JP5362999B2 - Organic EL device and dibenzophosphole oxide derivative - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL device having high light-emission efficiency, a long life, and a low driving voltage. <P>SOLUTION: The organic EL device comprises an organic thin film layer. Furthermore, the organic thin film layer comprises a dibenzophosphole oxide derivative represented by general formula (I) (wherein, R<SP>1</SP>and R<SP>2</SP>are each a hydrogen atom, an aliphatic or an aromatic hydrocarbon group or an aromatic heterocyclic group; a and b are each an integer of 1-4; L is a direct bond or a divalent group derived from a substituted or nonsubstituted aromatic hydrocarbon group, or an aromatic heterocyclic group; n is an integer of 1-4; Ar is a direct bond, a hydrogen atom or a mono- to a trivalent group derived from a substituted or nonsubstituted aromatic hydrocarbon group, or an aromatic heterocyclic group; and m is an integer of 1-3). <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

The present invention relates to an organic EL (electroluminescence) elements and dibenzophosphol hole oxide induced body. The use of di-benzo phosphole oxide derivative of the present invention, it is possible to achieve improved long life and the driving voltage of the organic EL element.

  An organic EL element using an organic material as a light-emitting substance (also referred to as an “organic electroluminescent element”) is a molecule in an excited state by recombination of holes injected from an anode and electrons injected from a cathode. Excitons are formed, and when the excitons return to the ground state, energy is emitted to emit light.

  In 1987, Eastman Kodak's CWTang and others announced an organic electroluminescent device with an organic film stacked between an anode and a cathode, and emitted light with high brightness at low voltage. (CWTang et al., “Applied Physics Letters”, 1987, Vol. 51, p. 913: Non-Patent Document 1).

  Since the announcement by Mr. Tan et al., Research has been actively conducted on organic electroluminescent devices, such as light emission of RGB three primary colors, luminance enhancement, stability, laminated structure, and manufacturing method. At present, organic electroluminescent devices have been partially put into practical use as displays for mobile phones and car audios, and are promising as next-generation flat displays to replace liquid crystal displays.

In an organic electroluminescent element, an electron transport material is often used in combination with a light emitting material.
The electron transport material is used to efficiently transport electrons injected from the cathode to the light emitting layer, and also serves to block holes. As the electron transport material, for example, oxadiazole derivatives and Alq ₃ (tris (8-hydroxyquinoline) aluminum) widely used as a green light emitting material are used.

（式中、Ｒは水素原子または置換基を有していてもよいアルキル基、シクロアルキル基、アルケニル基、シクロアルケニル基、アルキニル基、アルコキシ基、シクロアルキロキシ基、アルケニロキシ基、シクロアルケニロキシ基、アリール基、アラルキル基、アリーロキシ基、アラルキロキシ基もしくは複素環式基を示し、Ａｒはアリール基または芳香族複素環式基を示す）で表される９−オキソ−９−ホスファフルオレン誘導体が開示されている。 Japanese Patent Application Laid-Open No. 2004-256468 (Patent Document 1) discloses a formula that can be used as a constituent material of an organic electroluminescent element:

(In the formula, R represents a hydrogen atom or an optionally substituted alkyl group, cycloalkyl group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, cycloalkoxy group, alkenyloxy group, cycloalkenyloxy group. A 9-oxo-9-phosphafluorene derivative represented by a group, an aryl group, an aralkyl group, an aryloxy group, an aralkyloxy group or a heterocyclic group, and Ar represents an aryl group or an aromatic heterocyclic group) It is disclosed.

（式中、Ｒは水素原子または置換基を有していてもよいアルキル基、シクロアルキル基、アルケニル基、シクロアルケニル基、アルキニル基、アルコキシ基、シクロアルキロキシ基、アルケニロキシ基、シクロアルケニロキシ基、アリール基、アラルキル基、アリーロキシ基、アラルキロキシ基もしくは複素環式基を示し、Ｔｈは置換基を有していてもよいチオフェンジイル基を示し、ｎは３以上の自然数を示す）で表される９−オキソ−９−ホスファフルオレン−２，７−ジイル基を主鎖に含む重合体が開示されている。
しかしながら、このような従来の電子輸送材料は、いまだ有機電界発光素子に用いた際の駆動電圧が高く、寿命特性も不十分であり改善が望まれている。 Japanese Patent Application Laid-Open No. 2004-256469 (Patent Document 2) describes a formula that can be used as a constituent material of an organic electroluminescent element:

(In the formula, R represents a hydrogen atom or an optionally substituted alkyl group, cycloalkyl group, alkenyl group, cycloalkenyl group, alkynyl group, alkoxy group, cycloalkoxy group, alkenyloxy group, cycloalkenyloxy group. A group, an aryl group, an aralkyl group, an aryloxy group, an aralkyloxy group or a heterocyclic group, Th represents a thiophenediyl group which may have a substituent, and n represents a natural number of 3 or more) Polymers containing 9-oxo-9-phosphafluorene-2,7-diyl groups in the main chain are disclosed.
However, such a conventional electron transport material still has a high driving voltage when used in an organic electroluminescent device, has insufficient life characteristics, and is desired to be improved.

JP 2004-256468 A JP 2004-256469 A C.W.Tang et al., "Applied Physics Letters", 1987, 51, p.913.

  The present invention provides an organic EL device with high luminous efficiency, long life and low driving voltage, and further provides a dibenzophosphole oxide derivative particularly suitable as an electron transport material used in the organic EL device of the present invention. The task is to do.

As a result of intensive research in order to solve the above problems, the present inventors have used a specific dibenzophosphole oxide derivative as an electron transporting material, thereby achieving high luminous efficiency, long life, and low driving voltage. The present inventors have found that an organic EL element can be obtained and have completed the present invention.
The dibenzophosphole derivative of the present invention is similar to the material described in the above publication, but is different because it does not have a structure crosslinked at the 9-position of phosphafluorene.

  Thus, according to the present invention, in an organic EL device in which an organic thin film layer composed of one or more layers including at least a light emitting layer is sandwiched between an anode and a cathode, the organic thin film layer has the general formula (I):

(Wherein R ¹ and R ² are the same or different and are a hydrogen atom, an aliphatic or aromatic hydrocarbon group or an aromatic heterocyclic group; a and b are the same or different and each represents 1 to 4 A plurality of R ¹ and R ² may be the same or different when a and b are integers greater than or equal to ² ;
L is a divalent group derived from a bond or a substituted or unsubstituted aromatic hydrocarbon group or aromatic heterocyclic group; n is an integer of 1 to 4, and n is an integer of 2 or more. In some instances, multiple Ls may be the same or different;
Ar is a 1-3 valent group derived from a bond, a hydrogen atom, a substituted or unsubstituted aromatic hydrocarbon group or an aromatic heterocyclic group; m is an integer of 1 to 3, and m is A plurality of Ls may be the same or different when they are integers of 2 or more)
The organic EL element characterized by containing the dibenzophosphole oxide derivative represented by these is provided.

  Moreover, according to this invention, the dibenzophosphole oxide derivative characterized by represented by general formula (I) is provided.

Furthermore, according to the present invention,
In the presence of a metal catalyst and / or a base, an aryl halide and 9-hydro-dibenzophosphole and / or 9-hydro-dibenzophosphole oxide are reacted in a solvent, and then the phosphorus atom of the resulting reaction product Is oxidized with an oxidizing agent to obtain a dibenzophosphole oxide derivative of the above general formula (I), and a method for producing a dibenzophosphole oxide derivative, and 9-chloro-dibenzophosphole oxide and aryllithium or There is provided a process for producing a dibenzophosphole oxide derivative characterized by reacting an aryl Grignard reagent with a solvent in a solvent to obtain the dibenzophosphole oxide derivative of the above general formula (I).

  According to the present invention, a dibenzophosphole oxide derivative that is particularly suitable as an electron transport material for use in the organic EL device of the present invention is provided that provides an organic EL device with high luminous efficiency, long life, and low driving voltage. Can be provided.

  The organic EL device of the present invention is an organic EL device in which an organic thin film layer composed of one or more layers including at least a light emitting layer is sandwiched between an anode and a cathode, and the organic thin film layer is represented by the general formula (I). A dibenzophosphole oxide derivative.

R ¹ and R ² in the general formula (I) are the same or different and each represents a hydrogen atom, an aliphatic or aromatic hydrocarbon group or an aromatic heterocyclic group.

  Examples of the “aliphatic hydrocarbon group” include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, s-butyl group, isobutyl group, t-butyl group, n-pentyl group, and n-hexyl. Group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group and other alkyl groups having 1 to 10 carbon atoms, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, 4-methylcyclohexyl group Cycloalkyl groups having 3 to 10 carbon atoms such as 1-adamantyl group, 2-adamantyl group, 1-norbornyl group and 2-norbornyl group.

  Examples of the “aromatic hydrocarbon group” include phenyl group, 1-naphthyl group, 2-naphthyl group, 1-anthryl group, 2-anthryl group, 9-anthryl group, 1-phenanthryl group, 2-phenanthryl group, 3-phenanthryl group, 4-phenanthryl group, 9-phenanthryl group, 1-naphthacenyl group, 2-naphthacenyl group, 9-naphthacenyl group, 1-pyrenyl group, 2-pyrenyl group, 4-pyrenyl group, 2-biphenylyl group 3-biphenylyl group, 4-biphenylyl group, p-terphenyl-4-yl group, p-terphenyl-3-yl group, p-terphenyl-2-yl group, m-terphenyl-4- Yl group, m-terphenyl-3-yl group, m-terphenyl-2-yl group, o-tolyl group, m-tolyl group, p-tolyl group, pt-butylphenyl group p- (2-phenylpropyl) phenyl group, 3-methyl-2-naphthyl group, 4-methyl-1-naphthyl group, 4-methyl-1-anthryl group, 4′-methylbiphenylyl group, 4 ″ -t And -butyl-p-terphenyl-4-yl group.

  Among these, phenyl, 1-naphthyl, 2-naphthyl, 9- (10-phenyl) anthryl, 9- (10-naphthyl-1-yl) anthryl, 9- (10-naphthyl-2-) Yl) anthryl group, 9-phenanthryl group, 1-pyrenyl group, 2-pyrenyl group, 4-pyrenyl group, 2-biphenylyl group, 3-biphenylyl group, 4-biphenylyl group, o-tolyl group, m- A tolyl group, p-tolyl group, and pt-butylphenyl group are particularly preferred.

As the “aromatic heterocyclic group”, for example,
1-pyrrolyl group, 2-pyrrolyl group, 3-pyrrolyl group,
Pyrazinyl group, 2-pyridinyl group, 3-pyridinyl group, 4-pyridinyl group,
1-indolyl group, 2-indolyl group, 3-indolyl group, 4-indolyl group, 5-indolyl group, 6-indolyl group, 7-indolyl group,
1-isoindolyl group, 2-isoindolyl group, 3-isoindolyl group, 4-isoindolyl group, 5-isoindolyl group, 6-isoindolyl group, 7-isoindolyl group,

2-furyl group, 3-furyl group,
2-benzofuranyl group, 3-benzofuranyl group, 4-benzofuranyl group, 5-benzofuranyl group, 6-benzofuranyl group, 7-benzofuranyl group,
1-isobenzofuranyl group, 3-isobenzofuranyl group, 4-isobenzofuranyl group, 5-isobenzofuranyl group, 6-isobenzofuranyl group, 7-isobenzofuranyl group,

2-quinolyl group, 3-quinolyl group, 4-quinolyl group, 5-quinolyl group, 6-quinolyl group, 7-quinolyl group, 8-quinolyl group,
1-isoquinolyl group, 3-isoquinolyl group, 4-isoquinolyl group, 5-isoquinolyl group, 6-isoquinolyl group, 7-isoquinolyl group, 8-isoquinolyl group,
2-quinoxalinyl group, 5-quinoxalinyl group, 6-quinoxalinyl group,

1-carbazolyl group, 2-carbazolyl group, 3-carbazolyl group, 4-carbazolyl group, 9-carbazolyl group,
1-phenanthridinyl group, 2-phenanthridinyl group, 3-phenanthridinyl group, 4-phenanthridinyl group, 6-phenanthridinyl group, 7-phenanthridinyl group, 8- Phenanthridinyl group, 9-phenanthridinyl group, 10-phenanthridinyl group,
1-acridinyl group, 2-acridinyl group, 3-acridinyl group, 4-acridinyl group, 9-acridinyl group,

1,7-phenanthroline-2-yl group, 1,7-phenanthroline-3-yl group, 1,7-phenanthroline-4-yl group, 1,7-phenanthroline-5-yl group, 1,7-phenanthroline- 6-yl group, 1,7-phenanthroline-8-yl group, 1,7-phenanthroline-9-yl group, 1,7-phenanthroline-10-yl group,
1,8-phenanthroline-2-yl group, 1,8-phenanthroline-3-yl group, 1,8-phenanthroline-4-yl group, 1,8-phenanthroline-5-yl group, 1,8-phenanthroline- 6-yl group, 1,8-phenanthroline-7-yl group, 1,8-phenanthroline-9-yl group, 1,8-phenanthroline-10-yl group,

1,9-phenanthroline-2-yl group, 1,9-phenanthroline-3-yl group, 1,9-phenanthroline-4-yl group, 1,9-phenanthroline-5-yl group, 1,9-phenanthroline- 6-yl group, 1,9-phenanthroline-7-yl group, 1,9-phenanthroline-8-yl group, 1,9-phenanthroline-10-yl group,
1,10-phenanthrolin-2-yl group, 1,10-phenanthroline-3-yl group, 1,10-phenanthroline-4-yl group, 1,10-phenanthroline-5-yl group,

2,9-phenanthroline-1-yl group, 2,9-phenanthroline-3-yl group, 2,9-phenanthroline-4-yl group, 2,9-phenanthroline-5-yl group, 2,9-phenanthroline- 6-yl group, 2,9-phenanthroline-7-yl group, 2,9-phenanthroline-8-yl group, 2,9-phenanthroline-10-yl group,
2,8-phenanthroline-1-yl group, 2,8-phenanthroline-3-yl group, 2,8-phenanthroline-4-yl group, 2,8-phenanthroline-5-yl group, 2,8-phenanthroline- 6-yl group, 2,8-phenanthroline-7-yl group, 2,8-phenanthroline-9-yl group, 2,8-phenanthroline-10-yl group,

2,7-phenanthroline-1-yl group, 2,7-phenanthroline-3-yl group, 2,7-phenanthroline-4-yl group, 2,7-phenanthroline-5-yl group, 2,7-phenanthroline- 6-yl group, 2,7-phenanthroline-8-yl group, 2,7-phenanthroline-9-yl group, 2,7-phenanthroline-10-yl group,
1-phenazinyl group, 2-phenazinyl group, 1-phenothiazinyl group, 2-phenothiazinyl group, 3-phenothiazinyl group, 4-phenothiazinyl group, 10-phenothiazinyl group,
1-phenoxazinyl group, 2-phenoxazinyl group, 3-phenoxazinyl group, 4-phenoxazinyl group, 10-phenoxazinyl group,

2-oxazolyl group, 4-oxazolyl group, 5-oxazolyl group,
2-oxadiazolyl group, 5-oxadiazolyl group,
3-furazanyl group,
2-thienyl group, 3-thienyl group,
Dibenzothiophen-3-yl group, dibenzothiophendiox-3-yl group,

2-methylpyrrol-1-yl group, 2-methylpyrrol-3-yl group, 2-methylpyrrol-4-yl group, 2-methylpyrrol-5-yl group,
3-methylpyrrol-1-yl group, 3-methylpyrrol-2-yl group, 3-methylpyrrol-4-yl group, 3-methylpyrrol-5-yl group,
2-t-butylpyrrol-4-yl group,
3- (2-phenylpropyl) pyrrol-1-yl group,
2-methyl-1-indolyl group, 4-methyl-1-indolyl group, 2-methyl-3-indolyl group, 4-methyl-3-indolyl group,
2-t-butyl-1-indolyl group, 4-t-butyl-1-indolyl group, 2-t-butyl-3-indolyl group, 4-t-butyl-3-indolyl group 5-oxo-benzophosphoryl- Examples include 2-yl group, 5-oxo-benzophosphoryl-3-yl group, and 5-oxo-benzophosphoryl-4-yl group.

a and b are the same or different and are an integer of 1 to 4, and when a and b are an integer of 2 or more, a plurality of R ¹ and R ² may be the same or different.

  L is a divalent group derived from a bond or a substituted or unsubstituted aromatic hydrocarbon group or aromatic heterocyclic group.

Examples of the “divalent group derived from an aromatic hydrocarbon group” include a divalent group generated by further removing one hydrogen atom from the “aromatic hydrocarbon group”.
Of these, divalent groups derived from benzene, naphthalene, anthracene, phenanthrene, naphthacene, chrysene, pyrene, and the like are particularly preferable.

Examples of the “divalent group derived from an aromatic heterocyclic group” include a divalent group formed by further removing one hydrogen atom from the “aromatic heterocyclic group”, and the substituent is also the above substituent. The same thing is mentioned.
Among these, divalent groups generated from pyrrole, pyridine, indole, isoindole, quinoline, carbazole, phenanthroline, thiophene, furan, benzothiophene, dibenzothiophene, dibenzothiophene dioxide, benzofuran, benzimidazole, dibenzothiophene, dibenzofuran, etc. Particularly preferred. Examples thereof include a dibenzothiophene-3,6-diyl group and a dibenzothiophene dioxide-3,6-diyl group.
As the “divalent group derived from an aromatic heterocyclic group”, a substituted or unsubstituted fluorenylene group, a carbazolylene group and a substituted or unsubstituted 5-oxo-dibenzophosphorenyl group are particularly preferable.

  The divalent group derived from an aromatic hydrocarbon group or an aromatic heterocyclic group may have a substituent, and examples of such a substituent include an alkyl group, an alkoxy group, a halogen atom, and a cyano group. , A nitro group, an amino group and an aryl group.

  n is an integer of 1 to 4, and when n is an integer of 2 or more, the plurality of L may be the same or different.

Ar is a 1-3 valent group derived from a bond, a hydrogen atom, a substituted or unsubstituted aromatic hydrocarbon group or an aromatic heterocyclic group.
Examples of the “1- to 2-valent group derived from an aromatic hydrocarbon group or an aromatic heterocyclic group” include the above-mentioned “aromatic hydrocarbon group” and “divalent group derived from an aromatic hydrocarbon group”. , “Aromatic heterocyclic group” and “divalent group derived from aromatic heterocyclic group”.
As the “trivalent group derived from an aromatic hydrocarbon group or an aromatic heterocyclic group”, the “divalent group derived from an aromatic hydrocarbon group” and “derived from an aromatic heterocyclic group”, respectively. And “trivalent group derived from an aromatic hydrocarbon group” and “trivalent group derived from an aromatic heterocyclic group” generated by removing one hydrogen atom from the “divalent group”. It is done.
Moreover, those preferable examples are also the same, and those substituents are also the same as those described above.

  m is an integer of 1 to 3, and when m is an integer of 2 or more, the plurality of L may be the same or different.

（式中、Ｒ¹、Ｒ²、ａ、ｂ、Ｌおよびｎは、一般式（Ｉ）における定義と同義であり；Ａｒ¹は、水素原子または置換もしくは無置換の芳香族炭化水素環基もしくは芳香族複素環基から誘導される１価の基である） The dibenzophosphole oxide derivatives represented by the general formula (I) are preferably those represented by the sub-formulas (II) to (V).
Sub-formula (II):

Wherein R ¹ , R ² , a, b, L and n are as defined in general formula (I); Ar ¹ is a hydrogen atom or a substituted or unsubstituted aromatic hydrocarbon ring group or A monovalent group derived from an aromatic heterocyclic group)

（式中、Ｒ¹〜Ｒ⁴およびａ〜ｄは、それぞれ一般式（Ｉ）におけるＲ¹およびＲ²ならびにａおよびｂの定義と同義であり；Ｌおよびｎは、一般式（Ｉ）における定義と同義である） Sub-formula (III):

Wherein R ^{1 to} R ⁴ and a to d have the same definitions as R ¹ and R ² and a and b in the general formula (I), respectively; L and n are the definitions in the general formula (I) Is synonymous with

（式中、Ｒ¹〜Ｒ⁶およびａ〜ｆは、それぞれ一般式（Ｉ）におけるＲ¹およびＲ²ならびにａおよびｂの定義と同義であり；Ｌは、一般式（Ｉ）における定義と同義であり；ｑ、ｒおよびｓは、同一または異なって、一般式（Ｉ）におけるｎの定義と同義であり；Ａｒ²は、置換もしくは無置換の芳香族炭化水素環基もしくは芳香族複素環基から誘導される３価の基である） Sub-formula (IV):

Wherein R ^{1 to} R ⁶ and a to f have the same definitions as R ¹ and R ² and a and b in the general formula (I), respectively; L represents the same as the definition in the general formula (I). Q, r and s are the same or different and have the same definition as n in formula (I); Ar ² represents a substituted or unsubstituted aromatic hydrocarbon ring group or aromatic heterocyclic group Is a trivalent group derived from

（式中、Ｒ¹〜Ｒ⁶およびａ〜ｆは、それぞれ一般式（Ｉ）におけるＲ¹およびＲ²ならびにａおよびｂの定義と同義であり；Ａｒ²は、置換もしくは無置換の芳香族炭化水素環基もしくは芳香族複素環基から誘導される３価の基である） Sub-formula (V):

Wherein R ^{1 to} R ⁶ and a to f have the same definitions as R ¹ and R ² and a and b in the general formula (I), respectively; Ar ² represents a substituted or unsubstituted aromatic carbonization (It is a trivalent group derived from a hydrogen ring group or an aromatic heterocyclic group.)

The dibenzophosphole oxide derivative represented by the general formula (I) is:
Compound of sub-formula (II):

Compound of sub-formula (III):

Compound of sub-formula (IV):

から選択される化合物が好ましい。 Compound of sub-formula (V):

A compound selected from is preferred.

から選択される化合物が特に好ましい。 Among these,

A compound selected from is particularly preferred.

  The dibenzophosphole derivative of the present invention can be synthesized, for example, by the following two methods.

(Method 1)
Reaction of aryl halides with 9-hydro-dibenzophosphole and / or 9-hydro-dibenzophosphole oxide in a solvent (condensation, ie dehydrohalogenation) in the presence of a metal catalyst (condensation catalyst) and / or a base Reaction), and then the phosphorus atom of the reaction product obtained is oxidized with an oxidizing agent to obtain the dibenzophosphole oxide derivative of the above general formula (I) or (Ia).

(Method 2)
5-Chloro-dibenzophosphole oxide and an aryl lithium or aryl Grignard reagent are reacted in a solvent to obtain the dibenzophosphole oxide derivative of the above general formula (I) or (Ia).

The method 1 will be described.
In the presence of a metal catalyst and / or a base, an aryl halide and 9-hydro-dibenzophosphole are reacted in a solvent, and then the phosphorus atom of the resulting reaction product is oxidized with an oxidizing agent to produce the present invention. A dibenzophosphole oxide derivative is obtained.
9-hydro-dibenzophosphole can be obtained, for example, by the method described in EH Braye, I. Caplier and R. Saussez, Tetrahedron, 27, 5523 (1971) (Reference 1).
It is preferable to use 1 to 4 mole equivalent of 9-hydro-dibenzophosphole with respect to the halide atom of aryl halide.

  Examples of the solvent include polar organic solvents such as dimethyl sulfoxide (DMSO), dimethylformamide (DMF), dimethylacetamide (DMA), tetrahydrofuran (THF), dimethyldioxane, pyridine, benzene, toluene, and xylene. DMSO and DMA are particularly preferred in terms of rate.

Examples of the metal catalyst include palladium acetate [Pd (OAc) ₂ ], nickel acetate [Ni (OAc) ₂ ], and Pd (OAc) ₂ -1,3-bis (diphenylphosphino) propane [dppp], Pd (OAc) _2-1,2-bis (diphenylphosphino) ethane [dppe], Pd (OAc) 2 -1,4- bis (diphenylphosphino) butane [dppb], Ni (OAc) 2 -dppe, Ni Examples include complex compounds of platinum group elements such as (OAc) ₂ -dppp and bisphosphinoalkanes, and among these, Pd (OAc) ₂ , Pd (OAc) ₂ -dppp and Pd ( OAc) ₂ -dppb is particularly preferred.
The usage-amount of a catalyst is about 0.005-0.1 mol with respect to 1 mol of the halide atom of an aryl halide.

The base has a function of capturing hydrogen halide generated by condensation.
Examples of such a base include trialkylamines such as triethylamine, tripropylamine, and tributylamine, aliphatic tertiary amines such as N-ethyldiisopropylamine [edpa], pyridine, and N, N-dimethylaminopyridine. Aromatic tertiary amines such as [DMAP] and strong bases such as 1,8-diazabicyclo [5.4.0] undecene-7. Among these, edpa and DMAP are preferred in terms of boiling point. Particularly preferred.
The amount of the base used is about 1.0 to 5.0 mol with respect to an amount sufficient to capture the theoretical amount of the generated hydrogen halide, that is, 1 mol of the halide atom of the aryl halide.

60-180 degreeC is preferable and, as for the reaction temperature in reaction of the method 1, 80-150 degreeC is more preferable.
The reaction time is usually about 1 to 48 hours, although it depends on conditions such as the reaction temperature.
Subsequently, the phosphorous atom of the obtained reaction product is oxidized with an oxidizing agent to obtain a dibenzophosphole oxide derivative.
As the oxidizing agent, an oxidizing agent known in the art can be used. For example, hydrogen peroxide, air, metachlorobenzoic acid, cumene hydroperoxide and the like are preferably used.

Alternatively, an aryl halide and 9-hydro-dibenzophosphole oxide are reacted in a solvent in the presence of a metal catalyst and / or a base to obtain the dibenzophosphole oxide derivative of the present invention. The conditions are the same as above.
9-hydro-dibenzophosphole oxide is obtained, for example, by oxidizing 9-hydro-dibenzophosphole with hydrogen peroxide.

  Furthermore, in the presence of a metal catalyst and / or a base, an aryl halide and a mixture of 9-hydro-dibenzophosphole and 9-hydro-dibenzophosphole oxide are reacted in a solvent, and then the obtained reaction product Are oxidized with an oxidizing agent to obtain the dibenzophosphole oxide derivative of the present invention. The conditions are the same as above.

Method 2 will be described.
9-Chloro-dibenzophosphole oxide is reacted with aryllithium or aryl Grignard reagent in a solvent to give the dibenzophosphole oxide derivative of the present invention.
9-hydroxydibenzophosphole oxide can be obtained, for example, by the method described in S. Jhon, LRH Cornforth and RT Gray, J. Chem. Soc., Perkin trans I, 2289 (1982) (Reference 2).
9-chloro-dibenzophosphole oxide is, for example, 9-hydroxydibenzophosphole oxide is refluxed in 1 to 100 molar equivalents of thionyl chloride for 0.5 to 24 hours, and the reaction solution is concentrated on a rotary evaporator. Further, it can be obtained by vacuum drying.

  Examples of the solvent include dehydrated tetrahydrofuran (THF), diethyl ether, benzene, toluene, dimethylformamide (DMF), and the like. Among these, THF and diethyl ether are particularly preferable in terms of yield.

Examples of aryllithium include (biphenyl-4,4′-diyl) dilithium and (biphenyl-4-yl) lithium.
The amount of aryllithium used is about 0.5 to 2 moles per mole of 9-chloro-dibenzophosphole oxide.

Examples of the aryl Grignard reagent include (biphenyl-4-yl) magnesium bromide and 1-naphthylmagnesium bromide.
The usage-amount of an aryl Grignard reagent is about 0.5-2 mol with respect to 1 mol of 9-chloro- dibenzophosphole oxide.

The reaction temperature in the reaction of Method 2 is preferably -100 to 100 ° C, more preferably -80 to 80 ° C.
Moreover, although reaction time is based also on conditions, such as reaction temperature, about 0.5 to 24 hours are sufficient normally.

The organic EL element of the present invention will be described.
The organic EL device of the present invention is an organic EL device in which an organic thin film layer composed of one or more layers including at least a light emitting layer is sandwiched between an anode and a cathode, and at least one layer of the organic thin film layer is represented by the general formula ( The dibenzophosphole oxide derivative represented by I) is contained alone or as a component of a mixture.
In the organic EL device of the present invention, the light emitting layer preferably contains the dibenzophosphole oxide derivative of the present invention as a main component.
In the organic EL device of the present invention, the light emitting layer preferably contains the dibenzophosphole oxide derivative of the present invention as an electron transport material.

Although the element structure of the organic EL element of this invention is not specifically limited, For example, the following element structures are mentioned.
(A) Anode / light emitting layer / cathode (b) Anode / hole injection layer / light emitting layer / cathode (c) Anode / light emitting layer / electron injection layer / cathode (d) Anode / hole injection layer / light emitting layer / electron Injection layer / cathode (e) anode / organic semiconductor layer / light emitting layer / cathode (f) anode / organic semiconductor layer / electron barrier layer / light emitting layer / cathode (g) anode / organic semiconductor layer / light emitting layer / adhesion improving layer / Cathode (h) anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode (i) anode / insulating layer / light emitting layer / insulating layer / cathode (j) anode / inorganic semiconductor layer / insulating layer / Light emitting layer / insulating layer / cathode (k) anode / organic semiconductor layer / insulating layer / light emitting layer / insulating layer / cathode (l) anode / insulating layer / hole injection layer / hole transporting layer / light emitting layer / insulating layer / Cathode (m) anode / insulating layer / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode Among these, the element of normal (h) A configuration is particularly preferred.
The dibenzophosphole oxide derivative of the present invention may be used in any organic thin film layer of an organic EL device, but preferably has a light emission band or an electron transport band, and particularly preferably has an electron injection layer, an electron transport layer and / or a light emission layer.

(Translucent substrate)
The organic EL element of the present invention is usually formed on a translucent substrate.
The light-transmitting substrate is a substrate that supports the organic EL element, and is preferably a smooth substrate having a light transmittance in the visible region of 400 to 700 nm of 50% or more.
The material of the translucent substrate is not particularly limited, and a known material can be used, for example, soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, Examples thereof include glass such as quartz, polymers such as polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, and polysulfone.
The thickness should just be a grade which can support an organic EL element at least, and is about 0.05-10 mm.

(anode)
The anode has a function of injecting holes into the hole transport layer or the light emitting layer, and is preferably made of a material having a work function of 4.5 eV or more.
The material of the anode is not particularly limited, and a known material can be used. For example, indium tin oxide alloy (ITO), tin oxide (NESA), indium-zinc oxide (IZO), gold, silver, platinum, Examples include copper.
The anode can be formed using these electrode materials by a known thin film forming method such as a vacuum deposition method, a molecular beam deposition method (MBE method), or a sputtering method.
When light emission from the light emitting layer is taken out from the anode side, the transmittance of the anode for light emission is preferably greater than 10%, and the sheet resistance of the anode is preferably several hundred Ω / □ or less.
Although the film thickness of an anode is based also on material, it is 10 nm-1 micrometer normally, and 10-200 nm is preferable.

(Light emitting layer)
The light emitting layer has (1) an injection function of injecting holes from an anode or a hole injection layer when an electric field is applied, and electrons from a cathode or an electron injection layer, and (2) an injected electric charge (electrons and holes) in an electric field. (3) Provides a field for recombination of electrons and holes, and a light emitting function for connecting this to light emission.
However, there may be a difference between the ease of hole injection and the ease of electron injection, and the transport capability represented by the mobility of holes and electrons may be large or small. It is preferable to move the charge.

The organic EL device of the present invention preferably contains the dibenzophosphole oxide derivative of the present invention as a main component in the light-emitting layer, but other known light-emitting materials may be used as desired within the range that the object of the present invention is not impaired. In addition, another light-emitting layer containing other known light-emitting materials may be stacked.
Furthermore, the light emitting layer may contain a hole transport material, an electron transport material, and a polymer binder as necessary.

The phosphor oxide derivative of the present invention can be used in combination with known light-emitting materials and doping materials.
As the light emitting material, for example, anthracene, naphthalene, phenanthrene, pyrene, tetracene, coronene, chrysene, fluorescein, perylene, phthaloperylene, naphthaloperylene, perinone, phthaloperinone, naphthaloperinone, diphenylbutadiene, tetraphenylbutadiene, coumarin, oxadiazole, aldazine, Bisbenzoxazoline, bisstyryl, pyrazine, cyclopentadiene, quinoline metal complex, aminoquinoline metal complex, benzoquinoline metal complex, imine, diphenylethylene, vinylanthracene, diaminocarbazole, pyran, thiopyran, polymethine, merocyanine, imidazole chelating oxinoid compound Quinacridone, rubrene, and fluorescent dyes.

Examples of the doping material include a phosphorescent compound, and a compound containing a carbazole ring in the host material is particularly preferable.
The phosphorescent doping material is a compound that can emit light from triplet excitons and is not particularly limited as long as it emits light from triplet excitons, but is a group consisting of Ir, Ru, Pd, Pt, Os, and Re. A metal complex containing at least one metal selected from the group consisting of a porphyrin metal complex and an orthometalated metal complex is particularly preferable. These may be used alone or in combination of two or more.

As the porphyrin metal complex, a porphyrin platinum complex is particularly preferable.
There are various ligands that form orthometalated metal complexes, such as 2-phenylpyridine derivatives, 7,8-benzoquinoline derivatives, 2- (2-thienyl) pyridine derivatives, and 2- (1-naphthyl). Particularly preferred are pyridine derivatives, 2-phenylquinoline derivatives and the like. These derivatives may have a substituent as required, and those having a fluorinated product or a trifluoromethyl group introduced are particularly preferred as the blue dopant. Furthermore, you may have ligands other than the said ligands, such as acetylacetonate and picric acid, as an auxiliary ligand.

  A host suitable for phosphorescence emission comprising a compound containing a carbazole ring is a compound having a function of causing the phosphorescence emission compound to emit light as a result of energy transfer from the excited state to the phosphorescence emission compound. The host compound is not particularly limited as long as it is a compound capable of transferring exciton energy to a phosphorescent compound, and can be appropriately selected according to the purpose. You may have arbitrary heterocyclic rings other than a carbazole ring.

  The host compound is not particularly limited, and known materials can be used. For example, 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 dimethylidene compounds, porphyrin compounds, Anthraquinodimethane derivative, anthrone derivative, diphenylquinone derivative, thiopyrandioxide derivative, carbodiimide derivative, fluorenylidenemethane derivative, Various metal complexes represented by metal complexes of styrylpyrazine derivatives, heterocyclic tetracarboxylic anhydrides such as naphthaleneperylene, phthalocyanine derivatives, 8-quinolinol derivatives, metal phthalocyanines, benzoxazole and benzothiazole ligands Conductive polymer oligomers such as polysilane compounds, poly (N-vinylcarbazole) derivatives, aniline copolymers, thiophene oligomers, polythiophenes, polymer compounds such as polythiophene derivatives, polyphenylene derivatives, polyphenylene vinylene derivatives, polyfluorene derivatives, etc. These may be used alone or in combination of two or more.

There is no restriction | limiting in particular as content in the light emitting layer of a phosphorescence-emitting doping material, Although it can select suitably according to the objective, For example, it is 0.1 to 70 weight%, 1 to 30 mass% Is particularly preferred.
When the content of the phosphorescent doping material is less than 0.1% by weight, the light emission is weak and the effect of the content is not sufficiently exhibited. When the content exceeds 70% by weight, a phenomenon called concentration quenching occurs. It may become noticeable and the device performance may deteriorate.

The light emitting layer can be formed by a known thin film forming method such as a vacuum deposition method, a dipping method, a spin coating method, a casting method, a bar coating method, a roll coating method, or an LB method.
The light emitting layer is particularly preferably a molecular deposition film such as a thin film formed by deposition from a material compound in a gas phase state or a thin film formed by solidification from a material compound in a solution state or a liquid phase state. The molecular deposited film can be generally classified from a thin film (molecular accumulation film) formed by the LB method by a difference in an agglomeration structure, a higher order structure, and a functional difference resulting therefrom.

Further, the light emitting layer is prepared by dissolving a binder such as a resin and a material compound in a solvent as disclosed in, for example, Japanese Patent Laid-Open No. 57-51781 (Document 3). It can also be formed by thinning by a spin coating method or the like.
The film thickness of a light emitting layer is 5-100 nm normally, 7-80 nm is preferable and 10-50 nm is more preferable. If the thickness is less than 5 nm, the formation of the light emitting layer may be difficult, and adjustment of chromaticity may be difficult. If the thickness exceeds 100 nm, the driving voltage may increase.

(Hole injection layer / hole transport layer (hole transport zone))
The hole injection layer and the hole transport layer are layers that assist (promote) injection of holes into the light emitting layer and transport them to the light emitting region, have high hole mobility, and ionization energy is usually 5.5 eV or less. It is preferably made of a small material. Further, a material that transports holes to the light emitting layer with a lower electric field strength is preferable, and the mobility of holes is at least 10 ⁻⁴ cm ² / V · sec when an electric field of 10 ⁴ to 10 ⁶ V / cm is applied. Are preferred.

The dibenzophosphole oxide derivative of the present invention may be used alone to form a hole injection layer and a hole transport layer, may be used in combination with other materials, and may contain other materials. Layers may be stacked.
The material that can be used in a mixed manner is not particularly limited as long as it has the above-mentioned preferable properties, and known materials, materials that are commonly used as hole charge transport materials in optical transmission materials, and organic EL elements Those used in the hole injection layer and the hole transport layer can be selected and used.

Examples of such materials include the following. References in parentheses indicate reference documents.
Triazole derivatives (US Pat. No. 3,112,197)
Oxadiazole derivatives (US Pat. No. 3,189,447)
Imidazole derivatives (Japanese Patent Publication No. 37-16096)
Polyarylalkane derivatives (US Pat. Nos. 3,615,402, 3,820,989, 3,542,544, JP-B-45-555, 51-10983) (Japanese Patent Laid-Open Nos. 51-93224, 55-17105, 56-4148, 55-108667, 55-156953, and 56-36656)

Pyrazoline derivatives and pyrazolone derivatives (US Pat. Nos. 3,180,729, 4,278,746, JP-A-55-88064, JP-A-55-88065, JP-A-49-105537) No. 55-51086, No. 56-80051, No. 56-88141, No. 57-45545, No. 54-112737, No. 55-74546).
Phenylenediamine derivatives (US Pat. No. 3,615,404, JP-B 51-10105, JP-B 46-3712, JP-B 47-25336, JP-A 54-53435, 54- 110536, 54-1119925)

Arylamine derivatives (US Pat. Nos. 3,567,450, 3,180,703, 3,240,597, 3,658,520, 4,232,103, 4,175,961, 4,012,376, JP-B-49-35702, 39-27577, JP-A 55-144250, 56-119132, 56-22437, West German Patent 1,110,518)
Amino-substituted chalcone derivatives (US Pat. No. 3,526,501)
Oxazole derivatives (US Pat. No. 3,257,203)
Styrylanthracene derivative (Japanese Patent Laid-Open No. 56-46234)
Fluorenone derivative (Japanese Patent Laid-Open No. 54-110837)

Hydrazone derivatives (US Pat. No. 3,717,462, JP-A-54-59143, 55-52063, 55-52064, 55-46760, 55-85495) Gazette, 57-11350 gazette, 57-148749 gazette, and Japanese Laid-Open Patent Publication No. 2-31591)
Stilbene derivatives (Japanese Patent Laid-Open Nos. 61-210363, 61-228451, 61-14642, 61-72255, 62-47646, 62-36684, 62) No. -10652, No. 62-30255, No. 60-93455, No. 60-94462, No. 60-174749, No. 60-175052)

Silazane derivatives (US Pat. No. 4,950,950)
Polysilane (Japanese Patent Laid-Open No. 2-204996)
Aniline copolymer (JP-A-2-282263)
Conductive polymer oligomer (especially thiophene oligomer, Japanese Patent Laid-Open No. 1-211399)

Porphyrin compounds (Japanese Patent Laid-Open No. 63-295965)
Aromatic tertiary amine compounds and styrylamine compounds (US Pat. No. 4,127,412, JP-A-53-27033, 54-58445, 54-149634, 54- No. 64299, No. 55-79450, No. 55-144250, No. 56-119132, No. 61-295558, No. 61-98353, No. 63-295695, Aromatic Third (A tertiary amine compound is particularly preferred)

For example, 4,4′-bis (N- (1-naphthyl) -N-phenylamino) biphenyl (NPD) (US Pat. No. 5,061,569) having two condensed aromatic rings in the molecule book)
4,4 ′, 4 ″ -tris (N- (3-methylphenyl) -N-phenylamino) triphenylamine (MTDATA) in which three triphenylamine units are linked in a starburst type (Japanese Patent Laid-Open No. 4-308688) No.)
Inorganic compounds such as P-type Si and P-type SiC

The hole injection layer and the hole transport layer can be formed by a known thin film forming method such as a vacuum deposition method, a dipping method, a spin coating method, a casting method, a bar coating method, a roll coating method, or an LB method.
The film thicknesses of the hole injection layer and the hole transport layer are usually 5 nm to 5 μm.

(Electron injection layer / electron transport layer (electron transport band))
The electron injection layer and the electron transport layer are layers that assist (promote) injection of electrons into the light emitting layer and transport them to the light emitting region, and have a high electron mobility and a high electron affinity, usually 2.5 EV or more. Preferably it is. Alternatively, a material that transports electrons to the light emitting layer with a lower electric field strength is preferable, and the electron mobility is at least 10 ⁻⁶ cm ² / V · sec when an electric field of 10 ⁴ to 10 ⁶ V / cm is applied. Those are preferred.

The dibenzophosphole oxide derivative of the present invention may be used alone to form an electron injection layer and an electron transport layer, may be used in combination with other materials, and another layer containing other materials may be used. You may laminate.
The material that can be used in a mixed manner is not particularly limited as long as it has the above-mentioned preferable properties, and known materials, materials that are commonly used as hole charge transport materials in optical transmission materials, and organic EL elements Those used in the electron injection layer and the electron transport layer can be selected and used.
The electron injection layer and the electron transport layer can be formed by a known thin film forming method such as a vacuum deposition method, a dipping method, a spin coating method, a casting method, a bar coating method, a roll coating method, or an LB method.
The film thicknesses of the electron injection layer and the electron transport layer are usually 5 nm to 5 μm.

A preferred form of the organic EL device of the present invention is a device containing a reducing dopant capable of reducing an electron transporting compound in an electron transporting region or an interface region between a cathode and an organic layer.
The reducing dopant is not particularly limited as long as it has a certain reducing ability. For example, alkali metal, alkaline earth metal, rare earth metal, alkali metal oxide, alkali metal halide, alkaline earth Examples thereof include metal oxides, alkaline earth metal halides, rare earth metal oxides or rare earth metal halides, alkali metal organic complexes, alkaline earth metal organic complexes, and rare earth metal organic complexes.

Specifically, alkali metals such as Na (work function: 2.36 EV), K (work function: 2.2 eV), Rb (work function: 2.16 eV) and Cs (work function: 1.95 eV); Ca Alkaline earth metals such as (work function: 2.9 eV), Sr (work function: 2.0 to 2.5 eV) and Ba (work function: 2.52 eV) are mentioned, and the work function is 2.9 eV or less. Are preferred, alkali metals of K, Rb and Cs are preferred, Rb and Cs are more preferred, and Cs is particularly preferred. A combination of these alkali metals is also preferable, and a combination including Cs in particular, for example, a combination of Cs and Na, Cs and K, Cs and Rb, and Cs, Na, and K is preferable. By including Cs in combination, the reducing ability can be efficiently exhibited, and by adding to the electron injection region, the emission luminance and the life of the organic EL element can be improved.
Alkali metals have a particularly high reducing ability, and by adding a relatively small amount to the electron injection zone, it is possible to improve the emission luminance and extend the life of the organic EL element.

(Adhesion improvement layer)
In the organic EL device of the present invention, an adhesion improving layer may be provided.
The adhesion improving layer is a layer made of a material having particularly good adhesion to the cathode in the electron injection layer, and the formation method and film thickness thereof are the same as those of the electron injection layer and the electron transport layer.

(Organic semiconductor layer / inorganic semiconductor layer)
In the organic EL device of the present invention, an organic semiconductor layer or an inorganic semiconductor layer may be provided between the cathode and the organic layer as a layer for assisting hole injection or electron injection into the light emitting layer.
The organic semiconductor layer and the inorganic semiconductor layer are preferably formed of a material having a conductivity of 10 ⁻¹⁰ S / cm or more.
Examples of the material for the organic semiconductor layer include thiophene-containing oligomers, for example, conductive oligomers such as arylamine oligomers disclosed in JP-A-8-193191, and conductive dendrimers such as arylamine dendrimers.

  Examples of the material for the inorganic semiconductor layer include Ba, Ca, Sr, Yb, Al, Ga, In, Li, Na, Cd, Mg, Si, Ta, Sb, and an oxide, nitride, or nitride containing at least one element of Zn. Examples thereof include oxynitrides, and these can be used alone or in combination of two or more. These materials are preferably microcrystalline or amorphous insulating thin films. Moreover, since such an insulating thin film forms a more uniform thin film, pixel defects such as dark spots can be reduced.

In the organic EL device of the present invention, a layer composed of an alkali metal chalcogenide, an alkaline earth metal chalcogenide, an alkali metal halide, an alkaline earth metal halide, and a combination thereof may be provided between the cathode and the organic layer. Good.
Specifically, alkali metal chalcogenides such as Li ₂ O, K ₂ O, Na ₂ S, Na ₂ Se, and Na ₂ O; alkaline earth metal chalcogenides such as CaO, BaO, SrO, BeO, BaS, and CaSe; Alkali metal halides such as LiF, NaF, KF, LiCl, KCl and NaCl; Halides of alkaline earth metals such as CaF ₂ , BaF ₂ , SrF ₂ , MgF ₂ and BeF ₂ are mentioned.
By providing such a layer, the electron injection property of the organic EL element can be further improved.

(Insulating layer)
Since an organic EL element applies an electric field to an ultra-thin film, pixel defects due to current leakage or short-circuiting are likely to occur. To prevent this, it is preferable to insert an insulating thin film layer between a pair of electrodes.
Examples of the material for the insulating layer include aluminum oxide, lithium fluoride, lithium oxide, cesium fluoride, cesium oxide, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, aluminum nitride, titanium oxide, silicon oxide, and germanium oxide. , Silicon nitride, boron nitride, molybdenum oxide, ruthenium oxide, vanadium oxide, and the like, and a mixture or laminate thereof may be used.
The insulating layer can be formed by a known method, and the film thickness is about 0.1 to 10 nm.

(cathode)
The cathode has a function of injecting electrons into the electron injection layer, the electron transport layer, or the light emitting layer, and is preferably made of a material having a small work function of 4 eV or less.
The material of the cathode is not particularly limited, and a known material can be used. For example, sodium, sodium / potassium alloy, magnesium, lithium, magnesium / silver alloy, aluminum / aluminum oxide, aluminum / lithium alloy, indium, rare earth Examples include metals such as metals, alloys, electrically conductive compounds, and mixtures thereof.
The cathode can be formed using these electrode materials by a known thin film forming method such as a vacuum evaporation method, a molecular beam evaporation method (MBE method), or a sputtering method.
When light emitted from the light emitting layer is taken out from the cathode side, the transmittance for light emission from the cathode is preferably larger than 10%, and the sheet resistance of the anode is preferably several hundred Ω / □ or less.
Although the film thickness of the cathode depends on the material, it is usually 10 nm to 1 μm, preferably 50 to 200 nm.

(Manufacture of organic EL elements)
The organic EL device of the present invention can be produced by forming an anode, a light-emitting layer, and other layers as required, and further forming a cathode by the materials and formation methods exemplified above. The organic EL device of the present invention can also be produced in the reverse order from the cathode to the anode.
Hereinafter, an example of manufacturing an organic EL element having a structure in which an anode / a hole injection layer / a light emitting layer / an electron injection layer / a cathode are sequentially stacked on a translucent substrate will be described.

First, an anode having a thickness of 1 μm or less is formed on a light-transmitting substrate by using a known thin film forming method such as a vacuum evaporation method, a molecular beam evaporation method (MBE method), or a sputtering method using an anode material.
Next, using the material of the hole injection layer, positive deposition is performed on the anode by a known thin film formation method such as vacuum deposition, dipping, spin coating, casting, bar coating, roll coating, or LB. A hole injection layer is formed. Among these thin film forming methods, the vacuum evaporation method is particularly preferable from the standpoint that a homogeneous film is easily obtained and pinholes are hardly generated. The deposition conditions in the vacuum deposition method vary depending on the material of the hole injection layer used, the crystal structure and recombination structure of the target hole injection layer, etc., but generally the deposition source temperature is 50 to 450 ° C. and the degree of vacuum is 10 ⁻⁷ to It is preferable to set appropriately within a range of 10 ⁻³ torr, vapor deposition rate of 0.01 to 50 nm / second, substrate temperature of −50 to 300 ° C., and film thickness of 5 nm to 5 μm.

  Next, using an organic light emitting material, light is emitted on the hole injection layer by a known thin film forming method such as vacuum deposition, dipping, spin coating, casting, bar coating, roll coating, or LB. Form a layer. As with the hole injection layer, the light emitting layer is preferably formed by a vacuum vapor deposition method, and the vapor deposition conditions are preferably set as appropriate as with the hole injection layer.

Next, using an electron injection material, an electron injection layer is formed on the light emitting layer by a known thin film formation method such as a vacuum deposition method, a dipping method, a spin coating method, a casting method, a bar coating method, a roll coating method, or an LB method. Form. As with the hole injection layer, the electron injection layer is preferably formed by a vacuum evaporation method, and the evaporation conditions are preferably set as appropriate as with the hole injection layer.
The dibenzophosphole oxide derivative of the present invention varies depending on which layer in the emission band or the hole transport band, but in the case of the vacuum deposition method, it can be co-deposited with other materials, and can be spin-coated. In the case of the method, the containing layer can be formed by mixing with other materials.

Finally, by using a cathode material, a cathode having a thickness of 1 μm or less is formed on the electron injection layer by a known thin film forming method such as a vacuum evaporation method, a molecular beam evaporation method (MBE method), a sputtering method, etc. Get the element. Among these thin film forming methods, a vacuum vapor deposition method is particularly preferable because the underlying organic layer is not easily damaged during film formation.
The production of the organic EL element is preferably carried out consistently with a single vacuum in the same apparatus.

The formation method of each layer in the organic EL device of the present invention is not particularly limited, and is a vacuum deposition method, a molecular beam deposition method (MBE method), a dry method such as a sputtering method, a dipping method, a spin coating method, a casting method, a bar coating method. Known thin film forming methods such as a wet method by coating such as a coating method, a roll coating method, and an LB method.
The film thickness of each organic layer in the organic EL device of the present invention is not particularly limited. In general, if the film thickness is too thin, defects such as pinholes are likely to occur. Conversely, if it is too thick, a high applied voltage is required and the efficiency is deteriorated. Therefore, the range of several nm to 1 μm is usually preferable.

  In the organic EL device of the present invention, light emission can be observed by applying a DC voltage of 5 to 40 V with a positive polarity on the anode and a negative polarity on the cathode. When a voltage is applied with the opposite polarity, no current flows and no light emission occurs. In addition, when an alternating voltage is applied, uniform light emission is observed only when the anode has a positive polarity and the cathode has a negative polarity. The waveform of the alternating current to be applied may be arbitrary.

  The present invention will be described in more detail with reference to synthesis examples, examples and comparative examples, but the present invention is not limited to these synthesis examples and examples.

The physical properties of the synthesized compound were evaluated using the following equipment, and it was confirmed that the desired compound was obtained.
(Melting point)
Apparatus: Differential scanning calorimeter (manufactured by Seiko Instruments Inc., model number: EXSTAR6000)
Conditions: sample weight 5-8 mg, temperature rising rate: 10 ° C./min (FAB-MS)
Apparatus: Fast atom beam impact ionization mass spectrometer (manufactured by JEOL Ltd., model number: JMS-700MStation)
(IR)
Apparatus: Fourier transform infrared spectrophotometer (manufactured by Shimadzu Corporation, model number: FTIR-8600PC)
Conditions: KBr tablet method (1H-NMR)
Apparatus: FT NMR apparatus (manufactured by JEOL Ltd., model number: JNM-MY60FT)

(HPLC elution time)
Apparatus: High-performance liquid chromatography (HPLC, manufactured by GL Sciences Inc., model: GL-7400)
Separation column (GL Science Co., Ltd., Inertsil ODS-3 (registered trademark), column size 4.6 × 250 mm)
Conditions: Flow rate 1.0 ml / min Column temperature: 40 ° C
Eluent and elution conditions: 0 to 20 minutes: 30/70 → 0/100%
H ₂ O / MeOH linear gradient
After 20 minutes: MeOH isocratic

Synthesis Example 1 (Synthesis of 4,4'-bis (5-hydro-dibenzophosphole 5-oxide-5-yl) biphenyl (compound (9)))

Synthesis Example 1-1 (Synthesis using organolithium compound: Method 2)
4,4′-Bis (5-hydro-dibenzophosphole 5-oxide-5-yl) biphenyl (compound (9)) was synthesized by the following steps.

  8.64 g (4 mmol) of 5-hydroxy-5-hydro-dibenzophosphole 5-oxide obtained by the method described in Reference 2 was refluxed in 40 ml of thionyl chloride for 4 hours under an argon atmosphere. Thereafter, the obtained reaction solution was concentrated to glass by a rotary evaporator, and further dried in vacuum overnight to obtain 5-chloro-5-hydro-dibenzophosphole 5-oxide.

Next, 3.12 g (1 mmol) of 4,4′-dibromobiphenyl was dissolved in 4 ml of tetrahydrofuran (THF) and cooled to −78 ° C. under an argon atmosphere. To the obtained solution, 0.7 ml of 1.6M-n-butyllithium hexane solution was added dropwise over 5 minutes, and the solution was stirred as it was for 4 hours (solution 1).
Thereafter, the vacuum-dried 5-chloro-5-hydro-dibenzophosphole 5-oxide was dissolved in 4 ml of THF and added dropwise to the solution 1 at −78 ° C. for 10 minutes in an argon atmosphere. Next, the obtained reaction solution was heated to room temperature over 30 minutes and refluxed for 2 hours.
Distilled water (40 ml) was added to the resulting reaction solution, and the organic layer was extracted from dichloromethane. Then, it was made to dry with magnesium sulfate and the solvent was depressurizingly distilled.
The obtained residue was purified by silica gel column chromatography (developing solvent: dichloromethane / methanol), and further purified by sublimation to obtain white crystals (1.71 g).

When the physical properties of the obtained compound were evaluated, the following results were obtained, and the obtained compound was 4,4′-bis (5-hydro-dibenzophosphole 5-oxide-5-yl) biphenyl. It was confirmed. 1 and 2 show the IR measurement results and the NMR measurement results, respectively.
Melting point: 436 ° C
FAB-MS, m / z: 551 [M] ⁺
IR (cm < ^-1 >): 3051 (arC-H), 1202 (P = O)
¹ H-NMR (CDCl ₃ , 60 Hz): 7.90 to 7.26 (complex signal)
HPLC elution time: 10.8 minutes Yield: 31% yield (based on 4,4′-dibromobiphenyl)

Synthesis Example 1-2 (Synthesis Using Catalytic Reaction: Method 1)
4,4′-Bis (5-hydro-dibenzophosphole 5-oxide-5-yl) biphenyl (compound (9)) was synthesized by the following steps.

1.83 g (9.94 mmol) of 5-hydro-dibenzophosphole obtained by the method described in Reference 1, 509 mg (1.25 mmol) of 4,4′-diiodobiphenyl, N, N-dimethylaminopyridine (DMAP) ) 3.01 g (24.6 mmol), palladium acetate (Pd (OAc) ₂ ) 47.1 g (0.21 mmol) and 1,3-bis (diphenylphosphino) propane (DPPP) 89 mg (0.216 mmol) 20 ml of dimethylacetamide (DMA) was added dropwise. The resulting solution was reacted at 130 ° C. overnight under a nitrogen atmosphere.

The organic layer was extracted from the reaction solution obtained with dichloromethane, then dried over magnesium sulfate and concentrated on a rotary evaporator. At this point, when FAB-MS analysis was performed, it was confirmed that the mixture was a mixture of 5-hydro-dibenzophosphole and 5-hydro-dibenzophosphole 5-oxide.
Next, carbon tetrachloride and 142 mg of 30% hydrogen peroxide were added to the concentrated residue, and the mixture was stirred at room temperature for 30 minutes. Next, the organic layer was extracted from the reaction solution obtained with dichloromethane, then dried over magnesium sulfate, and concentrated on a rotary evaporator. The concentrated residue was separated by filler silica gel column chromatography (developing solvent: dichloromethane / ethanol) and concentrated by a rotary evaporator. The concentrated residue was then recrystallized from toluene / ethanol to obtain white crystals (2.78 g).

When the physical properties of the obtained compound were evaluated, the following results were obtained, and the obtained compound was 4,4′-bis (5-hydro-dibenzophosphole 5-oxide-5-yl) biphenyl. It was confirmed.
Melting point: 436 ° C
FAB-MS, m / z: 551 [M] ⁺
IR (cm < ^-1 >): 3051 (arC-H), 1202 (P = O)
¹ H-NMR (CDCl ₃ , 60 Hz): 7.90 to 7.26 (complex signal)
HPLC elution time: 10.8 minutes Yield: 43% yield (based on 4,4′-diiodobiphenyl)

Synthesis Example 1-3 (Synthesis using catalytic reaction: Method 1)
4,4′-Bis (5-hydro-dibenzophosphole 5-oxide-5-yl) biphenyl (compound (9)) was synthesized by the following steps.

The 5-hydro-dibenzophosphole 5-oxide produced as a by-product during the synthesis of 5-hydro-dibenzophosphole by the method described in Document 1 was separated by silica gel column chromatography.
The resulting 5-hydro-dibenzophosphole 5-oxide 6.0 g (3 mmol), 4,4′-diiodobiphenyl 203 mg (0.5 mmol), N, N-dimethylaminopyridine (DMAP) 3.01 g (9 mmol) ), Palladium acetate (Pd (OAc) ₂ ) 13.4 mg (0.06 mmol) and 1,3-bis (diphenylphosphino) propane (DPPP) 24.7 mg (0.06 mmol) were added to dimethylacetamide (DMA 2 ml was added dropwise. The resulting solution was reacted at 130 ° C. overnight under a nitrogen atmosphere.

  The concentrated residue was separated by filler silica gel column chromatography (developing solvent: dichloromethane / ethanol) and concentrated by a rotary evaporator. The concentrated residue was then recrystallized with toluene / ethanol to obtain white crystals (0.84 g).

When the physical properties of the obtained compound were evaluated, the following results were obtained, and the obtained compound was 4,4′-bis (5-hydro-dibenzophosphole 5-oxide-5-yl) biphenyl. It was confirmed.
Melting point: 436 ° C
FAB-MS, m / z: 551 [M] ⁺
IR (cm < ^-1 >): 3051 (arC-H), 1202 (P = O)
¹ H-NMR (CDCl ₃ , 60 Hz): 7.90 to 7.26 (complex signal)
HPLC elution time: 10.8 minutes Yield: 33% yield (relative to 4,4′-diiodobiphenyl)

Synthesis Example 2 (Synthesis of 5-biphenyl-4-yl-5-hydro-dibenzophosphole 5-oxide (compound (1)))
5-biphenyl-4-yl-5-hydro-dibenzophosphole 5-oxide (compound (1)) was synthesized in the following steps (Method 2).

A Grignard reagent was prepared using 4.66 g (2 mmol) of 4-bromobiphenyl, 0.48 g (2 mmol) of magnesium and 4 ml of THF. The obtained Grignard reagent was cooled to 0 ° C., and a solution of 4 mmol of 5-chloro-5-hydro-dibenzophosphole 5-oxide previously synthesized in the same manner as in Synthesis Example 1 in 4 ml of THF was applied over 10 minutes. And dripped. The resulting reaction solution was heated to room temperature over 5 minutes and refluxed for 2 hours.
Distilled water (40 ml) was added to the resulting reaction solution, and the organic layer was extracted from dichloromethane. Then, it was made to dry with magnesium sulfate and the solvent was depressurizingly distilled.
The obtained residue was purified by silica gel column chromatography (developing solvent: dichloromethane / methanol) and further purified by sublimation to obtain white crystals (2.53 g).

When the physical properties of the obtained compound were evaluated, the following results were obtained, and it was confirmed that the obtained compound was 5-biphenyl-4-yl-5-hydro-dibenzophosphole 5-oxide.
FAB-MS, m / z: 352 [M] ⁺
Yield: Yield 36% (based on 4-bromobiphenyl)

Synthesis Example 3 (Synthesis of 1,3,5-tris (5-hydro-dibenzophosphole 5-oxide-5-yl) benzene (compound (32)): Method 1)
1,3,5-Tris (5-hydro-dibenzophosphole 5-oxide-5-yl) benzene (compound (32)) was synthesized by the following steps.

1.21 g of a mixture of 5-hydro-dibenzophosphole and 5-hydro-dibenzophosphole 5-oxide obtained by the method described in Document 1 (6.55 mmol in terms of 5-hydro-dibenzophosphole), U. 230 mg (0.5 mmol) of 1,3,5-triiodobenzene obtained by the method described in Schoberl, TFMagnera, RMHarir, J. Am. Chem. Soc., 119, 3907 (1997) (Reference 3), N , N-dimethylaminopyridine (DMAP) 1.83 g (15.0 mmol), palladium acetate (Pd (OAc) ₂ ) 28.5 mg (0.127 mmol) and 1,3-bis (diphenylphosphino) propane (DPPP) 15 ml of DMA was added dropwise to a mixture of 52.0 mg (0.126 mmol). The resulting solution was reacted at 130 ° C. overnight under a nitrogen atmosphere.

  The organic layer was extracted from the reaction solution obtained with dichloromethane and then dried over magnesium sulfate. The obtained dried product was separated by filler silica gel column chromatography (developing solvent: dichloromethane / ethanol) and concentrated by a rotary evaporator. The concentrated residue was then recrystallized from toluene / ethanol to obtain white crystals (165 mg).

When the physical properties of the obtained compound were evaluated, the following results were obtained, and the obtained compound was 1,3,5-tris (5-hydro-dibenzophosphole 5-oxide-5-yl) benzene. I confirmed that there was. 3 and 4 show IR measurement results and NMR measurement results, respectively.
Melting point: 315 ° C
FAB-MS, m / z: 673 [M] ⁺
IR (cm < ^-1 >): 3053 (arC-H), 1202 (P = O)
¹ H-NMR (CDCl ₃ , 60 Hz): 8.20-7.27 (complex signal)
HPLC elution time: 6.10 minutes Yield: Yield 48.9% (based on 1,3,5-triiodobenzene)

Synthesis Example 4 (9,9-Dimethyl-2,7-bis (5-hydro-dibenzophosphole 5-oxide-5-yl) fluorene (Compound (17)): Method 1)
9,9-Dimethyl-2,7-bis (5-hydro-dibenzophosphole 5-oxide-5-yl) fluorene (compound (17)) was synthesized in the following steps.

Step 1 (Synthesis of 9,9-dimethylfluorene)
To 3.01 g (18 mmol) of fluorene, 4.32 g (108 mmol) of sodium hydroxide and 21.5 ml (2.38 g, 10.8 mmol) of 15-crown-5-ether, 120 ml of DMSO was added and stirred. Further, 8.22 mL (18.7 g, 132 mmol) of methyl iodide was added dropwise over 2 hours and stirred for 2 hours, and then 120 ml of water was added and stirred for 1.5 hours.
The organic layer was extracted from the reaction solution obtained with dichloromethane, then dried over magnesium sulfate and concentrated on a rotary evaporator. Separation was performed by silica gel column chromatography (developing solvent: cyclohexane / toluene). The concentrated residue was then recrystallized with ethanol to obtain white crystals (2.12 g). At this time, when FAB-MS analysis was performed, a result of m / z = 194 ([M ⁺ ]) was obtained, and it was confirmed that the obtained compound was 9,9-dimethylfluorene (contract). (Rate 59.9%).

Step 2 (Synthesis of 2,7-diiodo-9,9-dimethylfluorene)
Acetic acid (AcOH) / H ₂ O (= 6.67 ml / 1.0 ml) was mixed with 1.09 g (5.61 mmol) of 9,9-dimethylfluorene, and the mixture was heated to 75 ° C. A 5.68 g (35 mmol) aqueous solution of% iodine chloride / hydrochloric acid was added dropwise and allowed to react overnight.
The organic layer was extracted from the reaction solution obtained with toluene, and then the residual iodine was neutralized and separated with 8 ml of 10% aqueous sodium thiosulfate solution.
The resulting solution was neutralized with 10% aqueous NaOH solution and washed with water. The organic layer was extracted from the resulting solution, dried over magnesium sulfate, and concentrated to dryness on a rotary evaporator. Subsequently, the concentrated dry solid was recrystallized with ethanol to obtain white crystals (1.31 g). At this time, when FAB-MS analysis was performed, a result of m / z = 446 ([M ⁺ ]) was obtained, and the obtained compound was 2,7-diiodo-9,9-dimethylfluorene. Was confirmed (yield 52.5%).

Step 3 (Synthesis of 9,9-dimethyl-2,7-bis (5-hydro-dibenzophosphole 5-oxide-5-yl) fluorene)
737 mg (4 mmol) of a mixture of 5-hydro-dibenzophosphole and 5-hydro-dibenzophosphole 5-oxide obtained by the method described in Document 1, 226 mg of 2,7-diiodo-9,9-dimethylfluorene (0 .51 mmol), 1.22 g (10 mmol) of N, N-dimethylaminopyridine, 19.4 mg (0.086 mmol) of palladium acetate (Pd (OAc) ₂ ) and 1,3-bis (diphenylphosphino) propane (DPPP) 10 ml of DMA was added dropwise to a mixture of 36.0 mg (0.087 mmol). The resulting solution was reacted at 130 ° C. overnight under a nitrogen atmosphere.

  The organic layer was extracted from the reaction solution obtained with dichloromethane and then dried over magnesium sulfate. The obtained dried product was separated by filler silica gel column chromatography (developing solvent: dichloromethane / ethanol) and concentrated by a rotary evaporator. The concentrated residue was then recrystallized from toluene / ethanol to obtain white crystals (192 mg).

When the physical properties of the obtained compound were evaluated, the following results were obtained, and the obtained compound was 9,9-dimethyl-2,7-bis (5-hydro-dibenzophosphole 5-oxide-5- I) Fluorene was confirmed. 5 and 6 show IR measurement results and NMR measurement results, respectively.
Melting point: 328 ° C
FAB-MS, m / z: 591 [M] ⁺
IR (cm < ^-1 >): 3055 (arC-H), 1441, 1403 (C-H), 1203 (P = O)
¹ H-NMR (CDCl ₃ , 60 Hz): 8.19 to 7.20 (complex signal, 22H), 1.61 to 1.49 (d6H)
HPLC elution time: 12.1 minutes Yield: Yield 68.7% (relative to 2,7-diiodo-9,9-dimethylfluorene)

Example 1
A glass substrate (manufactured by Sanyo Vacuum Co., Ltd.) with an ITO transparent electrode (thickness 80 nm, width 2 mm) having a thickness of 50 mm × 50 mm × 0.8 mm was sequentially ultrasonically cleaned in an alkaline detergent and acetone for 5 minutes. Next, the glass substrate was boiled and washed in isopropyl alcohol for 5 minutes, and further washed with UV ozone for 15 minutes.
Next, the obtained glass substrate is mounted on a substrate holder in a vacuum deposition apparatus, the inside of the apparatus is evacuated to about 5 × 10 ⁻⁴ Pa, and N, N so as to cover the ITO transparent electrode functioning as a cathode. '-Di-1-naphthyl-N, N'-diphenylbenzidine was deposited to obtain a hole transport layer having a thickness of 80 nm.

Next, on the hole transport layer, tris (8-quinolinolato) aluminum, 4,4′-bis (5-hydro-dibenzophosphole-5-oxide-5-yl) biphenyl (compound (9)) and fluoride Lithium was sequentially deposited to obtain a laminate of a 20 nm thick light emitting layer, a 40 nm thick electron transport layer, and a 0.2 nm thick electron injection layer.
Finally, aluminum was vapor-deposited with a width of 2 mm so as to be orthogonal to the ITO electrode on the electron injection layer to obtain a cathode having a thickness of 100 nm, thereby completing an organic EL device.

When the obtained organic EL element was energized and driven, green light emission derived from tris (8-quinolinolato) aluminum serving as a light emitting layer was obtained.
This element exhibited a sufficiently low driving voltage of 4.7 V at a luminance of 100 cd / m ² . Further, when this device was driven at a constant current at a luminance of 500 cd / m ² , the time required for the luminance to decrease to 80% showed a long device life of 15 hours.

Example 2
Except that the electron transport layer is formed by vapor deposition of 1,3,5-tris (5-hydro-dibenzophosphole-5-oxide-5-yl) benzene (compound (32)), the same as in Example 1. An organic EL device was obtained.
When the obtained organic EL element was energized and driven, green light emission derived from tris (8-quinolinolato) aluminum serving as a light emitting layer was obtained.
This element exhibited a sufficiently low driving voltage of 6.5 V at a luminance of 100 cd / m ² . Further, when this element was driven at a constant current at a luminance of 500 cd / m ² , the time required for the reduction to a luminance of 80% showed a long element lifetime of 125 hours.

Example 3
Example 1 except that the electron transport layer is formed by vapor deposition of 9,9-dimethyl-2,7-bis (5-hydro-dibenzophosphole 5-oxide-5-yl) fluorene (compound (17)). In the same manner, an organic EL device was obtained.
When the obtained organic EL element was energized and driven, green light emission derived from tris (8-quinolinolato) aluminum serving as a light emitting layer was obtained.
This device showed a sufficiently low driving voltage of 3.7 V at a luminance of 100 cd / m ² . Further, when this element was driven at a constant current at a luminance of 500 cd / m ² , the time required for the luminance to decrease to 80% showed a long element lifetime of 11.3 hours.

Comparative Example An organic EL device was obtained in the same manner as in Example 1 except that the electron transport layer was formed by vapor deposition of tris (8-quinolinolato) aluminum.
When the obtained organic EL element was energized and driven, green light emission derived from tris (8-quinolinolato) aluminum serving as a light emitting layer was obtained.
This element showed a sufficiently low driving voltage of 4.7 V at a luminance of 100 cd / m ^2. However, when this element was driven at a constant current of 500 cd / m ² , the time required for the luminance to drop to 80% was obtained. Was 9.5 hours, which was shorter than that of the above example.

FIG. 4 is a diagram showing an IR measurement result of the compound of Synthesis Example 1. FIG. 4 is a diagram showing the NMR measurement result of the compound of Synthesis Example 1. FIG. 6 is a diagram showing an IR measurement result of the compound of Synthesis Example 3. FIG. 4 is a diagram showing the NMR measurement result of the compound of Synthesis Example 3. FIG. 6 is a diagram showing an IR measurement result of the compound of Synthesis Example 4. FIG. 4 is a diagram showing the NMR measurement result of the compound of Synthesis Example 4.

Claims (4)

In an organic EL element in which an organic thin film layer composed of one or more layers including at least a light emitting layer is sandwiched between an anode and a cathode, the organic thin film layer comprises:

An organic EL device comprising a dibenzophosphole oxide derivative selected from: The organic EL device according to claim 1 wherein the light emitting layer contains the dibenzophosphol hole oxide derivative as the main component. The light-emitting layer, the organic EL device according to claim 1 or 2 containing the dibenzophosphol hole oxide derivative as an electron transport material.

A dibenzophosphole oxide derivative characterized in that it is selected from:

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