

A white organic electroluminescent device having a pair of electrodes and at least one organic layer including a light emitting layer between the electrodes on a substrate,
The light emitting layer contains at least an aggregate light emitting material, a monomer light emitting material, and a host material,
The aggregate luminescent material is an aggregate of the monomer luminescent material;
The host material includes an indole compound represented by the following general formula (1),
The concentration of the luminescent material including the aggregate luminescent material and the monomer luminescent material of the luminescent layer is 25% by mass to 40% by mass,
The white organic electroluminescence device, wherein a peak wavelength of light emission from the aggregate light-emitting material is longer than a peak wavelength of light emission from the monomer light-emitting material.

(In general formula (1), R ^{101 to} R ¹⁰⁵ represent a hydrogen atom or a substituent. R ¹⁰⁶ represents a secondary or tertiary alkyl group. R ¹⁰¹ and R ¹⁰⁶ are bonded to each other to form a ring. L ¹⁰¹ represents a linking group, and n ¹⁰¹ represents an integer of 2 or more. 2. The white organic electroluminescent element according to claim 1, wherein the monomer light emitting material is a blue phosphorescent light emitting material having an emission peak wavelength of 420 nm or more and less than 500 nm. White organic electroluminescent device according to claim 1 or claim 2, wherein the monomer emission material is a metal complex. 4. The white organic electroluminescent device according to claim 3 , wherein the metal complex is a tetradentate platinum complex. The light emitting layer further comprises at least one of a green phosphorescent material having an emission peak wavelength of 500 nm or more and less than 570 nm and a red phosphorescent material having an emission peak wavelength of 570 nm or more and 650 nm or less. The white organic electroluminescent element according to claim 4 . The light-emitting layer includes a first light-emitting layer including the aggregate light-emitting material, the monomer light-emitting material, and the host material; a green phosphorescent light-emitting material having an emission peak wavelength of 500 nm or more and less than 570 nm; The white organic electroluminescent element according to claim 5 , further comprising a second light emitting layer containing at least one of red phosphorescent materials having a wavelength of 650 nm or less. Wherein the second light-emitting layer, in claim 6, characterized in that the green phosphorescent-emitting material and the emission peak wavelength the luminescence peak wavelength is less than 570nm or 500nm comprises a red phosphorescent material is 570nm or more 650nm or less The white organic electroluminescent element as described. The light emitting layer includes a first light emitting layer including the aggregate light emitting material, the monomer light emitting material and the host material; a second light emitting layer including a green phosphorescent light emitting material having an emission peak wavelength of 500 nm or more and less than 570 nm; And a third light emitting layer containing a red phosphorescent material having an emission peak wavelength of 570 nm to 650 nm. 6. The white organic electroluminescent device according to claim 5 . The white organic electroluminescent element according to any one of claims 1 to 8 , wherein the indole compound is a compound represented by the general formula (2):


(In General Formula (2), R ^{201 to} R ²⁰⁵ represent a hydrogen atom or a substituent. R ²⁰⁶ represents a secondary or tertiary alkyl group. R ²⁰¹ and R ²⁰⁶ are bonded to each other to form a ring. R ²⁰⁷ represents a substituent, n ²⁰¹ represents an integer of 2 to 6, and n ²⁰² represents an integer of 0 to 4, provided that n ²⁰¹ + n ²⁰² ≦ 6. The white organic electroluminescent device according to any one of claims 1 to 9 , wherein the indole compound is a compound represented by the general formula (3):


(In General Formula (3), R ^{301 to} R ³⁰⁵ represent a hydrogen atom or a substituent. R ³⁰⁶ represents a secondary or tertiary alkyl group. R ³⁰¹ and R ³⁰⁶ are bonded to each other to form a ring. R ^{311 to} R ³¹⁵ each represent a hydrogen atom or a substituent, R ³¹⁶ represents an alkyl group having a secondary or tertiary carbon atom, and R ³¹¹ and R ³¹⁶ are bonded to each other to form a ring. R ^{321 to} R ³²⁴ each represents a hydrogen atom or a substituent.