JP2008021687A - Organic electroluminescent element material, organic electroluminescent element composition, and organic electroluminescent element - Google Patents

Abstract

【選択図】なしAn organic electroluminescent element material useful for obtaining an organic electroluminescent element having high luminous efficiency and long life is provided.
A material for an organic electroluminescence device having a high triplet excitation level represented by formula (I) and good heat resistance (wherein R ^{1 to} R ⁸ are each a hydrogen atom or an arbitrary substitution) Each represents the same or different group, provided that at least one of R ^{1 to} R ⁸ is a substituted amino group such as an N-azolyl group.

[Selection figure] None

Description

  The present invention relates to an organic electroluminescence device and the like, and more particularly to an organic electroluminescence device using a material for an organic electroluminescence device having a high triplet excitation level and good heat resistance.

In recent years, an organic electroluminescent element using an organic thin film instead of an inorganic material has been developed as a thin film type electroluminescent element. An organic electroluminescent element usually has a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and the like between an anode and a cathode, and materials suitable for these layers have been developed.
An example of such a material is tris (8-quinolinolato) aluminum. In Patent Document 1, tris (8-quinolinolato) aluminum is contained in the light-emitting layer, and an amine compound having a specific structure is contained in each of the hole injection layer and the hole transport layer, so that the light emission luminance, light emission efficiency, and heat resistance are excellent. Organic electroluminescent devices have been proposed.

Conventionally, organic electroluminescent devices have used fluorescent light emission, but in order to increase the light emission efficiency of the device, it has been studied to use phosphorescent light emission instead of fluorescent light emission.
For example, in many organic electroluminescent devices using phosphorescent molecules developed so far, biphenyl derivatives having a carbazolyl group as shown below are used as the material (host material) of the light emitting layer.

International Publication No. 03/080760 Pamphlet Applied Physics Letters (Appl. Phys. Lett.), 1999, volume 75, page 4.

By the way, although the organic electroluminescent element developed so far is excellent in luminous luminance, luminous efficiency, and heat resistance to some extent, there is a further problem regarding the lifetime of the element.
For example, tris (8-quinolinolato) aluminum used for the light emitting layer is insufficient in terms of light emission efficiency, maximum light emission luminance, and color purity, and thus has a problem that application to full color display is limited. .
At present, attempts to use phosphorescence have not yet obtained sufficient luminous efficiency. Furthermore, in the case of a biphenyl derivative having a carbazolyl group, which has been developed as a phosphorescent material, the amorphous or electrochemical durability is insufficient, so that an element using the same has durability. Has a problem.
On the other hand, when considering applications such as in-car use, heat resistance needs to be good in consideration of the environment in the car in summer, and the current materials have a problem that this point is not sufficient.

The present invention has been made to solve the above-described problems.
That is, an object of the present invention is to provide a material for an organic electroluminescence device having a high triplet excitation level and good heat resistance.
Another object of the present invention is to provide a composition for an organic electroluminescent device using a material for an organic electroluminescent device having a high triplet excitation level and good heat resistance.
Another object of the present invention is to provide an organic electroluminescent device having a long lifetime and high luminous efficiency.

  Thus, according to the present invention, there is provided an organic electroluminescent element material represented by the following general formula (I).

(In formula (I), R ^{1 to} R ⁸ represent a hydrogen atom or an arbitrary substituent, and may be the same or different, provided that at least one of R ^{1 to} R ⁸ is A substituted amino group represented by the following formula (II).

(In the formula (II), Ar ¹ and Ar ² each represents an arbitrary substituent, and may be the same or different. Ar ¹ and Ar ² are bonded to each other to form a single ring or a condensed ring. A ring may be formed.)

Here, it is preferable that Ar ¹ and Ar ² are each independently an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent.
Further, the substituted amino group is more preferably an N-azolyl group, the substitution site is more preferably R ³ or R ⁶ , and further preferably, both R ³ and R ⁶ are substituted.

Next, according to the present invention, there is provided an organic electroluminescent element composition comprising the organic electroluminescent element material represented by the formula (I) and a solvent.
Here, it is preferable to further contain a phosphorescent dye.

  In addition, according to the present invention, there is provided an organic electroluminescent device having an anode, a cathode, and an organic light emitting layer provided between both electrodes on a substrate, the organic electroluminescent device represented by the above formula (I) There is provided an organic electroluminescent device characterized by having a layer containing a material for use.

  Here, the layer containing the organic electroluminescent element material is preferably an organic luminescent layer, and the organic luminescent layer uses the organic electroluminescent element material represented by the formula (I) described above as a host material, and the host The material is preferably doped with a phosphorescent material.

  The emission spectrum preferably has a peak in the wavelength range of 425 nm to 500 nm.

  ADVANTAGE OF THE INVENTION According to this invention, the organic electroluminescent element material with a high triplet excitation level and favorable heat resistance can be provided.

  Hereinafter, the best mode (embodiment) for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with various modifications within the scope of the gist. Also, the drawings used are used to describe the present embodiment and do not represent the actual size.

1. Organic Electroluminescent Element Material The organic electroluminescent element material to which the exemplary embodiment is applied is represented by the following formula (I).

(In formula (I), R ^{1 to} R ⁸ represent a hydrogen atom or an arbitrary substituent, and may be the same or different, provided that at least one of R ^{1 to} R ⁸ is A substituted amino group represented by the following formula (II).

(In the formula (II), Ar ¹ and Ar ² each represents an arbitrary substituent, and may be the same or different. Ar ¹ and Ar ² are bonded to each other to form a single ring or a condensed ring. A ring may be formed.)

In the above formula (I), an arbitrary substituent represented by R ^{1 to} R ⁸ is, for example, an alkyl group (preferably a linear or branched alkyl having 1 to 8 carbon atoms) which may have a substituent. Groups such as methyl, ethyl, n-propyl, 2-propyl, n-butyl, isobutyl, tert-butyl groups, etc.); an alkenyl group which may have a substituent (for example, having 1 to 8 carbon atoms) An alkynyl group such as vinyl, allyl, 1-butenyl group, etc.); an alkynyl group which may have a substituent (for example, an alkynyl group having 1 to 8 carbon atoms, ethynyl, propargyl group, etc.) An aralkyl group which may have a substituent (for example, an aralkyl group having 1 to 8 carbon atoms, such as a benzyl group); an amino group which may have a substituent ( Preferably, the substituent One having at least one alkyl group having 1 to 8 primes, for example, methylamino, dimethylamino, diethylamino, dibenzylamino group, etc.); arylamino group which may have a substituent (for example, , Phenylamino, diphenylamino, ditolylamino group, etc.); heteroarylamino group which may have a substituent (for example, pyridylamino, thienylamino, dithienylamino group etc. are included); An acylamino group which may have (for example, acetylamino, benzoylamino group, etc.); an alkoxy group which may have a substituent (preferably an optionally substituted carbon atom having 1 to 8 alkoxy groups, including methoxy, ethoxy, butoxy groups and the like; Si group (preferably having an aromatic hydrocarbon group or a heterocyclic group, including, for example, phenyloxy, 1-naphthyloxy, 2-naphthyloxy, pyridyloxy, thienyloxy groups, etc.); substitution An acyl group which may have a group (preferably an acyl group having 1 to 8 carbon atoms which may have a substituent, including formyl, acetyl, benzoyl group, etc.); An alkoxycarbonyl group which may have a substituent (preferably an alkoxycarbonyl group having 2 to 13 carbon atoms which may have a substituent, including, for example, a methoxycarbonyl, an ethoxycarbonyl group, etc.); An aryloxycarbonyl group (preferably an aryloxycarbonyl group having 2 to 13 carbon atoms which may have a substituent, such as an acetoxy group) A carboxyl group; a cyano group; a hydroxyl group; a thiol group; an alkylthio group optionally having a substituent (preferably an alkylthio group having 1 to 8 carbon atoms, including a methylthio group and an ethylthio group). It is. An arylthio group which may have a substituent (preferably an arylthio group having 1 to 8 carbon atoms, including a phenylthio group, a 1-naphthylthio group, etc.); A sulfonyl group (eg, including a mesyl group, a tosyl group, etc.); a silyl group that may have a substituent (eg, a trimethylsilyl group, a triphenylsilyl group, etc.); Boryl group (for example, including dimesitylboryl group, etc.); Phosphino group that may have a substituent (for example, including diphenylphosphino group); Aromatic carbonization that may have a substituent Hydrogen ring group (for example, benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, trif An aromatic heterocyclic group (for example, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, etc.) Carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring , Pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, and azulene ring). It is.

Moreover, in said formula (II), arbitrary substituents represented by Ar < ¹ > and Ar < ² > are the alkyl groups (preferably C1-C8 linear or branched) which may have a substituent, for example. An alkyl group such as methyl, ethyl, n-propyl, 2-propyl, n-butyl, isobutyl, tert-butyl group, etc.); an alkenyl group which may have a substituent (for example, 1 to An alkynyl group having 8 to 8 carbon atoms, such as vinyl, allyl, 1-butenyl group, etc.); an alkynyl group which may have a substituent (for example, an alkynyl group having 1 to 8 carbon atoms, ethynyl, propargyl group) An aralkyl group which may have a substituent (for example, an aralkyl group having 1 to 8 carbon atoms, such as a benzyl group); an aromatic which may have a substituent Group hydrocarbons Ring group (for example, benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, fluoranthene ring, etc.); aromatic heterocyclic group ( For example, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, Thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, iso Quinoline ring, sinoline ring, quinoxaline ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring and the like).
Among these, Ar ¹ and Ar ² are each preferably an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent.

  As specific examples of the substituted amino group represented by the formula (II), as shown in the following, R-1 as shown in the following, in which charge transportability and electrical redox durability are improved, or a moderately wide redox potential difference is obtained. Preferable examples are each compound of -R-10 and R-47.

In the above formula, L ¹ and L ² each independently represent a hydrogen atom or a group exemplified as a substituent that the substituted amino group represented by the following formula (II) may have.
Among them, R-1 to R-3, R-8, R-11, and R-47 are more preferable, and R-1 is most preferable from the viewpoint of a high triplet excited level.

On the other hand, the material for an organic electroluminescence device of the present embodiment improves the viewpoint and heat resistance by suppressing non-radiative deactivation (thermal deactivation) of excitons due to unnecessary molecular motion and improving emission quantum efficiency. From the viewpoint of making it possible, it is preferable that the Ar ¹ group and Ar ² group in the substituted amino group represented by the formula (II) are linked directly or via a linking group to form a ring.

  Further, from the viewpoint of improving charge transportability and electrical redox durability as a material for an organic electroluminescent device, the substituted amino group represented by the formula (II) is a non-atom on the N atom contained in itself. It is more preferable to have a π-electron that can be conjugated with a shared electron pair, more preferably an aromatic ring group, and most preferably an N-azolyl group or a carbazole group.

  As the substituted amino group represented by the formula (II), more preferable ring groups are specifically shown below from the above viewpoint.

  Among them, R-14 to R-16, R-20 to R-22, R-24, R-27, R-32, R-39, R-40 are more preferable, and R-14, R-15, R -21, R-22 and R-27 are more preferred, R-14 and R-27 are more preferred, and R-27 is most preferred.

The substituted amino group represented by the formula (II) may further have an arbitrary substituent, for example, an alkyl group (preferably a linear or branched group having 1 to 8 carbon atoms) which may have a substituent. And an alkenyl group (for example, having 1 carbon atom) which may have a substituent, such as methyl, ethyl, n-propyl, 2-propyl, n-butyl, isobutyl, tert-butyl group, etc. -8 alkenyl groups, such as vinyl, allyl, 1-butenyl group, etc.); alkynyl groups which may have a substituent (for example, alkynyl groups having 1 to 8 carbon atoms, ethynyl, propargyl An aralkyl group which may have a substituent (for example, an aralkyl group having 1 to 8 carbon atoms, such as a benzyl group); an amino which may have a substituent Group (preferably And a substituent having one or more alkyl groups having 1 to 8 carbon atoms, such as a methylamino, dimethylamino, diethylamino, dibenzylamino group, etc.); Arylamino group (for example, phenylamino, diphenylamino, ditolylamino group, etc.); heteroarylamino group (for example, pyridylamino, thienylamino, dithienylamino group, etc.) which may have a substituent is included. ); An acylamino group which may have a substituent (for example, acetylamino, benzoylamino group, etc.); an alkoxy group which may have a substituent (preferably, which may have a substituent) A good alkoxy group having 1 to 8 carbon atoms, including a methoxy group, an ethoxy group, and a butoxy group); An aryloxy group (preferably having an aromatic hydrocarbon group or a heterocyclic group, including, for example, phenyloxy, 1-naphthyloxy, 2-naphthyloxy, pyridyloxy, thienyloxy groups, etc.); An acyl group which may have a substituent (preferably an acyl group having 1 to 8 carbon atoms which may have a substituent, including formyl, acetyl, benzoyl group, etc.); An alkoxycarbonyl group (preferably an alkoxycarbonyl group having 2 to 13 carbon atoms which may have a substituent, including, for example, methoxycarbonyl, ethoxycarbonyl group, etc.); An aryloxycarbonyl group (preferably an aryloxycarbonyl group having 2 to 13 carbon atoms which may have a substituent, A carboxyl group; a cyano group; a hydroxyl group; a thiol group; an optionally substituted alkylthio group (preferably an alkylthio group having 1 to 8 carbon atoms; a methylthio group, an ethylthio group; Group etc. are included. An arylthio group which may have a substituent (preferably an arylthio group having 1 to 8 carbon atoms, including a phenylthio group, a 1-naphthylthio group, etc.); A sulfonyl group (eg, including a mesyl group, a tosyl group, etc.); a silyl group that may have a substituent (eg, a trimethylsilyl group, a triphenylsilyl group, etc.); Boryl group (for example, including dimesitylboryl group, etc.); Phosphino group that may have a substituent (for example, including diphenylphosphino group); Aromatic carbonization that may have a substituent Hydrogen ring group (for example, benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, trif An aromatic heterocyclic group (for example, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, etc.) Carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring , Pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, and azulene ring)
From the viewpoint of limiting molecular vibration, a hydrogen atom, a methyl group, or a phenyl group is more preferable.
Examples of the substituent that these substituents may have include those exemplified as the substituent of the substituted amino group. The substituted position, for example, locations where the indicated as ^{L 1} and ^{L 2} in the R-1 to R-47 are preferred.

In addition, when the organic electroluminescent element material of the present embodiment is used as a hole transport material, a hole injection material, or an electron blocking material, the amino group represented by the formula (II) has a moderately low oxidation potential. And having a reasonably high reduction potential. In particular, since it is necessary to be stable even in repeated electrical oxidation, Ar ¹ group and Ar ² group are connected directly or via a connecting group to form a condensed ring (for example, a diarylamino group) Is preferred. More preferable examples from this viewpoint are R-1 to R-3, R-8, and R-1 is most preferable.
When the organic electroluminescent element material of the present embodiment is used as a hole transport material, a hole injection material or an electron blocking material, it is mixed with another hole transport material, a hole injection material or an electron blocking material. Can be used, but it is preferably used at a rate of 100%.

On the other hand, when used as an electron transport material or a hole blocking material, the amino group represented by the formula (II) preferably has a moderately high oxidation potential and a moderately low reduction potential. In particular, since it is necessary to be stable for repeated electric reduction, it is preferable that the Ar ¹ group and the Ar ² group are linked directly or via a linking group to form a condensed ring. Furthermore, it is more preferable that the structure contains a lot of N atoms and condensed ring groups. More preferred examples are R-14, R-15, R-20, R-21, R-24 to R-37, R-40 to R-46, and R-14, R-15, R- 20, R-21, R-24, R-27, R-28, R-32, R-34 and R-40 are more preferred.
When the organic electroluminescent element material of the present embodiment is used as an electron transport material or a hole blocking material, it can be used by mixing with other electron transport material or hole blocking material, but at a rate of 100%. It is preferred to use.

Further, when used as a host material in the light emitting layer, the amino group represented by the formula (II) desirably has a moderately high oxidation potential and a moderately high reduction potential. Therefore, it is desirable that the Ar ¹ group and the Ar ² group be connected directly or via a linking group to form a condensed ring, and further, an aromatic heterocyclic ring. It is more preferable that the structure has a moderate amount of condensed ring groups. More preferred examples are R-14 to R-16, R-21, R-22, R-24, R-27, R-32, R-39, R-40, and R-14, R- 15, R-21, R-22, and R-27 are more preferable, R-14 and R-27 are more preferable, and R-27 is most preferable.
When the organic electroluminescent element material of the present embodiment is used as a host material in the light emitting layer, it is usually 50% by weight or more, preferably 80% by weight or more, based on the total weight with the light emitting material (dopant). It is preferably 90% by weight or more, and usually 99% by weight or less, preferably 98% by weight or less, more preferably 95% by weight or less.

In the organic electroluminescent element material represented by the formula (I), R ³ is preferably a substituted amino group represented by the formula (II), and further the organic electroluminescence represented by the formula (I) R ^{6 of the} element material is preferably a substituted amino group represented by the formula (II).
At that time, it is preferable ^{R 3} and ^{R 6} are the same.

  The molecular weight of the organic electroluminescent element material to which this exemplary embodiment is applied is preferably 5000 or less. Further, it is more preferably 3000 or less. Moreover, 400 or more are preferable and 500 or more are still more preferable.

  Below, the specific example of the material for organic electroluminescent elements to which this Embodiment is applied is shown.

2. Next, the composition for organic electroluminescent elements will be described.
The composition for organic electroluminescent elements to which this exemplary embodiment is applied contains at least the material for organic electroluminescent elements described above. Usually, it contains a solvent, preferably a light emitting material.

(1) Luminescent material A luminescent material refers to the component which mainly light-emits in the composition for organic electroluminescent elements, and corresponds to the dopant component in an organic EL device. Of the amount of light (unit: cd / m ² ) emitted from the composition for organic electroluminescent elements, it is usually 10% to 100%, preferably 20% to 100%, more preferably 50% to 100%, and most preferably 80%. If% -100% is identified as luminescence from a component material, it is defined as the luminescent material.

  As the luminescent material, any known material can be applied, and a fluorescent luminescent material or a phosphorescent luminescent material can be used alone or in combination. A phosphorescent luminescent material is preferable from the viewpoint of internal quantum efficiency.

  For the purpose of improving the solubility in a solvent, it is also important to reduce the symmetry and rigidity of the light emitting material molecule or introduce a lipophilic substituent such as an alkyl group.

  Examples of the fluorescent material that gives blue light emission include perylene, pyrene, anthracene, coumarin, p-bis (2-phenylethenyl) benzene, and derivatives thereof. Examples of the fluorescent material that gives green light emission include quinacridone derivatives and coumarin derivatives. Examples of the fluorescent material that gives yellow light include rubrene and perimidone derivatives. Examples of the fluorescent material that emits red light include DCM compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, azabenzothioxanthene, and the like.

  Examples of the phosphorescent material include organometallic complexes containing a metal selected from Groups 7 to 11 of the periodic table.

Preferred examples of the metal in the phosphorescent organometallic complex containing a metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. Preferred examples of these organometallic complexes include compounds represented by the following general formula (III) or the following general formula (IV).
ML ″ _(q−j) L ′ _j (III)
(In the general formula (III), M represents a metal, q represents the valence of the metal, L ″ and L ′ represent a bidentate ligand, and j represents 0, 1 or 2. )

(In General Formula (IV), M ^d represents a metal, T represents carbon or nitrogen. R ^{92 to} R ⁹⁵ each independently represent a substituent. However, when T is nitrogen, R ⁹⁴ and R ⁹⁵ is not.

Hereinafter, the compound represented by formula (III) will be described.
In general formula (III), M represents an arbitrary metal, and specific examples of preferable ones include the metals described above as metals selected from Groups 7 to 11 of the periodic table.
In addition, bidentate ligands L ″ and L ′ in the general formula (III) each represent a ligand having the following partial structure.

  L ′ is particularly preferably the following from the viewpoint of the stability of the complex.

  In the partial structures of L ″ and L ′, the ring A1 represents an aromatic hydrocarbon group or an aromatic heterocyclic group, which may have a substituent. The ring A2 is a nitrogen-containing aromatic group. Represents a heterocyclic group, and these may have a substituent.

  When the rings A1 and A2 have a substituent, preferred substituents include halogen atoms such as fluorine atoms; alkyl groups such as methyl groups and ethyl groups; alkenyl groups such as vinyl groups; methoxycarbonyl groups and ethoxycarbonyl groups. Alkoxycarbonyl groups; alkoxy groups such as methoxy groups and ethoxy groups; aryloxy groups such as phenoxy groups and benzyloxy groups; dialkylamino groups such as dimethylamino groups and diethylamino groups; diarylamino groups such as diphenylamino groups; carbazolyl groups; An acyl group such as an acetyl group; a haloalkyl group such as a trifluoromethyl group; a cyano group; an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, and a phenanthyl group.

  More preferable examples of the compound represented by the general formula (III) include compounds represented by the following general formulas (IIIa), (IIIb), and (IIIc).

(In general formula (IIIa), M ^a represents the same metal as M, w represents the valence of the above metal, and ring A1 represents an aromatic hydrocarbon group which may have a substituent. Ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

(In the general formula (IIIb), M ^b represents the same metal as M, w represents the valence of the metal. Further, the ring A1 is an aromatic optionally substituted hydrocarbon group or a substituted Represents an aromatic heterocyclic group which may have a group, and ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.)

(In general formula (IIIc), M ^c represents the same metal as M, w represents the valence of the metal, j represents 0, 1 or 2. Furthermore, ring A1 and ring A1 ′ are Each independently represents an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group, and ring A2 and ring A2 ′ are each independently Represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

  In the general formulas (IIIa), (IIIb), and (IIIc), the group of the ring A1 and the ring A1 ′ is preferably, for example, a phenyl group, a biphenyl group, a naphthyl group, an anthryl group, a thienyl group, a furyl group, a benzoic group. Examples include thienyl group, benzofuryl group, pyridyl group, quinolyl group, isoquinolyl group, carbazolyl group and the like.

  In addition, the group of ring A2 and ring A2 ′ is preferably a pyridyl group, pyrimidyl group, pyrazyl group, triazyl group, benzothiazole group, benzoxazole group, benzimidazole group, quinolyl group, isoquinolyl group, quinoxalyl group, A phenanthridyl group and the like can be mentioned.

  Furthermore, the substituents that the compounds represented by the general formulas (IIIa), (IIIb), and (IIIc) may have include a halogen atom such as a fluorine atom; an alkyl group such as a methyl group and an ethyl group; vinyl Alkenyl groups such as methoxycarbonyl groups and ethoxycarbonyl groups; alkoxy groups such as methoxy groups and ethoxy groups; aryloxy groups such as phenoxy groups and benzyloxy groups; dialkyls such as dimethylamino groups and diethylamino groups An amino group; a diarylamino group such as a diphenylamino group; a carbazolyl group; an acyl group such as an acetyl group; a haloalkyl group such as a trifluoromethyl group; a cyano group;

  When the said substituent is an alkyl group, the carbon number is 1 or more and 6 or less normally. Furthermore, when the substituent is an alkenyl group, the carbon number is usually 2 or more and 6 or less. When the substituent is an alkoxycarbonyl group, the carbon number is usually 2 or more and 6 or less. Further, when the substituent is an alkoxy group, the carbon number is usually 1 or more and 6 or less. Moreover, when a substituent is an aryloxy group, the carbon number is 6 or more and 14 or less normally. Furthermore, when the substituent is a dialkylamino group, the carbon number is usually 2 or more and 24 or less. When the substituent is a diarylamino group, the carbon number is usually 12 or more and 28 or less. Furthermore, when the substituent is an acyl group, the carbon number is usually 1 or more and 14 or less. Moreover, when a substituent is a haloalkyl group, the carbon number is 1 or more and 12 or less normally.

  These substituents may be connected to each other to form a ring. As a specific example, a substituent of the ring A1 and a substituent of the ring A2 are bonded, or a substituent of the ring A1 ′ and a substituent of the ring A2 ′ are bonded. Two fused rings may be formed. Examples of such a condensed ring group include a 7,8-benzoquinoline group.

  Among them, as a substituent of ring A1, ring A1 ′, ring A2 and ring A2 ′, more preferably an alkyl group, an alkoxy group, an aromatic hydrocarbon group, a cyano group, a halogen atom, a haloalkyl group, a diarylamino group, a carbazolyl group Is mentioned.

In general formula (IIIa), (IIIb), preferably a ^{M a, M b, M c} in (IIIc), ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold.

  Specific examples of the organometallic complex represented by the general formula (III), (IIIa), (IIIb) or (IIIc) are shown below, but are not limited to the following compounds (in the following, Ph is phenyl Represents a group).

  Among the organometallic complexes represented by the above general formulas (III), (IIIa), (IIIb), and (IIIc), in particular, as the ligand L ″ and / or L ′, a 2-arylpyridine-based ligand, That is, a compound having 2-arylpyridine, a compound in which an arbitrary substituent is bonded thereto, and a compound in which an arbitrary group is condensed to this is preferable.

Next, the compound represented by the general formula (IV) will be described.
In the general formula (IV), M ^d represents a metal, and specific examples include the metals described above as the metal selected from Groups 7 to 11 of the periodic table. Among these, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold is preferable, and divalent metals such as platinum and palladium are particularly preferable.

In the general formula (IV), R ⁹² and R ⁹³ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, or a carboxyl group. Represents an alkoxy group, an alkylamino group, an aralkylamino group, a haloalkyl group, a hydroxyl group, an aryloxy group, an aromatic hydrocarbon group or an aromatic heterocyclic group.

Further, when T is carbon, R ⁹⁴ and R ⁹⁵ each independently represent a substituent represented by the same examples as R ⁹² and R ⁹³ . Further, as described above, when T is nitrogen, there is no R ⁹⁴ or R ⁹⁵ .

R ^{92 to} R ⁹⁵ may further have a substituent. In this case, the substituent which may further be present is not particularly limited, and any group can be used as the substituent.
Furthermore, R ^{92 to} R ⁹⁵ may be connected to each other to form a ring, and this ring may further have an arbitrary substituent.

  Specific examples (T-1, T-10 to T-15) of the organometallic complex represented by the general formula (IV) are shown below, but are not limited to the following exemplified compounds. In the following, Me represents a methyl group, and Et represents an ethyl group.

  Moreover, as an organometallic complex, the compounds described in WO2005 / 019373 can also be used.

(2) Solvent Various solvents are applicable as the solvent contained in the composition for organic electroluminescent elements to which the present embodiment is applied, and are not particularly limited. For example, aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene and tetralin; halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene and trichlorobenzene; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene and anisole , Phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole and other aromatic ethers; phenyl acetate, phenyl propionate, methyl benzoate, benzoic acid Aromatic esters such as ethyl, propyl benzoate and n-butyl benzoate; ketones having an alicyclic ring such as cyclohexanone and cyclooctanone; aliphatic ketones such as methyl ethyl ketone and dibutyl ketone; methyl ethyl ketone and cyclohexano Alcohol having an alicyclic ring such as ruthenium or cyclooctanol; Aliphatic alcohol such as butanol or hexanol; Aliphatic ether such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether or propylene glycol-1-monomethyl ether acetate (PGMEA); Ethyl acetate And aliphatic esters such as n-butyl acetate, ethyl lactate and n-butyl lactate.
Of these, aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene, tetralin and the like are preferable in that they have low water solubility and are not easily altered.

  Since organic electroluminescent devices use many materials such as cathodes that deteriorate significantly due to moisture, the presence of moisture in the composition causes moisture to remain in the dried film, degrading the device characteristics. The possibility is considered and it is not preferable.

  Examples of the method for reducing the amount of water in the composition include nitrogen gas sealing, use of a desiccant, dehydration of the solvent in advance, use of a solvent having low water solubility, and the like. In particular, it is preferable to use a solvent having low water solubility because the solution film can prevent whitening by absorbing moisture in the atmosphere during the wet film-forming process. From such a viewpoint, the composition for organic electroluminescent elements to which the present embodiment is applied includes, for example, a solvent having a water solubility at 25 ° C. of 1% by weight or less, preferably 0.1% by weight or less. It is preferable to contain 10% by weight or more in the composition.

  Further, in order to reduce deterioration in film formation stability due to solvent evaporation from the composition during wet film formation, the boiling point is 100 ° C. or higher, preferably 150 ° C. as a solvent for the composition for organic electroluminescent elements. It is effective to use a solvent having a boiling point of 200 ° C. or higher, more preferably 200 ° C. or higher. In order to obtain a more uniform film, it is necessary for the solvent to evaporate from the liquid film immediately after film formation at an appropriate rate. For this purpose, the boiling point is usually 80 ° C. or higher, preferably 100 ° C. or higher. It is effective to use a solvent having a boiling point of 120 ° C. or more, usually less than 270 ° C., preferably less than 250 ° C., more preferably less than 230 ° C.

  A solvent that satisfies the above-mentioned conditions, ie, solute solubility, evaporation rate, and water solubility conditions, may be used alone. However, if a solvent that satisfies all the conditions cannot be selected, two or more solvents may be mixed. It can also be used.

3. Organic Electroluminescent Device Next, the organic electroluminescent device will be described.
The organic electroluminescent device to which the present embodiment is applied has at least an anode, a cathode and a light emitting layer provided between both electrodes on a substrate, and is represented by the general formula (I) described above. It has the layer containing the material for organic electroluminescent elements, It is characterized by the above-mentioned. This layer is preferably a layer formed by a wet film forming method, and in particular, this layer is preferably an organic light emitting layer.

  FIG. 1 is a schematic cross-sectional view showing a structural example suitable for an organic electroluminescent element to which the present exemplary embodiment is applied. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, 5 is a light emitting layer (organic light emitting layer), 6 is a hole blocking layer, 7 is an electron transport layer, 8 Represents an electron injection layer, and 9 represents a cathode.

[1] Substrate The substrate 1 serves as a support for the organic electroluminescence device, and a quartz or glass plate, a metal plate or a metal foil, a plastic film, a sheet, or the like is used. In particular, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, polysulfone or the like is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too small, the organic electroluminescent element may be deteriorated by the outside air that has passed through the substrate, which is not preferable. For this reason, a method of securing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also one of preferable methods.

[2] Anode An anode 2 is provided on the substrate 1. The anode 2 plays a role of hole injection into a layer on the light emitting layer side (such as the hole injection layer 3 or the light emitting layer 5).
This anode 2 is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum, a metal oxide such as an oxide of indium and / or tin, a metal halide such as copper iodide, carbon black, or It is composed of a conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline.

In general, the anode 2 is often formed by a sputtering method, a vacuum deposition method, or the like. In addition, when forming the anode 2 using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, and conductive polymer fine powder, an appropriate binder resin solution It is also possible to form the anode 2 by dispersing it and applying it onto the substrate 1. Furthermore, in the case of a conductive polymer, a thin film can be directly formed on the substrate 1 by electrolytic polymerization, or the anode 2 can be formed by applying a conductive polymer on the substrate 1 (Appl. Phys. Lett. 60, 2711, 1992).
The anode 2 usually has a single-layer structure, but it can also have a laminated structure made of a plurality of materials if desired.

  The thickness of the anode 2 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably about 500 nm or less. When it may be opaque, the thickness of the anode 2 is arbitrary, and the anode 2 may be the same as the substrate 1. Furthermore, it is also possible to laminate different conductive materials on the anode 2 described above.

  For the purpose of removing impurities adhering to the anode 2 and adjusting the ionization potential to improve the hole injection property, the surface of the anode 2 is treated with ultraviolet (UV) / ozone, or with oxygen plasma or argon plasma. It is preferable to do.

[3] Hole Injection Layer Since the hole injection layer 3 is a layer that transports holes from the anode 2 to the light emitting layer 5, the hole injection layer 3 preferably contains a hole transporting compound.

The hole injection layer 3 preferably contains a hole transporting compound, and more preferably contains a hole transporting compound and an electron accepting compound. The hole injection layer 3 preferably contains a cation radical compound, and more preferably contains a cation radical compound and a hole transporting compound.
Furthermore, the hole injection layer 3 may contain a binder resin that does not easily trap charges and a coating property improving agent as necessary.

  However, as the hole injection layer 3, only the electron-accepting compound is formed on the anode 2 by a wet film forming method, and the organic electroluminescent element composition of the present embodiment is directly applied and laminated thereon. It is also possible. In this case, a part of the composition of the present embodiment interacts with the electron-accepting compound, so that a layer having excellent hole injecting property is formed.

(Hole transporting compound)
As the hole transporting compound, a compound having an ionization potential of 4.5 eV to 6.0 eV is preferable.
Examples of the hole transporting compound include aromatic amine compounds, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, and the like. Of these, aromatic amine compounds are preferred from the viewpoints of amorphousness and visible light transmittance.

  An aromatic tertiary amine compound is particularly preferable. Here, the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine.

The kind of the aromatic tertiary amine compound is not particularly limited, but a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less (polymerized hydrocarbon compound in which repeating units are linked) is more preferable from the viewpoint of the surface smoothing effect.
Preferable examples of the aromatic tertiary amine polymer compound include a polymer compound having a repeating unit represented by the following general formula (V).

(In general formula (V), each of Ar ²¹ and Ar ²² independently represents an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. Ar ^{23 to} Ar ²⁵ each independently represents a divalent aromatic hydrocarbon group which may have a substituent, or a divalent aromatic heterocyclic group which may have a substituent. Y represents a linking group selected from the following group of linking groups, and among Ar ^{21 to} Ar ²⁵ , two groups bonded to the same N atom are bonded to each other to form a ring. May be.)

(In the above formulas, Ar ^{31 to} Ar ⁴¹ are each independently 1 derived from an aromatic hydrocarbon ring which may have a substituent, or an aromatic heterocyclic ring which may have a substituent. And R ⁵¹ and R ⁵² each independently represents a hydrogen atom or an arbitrary substituent.)

As Ar ^{21 to} Ar ²⁵ and Ar ^{31 to} Ar ⁴¹ , any monovalent or divalent group derived from any aromatic hydrocarbon ring or aromatic heterocyclic ring is applicable. These may be the same or different from each other. Moreover, you may have arbitrary substituents.

The groups derived from the aromatic hydrocarbon rings and / or aromatic heterocycles of Ar ^{21 to} Ar ²⁵ and Ar ^{31 to} Ar ⁴¹ may further have a substituent. The molecular weight of the substituent is usually 400 or less, preferably about 250 or less.

Ar ²¹ and Ar ²² are preferably monovalent groups derived from a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene ring, or a pyridine ring from the viewpoint of the solubility, heat resistance, and hole injection / transport properties of the polymer compound. More preferred are a phenyl group and a naphthyl group.

Ar ^{23 to} Ar ²⁵ are preferably divalent groups derived from a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring from the viewpoint of heat resistance and hole injection / transport properties including redox potential. A group, a biphenylene group, and a naphthylene group are more preferable.

  Specific examples of the aromatic tertiary amine polymer compound having a repeating unit represented by the general formula (V) include those described in WO2005 / 089024.

  The hole transporting compound used as the material for the hole injection layer 3 may contain any one of these compounds alone, or may contain two or more. When two or more hole transporting compounds are contained, the combination thereof is arbitrary, but one or more aromatic tertiary amine polymer compounds and one or two other hole transporting compounds are used. It is preferable to use the above together.

(Electron-accepting compound)
The electron-accepting compound is preferably a compound having an oxidizing power and the ability to accept one electron from the above-described hole transporting compound, specifically, a compound having an electron affinity of 4 eV or more is preferable, and 5 eV or more. The compound which is the compound of these is further more preferable.

  Examples include onium salts substituted with organic groups such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate, iron (III) chloride (Japanese Patent Laid-Open No. 11-251067), ammonium peroxodisulfate, etc. High valent inorganic compounds, cyano compounds such as tetracyanoethylene, aromatic boron compounds such as tris (pentafluorophenyl) borane (Japanese Patent Laid-Open No. 2003-31365), fullerene derivatives, iodine and the like.

  Of the above compounds, onium salts substituted with organic groups and high valent inorganic compounds are preferred because of their strong oxidizing power, and organic groups are substituted because they are soluble in various solvents and applicable to wet coating. Preferred are onium salts, cyano compounds, and aromatic boron compounds.

  Specific examples of an onium salt substituted with an organic group, a cyano compound, and an aromatic boron compound suitable as an electron-accepting compound include those described in WO 2005/089024, and suitable examples thereof are also the same. Although the compound (A-2) represented by the following structural formula is mentioned, it is not limited to them at all.

(Cation radical compound)
The cation radical compound is an ionic compound composed of a cation radical which is a chemical species obtained by removing one electron from a hole transporting compound and a counter anion. However, when the cation radical is derived from a hole transporting polymer compound, the cation radical has a structure in which one electron is removed from the repeating unit of the polymer compound.

  The cation radical is preferably a chemical species obtained by removing one electron from the aforementioned compound in the hole transporting compound, and is preferably a chemical species obtained by removing one electron from a compound more preferable as the hole transporting compound. From the viewpoints of visible light transmittance, heat resistance, solubility, and the like.

  The cation radical compound can be generated by mixing the hole transporting compound and the electron accepting compound. That is, by mixing the hole transporting compound and the electron accepting compound, electron transfer occurs from the hole transporting compound to the electron accepting compound, and the cation radical and the counter anion of the hole transporting compound are included. A cation ion compound is formed.

  Cationic radical compounds derived from polymer compounds such as PEDOT / PSS (Adv. Mater., 2000, 12, 481) and emeraldine hydrochloride (J. Phys. Chem., 1990, 94, 7716) It is also generated by oxidative polymerization (dehydrogenation polymerization), that is, by oxidizing a monomer chemically or electrochemically with peroxodisulfate in an acidic solution. In the case of this oxidative polymerization (dehydrogenation polymerization), the monomer is oxidized to be polymerized, and the cation radical is formed by removing one electron from the repeating unit of the polymer with an anion derived from an acidic solution as a counter anion. Produces.

  The hole injection layer 3 is formed on the anode 2 by a wet film forming method or a vacuum deposition method.

  In the case of layer formation by the wet film-forming method, a predetermined amount of one or more of the aforementioned materials (hole transporting compound, electron accepting compound, cation radical compound) does not become a charge trap if necessary. Add binder resin and coatability improver, dissolve in solvent, prepare coating solution, by wet film forming method such as spin coating, spray coating, dip coating, die coating, flexographic printing, screen printing, inkjet method etc. It is applied on the anode 2 and dried to form the hole injection layer 3.

  As the solvent used for the layer formation by the wet film forming method, any solvent can be used as long as it can dissolve the above-mentioned materials (hole transporting compound, electron accepting compound, cation radical compound). Is not particularly limited, but generates a deactivated substance or deactivated substance that may deactivate each material (hole transporting compound, electron accepting compound, cation radical compound) used for the hole injection layer 3 What does not contain a thing is preferable. An ether solvent or an ester solvent is preferable.

In the case of forming a layer by vacuum deposition, one or more of the aforementioned materials (hole transporting compound, electron accepting compound, cation radical compound) are put in a crucible installed in a vacuum vessel ( When two or more materials are used, put them in each crucible), and after evacuating the inside of the vacuum vessel to about 10 ⁻⁴ Pa with an appropriate vacuum pump, heat the crucible (if using two or more materials, each The crucible is heated) and evaporated by controlling the amount of evaporation (when two or more materials are used, the amount of evaporation is controlled independently), and on the anode 2 of the substrate 1 placed facing the crucible Then, the hole injection layer 3 is formed. When two or more kinds of materials are used, a mixture thereof can be put into a crucible, heated and evaporated to be used for forming the hole injection layer 3.

  The film thickness of the hole injection layer 3 thus formed is usually in the range of 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less. The hole injection layer 3 may be omitted.

[4] Hole Transport Layer The hole transport layer 4 is provided on the hole injection layer 3. The conditions required for the material of the hole transport layer 4 are that the hole injection efficiency from the anode 2 is high and the material can efficiently transport the injected holes. For this purpose, the ionization potential is low, the transparency to visible light is high, the hole mobility is high, the stability is high, and impurities that become traps are unlikely to be generated during manufacturing or use. Required. Further, in order to contact the light emitting layer 5, it is required not to quench the light emitted from the light emitting layer 5 or to form an exciplex with the light emitting layer 5 to reduce the efficiency. In addition to the above general requirements, when the application for in-vehicle display is considered, the element is further required to have heat resistance. Accordingly, a material having a glass transition temperature of 80 ° C. or higher, more preferably 85 ° C. or higher is preferable.

  As such a hole transporting material, 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl is used similarly to the hole transporting material used for the host material of the light emitting layer 5. Aromatic diamines containing two or more representative tertiary amines and having two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234811), 4,4 ′, 4 ″ -tris (1 -Aromatic amine compounds having a starburst structure such as naphthylphenylamino) triphenylamine (J. Lumin., 72-74, 985, 1997), aromatic amine compounds comprising tetramers of triphenylamine (Chem. Commun., 2175, 1996), spiro compounds such as 2,2 ′, 7,7′-tetrakis- (diphenylamino) -9,9′-spirobifluorene ( ynth.Metals, 91, 209, 1997), carbazole derivatives such as 4,4′-N, N′-dicarbazolebiphenyl, etc. These compounds may be used alone. In addition, a plurality of types may be mixed and used as necessary.

  In addition to the above compounds, polyarylene ether sulfone (Polym. Adv. Tech.) Containing polyvinyl carbazole, polyvinyl triphenylamine (Japanese Patent Laid-Open No. 7-53953), and tetraphenylbenzidine as a material for the hole transport layer 4. 7, Vol. 33, 1996).

  The hole transport layer 4 may be formed by a normal coating method such as a spray method, a printing method, a spin coating method, a dip coating method, or a die coating method, a wet film forming method such as various printing methods such as an ink jet method or a screen printing method, or a vacuum. It can be formed by a dry film formation method such as a vapor deposition method.

  In the case of the coating method, an additive such as a binder resin or a coating property improving agent that does not trap holes is added to one or more of the hole transport materials, if necessary, and dissolved in a suitable solvent. A solution is prepared, applied onto the anode 2 by a method such as spin coating, and dried to form the hole transport layer 4. Examples of the binder resin include polycarbonate, polyarylate, and polyester. When the amount of the binder resin added is large, the hole mobility is lowered. Therefore, the smaller amount is desirable, and the content in the hole transport layer is usually preferably 50% by weight or less.

In the case of the vacuum deposition method, the hole transport material is put in a crucible installed in a vacuum vessel, the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with a suitable vacuum pump, and then the crucible is heated, The hole transport material is evaporated and a hole transport layer 4 is formed on the substrate 1 on which the anode 2 is formed, which is placed facing the crucible.

  The thickness of the hole transport layer 4 is usually 5 nm or more, preferably 10 nm or more, and is usually 300 nm or less, preferably 100 nm or less. In order to uniformly form such a thin film, a vacuum deposition method is generally used.

[5] Light emitting layer (organic light emitting layer)
A light emitting layer 5 is usually provided on the hole transport layer 4. The light emitting layer 5 is, for example, a layer containing the above-described light emitting material. Between the electrodes to which an electric field is applied, holes injected from the anode 2 through the hole injection layer 3 and holes injected from the cathode 9 through the electron injection layer 8 are used. It is a layer that is excited by recombination with other electrons and becomes the main light emitting source. The light emitting layer 5 preferably contains a light emitting material (dopant) and one or more host materials, and the light emitting layer 5 more preferably contains the organic electroluminescent element material of the present embodiment as a host material, Although it may be formed by a vacuum deposition method, a layer formed by a wet film forming method is particularly preferable.
The light emitting layer 5 may contain other materials and components as long as the performance of the organic electroluminescent device of the present embodiment is not impaired.

  In general, in the organic electroluminescence device, when the same material is used, the thinner the film thickness between the electrodes is, the larger the effective electric field is. For this reason, the driving voltage of the organic electroluminescence device decreases when the total film thickness between the electrodes is thin, but if it is too thin, a short circuit occurs due to the protrusion caused by the electrode such as ITO. Necessary.

  In the present embodiment, in addition to the light emitting layer 5, when the organic layer such as the hole injection layer 3 and the electron injection layer 8 described later is provided, the light emitting layer 5, the hole injection layer 3, and the electron injection layer 8 other than The total film thickness combined with the organic layer is usually 30 nm or more, preferably 50 nm or more, more preferably 100 nm or more, usually 1000 nm or less, preferably 500 nm or less, and more preferably 300 nm or less. In addition, when the conductivity of the hole injection layer 3 other than the light emitting layer 5 and the electron injection layer 8 described later is high, the amount of charge injected into the light emitting layer 5 increases. It is also possible to reduce the drive voltage while increasing the thickness to reduce the thickness of the light emitting layer 5 while maintaining the total thickness to some extent.

  Therefore, the film thickness of the light emitting layer 5 is usually 10 nm or more, preferably 20 nm or more, and usually 300 nm or less, preferably 200 nm or less. When the element of the present embodiment has only the light emitting layer 5 between the anode 2 and the cathode 9, the thickness of the light emitting layer 5 is usually 30 nm or more, preferably 50 nm or more, and usually 500 nm or less, preferably Is 300 nm or less.

[6] Hole blocking layer When a phosphorescent dye is used as the luminescent substance or a fluorescent material that gives blue light is used, it is effective to provide the hole blocking layer 6. The hole blocking layer 6 has a function of confining holes and electrons in the light emitting layer 5 and improving luminous efficiency. That is, the hole blocking layer 6 is generated by increasing the recombination probability with electrons in the light emitting layer 5 by blocking the holes moving from the light emitting layer 5 from reaching the electron transport layer 7. There is a role of confining excitons in the light emitting layer 5 and a role of efficiently transporting electrons injected from the electron transport layer 7 in the direction of the light emitting layer 5.

  The hole blocking layer 6 can prevent holes moving from the anode 2 from reaching the cathode 9 and can efficiently transport electrons injected from the cathode 9 toward the light emitting layer 5. The compound is laminated on the light emitting layer 5 so as to be in contact with the interface of the light emitting layer 5 on the cathode 9 side.

  The physical properties required for the material constituting the hole blocking layer 6 include high electron mobility, low hole mobility, a large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high.

  Examples of the material of the hole blocking layer 6 that satisfies such conditions include bis (2-methyl-8-quinolinolato) (phenolato) aluminum, bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum, and the like. Mixed ligand complexes, metal complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinato) aluminum binuclear metal complexes, styryls such as distyrylbiphenyl derivatives Compounds (JP-A-11-242996), triazole derivatives such as 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole (JP-A-7- 41759) and phenanthroline derivatives such as bathocuproine (Japanese Patent Laid-Open No. 10-79297).

  Furthermore, a compound having at least one pyridine ring substituted at the 2,4,6-positions described in WO2005 / 022962 is also preferable as the hole blocking material.

  The film thickness of the hole blocking layer 6 is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less. The hole blocking layer 6 can be formed by the same method as the hole injection layer 3, but usually a vacuum deposition method is used.

[7] Electron Transport Layer The electron transport layer 7 is provided between the light emitting layer 5 and the electron injection layer 8 for the purpose of further improving the light emission efficiency of the device.
The electron transport layer 7 is formed of a compound that can efficiently transport electrons injected from the cathode 9 between electrodes to which an electric field is applied in the direction of the light emitting layer 5. As the electron transporting compound used for the electron transport layer 7, the electron injection efficiency from the cathode 9 or the electron injection layer 8 is high, and the injected electrons can be efficiently transported with high electron mobility. It must be a compound.
Materials satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, oxadiazole derivatives, di- Styryl biphenyl derivative, silole derivative, 3- or 5-hydroxyflavone metal complex, benzoxazole metal complex, benzothiazole metal complex, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compound No. 207169), phenanthroline derivatives (Japanese Patent Laid-Open No. 5-331459), 2-t-butyl-9,10-N, N′-dicyanoanthraquinonediimine, n-type hydrogenated amorphous silicon carbide, n-type sulfide Examples include zinc and n-type zinc selenide.

  The lower limit of the thickness of the electron transport layer 7 is usually 1 nm, preferably about 5 nm, and the upper limit is usually about 300 nm, preferably about 100 nm. The electron transport layer 7 is formed by laminating on the light emitting layer 5 by a wet film forming method or a vacuum deposition method in the same manner as the hole injection layer 3. Usually, a vacuum deposition method is used.

[8] Electron Injection Layer The electron injection layer 8 serves to efficiently inject electrons injected from the cathode 9 into the light emitting layer 5. In order to perform electron injection efficiently, the material for forming the electron injection layer 8 is preferably a metal having a low work function, and an alkali metal such as sodium or cesium, or an alkaline earth metal such as barium or calcium is used. The thickness of the electron injection layer 8 is preferably 0.1 to 5 nm.

Also, an ultrathin insulating film (0.1 to 5 nm) such as LiF, MgF ₂ , Li ₂ O, Cs ₂ CO ₃ may be inserted at the interface between the cathode 9 and the light emitting layer 5 or the electron transport layer 7 described later. This is an effective method for improving the efficiency of the device (Appl. Phys. Lett., 70, 152, 1997; Japanese Patent Laid-Open No. 10-74586; IEEE Trans. Electron. Devices, 44, 1245, 1997). Year; SID 04 Digest, page 154).

  Further, organic electron transport materials represented by metal complexes such as nitrogen-containing heterocyclic compounds such as bathophenanthroline and aluminum complexes of 8-hydroxyquinoline described later are doped with alkali metals such as sodium, potassium, cesium, lithium and rubidium. (Described in Japanese Patent Application Laid-Open No. 10-270171, Japanese Patent Application Laid-Open No. 2002-1000047, Japanese Patent Application Laid-Open No. 2002-1000048, and the like), the electron injecting / transporting property is improved and excellent film quality can be achieved. Therefore, it is preferable. The film thickness in this case is usually 5 nm or more, preferably 10 nm or more, and usually 200 nm or less, preferably 100 nm or less.

The electron injection layer 8 is formed by laminating on the light emitting layer 5 by the wet film forming method or the vacuum deposition method in the same manner as the light emitting layer 5. In the case of the vacuum evaporation method, the evaporation source is put into a crucible or metal boat installed in a vacuum vessel, and the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with an appropriate vacuum pump, and then the crucible or metal boat is By heating and evaporating, the electron injection layer 8 is formed on the substrate placed facing the crucible or metal boat.

The alkali metal is deposited using an alkali metal dispenser in which nichrome is filled with an alkali metal chromate and a reducing agent. By heating the dispenser in a vacuum container, the alkali metal chromate is reduced and the alkali metal is evaporated. In the case of co-evaporating the organic electron transport material and the alkali metal, the organic electron transport material is put in a crucible installed in a vacuum vessel, and the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with a suitable vacuum pump. Each crucible and dispenser are heated simultaneously to evaporate, and an electron injection layer 8 is formed on the substrate 1 placed facing the crucible and dispenser. At this time, co-evaporation is uniformly performed in the film thickness direction of the electron injection layer 8, but there may be a concentration distribution in the film thickness direction. The electron injection layer 8 may be omitted.

[9] Cathode The cathode 9 plays a role of injecting electrons into a layer (such as the electron injection layer 8 or the light emitting layer 5) on the light emitting layer 5 side. The material used for the cathode 9 can be the material used for the anode 2, but a metal having a low work function is preferable for efficient electron injection. Tin, magnesium, indium, calcium, aluminum A suitable metal such as silver or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

  The film thickness of the cathode 9 is usually the same as that of the anode 2. For the purpose of protecting the cathode 9 made of a low work function metal, further laminating a metal layer having a high work function and stable to the atmosphere increases the stability of the device. For this purpose, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used.

[10] Other Constituent Layers Although the above description has focused on the element having the layer structure shown in FIG. 1, in the present embodiment, the anode 2 and the cathode 9 in the organic electroluminescent element and the light emitting layer 5 are interposed. May have any layer as long as its performance is not impaired, and any layer other than the light emitting layer 5 may be omitted. For example, the electron transport layer 7 and the hole blocking layer 6 may be appropriately provided as necessary. 1) Only the electron transport layer, 2) Only the hole blocking layer, and 3) The hole blocking layer / electron transport layer There are usages such as stacking, 4) not using, etc.

  For the same purpose as the hole blocking layer 6, it is also effective to provide an electron blocking layer (not shown) between the hole injection layer 3 and the light emitting layer 5. The electron blocking layer prevents electrons moving from the light emitting layer 5 from reaching the hole injection layer 3, thereby increasing the recombination probability with holes in the light emitting layer 5, and generating generated excitons. There is a role of confining in the light emitting layer 5 and a role of efficiently transporting holes injected from the hole injection layer 3 in the direction of the light emitting layer 5.

The characteristics required for the electron blocking layer include high hole transportability, a large energy gap (difference between HOMO and LUMO), and a high excited triplet level (T1). In addition, when the light emitting layer 5 is formed by a wet film forming method, it is preferable that the electron blocking layer is also formed by a wet film forming method because the device manufacturing becomes easy.
For this reason, it is preferable that the electron blocking layer also has wet film forming compatibility, and examples of the material used for such an electron blocking layer include dioctyl typified by F8-TFB in addition to the organic electroluminescent element composition described above. And a copolymer of fluorene and triphenylamine (described in WO 2004/084260).

Note that the structure opposite to that shown in FIG. 1, that is, the cathode 9, the electron injection layer 8, the light emitting layer 5, the hole injection layer 3, and the anode 2 can be laminated on the substrate 1 in this order. It is also possible to provide an organic electroluminescent element between two substrates, at least one of which is highly transparent.
Furthermore, a structure in which a plurality of layers shown in FIG. 1 are stacked (a structure in which a plurality of light emitting units are stacked) may be employed. In that case, instead of the interfacial layer (between the light emitting units) (when the anode is ITO and the cathode is Al, the two layers), for example, V ₂ O ₅ is used as the charge generation layer (CGL). This is more preferable from the viewpoint of luminous efficiency and driving voltage.

  The organic electroluminescence device to which the present embodiment is applied applies to any of a single device, a device having a structure arranged in an array, and a structure in which an anode and a cathode are arranged in an XY matrix. be able to.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to description of a following example, unless the summary is exceeded.

[Synthesis example of material for organic electroluminescence device]
(Example 1)
A synthesis example of the organic electroluminescent element material (target E-1) represented by the formula (I) is shown below.

In a nitrogen stream, 3,6-diphenylcarbazole (3.99 g), 2,8-diiododibenzo [b, d] furan (2.10 g), CuI (0.02 g), tripotassium phosphate (4.25 g) ) And 1,4-dioxane (25 ml), 1,2-cyclohexanediamine (0.12 ml) was added, and the mixture was stirred for 5.7 hours under heating to reflux. Methanol (40 ml) and water (10 ml) were added to the resulting mixture, and the deposited precipitate was filtered and washed by shaking with methanol, and extracted with dichloromethane (250 ml) and toluene (250 ml). The liquid was concentrated and purified by silica gel column chromatography and recrystallization from a toluene-ethanol mixed solvent to obtain the desired product 1 (2.82 g). A part of this was further purified by sublimation at 450 ° C. under high vacuum to obtain a high-purity product (1.85 g) of the target product E-1.
Using a mass spectrometer (JEOL JMS-700 / MStation mass spectrometer, acceleration voltage 10 kV, ionization voltage 70 eV), desorption electron ionization-mass spectrum (hereinafter referred to as DEI-MS). As a result, the mass analysis value (M ⁺ ) was 802, which confirmed that it was the target product E-1.

The physical properties of the organic electroluminescent element material (target E-1) synthesized by the above procedure are as follows. It was a material excellent in heat resistance and amorphousness.
Glass transition temperature: 171 ° C
Melting point: 302 ° C
Vaporization temperature: 560 ° C

(Example 2)
A synthesis example of the organic electroluminescent element material (target E-2) represented by the formula (I) is shown below.

In a nitrogen stream, 2,8-diiododibenzo [b, d] furan (3.36 g), diphenylamine (5.42 g), copper powder (1.02 g), potassium carbonate (5.53 g), tetraglyme (6 4 ml) was stirred at 180 ° C. for 1.3 hours and at 200 ° C. for 6.3 hours. Dichloromethane (200 ml) was added to the resulting reaction mixture, and after stirring well, the mixture was filtered and the filtrate was washed with brine. After adding anhydrous magnesium sulfate and activated clay, the mixture was filtered, and the filtrate was concentrated, suspended and washed with methanol, and further purified by recrystallization from an ethyl acetate-toluene mixed solvent to obtain the desired product 2 (2.04 g). Got. This was further purified by sublimation at 280 ° C. under high vacuum to obtain a high-purity product (1.81 g) of the target product E-2.
As a result of DEI-MS, the mass analysis value (M ⁺ ) was 502, which confirmed that it was the target product E-2.

The physical properties of the organic electroluminescent element material (target E-2) synthesized by the above procedure are as follows. It was a material excellent in heat resistance and amorphousness and having a high triplet excited level.
Glass transition temperature: 82 ° C
Melting point: 250 ° C
Vaporization temperature: 393 ° C.

(Measurement Example 1)
The triplet excitation level of each material calculated from the phosphorescence emission spectrum when the target product E-1 or E-2 is dissolved in 2-methyltetrahydrofuran solvent at 77 K under a nitrogen atmosphere and excited with a 337 nm wavelength laser is It was as follows.
Object E-1: 450 nm (2.76 eV)
Target product E-2: 441 nm (2.81 eV)

(Reference measurement example 1)
When the following compound was evaluated in the same manner as in Measurement Example 1, it was found that the triplet excitation level was 511 nm, which was not suitable for a phosphorescent device. Further, it has a glass transition temperature of 74 ° C. and a melting point of 179 ° C., and it has been found that there is a problem in heat resistance.

[Manufacture and evaluation of organic electroluminescence devices]
(Example 3)
It was measured by electrochemical measurement (cyclic voltammetry). As a supporting electrolyte, a solution obtained by dissolving 0.1 mol / L of tetrabutylammonium perchlorate in a solvent of acetonitrile: THF = 1: 1, and further measuring 1 mmol / L of one of the above compounds was measured. went. The working electrode was measured using glassy carbon (manufactured by BAS), a platinum wire as a counter electrode, a silver wire as a reference electrode, and a running speed of 100 mV / sec. The redox potential is ferrocene / ferrocenium (Fc / FC ⁺ ) as an internal standard, and this electrode is +0.41 V v. s. The potential was converted to a saturated sweet potato electrode (SCE) as SCE.
The oxidation potential of the target product E-1 was 1.14V, and similarly the reduction potential was -2.39V.

  In electrochemical measurement (cyclic voltammetry), a glassy carbon as a working electrode was prepared by dissolving an appropriate amount of the target product E-1 in methylene chloride containing 0.1 mol / L of tetrabutylammonium perchlorate as a supporting electrolyte. Measurement was performed at a sweep rate of 100 mV / sec using a platinum electrode as an electrode and a counter electrode, and the oxidation potential and reduction potential of the target product E-1 were determined by comparing with the oxidation potential of ferrocene.

Example 4
An organic electroluminescent element having the structure shown in FIG. 1 was produced by the following method.

  An indium tin oxide (ITO) transparent conductive film deposited on a glass substrate 1 having a thickness of 150 nm (sputtered film product; sheet resistance 15 Ω) is a stripe having a width of 2 mm using ordinary photolithography technology and hydrochloric acid etching. The anode 2 was formed by patterning.

  The patterned ITO substrate was cleaned in the order of ultrasonic cleaning with acetone, water with pure water, and ultrasonic cleaning with isopropyl alcohol, dried with nitrogen blow, and finally subjected to ultraviolet ozone cleaning.

  The hole injection layer 3 was formed by a wet coating method as follows. As a material for the hole injection layer 3, a polymer compound having an aromatic amino group represented by the structural formula shown below (P-1 (weight average molecular weight: 29400, number average molecular weight: 12600)) and an electron having the structural formula shown below. Using the accepting compound (A-1), spin coating was performed under the following conditions.

Spin coating conditions Solvent Ethyl benzoate Coating solution concentration P-1 2.0% by weight
A-1 0.4% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds Drying conditions 230 ° C. × 15 minutes A uniform thin film having a thickness of 30 nm was formed by the above spin coating.

Subsequently, the hole transport layer 4 was formed by a vacuum deposition method using a triphenylamine derivative shown below. At this time, the temperature of the crucible of the triphenylamine derivative was set to 253 ° C. to 274 ° C., and the film was stacked with a film thickness of 40.1 nm at a deposition rate of 0.08 nm / second to 0.11 nm / second. The degree of vacuum during deposition was ^{6.2 × 10 -5 Pa~5.8 × 10 -5} Pa.

Subsequently, a light emitting layer 5 was deposited on the hole transport layer 4. As a material for the light-emitting layer 5, the target product E-1 is used together with an iridium complex (D-1) having the structural formula shown below. The target product E-1 is a crucible temperature of 374 ° C. to 381 ° C., and a deposition rate of 0.08 nm. The iridium complex D-1 was laminated at 31.9 nm at a crucible temperature of 261 ° C. to 267 ° C. and a deposition rate of 0.005 nm / second. The degree of vacuum at the time of vapor deposition was 6.1 × 10 ⁻⁵ Pa.

Next, a pyridine derivative (HB-1) shown below was laminated as the hole blocking layer 6 at a crucible temperature of 228 ° C. to 233 ° C. with a deposition rate of 0.08 nm / second to 0.11 nm / second and a film thickness of 5 nm. . The degree of vacuum during deposition was ^{6.0 × 10 -5 Pa~6.3 × 10 -5} Pa.

Next, an aluminum 8-hydroxyquinoline complex (ET-1) shown below was deposited as an electron transport layer 7 on the hole blocking layer 6 in the same manner. The temperature of the crucible for the aluminum 8-hydroxyquinoline complex in this procedure was controlled within the range of 374 ℃ ~348 ℃, vacuum degree during deposition was ^{6.8 × 10 -5 Pa~6.0 × 10 -5} Pa, deposition The speed was 0.08 nm / second to 0.11 nm / second, and the film thickness was 30 nm.

  The substrate temperature during vacuum deposition of the hole transport layer 4, the light emitting layer 5, the hole blocking layer 6 and the electron transport layer 7 was kept at room temperature.

Here, the element that has been deposited up to the electron transport layer 7 is once taken out from the vacuum deposition apparatus into the atmosphere, and a 2 mm wide striped shadow mask is used as a cathode deposition mask. The device was placed in close contact with each other so as to be orthogonal to each other, placed in another vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus was 2.1 × 10 ⁻⁴ Pa or less in the same manner as the organic layer. As the cathode 9, first, lithium fluoride (LiF) was deposited at a deposition rate of 0.01 nm / second to 0.06 nm / second, a degree of vacuum of 2.4 × 10 ⁻⁴ Pa, and 0.5 nm using a molybdenum boat. A film was formed on the electron transport layer 7 in a film thickness. Next, aluminum was heated in the same molybdenum boat, deposition rate 0.1 nm / sec ～0.3Nm / sec, the film thickness at a vacuum degree ^{4.0 × 10 -4 Pa~6.7 × 10 -4} Pa The cathode 9 was completed by forming an aluminum layer of 80 nm. The substrate temperature at the time of vapor deposition of the above two-layered cathode 9 was kept at room temperature.

As described above, an organic electroluminescent element having a light emitting area portion having a size of 2 mm × 2 mm was obtained. The maximum light emission luminance of this element was 55700 cd / m ² .
The maximum wavelength of the emission spectrum of the device was 514 nm, which was identified as that from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.302, 0.625).

(Example 5)
Example 4 except that instead of E-1, the material of the light emitting layer 5 was 1: 1 coevaporation of E-1 and HB-1 (deposition rate: 0.08 nm / second to 0.11 nm / second). In the same manner, an organic electroluminescent element was obtained.
The maximum light emission luminance of this element was 71200 cd / m ² , and the current efficiency at the time of lighting 2500 cd / m ² was 40.7 cd / A.
The maximum wavelength of the emission spectrum of the device was 512 nm, which was identified as from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.306, 0.619).

(Comparative Example 1)
An organic electroluminescent element was obtained in the same manner as in Example 4 except that the following compound was used in place of the target product E-1 as the material of the light emitting layer 5. The maximum light emission luminance of this element was 47680 cd / m ² .
The maximum wavelength of the emission spectrum of the device was 513 nm, which was identified as from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.294, 0.627).

As described above, the organic electroluminescent element material described in detail in this embodiment has a high triplet excitation level and good heat resistance.
For this reason, according to the composition for organic electroluminescent elements containing this organic electroluminescent element material, an organic electroluminescent element with a long lifetime and high luminous efficiency is provided.

It is a schematic diagram of the cross section which shows the structural example suitable for the organic electroluminescent element to which this Embodiment is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Anode, 3 ... Hole injection layer, 4 ... Hole transport layer, 5 ... Light emitting layer (organic light emitting layer), 6 ... Hole blocking layer, 7 ... Electron transport layer, 8 ... Electron injection layer , 9 ... Cathode

Claims (10)

An organic electroluminescent element material represented by the following formula (I):

(In formula (I), R ^{1 to} R ⁸ represent a hydrogen atom or an arbitrary substituent, and may be the same or different, provided that at least one of R ^{1 to} R ⁸ is A substituted amino group represented by the following formula (II).

(In the formula (II), Ar ¹ and Ar ² each represents an arbitrary substituent, and may be the same or different. Ar ¹ and Ar ² are bonded to each other to form a single ring or a condensed ring. A ring may be formed.) The Ar ¹ and Ar ² are each independently an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. 2. The material for an organic electroluminescent element according to 1.   The organic electroluminescent element material according to claim 1, wherein the substituted amino group is an N-azolyl group. The organic electroluminescent element material according to any one of claims 1 to ³ , wherein the R ³ is the substituted amino group. The organic electroluminescent element material according to claim 4, wherein R ⁶ is the substituted amino group.   An organic electroluminescent element composition comprising the organic electroluminescent element material according to any one of claims 1 to 5 and a solvent.   The composition for organic electroluminescent elements according to claim 6, further comprising a phosphorescent dye.   An organic electroluminescent device having an anode, a cathode, and an organic light emitting layer provided between both electrodes on a substrate, comprising the organic electroluminescent device material according to any one of claims 1 to 5. An organic electroluminescent element characterized by having a layer formed as described above.   The organic electroluminescent element according to claim 8, wherein the layer containing the organic electroluminescent element material according to claim 1 is an organic light emitting layer.   10. The organic light emitting layer according to claim 9, wherein the organic electroluminescent element material according to claim 1 is used as a host material, and the host material is doped with a phosphorescent material. Organic electroluminescent element.

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