JP2005123168A - Organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminscent element which has satisfactory luminescence characteristics, has high durability, and is suitable for manufacturing. <P>SOLUTION: The electroluminescent element has a luminescent layer between a pair of electrodes, together with a hole transport layer and an electron transport layer adjacent to the luminescent layer. The luminescent layer contains at least two host materials and at least a red phosphorous luminescent material therein. The ionic potential of the hole transport material in the hole transporting layer is smaller than that of the two host materials in the luminescent layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an organic electroluminescent element capable of emitting light by converting electric energy into light.

  An organic electroluminescence (EL) element has attracted attention as a promising display element because it can emit light with high luminance at a low voltage. Studies on increasing the durability of organic EL elements have been conducted, and various structures of hole injection materials, hole transport materials, light emitting materials, host materials, electron transport materials, and electron injection materials have been studied.

In the singlet light-emitting device, an example in which a metal complex composed of a nitrogen-containing ligand, a nitrogen-containing heterocyclic compound, an electron-transporting compound that is a Si-containing ring compound, and an anthryl compound are mixed as a host has been investigated. It is disclosed (for example, Patent Document 1). An example in which a nonpolar organic compound capable of transporting both electrons and holes and an organic compound having a higher polarity than the component is mixed as a host is disclosed (for example, Patent Document 2). In addition, examples in which a host is mixed with a triplet light-emitting element capable of emitting light with high efficiency are disclosed (for example, Patent Document 3, Patent Document 4, Patent Document 5, and Patent Document 6). However, there are problems in terms of efficiency, color purity, and durability, and improvements have been desired. Patent Documents 4 and 5 disclose triplet red light-emitting elements using a mixed host, but their manufacturing methods are complicated. The device suitability is low.
JP 2001-284050 A European Patent Application No. 1221473 JP 2002-313583 A JP 2002-313584 A JP 2002-313585 A JP 2002-319492 A

  An object of the present invention is to provide an organic electroluminescent device having good light emission characteristics and durability, and excellent manufacturing suitability.

As a result of studying the above problems, the present inventors have reached the present invention by the following means.
1. An organic electroluminescent device having a light emitting layer, a hole transport layer, and an electron transport layer between a pair of electrodes, the light emitting layer containing at least two host materials and at least one red phosphorescent light emitting material, An organic electroluminescence device, wherein an ionization potential of a hole transport material in a transport layer is smaller than an ionization potential of two host materials in the light-emitting layer.
2. The lowest excited triplet energy level of at least one of the red phosphorescent materials in the light emitting layer is 167.6 kJ / mol (40 Kcal / mol) or more and 230.5 kJ / mol (55 Kcal / mol) or less. The above 1. The organic electroluminescent element of description.
3. All of the host material in the light emitting layer is a non-metallic complex compound. Or 2. The organic electroluminescent element of description.
4). 1. The lowest excited triplet energy level in the film state of the host material in the light emitting layer is larger than the lowest excited triplet energy level of the red phosphorescent compound. ~ 3. Organic electroluminescent element as described in any one of these.

5). 2. At least one of the host materials in the light emitting layer is made of a compound having a heterocyclic skeleton containing two or more heteroatoms. The organic electroluminescent element of description.
6). 4. The host material comprising a compound having a heterocyclic skeleton containing two or more heteroatoms is represented by the following general formula (I): The organic electroluminescent element of description.

(In the formula, R represents a hydrogen atom or a substituent. X represents —O—, —S—, ═N— or ═N—Ra, where Ra is a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group. Q represents a group of atoms necessary for bonding with N and X to form a condensed heterocycle.)
7). 5. The host material comprising a compound having a heterocyclic skeleton containing two or more heteroatoms contains a compound represented by the general formula (HI). The organic electroluminescent element of description.

(In the formula, R represents a hydrogen atom or a substituent. X represents —O—, —S—, ═N— or ═N—Ra, where Ra is a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group. Z represents an atomic group necessary for forming an aromatic ring.)
8). 6. The host material comprising a compound having a heterocyclic skeleton containing two or more heteroatoms contains a compound represented by the general formula (H-II). The organic electroluminescent element of description.

(Wherein, X _E is -O -, - S -., = N- or = N-Ra (Ra is hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group) .Z _E Represents an atomic group necessary for forming an aromatic ring, B represents a linking group, and m represents an integer of 2 or more.
9. 5. The host material comprising a compound having a heterocyclic skeleton containing two or more heteroatoms contains a compound represented by the general formula (H-III). The organic electroluminescent element of description.

(In the formula, R _E31 , R _E32 and R _E33 each represent a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group.)
10. 5. The host material comprising a compound having a heterocyclic skeleton containing two or more heteroatoms contains a compound represented by the following general formula (H-IV). The organic electroluminescent element of description.
General formula (H-IV)

(In the formula, R ₁ represents a substituent, L ₁ represents a linking group, n ₁ represents an integer of 0 to 4, and m ₁ represents an integer of 2 or more.)
11. 5. The host material comprising a compound having a heterocyclic skeleton containing two or more heteroatoms contains a compound represented by the following general formula (HV). The organic electroluminescent element of description.
General formula (HV)

(In the formula, R ₂ represents a substituent, L ₂ represents a linking group, n ₂ represents an integer of 0 to 4, and m ₂ represents an integer of 2 or more.)
12 6. The host material comprising a compound having a heterocyclic skeleton containing two or more heteroatoms contains a compound represented by the general formula (H-VI). The organic electroluminescent element of description.
General formula (H-VI)

(Wherein R ^A1 , R ^A2 and R ^A3 each represent a hydrogen atom or an aliphatic hydrocarbon group. R ^A4 , R ^A5 and R ^A6 each represent a substituent. N ^A1 , n ^A2 and n ^A3 Each represents an integer of 0 to 3. X ^A1 , X ^A2 and X ^A3 each represent a nitrogen atom or C—R ^X (R ^X represents a hydrogen atom or a substituent) Y ^A1 , Y ^A2 And Y ^A3 each represents a nitrogen atom or C—R ^YX (where R ^YX represents a hydrogen atom or a substituent).
13. 6. The host material comprising a compound having a heterocyclic skeleton containing two or more heteroatoms contains a compound represented by the following general formula (H-VII): The organic electroluminescent element of description.
General formula (H-VII)

(Wherein R ₁₁ represents a substituent, R ₁₂ represents a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group, R ₁₃ represents a hydrogen atom or a substituent, and n represents 0 to 2) Represents an integer, L represents a single bond or a linking group, and m represents an integer of 2 or more.)
14 The organic electroluminescent element contains an electron transport layer, and the electron transport layer contains a compound represented by the general formula (E1). To 13 above. Organic electroluminescent element as described in any one of these.

(In the formula, R _E represents a hydrogen atom or a substituent. X _E represents —O—, —S—, ═N— or ═N—Ra, where Ra represents a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a hetero group. Q _E represents a group of atoms necessary to form a heterocyclic ring by combining with N and X _E. )
15. The electron transport layer contains a compound represented by the general formula (E-II). The organic electroluminescent element of description.

(Wherein, X _E is -O -, - S -., = N- or = N-Ra (Ra is hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group) .Z _E Represents an atomic group necessary for forming an aromatic ring, B represents a linking group, and m represents an integer of 2 or more.
16. 15. The above-mentioned 14., wherein the electron transport layer contains a compound represented by the general formula (E-III). The organic electroluminescent element of description.

(In the formula, R _E31 , R _E32 and R _E33 represent a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group.)
17. The electron transport layer contains a compound represented by the general formula (E-IV). The organic electroluminescent element of description.
Formula (E-IV)

(In the formula, R ^A1 , R ^A2 and R ^A3 each represent a hydrogen atom or an aliphatic hydrocarbon group. R ^A4 , R ^A5 and R ^A6 each represent a substituent. N ^A1 , n ^A2 and n ^A3 Each represents an integer of 0 to 3. X ^A1 , X ^A2 and X ^A3 each represent a nitrogen atom or C—R ^X (R ^X represents a hydrogen atom or a substituent) Y ^A1 , Y ^A2 And Y ^A3 each represents a nitrogen atom or C—R ^YX (where R ^YX represents a hydrogen atom or a substituent).
18. In an organic electroluminescent device having a light emitting layer between a pair of electrodes and a hole transport layer and an electron transport layer adjacent to the light emitting layer, at least two host materials and at least one red phosphorescent light emitting material in the light emitting layer And an organic electroluminescence device characterized in that at least one host material in the light emitting layer is a compound represented by the following general formula (I).

  (In the formula, R represents a hydrogen atom or a substituent. X represents —O—, —S—, ═N— or ═N—Ra, where Ra is a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group. Q represents a group of atoms necessary to form a condensed heterocycle by combining with N and X. Hereinafter, in the present specification, a double bond at = N- represents Q The bond between X and X is a double bond, and the double bond in = N-Ra represents two single bonds, and the single bond between Q and X, and X, R and N are Represents a single bond with a bonded carbon atom.)

The light-emitting element of the present invention is excellent in light emission characteristics (color purity and external quantum efficiency (φ _EL )) and durability (small increase in drive voltage and decrease in luminance over time).

  Hereinafter, the best mode for carrying out the present invention will be described in detail. In the present specification, “to” indicates a range including numerical values described before and after that as a minimum value and a maximum value, respectively.

The present invention is an organic electroluminescent device having a light emitting layer, a hole transport layer, and an electron transport layer between a pair of electrodes, wherein at least two types of host materials and at least one type of red light are included in the light emitting layer. And a phosphorescent material. Japanese Patent Application Laid-Open No. 2002-305085 discloses a similar red light emitting triplet element, in which the hole transport material adjacent to the light emitting layer, the electron transport layer or the block layer is formed as the light emitting layer host, It is described that a mixture of an electron transport material and a block material is used and the energy barrier at the interface between the light-emitting layer and the adjacent layer is reduced, so that the carrier is lubricated and the element life is improved. However, if the material constituting the adjacent layer of the light emitting layer is used as the light emitting layer host, for example, the compounds that can be selected in terms of hole injection / transport properties and electron injection / transport properties from the electrode are limited, which is sufficient from the viewpoint of durability. A stable compound cannot be selected. In Japanese Patent Laid-Open No. 2002-305085, BAlq is used as a mixed host. However, such a metal complex has low stability of radical cations generated upon energization, and its durability is not sufficient.
The present invention is characterized in that at least two host materials are used in the light emitting layer, and the ionization potential of the hole transport material in the hole transport layer is smaller than the ionization potential of the two host materials in the light emitting layer, and the resulting layer interface The radical cation formation region is adjusted by controlling the hole injection property using the energy difference, and more preferably, a more stable non-complex host is used to improve device stability. is there. Next, the material which comprises the light emitting layer of this invention is demonstrated.

  A material that emits phosphorescence is referred to as a “phosphorescent material”. The light emitting device of the present invention includes at least one phosphorescent material. The phosphorescent material used in the present invention is not particularly limited, but a transition metal complex is preferable. The central metal of the transition metal complex is not particularly limited, but is preferably iridium, platinum, rhenium, or ruthenium, more preferably iridium or platinum, and particularly preferably iridium. Of the transition metal complexes, orthometalated complexes are very preferred. Orthometalated Complexes are written by Akio Yamamoto, “Organic Metals Fundamentals and Applications”, pages 150 and 232, Houbobo (1982) and H.C. Yersin, “Photochemistry and Photophysics of Coordination Compound”, pages 71 to 77 and pages 135 to 146, Springer-Verlag (1987), etc.

The phosphorescent material preferably has a phosphorescent quantum yield of 70% or higher at 20 ° C. or higher, more preferably 80% or higher, and still more preferably 85% or higher.
The phosphorescence lifetime (room temperature) of the phosphorescent compound of the present invention is not particularly limited, but is preferably 1 ms or less, more preferably 100 μs or less, and even more preferably 10 μs or less.

  Examples of the phosphorescent compound of the present invention include US Patent (US) 6303238B1, US6097147, International Publication (WO) 00/57676, WO00 / 70655, WO01 / 08230, WO01 / 39234A2, WO01 / 41512A1, WO02 / 02714A2, WO02. / 15645A1, Japanese Patent Application No. 2001-247859, Japanese Patent Application No. 2000-33561, Japanese Patent Application No. 2001-189539, Japanese Patent Application No. 2001-248165, Japanese Patent Application No. 2001-339684, Japanese Patent Application No. 2001-239281, Japanese Patent Application No. 2001-219909, EP121212 -226495, JP 2002-234894, JP 2001-247659, JP 2001-298470, JP 2002-173684, JP 2002-203678, JP 20 2-203679, Nature, 395, 151 (1998), Applied Physics Letters, 75, 4 (1999), Polymer Preprints, 41, 770 (2000), Journal of. Red phosphorescent materials described in non-patent documents such as American Chemical Society, 123, 4304 (2001) and Applied Physics Letters, 79, 2082 (1999) can be suitably used. Preferably, red phosphorescent materials described in US Pat. No. 6,303,238B1, WO01 / 41512A1, WO02 / 45466A1, JP2001247478, JP2001298470, JP2002-203678, Japanese Patent Application 2002-251871, Japanese Patent Application 2003-157006 Can be mentioned.

  The red light emitting material preferably has an emission maximum of 550 nm to 700 nm, more preferably 560 nm to 680 nm, and particularly preferably 580 nm to 660 nm. The lowest excited triplet energy level of the red light emitting material is preferably 167.6 kJ / mol (40 Kcal / mol) or more and 243.0 kJ / mol (58 Kcal / mol or less, more preferably 188.6 kJ / mol (45 Kcal / mol). ) To 230.5 kJ / mol (55 Kcal / mol), particularly preferably 188.6 kJ / mol (45 Kcal / mol) to 217.9 kJ / mol (52 Kcal / mol).

  The concentration of the phosphorescent compound of the present invention in the light emitting layer is preferably 1% by mass to 50% by mass, more preferably 1% by mass to 30% by mass, and more preferably 1% by mass to 10% by mass. More preferably, it is% or less.

Next, the host material contained in the light emitting layer will be described. The compound used as the host material is a compound that can inject holes and electrons, and the minimum excited triplet energy of the film state may be equal to or higher than the lowest excited triplet energy of the red light emitting material.
Specifically, a 5- to 7-membered heterocyclic compound containing a nitrogen atom, an oxygen atom, or a sulfur atom (for example, pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoxaline, quinazoline, phthalazine, cinnoline, isoquinoline, pteridine, acridine, Phenazine, pyrrole, furan, thiophene, tetrazole, pyrazole, imidazole, thiazole, oxazole, indazole, benzimidazole, benzotriazole, benzoxazole, benzothiazole, carbazole, indole, purine, triazolopyridazine, triazolopyrimidine, tetrazaindene, Pyralidine, pyrrolopyridine, thiadiazolopyridine, dibenzazepine, tribenzazepine, etc.), polyarylene compounds, fluorene compounds, cyclope Tadiene compounds, condensed aromatic carbocyclic compounds (preferably 2 to 5 rings, more preferably 2 to 4 rings, particularly preferably 2 to 3 rings, for example, compounds having naphthalene, phenanthrene, anthracene and the like. ), A triarylamine compound, and a metal complex having a nitrogen-containing heterocyclic compound as a ligand (in addition, a compound represented by the general formula (I) described in JP-A No. 2000-302754).

More preferably, the host material is a non-metal complex compound, which is a triarylamine compound, a carbazole compound, an indole compound, a pyrrole compound, a pyrazole compound, a thiophene compound, a polyarylene compound, a condensed aromatic carbocyclic compound, or two heteroatoms. Examples thereof include compounds having a heterocyclic skeleton.
The compound having a heterocyclic skeleton containing two or more heteroatoms used in the present invention is a compound having two or more atoms other than carbon atoms and hydrogen atoms in the basic skeleton forming a ring, and is monocyclic or condensed. It may be. The heterocyclic skeleton is preferably an aromatic heterocyclic ring having at least two atoms selected from N, O and S atoms, more preferably an aromatic heterocyclic ring in which at least one of the heteroatoms is an N atom. Is an aromatic heterocycle having two or more N atoms in the skeleton. In addition, the heteroatom may be in a condensed position or a non-condensed position. Examples of the heterocyclic skeleton containing two or more heteroatoms include pyrazole, imidazole, pyrazine, pyrimidine, indazole, benzimidazole, purine, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, phenanthroline, pyrroloimidazole, pyrrolotriazole, pyra Zoloimidazole, pyrazolotriazole, pyrazolopyrimidine, pyrazolotriazine, imidazoimidazole, imidazopyridazine, imidazopyridine, imidazopyrazine, triazolopyridine, triazolopyridazine, triazolopyrimidine, benzimidazole, naphthimidazole, benzoxazole, naphthoxazole , Benzothiazole, naphthothiazole, benzotriazole, tetrazaindene, triazine Etc. can be mentioned, preferably 5 to have two or more heteroatoms in one ring is a six-membered ring, in the case of 5-membered one having a ring hetero rings are condensed is more preferable. For example, imidazopyridazine, imidazopyridine, imidazopyrazine, benzimidazole, triazolopyridazine, triazolopyrimidine, purine, naphthimidazole, benzoxazole, naphthoxazole, benzothiazole, naphthothiazole, triazine, more preferably imidazopyridine, imidazopyrazine , Benzimidazole, triazolopyridazine, triazolopyrimidine, purine, naphthimidazole, triazine, more preferably imidazopyridine, benzimidazole, triazolopyridazine, triazolopyrimidine, purine, naphthimidazole, triazine, particularly preferably Imidazopyridine, triazolopyridazine, triazolopyrimidine, purine, and triazine.

  As the host material, triarylamine compounds, carbazole compounds, indole compounds described in JP-A No. 2002-305084, pyrrole compounds, pyrazole compounds, polyarylene compounds described in JP-A No. 2003-27048, and JP-A No. 2001-192651 are particularly preferable. The condensed aromatic carbocyclic compounds described above, and compounds composed of condensed rings containing two or more heteroatoms represented by the following general formula (I).

  (In the formula, R represents a hydrogen atom or a substituent. X represents —O—, —S—, ═N— or ═N—Ra, where Ra is a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group. Q represents a group of atoms necessary for bonding with N and X to form a condensed heterocycle.)

  In general formula (I), R represents a hydrogen atom or a substituent. X represents O, S, N, or N-Ra (Ra represents a hydrogen atom, an aliphatic hydrocarbon group, an aryl group, or a heterocyclic group). Q represents an atomic group necessary for bonding with N and X to form a condensed heterocycle. R and X, and R and Q may be combined to form a ring, if possible.

  Examples of the substituent represented by R include, for example, 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, and iso-propyl. , Tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, Particularly preferably, it has 2 to 10 carbon atoms, and examples thereof include vinyl, allyl, 2-butenyl, 3-pentenyl, etc.), an alkynyl group (preferably 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, Particularly preferably, it has 2 to 10 carbon atoms, and examples thereof include propargyl and 3-pentynyl), an aryl group (preferably Or 6 to 20 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenyl, p-methylphenyl, naphthyl, and the like, and amino groups (preferably carbon atoms). Number 0 to 30, more preferably 0 to 24 carbon atoms, particularly preferably 0 to 20 carbon atoms, such as amino, methylamino, dimethylamino, diethylamino, dibenzylamino, diphenylamino, ditolylamino, dinaphthylamino and the like. And particularly preferably a diphenylamino, ditolylamino, dinaphthylamino group), an alkoxy group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms). Methoxy, ethoxy, butoxy, 2-ethylhexyloxy, etc.), An aryloxy group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, and examples thereof include phenoxy, 1-naphthoxy, 2-naphthoxy and the like), a heterocyclic ring. An oxy group (preferably having 2 to 20 carbon atoms, more preferably 3 to 16 carbon atoms, particularly preferably 4 to 12 carbon atoms, such as pyridinooxy, pyrimidinooxy, pyridazinooxy, benzimidazolyloxy, etc.), a silyloxy group. (Preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, and particularly preferably 3 to 20 carbon atoms. Examples thereof include trimethylsilyloxy, t-butyldimethylsilyloxy, and triphenylsilyloxy.) An acyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20, particularly preferably 2 to 12 carbon atoms, such as acetyl, benzoyl, formyl, pivaloyl and the like. ), An alkoxycarbonyl group (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonyl, ethoxycarbonyl, etc.), aryloxycarbonyl A group (preferably having 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenoxycarbonyl), an acyloxy group (preferably having 2 to 30 carbon atoms). More preferably 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, such as acetoxy and benzoyloxy), acylamino group (preferably 2 to 30 carbon atoms, more preferably 2 carbon atoms). -20, particularly preferably 2 to 10 carbon atoms, such as acetylamino, 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). An aryloxycarbonylamino group (preferably having a carbon number of 7 to 30, more preferably a carbon number of 7 to 20, particularly preferably a carbon number of 7 to 12, such as phenoxycarbonylamino), a sulfonylamino group (preferably Has 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include methanesulfonylamino and benzenesulfonylamino.), A sulfamoyl group (preferably 0 carbon atoms). To 30, more preferably 0 to 20 carbon atoms, particularly preferably 0 to 12 carbon atoms. For example, sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, phenylsulfamoyl, etc.), carbamoyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably carbon 1 to 12, for example, carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl, etc.), alkylthio group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably carbon number). 1 to 12, for example, methylthio, ethylthio, etc.), arylthio groups (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenylthio A heterocyclic thio group (preferably having a carbon number) 1-30, More preferably, it is C1-C20, Most preferably, it is C1-C12, for example, pyridylthio, 2-benzimidazolylthio, 2-benzoxazolylthio, 2-benzthiazolylthio etc. are mentioned. . ), A sulfonyl group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms such as mesyl and tosyl), a sulfinyl group (preferably carbon). 1 to 30, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfinyl, benzenesulfinyl, etc.), ureido group (preferably 1 to 30 carbon atoms, more Preferably it is C1-C20, Most preferably, it is C1-C12, for example, ureido, methylureido, phenylureido etc. are mentioned), phosphoric acid amide group (preferably C1-C30, more preferably It has 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms. Examples thereof include diethyl phosphoric acid amide and phenyl phosphoric acid amide. Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group Group, heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom and a sulfur atom, specifically, for example, imidazolyl, pyridyl and quinolyl. , Furyl, thienyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzothiazolyl, carbazolyl, azepinyl, etc.), silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably Has 3 to 24 carbon atoms, such as trimethylsilyl, tri Enirushiriru and the like.), And the like. These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different. If possible, they may be linked to form a ring.

  The substituent represented by R is preferably an aliphatic hydrocarbon group, an aryl group or a heterocyclic group, more preferably an aryl group or an aromatic heterocyclic group, still more preferably an aryl group, 5 or 6 member. And particularly preferably an aryl group, a 5- or 6-membered aromatic heterocyclic group containing at least one of N, S and O atoms, and most preferably an aryl group.

  X represents O, S, N, or N-Ra. Ra represents a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group. The aliphatic hydrocarbon group represented by Ra is a linear, branched or cyclic alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms, Methyl, ethyl, iso-propyl, tert-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably). Has 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms, and examples thereof include vinyl, allyl, 2-butenyl, 3-pentenyl and the like, and an alkynyl group (preferably having 2 to 20 carbon atoms, more preferably Has 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms, and examples thereof include propargyl and 3-pentynyl. Mashiku is an alkyl group.

  The aryl group represented by Ra is a monocyclic or condensed aryl group, preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and further preferably 6 to 12 carbon atoms. 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2-methoxyphenyl, 3-trifluoromethylphenyl, pentafluorophenyl, 1-naphthyl, 2-naphthyl and the like. The heterocyclic group represented by Ra is a monocyclic or condensed heterocyclic group (preferably a heterocyclic group having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, still more preferably 2 to 10 carbon atoms). And preferably an aromatic heterocyclic group containing at least one of a nitrogen atom, an oxygen atom, a sulfur atom and a selenium atom. Specific examples of the heterocyclic group represented by Ra include, for example, pyrrolidine, piperidine, piperazine, morpholine, thiophene, selenophene, furan, pyrrole, imidazole, pyrazole, pyridine, pyrazine, pyridazine, pyrimidine, triazole, triazine, indole, Indazole, purine, thiazoline, thiazole, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzothiazole Benzotriazole, tetrazaindene, carbazole, azepine and the like, preferably furan, Thiophene, pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, more preferably furan, thiophene, pyridine, quinoline, further more preferably quinoline.

  The aliphatic hydrocarbon group, aryl group, and heterocyclic group represented by Ra may have a substituent, and as the substituent, those exemplified as the group represented by R in the general formula (I) are applied. The preferred substituents are also the same. Ra is preferably an alkyl group, an aryl group, or an aromatic heterocyclic group, more preferably an aryl group or an aromatic heterocyclic group, and still more preferably an aryl group.

  X is preferably O, N or N-Ra, more preferably N or N-Ra, particularly preferably N or N-Ar (Ar is an aryl group (preferably having 6 to 30 carbon atoms, more preferably). An aryl group having 6 to 20 carbon atoms, more preferably an aryl group having 6 to 12 carbon atoms), an aromatic heterocyclic group (preferably 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, still more preferably 2 to 10 carbon atoms). Aromatic heterocyclic group), preferably an aryl group.

Q represents a group of atoms necessary for bonding with N and X to form a condensed heterocyclic ring. The fused heterocycle formed by Q is preferably an aromatic fused heterocycle, more preferably a ring to which N and X are bonded is a 5- to 8-membered aromatic heterocycle, still more preferably N and X The ring to which is bonded is a 5- or 6-membered aromatic heterocycle. Specific examples of the heterocyclic ring to which N and X are bonded include imidazole ring, oxazole ring, thiazole ring, selenazole ring, tellurazole ring, triazole ring, tetrazole ring, oxadiazole ring, thiadiazole ring, oxatriazole ring, thiatriazole Ring, pyrimidine ring, pyridazine ring, pyrazine ring, triazine ring, tetrazine ring and the like are preferable, preferably imidazole ring, oxazole ring, thiazole ring, triazole ring, triazine ring, more preferably imidazole ring, oxazole ring, triazole. A ring and a triazine ring, and more preferably an imidazole ring, a triazole ring and a triazine ring. The heterocyclic ring to which N and X are bonded is further condensed with another ring to form a ring. In addition, the fused heterocycle may have a substituent.
Examples of the substituent include those exemplified as the group represented by R. The substituent for Q is preferably an alkyl group, alkenyl group, alkynyl group, aryl group, amino group, alkoxy group, aryloxy group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, acyloxy group, acylamino group, sulfonylamino group , Sulfamoyl group, carbamoyl group, alkylthio group, arylthio group, sulfonyl group, halogen atom, cyano group, heterocyclic group, more preferably alkyl group, alkenyl group, aryl group, alkoxy group, aryloxy group, halogen atom, A cyano group and a heterocyclic group, more preferably an alkyl group, an aryl group, an alkoxy group, an aryloxy group and an aromatic heterocyclic group, particularly preferably an alkyl group, an aryl group, an alkoxy group and an aromatic heterocyclic group. It is.

  Preferred forms of the compound represented by general formula (I) are represented by general formula (HI), general formula (H-III), general formula (HI-IV), and general formula (HV). A compound.

  In general formula (HI), R has the same meaning as that in general formula (I), and the preferred range is also the same. X represents -O-, -S- or = N-Ra. Ra has the same meaning as that in formula (I), and the preferred range is also the same. X is preferably -O-, = N-Ra, more preferably = N-Ra, particularly preferably = N-Ar (Ar is an aryl group (preferably having 6 to 30 carbon atoms, more preferably carbon). An aryl group having 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms, and an aromatic heterocyclic group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, still more preferably 2 to 10 carbon atoms). Aromatic heterocyclic group), preferably an aryl group. Z represents an atomic group necessary for forming an aromatic ring. The aromatic ring formed by Z may be either an aromatic hydrocarbon ring or an aromatic heterocycle. Specific examples include, for example, a benzene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a pyridazine ring, a triazine ring, and a pyrrole ring. , Furan ring, thiophene ring, selenophene ring, tellurophen ring, imidazole ring, thiazole ring, selenazole ring, tellurazole ring, thiadiazole ring, oxadiazole ring, pyrazole ring, etc., preferably benzene ring, pyridine ring, pyrazine ring , A pyrimidine ring and a pyridazine ring, more preferably a benzene ring, a pyridine ring, a pyrazine ring and a pyrimidine ring, still more preferably a benzene ring, a pyridine ring and a pyrimidine ring, and particularly preferably a pyridine ring. The aromatic ring formed by Z may further form a condensed ring with another ring, and may have a substituent. As the substituent, for example, those exemplified as the group represented by R in the general formula (I) can be applied, and the substituent of the aromatic ring formed by Z is preferably an alkyl group, an alkenyl group, an alkynyl group, an aryl group. Amino group, alkoxy group, aryloxy group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, acyloxy group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino group, sulfamoyl group, carbamoyl group, Alkylthio group, arylthio group, sulfonyl group, halogen atom, cyano group, heterocyclic group, more preferably alkyl group, alkenyl group, aryl group, alkoxy group, aryloxy group, halogen atom, cyano group, heterocyclic group Yes, more preferably Group, an aryl group, an alkoxy group, an aryloxy group, an aromatic heterocyclic group, particularly preferably an alkyl group, an aryl group, an alkoxy group, an aromatic heterocyclic group.

The more preferable form of the compound represented by general formula (HI) is general formula (H-II), general formula (H-VI), and general formula (H-VII).
General formula (H-II) is synonymous with general formula (B-II) described in JP-A No. 2002-319491, and the preferred range is also the same. -III) to (BX).
General formula (H-IV) is synonymous with general formula (A) of Unexamined-Japanese-Patent No. 2002-1000047, A preferable range is also the same.
General formula (H-VII) is synonymous with general formula (I) of Unexamined-Japanese-Patent No. 2002-338579, and its preferable range is also the same.

General formula (H-III) is synonymous with general formula (C-II) of Unexamined-Japanese-Patent No. 2002-319491, and its preferable range is also the same.
General formula (HV) and general formula (H-VI) are synonymous with general formula (I) and general formula (II) of Unexamined-Japanese-Patent No. 2002-356489, and their preferable range is also the same.

The metal complex having a nitrogen-containing heterocyclic compound represented by the general formula (II) as a ligand is synonymous with the general formula (I) described in JP-A No. 2000-302754, and the preferred range is also the same.

The organic electroluminescent element of the present invention is preferably a compound having a heterocyclic skeleton in which at least one of the host materials in the light emitting layer contains two or more heteroatoms as described above.
Other particularly preferable hosts are represented by the general formula (I) described in JP-A-2002-1000047, and more preferably the general formula (A-1), the general formula (B-1), and the general formula (C- 1), compounds represented by general formula (D-1), and the following specific examples.

  The concentration of at least one host material of the present invention in the light emitting layer is preferably 1% by mass or more and 99% by mass or less, more preferably 5% by mass or more and 90% by mass or less, and more preferably 10% by mass or more. More preferably, it is 80% by mass or less, and the rest is phosphorescent light emitting material and other host material.

  All the host materials in the light emitting layer are preferably all non-metallic complex compounds, more preferably at least one host material is a compound having a heterocyclic skeleton, and more preferably, at least one host material is a heteroatom. In particular, at least one host material is a heterocyclic condensed ring compound having two or more heteroatoms in one ring.

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

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

  The light emitting layer of the organic electroluminescent element of the present invention may have a plurality of domain structures of an electron transport compound and a hole transport compound. The light emitting layer may have another domain structure. The diameter of each domain is preferably from 0.2 nm to 10 nm, more preferably from 0.3 nm to 5 nm, still more preferably from 0.5 nm to 3 nm, and particularly preferably from 0.7 nm to 2 nm.

The material constituting the electron injection / transport layer of the present invention will be described.
The material for the electron injection layer and the electron transport layer of the present invention is any material that has one of the function of injecting electrons from the cathode, the function of transporting electrons, and the function of blocking holes injected from the anode. good. As the material for the electron transport layer, an electron withdrawing group (preferably an electron withdrawing group having a Hammett σp value of 0.2 or more, more preferably an aryl group, an aromatic heterocyclic group, a cyano group, a carbonyl group, Group, thiocarbonyl group, oxycarbonyl group, acylamino group, carbamoyl group, sulfamoyl group, sulfonyl group, imino group, halogen atom, etc.) substituted aromatic carbocyclic compounds (preferably benzene, naphthalene, anthracene, Phenanthracene, tetracene, pyrene, pentacene, perylene, coronene, chrysene, picene, pericyclene, acenaphthene, fluoranthene, etc.), nitrogen-containing aromatic heterocycle (5- to 6-membered aromatic nitrogen-containing heterocycle) As a hetero atom, oxygen atom, nitrogen atom, sulfur atom It may contain silicon atoms and may form 2 to 10 condensed rings such as pyridine structure, pyrazine structure, pyrimidine structure, pyridazine structure, pyrrole structure, pyrazole structure, imidazole structure, oxazole structure, thiazole structure, triazole. Structure and combinations thereof), and metal complexes.
Specific examples include aromatics such as triazole, oxazole, oxadiazole, imidazole, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyrandioxide, carbodiimide, fluorenylidenemethane, distyrylpyrazine, naphthalene, and perylene. Examples thereof include metal complexes of detracarboxylic anhydride, phthalocyanine, 8-quinolinol derivatives, metal phthalocyanines, metal complexes represented by benzoxazole and benzothiazole ligands, organosilane compounds, and derivatives thereof.

  The material contained in the electron transport layer is preferably a compound represented by general formula (I) described in JP-A No. 2002-319491 (here, a compound represented by general formula (I) is represented by general formula (E1)). And a compound represented by the general formula (A) described in JP-A-2002-1000047 (here, the compound represented by the general formula (A) is represented by the general formula (E-IV)). It is displayed as a compound represented by

(In the formula, R _E represents a hydrogen atom or a substituent. X _E represents —O—, —S—, ═N— or ═N—Ra, where Ra represents a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a hetero group. Q _E represents a group of atoms necessary to form a heterocyclic ring by combining with N and X _E. The explanation of each group is the general description in JP-A-2002-319491. The same as in formula (I).

  The preferable form of the compound represented by general formula (E1) is the following general formula (E2) or general formula (E-III).

In the formula, R _E and X _E have the same meanings as those in formula (E1). Z _E represents an atomic group necessary for forming an aromatic ring, and is the same as Z described in the general formula (II) described in JP-A-2002-319491.

A more preferable form of the compound represented by the general formula (E2) is the general formula (E-II), in which Z _E , X _E and B are the general formulas (B- It is synonymous with that described in II), and the preferred range is also the same, and compounds represented by general formulas (B-III) to (BX) described in JP-A No. 2002-319491.
B in the general formula (E-II) and the general formula (H-II) represents a linking group, and the linking group represented by B is preferably formed of C, N, O, S, Si, Ge, or the like. A linking group. B is preferably a carbon atom, an alkylene, an alkenylene, an alkynylene, an arylene, a polyvalent aromatic ring (may be an aromatic ring consisting of only a carbon atom or a heterocyclic ring, and preferably a heterocyclic ring such as an azole, thiophene, furan ring And a group consisting of a combination of N and these, more preferably an arylene, a trivalent aromatic ring and a group consisting of a combination of N and these, and more preferably Is a group composed of a trivalent aromatic ring and N and a combination thereof, and particularly preferably a 1,3,5-benzenetriyl group.

In the formula, R _E31 , R _E32 and R _E33 represent a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group, and are represented by the general formula (C-II) described in JP-A No. 2002-319491. It is synonymous with a compound, and its preferable range is also the same. Specific examples of the compound represented by the general formula (E1) used in the present invention are specific examples (Compound Nos. 205 to 306, 367 to 381) described in JP-A No. 2002-319491. It is not limited.
Formula (E-IV)

In the formula, R ^A1 , R ^A2 and R ^A3 each represent a hydrogen atom or an aliphatic hydrocarbon group. R ^A4 , R ^A5 and R ^A6 each represent a substituent. n ^A1 , n ^A2 and n ^A3 each represent an integer of 0 to 3. X ^A1 , X ^A2 and X ^A3 each represent a nitrogen atom or C—R ^X (R ^X represents a hydrogen atom or a substituent). Y ^A1 , Y ^A2 and Y ^A3 each represents a nitrogen atom or C—R ^YX (R ^YX represents a hydrogen atom or a substituent), and is represented by the general formula (A) described in JP-A No. 2002-1000047. And the preferred range is also the same.

Next, a method for creating a configuration of the light emitting device of the present invention will be described.
The method for forming the organic layer of the light emitting device of the present invention is not particularly limited, and methods such as resistance heating vapor deposition, electron beam, sputtering, molecular lamination method, coating method, ink jet method, and printing method are used. Resistance heating vapor deposition, coating method, and transfer method are preferable in terms of characteristics and production.

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

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

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

  The cathode supplies electrons to the electron injection layer, the electron transport layer, the light emitting layer, etc., and the adhesion, ionization potential, stability, etc., between the negative electrode and the adjacent layer such as the electron injection layer, electron transport layer, light emitting layer, etc. Selected in consideration of As a material for the cathode, a metal, an alloy, a metal halide, a metal oxide, an electrically conductive compound, or a mixture thereof can be used. Specific examples include an alkali metal (for example, Li, Na, K, etc.) and its fluoride. Or oxides, alkaline earth metals (eg Mg, Ca, etc.) and fluorides or oxides thereof, gold, silver, lead, aluminum, sodium-potassium alloys or their mixed metals, lithium-aluminum alloys or their mixtures Examples thereof include metals, magnesium-silver alloys or mixed metals thereof, rare earth metals such as indium and ytterbium, preferably materials having a work function of 4 eV or less, more preferably aluminum, lithium-aluminum alloys or mixed metals thereof. , Magnesium-silver alloys or mixed metals thereof. The cathode can take not only a single layer structure of the compound and the mixture but also a laminated structure including the compound and the mixture. For example, a laminated structure of aluminum / lithium fluoride and aluminum / lithium oxide is preferable. The film thickness of the cathode can be appropriately selected depending on the material, but is usually preferably in the range of 10 nm to 5 μm, more preferably 50 nm to 1 μm, still more preferably 100 nm to 1 μm.

  For production of the cathode, methods such as an electron beam method, a sputtering method, a resistance heating vapor deposition method, and a coating method are used, and a metal can be vapor-deposited alone or two or more components can be vapor-deposited simultaneously. Furthermore, a plurality of metals can be vapor-deposited simultaneously to form an alloy electrode, or a previously prepared alloy may be vapor-deposited. The sheet resistance of the anode and the cathode is preferably low, and is preferably several hundred Ω / □ or less.

  Although the film thickness of a light emitting layer is not specifically limited, Usually, the thing of the range of 1 nm-5 micrometers is preferable, More preferably, it is 5 nm-1 micrometer, More preferably, it is 10 nm-500 nm.

  The method for forming the light emitting layer is not particularly limited, but resistance heating vapor deposition, electron beam, sputtering, molecular lamination method, coating method (spin coating method, casting method, dip coating method, etc.), inkjet method, printing method , LB method, transfer method and the like are used, preferably resistance heating vapor deposition and coating method.

  The material of the hole injection layer and the hole transport layer may be any one having a function of injecting holes from the anode, a function of transporting holes, or a function of blocking electrons injected from the cathode. Good. Specific examples include carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives. , Fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, porphyrin compounds, polysilane compounds, poly (N-vinylcarbazole) derivatives, aniline compounds Examples include copolymers, thiophene oligomers, conductive polymer oligomers such as polythiophene, organic silane derivatives, carbon films, and the compounds of the present invention. The film thicknesses of the hole injection layer and the hole transport layer are not particularly limited, but are usually preferably in the range of 1 nm to 5 μm, more preferably 5 nm to 1 μm, and still more preferably 10 nm to 500 nm. . The hole injection layer and the hole transport layer may have a single-layer structure composed of one or more of the materials described above, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

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

  Although the film thickness of an electron injection layer and an electron carrying layer is not specifically limited, The thing of the range of 1 nm-5 micrometers is preferable normally, More preferably, it is 5 nm-1 micrometer, More preferably, it is 10 nm-500 nm. The electron injection layer and the electron transport layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.

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

As a material for the protective layer, any material may be used as long as it has a function of preventing substances 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 O. ₃ , metal oxides such as Y ₂ O ₃ and TiO ₂ , metal fluorides such as MgF ₂ , LiF, AlF ₃ and CaF ₂ , SiO _x N _y , polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetra Copolymers obtained by copolymerizing fluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, a copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, and a monomer mixture containing tetrafluoroethylene and at least one comonomer. Polymer, fluorine-containing copolymer having a cyclic structure in the copolymer main chain, water absorption of 1% or less The above water-absorbing substances, moisture-proof substances having a water absorption rate of 0.1% or less, and the like are mentioned.

There is no particular limitation on the method for forming the protective layer. For example, vacuum deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency excitation ions) Plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method,
Printing and transfer methods 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 surface shape of the substrate (for example, forming a fine uneven 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 method in which light emission is extracted from the cathode side.

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

  The organic electroluminescent element of the present invention can be suitably used in the fields of display elements, displays, backlights, electrophotography, illumination light sources, recording light sources, exposure light sources, reading light sources, signs, signboards, interiors, optical communications, and the like.

[Example]
Examples of the present invention will be described below, but the embodiments of the present invention are not limited thereto.

(Comparative example)
As an element containing two or more types of host materials and a red phosphorescent compound in the light emitting layer, Japanese Patent Application Laid-Open Nos. 2002-313584 and 2002-313585, BAlq and α-NPD (N, N An element using PtOEP (T ₁ = 45 Kcal / mol) as a light emitting material is disclosed in which '-diphenyl-N, N'-di (α-naphthyl) -benzidine) is mixed. Therefore, the following elements were produced. The cleaned ITO substrate was put into a vapor deposition apparatus, copper phthalocyanine was deposited to 10 nm, and α-NPD was deposited to 40 nm thereon to form a hole transport layer. On top of this, NPD is used as the first host, BAlq is used as the second host, and PtOEP is used as the light emitting material so that the film thickness becomes 20 nm at 0.4 nm / sec, 0.1 nm / sec, and 0.03 nm / sec, respectively. Co-evaporated to form a light emitting layer. On top of that, BAlq was vapor-deposited at 10 nm and Alq was vapor-deposited at 40 nm. A patterned mask (a mask with a light emission area of 2 mm × 2 mm) is placed on the organic thin film, 5 nm of lithium fluoride is deposited in the deposition apparatus, 500 nm of aluminum is then deposited, and the device is subsequently sealed to form an EL device. (Element No-101, emission wavelength: 648 nm). The light emitting material was changed to I-1 by the same operation as described above, and an EL element was produced (element No-102, emission wavelength: 620 nm).

After depositing α-NPD in the same manner as in the comparative example, the first host, the second host, and the light emitting material (T-1 of I- ₁ : 49 Kcal / mol) described in Table 1 were each 0.4 nm / second, A light emitting layer was formed by co-evaporation so that the film thickness was 20 nm at 0.1 nm / second and 0.03 nm / second. On top of that, an electron transport material shown in Table 1 was deposited by 50 nm, and then the cathode was deposited and sealed in the same manner as described above to produce EL devices (devices 103 to 107, emission wavelength of device 103: 620 nm).

Next, each element was evaluated as follows.
Using a source measure unit 2400 made by Toyo Technica on an organic thin film, a DC constant current is applied to the EL element to cause the comparative example and the element of the present invention to emit light, and the luminance is measured by Topcon's luminance meter BM-8. Was measured using a spectrum analyzer PMA-11 manufactured by Hamamatsu Photonics Co., Ltd. to determine the luminous efficiency. The results are shown in Table 1.

  Compared with the element 101 and the element 102 containing a host common to the hole transport material, the elements of the present invention using the host having a large Ip (elements 103 to 107) exhibit better luminous efficiency and durability. Further, an element in which all of the hosts in the light emitting layer are non-complex (elements 104 to 107) shows better luminous efficiency, and in particular, an element using a heterocyclic host having two or more heteroatoms in one ring (105 -107) shows even better luminous efficiency. Also. The light emitting device of the present invention is also excellent in durability. As described above, the element of the present invention realizes a triplet light emitting element that is excellent in light emission efficiency, in particular, excellent in light emission, durability, and aging characteristics excellent in blue purity. Further, the device of the present invention is not complicated in vapor deposition operation as in the devices of JP-A-2002-313584 and JP-A-2002-313585, and is excellent in device fabrication suitability.

Claims (10)

  An organic electroluminescent device having a light emitting layer, a hole transport layer, and an electron transport layer between a pair of electrodes, wherein at least two kinds of host materials and at least one kind of red phosphorescent light emitting material are contained in the light emitting layer. And an ionization potential of the hole transport material in the hole transport layer is smaller than the ionization potentials of the two types of the host materials in the light-emitting layer.   The lowest excited triplet energy level of at least one kind of the red phosphorescent material in the light emitting layer is 167.6 kJ / mol (40 Kcal / mol) or more and 230.5 kJ / mol (55 Kcal / mol) or less. The organic electroluminescent element according to claim 1.   The organic electroluminescent element according to claim 1, wherein all the host materials in the light emitting layer are non-metallic complex compounds.   4. The organic electroluminescent device according to claim 3, wherein at least one of the host materials in the light emitting layer is a compound having a heterocyclic skeleton containing two or more heteroatoms. The organic electroluminescence device according to claim 4, wherein the compound having a heterocyclic skeleton containing two or more heteroatoms is represented by the following general formula (I).

(In the formula, R represents a hydrogen atom or a substituent. X represents —O—, —S—, ═N— or ═N—Ra, where Ra is a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group. Q represents a group of atoms necessary for bonding with N and X to form a condensed heterocycle.) The organic electroluminescent device contains an electron transport layer, and the electron transport layer contains a compound represented by the general formula (E1). Organic electroluminescent element.

(In the formula, R _E represents a hydrogen atom or a substituent. X _E represents —O—, —S—, ═N— or ═N—Ra, where Ra represents a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a hetero group. Q _E represents a group of atoms necessary to form a heterocyclic ring by combining with N and X _E. ) The organic electroluminescence device according to claim 6, wherein the electron transport layer contains a compound represented by the general formula (E-II).

(Wherein, X _E is -O -, - S -., = N- or = N-Ra (Ra is hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group) .Z _E Represents an atomic group necessary for forming an aromatic ring, B represents a linking group, and m represents an integer of 2 or more. The organic electroluminescent element according to claim 6, wherein the electron transport layer contains a compound represented by the general formula (E-III).

(In the formula, R _E31 , R _E32 and R _E33 each represent a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group.) The organic electroluminescent element according to claim 6, wherein the electron transport layer contains a compound represented by the general formula (E-IV).

(In the formula, R ^A1 , R ^A2 and R ^A3 each represent a hydrogen atom or an aliphatic hydrocarbon group. R ^A4 , R ^A5 and R ^A6 each represent a substituent. N ^A1 , n ^A2 and n ^A3 Each represents an integer of 0 to 3. X ^A1 , X ^A2 and X ^A3 each represent a nitrogen atom or C—R ^X (R ^X represents a hydrogen atom or a substituent) Y ^A1 , Y ^A2 And Y ^A3 each represents a nitrogen atom or C—R ^YX (where R ^YX represents a hydrogen atom or a substituent). In an organic electroluminescent device having a light emitting layer between a pair of electrodes and a hole transport layer and an electron transport layer adjacent to the light emitting layer, at least two host materials and at least one red phosphorescent light emitting material are contained in the light emitting layer. An organic electroluminescence device containing, wherein at least one host material in the light emitting layer is a compound represented by the following general formula (I):

(In the formula, R represents a hydrogen atom or a substituent. X represents —O—, —S—, ═N— or ═N—Ra, where Ra is a hydrogen atom, an aliphatic hydrocarbon group, an aryl group or a heterocyclic group. Q represents a group of atoms necessary for bonding with N and X to form a condensed heterocycle.)