JP5098199B2 - Polymer compound, composition for organic electroluminescence device, thin film for organic electroluminescence device, and organic electroluminescence device - Google Patents

Description

  The present invention is excellent in solubility and heat resistance to various solvents, a polymer compound having an appropriate ionization potential, a composition organic electroluminescent device containing the polymeric compound, this composition for organic electroluminescence element The present invention relates to an organic electroluminescent element and a thin film thereof that can be driven at a low voltage, have high luminous efficiency, and high driving stability.

  In recent years, an electroluminescent element (organic electroluminescent element) using an organic material instead of an inorganic material such as ZnS has been developed. In general, a hole injection layer is provided between the anode and the light emitting layer in order to increase the efficiency and life of the electroluminescent device.

  In addition, by forming the hole injection layer by a wet film-forming method, the heat resistance and surface flatness of the device are improved compared to the case of forming by a vacuum vapor deposition method, the emission luminance is reduced, and constant current driving is performed. It has been reported that the voltage rise at the time, the occurrence of non-light emitting portions (dark spots), and the like are suppressed.

  For example, in Patent Document 1 and Patent Document 2, it is reported that a hole transporting polymer compound having a high glass transition temperature is dissolved in an organic solvent together with an electron accepting compound, and a hole injection layer is formed by a wet film forming method. Has been. However, the hole-transporting polymer compounds described in Patent Document 1 and Patent Document 2 have a problem of low ionization potential.

  If the difference between the ionization potential of the material used for the hole injection layer and the ionization potential of the material used for the light emitting layer is driven a large element, the recombination of holes and electrons near the interface of the hole injection layer and the luminescent layer Sites are localized, and the luminous efficiency and driving life of the device are limited. For this reason, a material having a relatively large ionization potential and a small difference from the ionization potential of the material used for the light emitting layer has been demanded as a constituent material of the hole injection layer.

Patent Document 3 proposes that a polycarbonate resin containing a 3,6,9-triarylcarbazole structure is used for an organic electroluminescent element. However, polycarbonate resin has insufficient solubility, so the coating solvent is limited, and furthermore, heat resistance and electrochemical stability are insufficient, so further improvement is necessary for use in organic electroluminescent devices. Met.
JP 2000-36390 A JP 2004-2740 A JP 2005-54165 A

  The present invention is a polymer compound having excellent solubility in various solvents, excellent heat resistance, and having an appropriate ionization potential, a composition for an organic electroluminescent device comprising the polymer compound, and the polymer An object of the present invention is to provide an organic electroluminescence device capable of being driven at a low voltage using a compound, having high luminous efficiency, and high driving stability, and a thin film thereof.

  As a result of intensive studies by the present inventors, the polymer compound having the following specific repeating unit is excellent in solubility in various solvents, has excellent heat resistance, and has an appropriate ionization potential. It has been found that an organic electroluminescent device that can be driven at a low voltage, has high luminous efficiency, and has high driving stability can be obtained.

The present invention has been achieved based on such knowledge, and the gist thereof includes a polymer compound containing a repeating unit represented by the following formula ( II-1 ) and an electron accepting compound. The composition for an organic electroluminescent device (Claim 1).

［式（II−１）中、環Ａおよび環Ｂは、それぞれカルバゾール環を構成する、置換基を有していてもよいベンゼン環を表す。Ｑ^１およびＱ^２は、各々独立して、直接結合、置換基を有していてもよい芳香族炭化水素基、または、置換基を有していてもよい芳香族複素環基を表す。Ｒ^１は、置換基を有していてもよいアルキル基、置換基を有していてもよい芳香族炭化水素基、または、置換基を有していてもよい芳香族複素環基を表す。Ｘは、下記の連結基群Ｘ^１の中から選ばれる連結基を表す。
〈連結基群Ｘ^１〉

（上記連結基群Ｘ^１において、Ａｒ^１１〜Ａｒ^２７は、各々独立して、置換基を有していてもよい芳香族炭化水素基、または、置換基を有していてもよい芳香族複素環基を表す。）］

[In Formula ( II-1 ), Ring A and Ring B each represent a benzene ring that may have a substituent and that constitutes a carbazole ring. Q ¹ and Q ² each independently represent a direct bond, an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. R ¹ represents an alkyl group that may have a substituent, an aromatic hydrocarbon group that may have a substituent, or an aromatic heterocyclic group that may have a substituent. X represents a linking group selected from the group of linkage groups X ¹ below.
<Linking group group ^X 1>

(In the linking group group X ¹ , Ar ^{11 to} Ar ²⁷ are each independently an aromatic hydrocarbon group which may have a substituent, or an aromatic complex which may have a substituent. Represents a cyclic group.)]

Another gist of the present invention resides in a thin film for an organic electroluminescent element (Claim 4 ) formed by a wet film forming method using the composition for an organic electroluminescent element.

Yet another aspect of the present invention, by using the composition for organic electroluminescence element, an organic electroluminescent device having a layer formed by a wet film-forming method (claim 5), consists in.

  Since the polymer compound of the present invention contains a specific structure in the repeating unit, it has excellent solubility in various solvents, excellent heat resistance, and an appropriate ionization potential. For this reason, the organic electroluminescent device manufactured using the polymer compound of the present invention can be driven at a low voltage, has high luminous efficiency, high heat resistance, and light emission luminance at constant current driving. Decrease, voltage increase, generation of non-light emitting part (dark spot), short circuit defect, and the like are suppressed.

  Accordingly, the organic electroluminescent device produced using the polymer compound of the present invention includes a light source (e.g., a copying machine utilizing the characteristics as a flat panel display (e.g., for OA computers and wall-mounted televisions) and a surface luminous body Considering application to light sources, backlight sources for liquid crystal displays and instruments), display boards, and marker lamps, the technical value is high.

  In addition, since the polymer compound of the present invention has essentially excellent solubility and electrochemical durability, it is not limited to an organic electroluminescent device, but also an electrophotographic photoreceptor, an organic electroluminescent device, a photoelectric conversion. It can also be effectively used for elements, organic solar cells, organic rectifying elements, and the like.

  Embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention does not exceed the gist thereof. It is not specified in the contents.

[Polymer compound]
First, the polymer compound of the present invention will be described.
The polymer compound of the present invention contains a repeating unit represented by the following formula (I) (hereinafter sometimes referred to as “repeating unit (I)”).

［式（Ｉ）中、環Ａおよび環Ｂは、それぞれカルバゾール環を構成する、置換基を有していてもよいベンゼン環を表す。Ｑ^１およびＱ^２は、各々独立して、直接結合、置換基を有していてもよい芳香族炭化水素基、または、置換基を有していてもよい芳香族複素環基を表す。Ｒ^１は、置換基を有していてもよいアルキル基、置換基を有していてもよい芳香族炭化水素基、または、置換基を有していてもよい芳香族複素環基を表す。Ｘは、下記の連結基群Ｘ^１の中から選ばれる連結基を表す。
〈連結基群Ｘ^１〉

（上記連結基群Ｘ^１において、Ａｒ^１１〜Ａｒ^２７は、各々独立して、置換基を有していてもよい芳香族炭化水素基、または、置換基を有していてもよい芳香族複素環基を表す。）］

[In Formula (I), Ring A and Ring B each represent a benzene ring which may have a substituent and constitutes a carbazole ring. Q ¹ and Q ² each independently represent a direct bond, an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. R ¹ represents an alkyl group that may have a substituent, an aromatic hydrocarbon group that may have a substituent, or an aromatic heterocyclic group that may have a substituent. X represents a linking group selected from the group of linkage groups X ¹ below.
<Linking group group ^X 1>

(In the linking group group X ¹ , Ar ^{11 to} Ar ²⁷ are each independently an aromatic hydrocarbon group which may have a substituent, or an aromatic complex which may have a substituent. Represents a cyclic group.)]

{Ring A and Ring B}
Ring A and ring B are each a benzene ring which may form a carbazole ring and may have a substituent.

  The benzene rings of ring A and ring B may each independently have an arbitrary substituent. As an arbitrary substituent which the ring A and the ring B may have, 1 type (s) or 2 or more types of the following substituent group Z are mentioned.

<Substituent group Z>
Preferably an alkyl group having 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, such as a methyl group and an ethyl group;
An alkenyl group having preferably 2 to 11 carbon atoms, more preferably 2 to 5 carbon atoms, such as a vinyl group;
Preferably an alkynyl group having 2 to 11 carbon atoms, more preferably 2 to 5 carbon atoms, such as an ethynyl group;
Preferably an alkoxy group having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, such as a methoxy group and an ethoxy group;
An aryloxy group having preferably 4 to 25 carbon atoms, more preferably 5 to 14 carbon atoms, such as a phenoxy group, a naphthoxy group, and a pyridyloxy group;
An alkoxycarbonyl group having preferably 2 to 11 carbon atoms, more preferably 2 to 7 carbon atoms, such as a methoxycarbonyl group and an ethoxycarbonyl group;
A dialkylamino group having preferably 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, such as a dimethylamino group and a diethylamino group;
A diarylamino group having preferably 10 to 30 carbon atoms, more preferably 12 to 22 carbon atoms, such as a diphenylamino group, a ditolylamino group, or an N-carbazolyl group;
An arylalkylamino group having preferably 6 to 25 carbon atoms, more preferably 7 to 17 carbon atoms, such as a phenylmethylamino group;
Preferably an acyl group having 2 to 10 carbon atoms, preferably 2 to 7 carbon atoms, such as an acetyl group and a benzoyl group;
Halogen atoms such as fluorine atoms and chlorine atoms;
Preferably a haloalkyl group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, such as a trifluoromethyl group;
Preferably an alkylthio group having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, such as a methylthio group and an ethylthio group;
A phenylthio group, a naphthylthio group, a pyridylthio group and the like, preferably an arylthio group having 4 to 25 carbon atoms, more preferably 5 to 14 carbon atoms;
A silyl group having preferably 2 to 33 carbon atoms, more preferably 3 to 26 carbon atoms, such as a trimethylsilyl group and a triphenylsilyl group;
Preferably a C2-C33, more preferably C3-C26 siloxy group such as a trimethylsiloxy group, a triphenylsiloxy group;
A cyano group;
An aromatic hydrocarbon group having preferably 6 to 30 carbon atoms, more preferably 6 to 18 carbon atoms, such as a phenyl group and a naphthyl group;
An aromatic heterocyclic group having preferably 3 to 28 carbon atoms, more preferably 4 to 17 carbon atoms, such as thienyl group and pyridyl group

  The molecular weight of each of the substituents is preferably 400 or less, more preferably about 250 or less.

The substituent for ring A and ring B is preferably an alkyl group, an aromatic hydrocarbon group, or an aromatic heterocyclic group, and most preferably a linking group for linking ring A and ring B and Q ¹ , It has no substituent other than Q ² and N—R ¹ .

{Q ¹ and Q ² }
Q ¹ and Q ² each independently represent a direct bond or a divalent linking group, and as the divalent linking group, any aromatic hydrocarbon group or aromatic heterocyclic group is applicable. Q ¹ and Q ² may be the same as or different from each other, and may have an arbitrary substituent. Preferably Q ¹ and Q ² are identical to each other.

  Examples of the aromatic hydrocarbon group include benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, and fluoranthene ring. Examples thereof include a group derived from a 6-membered monocyclic ring or a 2-5 condensed ring.

  Examples of the aromatic heterocyclic group include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolo Pyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyrazine ring, pyrimidine ring, triazine Ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring, etc. It includes groups derived from.

Q ¹ and Q ² may be one or two or more of the above aromatic hydrocarbon groups and / or aromatic heterocyclic groups connected by a direct bond or any divalent group. Good. Examples of any divalent group as the linking group in this case include an alkylene group, an alkenylene group, an alkynylene group, an arylamino group, an alkylamino group, a carbonyl group, and an ether group.

Q ¹ and Q ² are preferably a direct bond or an aromatic hydrocarbon group, and more preferably a direct bond or a group derived from a benzene ring from the viewpoint of heat resistance, solubility, and electrochemical durability. Examples of the group derived from a benzene ring include a phenylene group, a biphenylene group, a terphenylene group, and the like, and particularly preferably a phenylene group.

Examples of the substituent that the aromatic hydrocarbon group or aromatic heterocyclic group of Q ¹ or Q ² may have include one or more of the substituent group Z. Among these, an alkyl group, an aromatic hydrocarbon group, and an aromatic heterocyclic group are preferable, and Q ¹ and Q ² are most preferably not having a substituent other than each linking portion.

Since the heat resistance is excellent and the production is easy, the repeating unit (I) has Q ¹ bonded to ring A and Q ² bonded to ring B as represented by the following formula (II-1). It is preferable to do. That is, the polymer compound of the present invention preferably contains a repeating unit represented by the following formula (II-1). In particular, Q ¹ and Q ² are preferably bonded to the 3rd and 6th positions of the carbazole ring, respectively.

（式（II−１）中、環Ａ、環Ｂ、Ｑ^１、Ｑ^２、Ｒ^１、Ｘは、式（Ｉ）におけると同義である。）

(In formula (II-1), ring A, ring B, Q ¹ , Q ² , R ¹ and X have the same meanings as in formula (I).)

{R ¹ }
R ¹ represents an alkyl group, an aromatic hydrocarbon group, or an aromatic heterocyclic group, and these may have an arbitrary substituent. As an arbitrary substituent, the 1 type (s) or 2 or more types of the said substituent group Z are mentioned. Among these, the substituent preferably has a phenyl group.

R ¹ is preferably a phenyl group which may have a substituent from the viewpoints of heat resistance, solubility, and electrochemical durability. That is, the polymer compound of the present invention preferably contains a repeating unit represented by the following formula (II-2).

（式（II−２）中、環Ｄは置換基を有していてもよいベンゼン環を表し、環Ａ、環Ｂ、Ｑ^１、Ｑ^２、Ｘは、式（Ｉ）におけると同義である。）

(In Formula (II-2), Ring D represents an optionally substituted benzene ring, and Ring A, Ring B, Q ¹ , Q ² , and X have the same meanings as in Formula (I). .)

  Examples of the substituent of the ring D include one or more of the substituent group Z, and a phenyl group is preferable.

{X}
X represents a linking group selected from the group of linkage groups X ¹ below.

（上記連結基群Ｘ^１において、Ａｒ^１１〜Ａｒ^２７は、各々独立して、置換基を有していてもよい芳香族炭化水素基、または、置換基を有していてもよい芳香族複素環基を表す。） <Linking group group ^X 1>

(In the linking group group X ¹ , Ar ^{11 to} Ar ²⁷ are each independently an aromatic hydrocarbon group which may have a substituent, or an aromatic complex which may have a substituent. Represents a cyclic group.)

In the linking group group X ¹ , Ar ^{11 to} Ar ²⁷ are any aromatic hydrocarbon group or aromatic heterocyclic group, each of which may be the same or different, and has any substituent. You may do it.

  Examples of the aromatic hydrocarbon group include benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, and fluoranthene ring. Examples thereof include monovalent or divalent groups derived from a 6-membered monocyclic ring or a 2-5 condensed ring.

  Examples of the aromatic heterocyclic group include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolo Pyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyrazine ring, pyrimidine ring, triazine Ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring, etc. Derived include monovalent or divalent radical.

Ar ^{11 to} Ar ¹⁶ , Ar ¹⁸ , Ar ¹⁹ , Ar ^{21 to} Ar ²⁶ may be one or two or more of the above aromatic hydrocarbon groups and / or aromatic heterocyclic groups directly bonded or any 2 They may be linked by a valent group. Examples of any divalent group as the linking group in this case include an alkylene group, an alkenylene group, an alkynylene group, an arylamino group, an alkylamino group, a carbonyl group, and an ether group.

が好ましい。 The X, among the group of linkage groups X ^1, from the viewpoint of excellent solubility and positive hole-transporting property, particularly

Is preferred.

Examples of the substituent that the aromatic hydrocarbon group and aromatic heterocyclic group of Ar ^{11 to} Ar ^{27 in} the linking group group X ¹ may have include one or more of the substituent group Z. Among these, an alkyl group, an alkoxy group, an aromatic hydrocarbon group, and an aromatic heterocyclic group are preferable.

{Preferred examples of repeating units}
The repeating unit constituting the polymer compound of the present invention is represented by the formula (I), preferably the formula (II-1) to the formula (II-2), particularly represented by the following formula (II). Is preferred.

（式（II）中、環Ｃは置換基を有していてもよいベンゼン環を表す。環Ａ、環Ｂ、Ｑ^１、Ｑ^２、Ｘは、式（Ｉ）におけると同義である。）

(In formula (II), ring C represents an optionally substituted benzene ring. Ring A, ring B, Q ¹ , Q ² and X have the same meanings as in formula (I).)

  Specific examples of preferable repeating units constituting the polymer compound of the present invention are shown below, but the present invention is not limited thereto.

（Ｘは、前記連結基群Ｘ^１の中から選ばれる連結基を表す。） {Sequence and ratio of repeating unit (I)}
The polymer compound of the present invention is not limited as long as it has the repeating unit (I), and may be a polymer compound obtained by repeating only the repeating unit represented by the formula (I), or other repeating units. May be included. Moreover, 2 or more types of repeating units (I) may be included, and another unit may be further included in this. A polymer compound obtained by repeating only the repeating unit represented by the formula (I) is preferable. Examples of other repeating units that can be included in the polymer compound of the present invention include one or more selected from the following repeating unit group K.
<Repeating unit group K>

(X represents a linking group selected from the group of linkage groups X ^1.)

  When the repeating unit (I) and other repeating units such as the repeating unit group K are used, the manner of entering these repeating units may be regular or random, but from the viewpoint of solubility Random is preferable.

  When the way of repeating unit (I) and other repeating units is regular, for example, repeating unit (I) and other repeating units are alternately connected one by one, or multiple units are alternately connected And the like.

  From the viewpoint of charge transportability and electrochemical durability, the content of the repeating unit (I) in the polymer compound is generally 20 mol% or more, preferably 50 mol% or more, more preferably 80 mol% in total. Above, most preferably 100 mol%. That is, the polymer compound of the present invention is most preferably a compound comprising the repeating unit (I).

{Molecular weight of polymer compound}
The weight average molecular weight of the polymer compound of the present invention is usually 1,000,000 or less, preferably 300,000 or less, more preferably 100,000 or less, and usually 1,000 or more, preferably 3,000 or more. More preferably, it is 10,000 or more.

  Usually, this weight average molecular weight is determined by SEC (size exclusion chromatography) measurement. In SEC measurement, the elution time is shorter for higher molecular weight components and the elution time is longer for lower molecular weight components, but using the calibration curve calculated from the elution time of polystyrene (standard sample) with a known molecular weight, the elution time of the sample is changed to the molecular weight. The weight average molecular weight is calculated by conversion.

  If the molecular weight exceeds this upper limit, the solubility may be significantly reduced. If the molecular weight is lower than this lower limit, the glass transition temperature, melting point, vaporization temperature, etc. will decrease, and heat resistance will be significantly impaired. There is a fear.

  For the same reason, the molecular weight of the repeating unit (I) is usually 4000 or less, preferably 2000 or less, and usually 200 or more, preferably 400 or more.

{Physical properties of polymer compounds}
The glass transition temperature of the polymer compound of the present invention is usually 100 ° C. or higher, preferably 150 ° C. or higher, more preferably 200 ° C. or higher, from the viewpoint of driving stability including the heat resistance of the organic electroluminescent element.

  The potential to be oxidized is generally + 0.7 to + 1.6Vvs.SCE, in terms of hole injecting and transporting, preferably + 0.9 to + 1.4Vvs.SCE, more preferably + 1.0 +1.3 V vs. SCE, and the ionization potential is usually 5.0 to 5.9 eV, preferably 5.2 to 5.7 eV, more preferably 5.3 to 5.3 from the viewpoint of hole injection / transport properties. 5.6 eV.

[Synthesis method]
The polymer compound of the present invention is synthesized, for example, by reacting a dihydroxy compound represented by the following general formula (VI) with a dihalide represented by the following general formula (VII). Usually, the reaction is carried out in the presence of a base such as potassium carbonate, tert-butoxy sodium or triethylamine, and if necessary, can also be carried out in the presence of a transition metal catalyst such as copper or palladium complex.

（式（VI）、（VII）中、環Ａ、環Ｂ、Ｑ^１、Ｑ^２、Ｒ^１、Ｘは式（Ｉ）におけると同義であり、Ｘ’はフッ素原子、塩素原子、臭素原子などのハロゲン原子を表す。ｎは重合度を表す数である。）

(In formulas (VI) and (VII), ring A, ring B, Q ¹ , Q ² , R ¹ , X are as defined in formula (I), X ′ is a fluorine atom, a chlorine atom, a bromine atom, etc. (Where n is a number representing the degree of polymerization)

[Composition for organic electroluminescence device]
Next, the composition for organic electroluminescent elements of the present invention will be described.
The composition for organic electroluminescent elements of the present invention contains the polymer compound of the present invention. Usually, the composition for organic electroluminescent elements of the present invention contains a solvent, and preferably further contains an electron-accepting compound. Moreover, the organic electroluminescent element composition may contain various additives such as a leveling agent and an antifoaming agent.

  Since the thin film formed using the composition for organic electroluminescent elements of the present invention is excellent in heat resistance and charge transportability, the composition for organic electroluminescent elements of the present invention is useful for organic electroluminescent elements.

{solvent}
The solvent contained in the composition for organic electroluminescent elements of the present invention is not particularly limited as long as it is a solvent that dissolves the polymer compound of the present invention contained in the composition for organic electroluminescent elements of the present invention. . Here, the solvent that dissolves the polymer compound is a solvent that usually dissolves the polymer compound in an amount of 0.05% by weight or more, preferably 0.5% by weight or more, and more preferably 1% by weight or more. Since the polymer compound of the present invention has high solvent solubility, various solvents can be applied.

  In particular, in an organic electroluminescent device, a hole injection layer containing an electron-accepting compound should be formed in order to increase the hole injection / transport property and lower the driving voltage of the organic electroluminescent device. Is preferred. For this reason, in the composition for organic electroluminescent elements for forming the hole injection layer of the organic electroluminescent element by a wet film forming method, the solvent used is 0.005% by weight of the electron-accepting compound. It is preferably dissolved above, more preferably 0.05% by weight or more, and even more preferably 0.5% by weight or more.

  Further, as described above, the solvent used for forming the hole injection layer of the organic electroluminescence device by the wet film-forming method is the polymer of the present invention contained in the composition for organic electroluminescence device of the present invention. compound hole transporting compound such as an electron-accepting compound, it is preferable that do not include those causing deactivation agent or inactivating agent to inactivate the cation radical of them mixed hole transporting compound resulting from the.

  Note that the cation radical of the hole transporting compound, the electron accepting compound, or the hole transporting compound resulting from the mixture thereof may be altered. This alteration is considered to be caused by interaction such as charge transfer with other compounds contained in the same layer formed in the organic electroluminescence device. When these are altered, there is a problem that hole injection / transport properties of a layer formed of these materials and the like are lowered. Many of these alterations are considered to be caused by the solvent or impurities contained in the solvent, and in order to form a layer having a high hole injection / transport property, as a solvent of the composition for organic electroluminescent elements, It is necessary to select an appropriate solvent that must not be. In addition, due to the above-mentioned alteration, impurities tend to be more easily generated in the composition for organic electroluminescent elements prepared for the wet film forming method, and the storage stability of the composition for organic electroluminescent elements is reduced. There is a problem.

  Preferred solvents that satisfy the above conditions include, for example, ether solvents and ester solvents. Specifically, examples of the ether solvent include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1, 3 - dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxy toluene, 4-methoxy toluene, 2,3-dimethyl anisole, and aromatic ethers such as 2,4-dimethyl anisole and the like. Examples of ester solvents include aliphatic esters such as ethyl acetate, n-butyl acetate, ethyl lactate, and n-butyl lactate; phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and benzoic acid. Examples include aromatic esters such as n-butyl. These solvents may be used alone or in combination of two or more.

  The concentration of these solvents in the composition for organic electroluminescent elements is usually 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more, and usually 99.999% by weight or less, preferably 99%. It is .99% by weight or less, and more preferably 99.9% by weight or less.

  In addition to the solvents described above, various other solvents may be included as necessary as the solvent. Examples of such other solvents include aromatic hydrocarbon solvents such as benzene, toluene and xylene, amide solvents such as N, N-dimethylformamide and N, N-dimethylacetamide, and dimethyl sulfoxide. . However, aromatic hydrocarbon solvents such as benzene, toluene and xylene have low ability to dissolve cation radicals of hole transporting compounds, electron accepting compounds, and hole transporting compounds resulting from the mixture thereof. It is preferable to use a mixture with a system solvent, an ester solvent or the like.

  A hole-transporting compound such as the polymer compound of the present invention, an electron-accepting compound, a deactivated substance that deactivates the cation radical of the hole-transporting compound resulting from a mixture thereof, or a compound that generates such a deactivated substance Examples thereof include alcohol solvents such as ethyl alcohol. When a layer containing a hole transporting compound such as the polymer compound of the present invention and an electron accepting compound is formed by a wet film forming method using the composition for an organic electroluminescent element of the present invention, organic electroluminescence When these are contained in the element composition, a solvent that easily undergoes oxidation, such as the alcohol solvent, reacts with the electron-accepting compound.

  Further, hole transporting compound such as a polymer compound of the present invention, an electron-accepting compound, a hole deactivating agent to inactivate the cation radical of transporting compound or such deactivation substances resulting from their mixing generation Examples of the compound to be made include a protonic acid and a halogen-based solvent. Specifically, examples of the protonic acid include inorganic acids such as hydrochloric acid and hydrobromic acid; and organic acids such as formic acid, acetic acid, and lactic acid. Examples of the halogen-based solvent include a chlorine solvent, a bromine-containing solvent, and an iodine-containing solvent.

  When forming a layer by a wet film-forming method using a composition for an organic electroluminescence device containing a hole transporting compound such as a polymer compound of the present invention and an electron accepting compound, the composition for an organic electroluminescence device If an organic acid or halogen-based solvent is contained in the product, for example, the organic acid reacts with the hole injection / transport site and transforms into an ammonium salt.・ Transportability decreases. In addition, when a halogen-based solvent is contained, these halogen-based solvents often contain a corresponding acid, and this acid, like the above-mentioned organic acid, is used for hole injection / transport. Since the property site is altered, the hole injection / transport property of the obtained layer also deteriorates. In addition, it is not preferable that halides are mixed even in terms of a large environmental load.

  In addition, since an organic electroluminescent element is formed by laminating a plurality of layers made of organic compounds, each layer is required to be a uniform layer. When a layer is formed by a wet film forming method, moisture is mixed in the solution (composition) for forming the layer, so that moisture is mixed into the coating film and the uniformity of the film is impaired. The water content in the product is preferably as low as possible.

  Specifically, when a layer is formed by a wet coating method using the composition for organic electroluminescent elements of the present invention, the amount of water contained in the composition for organic electroluminescent elements is preferably 1% by weight or less, preferably Is 0.1% by weight or less, more preferably 0.05% by weight or less.

  In general, since organic electroluminescent elements use many materials such as cathodes that deteriorate significantly due to moisture, the presence of moisture is not preferable from the viewpoint of element degradation.

  Examples of the method for reducing the amount of water in the composition for organic electroluminescent elements include methods such as nitrogen gas sealing, use of a desiccant, dehydration of the solvent in advance, and use of a solvent with low water solubility. . In particular, it is preferable to use a solvent having low water solubility, because the formed film can prevent whitening due to absorption of moisture in the atmosphere during the wet film-forming process.

  From such a point of view, when the composition for organic electroluminescent elements of the present invention is used for use in forming a film by a wet film forming method, the composition for organic electroluminescent elements is, for example, at 25 ° C. It is preferable to contain 10% by weight or more of a solvent having a water solubility of 1% by weight or less, preferably 0.1% by weight or less. In addition, it is more preferable if the solvent which satisfy | fills this water solubility condition is 30 weight% or more in an organic electroluminescent element composition, and it is especially preferable if it is 50 weight% or more.

{Electron-accepting compound}
Next, the electron-accepting compound that is preferably contained in the composition for organic electroluminescent elements of the present invention will be described.

  The electron-accepting compound is preferably a compound having an oxidizing power and the ability to accept one electron from a hole-transporting compound such as the polymer compound of the present invention. Specifically, the electron-affinity compound has an electron affinity of 4 eV or more. A compound is preferable, and a compound which is a compound of 5 eV or more is more preferable.

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

  Of the above compounds, the substitution of a strong onium salts substituted with organic groups in having oxidizing power, high-valence inorganic compounds are preferred, organic groups in that they are applicable to the wet coating soluble in various solvents Preferred are onium salts, cyano compounds, and aromatic boron compounds. In particular, an onium salt substituted with an organic group is preferable, and an iodonium salt is particularly preferable.

  In particular, as the electron-accepting compound, an ionic compound represented by the following formula is preferable.

（式中、Ｒ¹¹、Ｒ²¹及びＲ³¹は、各々独立に、Ａ¹〜Ａ³と炭素原子で結合する有機基を表す。Ｒ¹²、Ｒ²²、Ｒ²³及びＲ³²〜Ｒ³⁴は、各々独立に、任意の基を表す。Ｒ¹¹〜Ｒ³⁴のうち隣接する２以上の基が、互いに結合して環を形成していてもよい。Ａ¹〜Ａ³は何れも周期表第３周期以降の元素であって、Ａ¹は長周期型周期表の第１７族に属する元素を表し、Ａ²は長周期型周期表の第１６族に属する元素を表し、Ａ³は長周期型周期表の第１５族に属する元素を表す。Ｚ₁ ^n1-〜Ｚ₃ ^n3-は、各々独立に、対アニオンを表す。ｎ_１〜ｎ_３は、各々独立に、対アニオンのイオン価を表す。）

(Wherein R ¹¹ , R ²¹ and R ³¹ each independently represents an organic group bonded to A ^{1 to} A ³ by a carbon atom. R ¹² , R ²² , R ²³ and R ^{32 to} R ³⁴ are each independently, .R ¹¹ to R 2 or more neighboring groups of ^34, bonded optionally form a ring .A ¹ to a ³ are both periodic table 3 together represent any group A ¹ represents an element belonging to group 17 of the long-period periodic table, A ² represents an element belonging to group 16 of the long-period periodic table, and A ³ represents a long-period element. Represents an element belonging to Group 15 of the periodic table, Z ₁ ^{n1 to} Z ₃ ⁿ³ each independently represents a counter anion, and n _{1 to} n ₃ each independently represents an ionic value of the counter anion. .)

  Specific examples of the organic group-substituted onium salts, cyano compounds, and aromatic boron compounds suitable as the electron-accepting compound include those described in WO 2005/089024, and the preferred examples thereof are also the same. It is not limited to them at all.

  An electron-accepting compound may be used individually by 1 type, and 2 or more types may be mixed and used for it.

{Hole transporting compound}
The composition for organic electroluminescent elements of the present invention may contain a hole transporting compound in addition to the polymer compound of the present invention described above. The hole transporting compound will be described below.

  As the hole transporting compound, a compound having an ionization potential of 4.5 eV to 5.5 eV is preferable in terms of hole transporting property. For example, an aromatic amine compound, a phthalocyanine derivative or a porphyrin derivative, a diarylamino group is used. Examples include 8-hydroxyquinoline derivative metal complexes and oligothiophene derivatives.

  Moreover, as said hole transport material, the hole transportable compound which is easy to melt | dissolve in a various solvent is preferable.

  As the aromatic tertiary amine compound, for example, a binaphthyl compound (Japanese Patent Laid-Open No. 2004-014187) and an asymmetric 1,4-phenylenediamine compound (Japanese Patent Laid-Open No. 2004-026732) are preferable. In addition, compounds that have been conventionally used as a hole injecting / transporting thin film forming material in an organic electroluminescent device may be appropriately selected from compounds that are easily dissolved in various solvents.

Examples of conventionally known compounds that have been utilized as hole injection / transport thin film forming materials include tertiary aromatic amine units such as 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane. Two or more tertiary amines typified by 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl; aromatic diamine compounds linked to each other (JP-A-59-194393); An aromatic amine compound having two or more condensed aromatic rings substituted with a nitrogen atom (Japanese Patent Laid-Open No. 5-234681); a derivative of triphenylbenzene and an aromatic triamine compound having a starburst structure (US Pat. No. 4 , 923,774); aromatic diamine compounds such as N, N′-diphenyl-N, N′-bis (3-methylphenyl) biphenyl-4,4′-diamine (rice (Japanese Patent No. 4,764,625); α, α, α ′, α′-tetramethyl-α, α′-bis (4-di (p-tolyl) aminophenyl) -p-xylene -2699084); a sterically asymmetric triphenylamine derivative as a whole molecule (JP-A-4-129271); a compound in which a plurality of aromatic diamino groups are substituted on a pyrenyl group (JP-A-4-175395) An aromatic diamine compound in which a tertiary aromatic amine unit is linked with an ethylene group (JP-A-4-264189); an aromatic diamine having a styryl structure (JP-A-4-290851); an aromatic 3 with a thiophene group Compound in which secondary amine unit is linked (JP-A-4-304466); Starburst type aromatic triamine compound (JP-A-4-308688); benzyl Phenyl compounds (JP-A-4-364153); compounds in which a tertiary amine is linked by a fluorene group (JP-A-5-25473); triamine compounds (JP-A-5-239455); bisdipyridylaminobiphenyl (specialty) No. 5-320634); N, N, N-triphenylamine derivatives (JP-A-6-1972); aromatic diamines having a phenoxazine structure (JP-A-7-138562); diaminophenylphenant Lysine derivatives (JP-A-7-252474); hydrazone compounds (JP-A-2-311591); silazane compounds (US Pat. No. 4,950,950);
Examples thereof include silanamine derivatives (JP-A-6-49079); phosphamine derivatives (JP-A-6-25659); quinacridone compounds and the like. Preferred examples of the phthalocyanine derivative or porphyrin derivative include porphyrin, 5,10,15,20-tetraphenyl-21H, 23H-porphyrin, 5,10,15,20-tetraphenyl-21H, 23H-porphyrin cobalt. (II), 5,10,15,20-tetraphenyl-21H, 23H-porphyrin copper (II), 5,10,15,20-tetraphenyl-21H, 23H-porphyrin zinc (II), 5,10, 15,20-tetraphenyl-21H, 23H-porphyrin vanadium (IV) oxide, 5,10,15,20-tetra (4-pyridyl) -21H, 23H-porphyrin, 29H, 31H-phthalocyanine copper (II), phthalocyanine Zinc (II), phthalocyanine titanium, phthalocyanine oxy Magnesium, phthalocyanine lead, phthalocyanine copper (II), 4,4 ', 4 ", 4''' - tetraaza-29H, 31H-phthalocyanine, and the like.

  Specific examples of preferred oligothiophene derivatives include α-terthiophene and derivatives thereof, α-sexithiophene and derivatives thereof, and oligothiophene derivatives containing a naphthalene ring (Japanese Patent Laid-Open No. 6-256341).

  These hole transporting compounds may be used in combination of two or more as required.

{Material concentration and compounding ratio}
The solid content concentration of the polymer compound of the present invention, the electron-accepting compound and components that can be added as necessary (hole transporting compound, leveling agent, etc.) in the composition for organic electroluminescent elements of the present invention is as follows: Usually 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, further preferably 0.5% by weight or more, most preferably 1% by weight or more, usually 80% by weight. % Or less, preferably 50% by weight or less, more preferably 40% by weight or less, still more preferably 30% by weight or less, and most preferably 20% by weight or less. When this concentration is below the lower limit, it is difficult to form a thick film when forming a thin film, and when it exceeds the upper limit, it is difficult to form a thin film.

  In the composition for organic electroluminescent elements of the present invention, the weight mixing ratio of electron accepting compound / polymer compound is usually 0.1 / 99.9 or more, more preferably 0.5 / 99.5. More preferably, it is 1/99 or more, most preferably 2/98 or more, usually 90/10 or less, more preferably 70/30 or less, and further preferably 50/50 or less. . If this ratio falls below the lower limit or exceeds the upper limit, the hole injection property and heat resistance may be reduced.

{Preparation method}
The composition for an organic electroluminescence device of the present invention is prepared by dissolving a solute composed of the polymer compound of the present invention, an electron accepting compound, and components that can be added as necessary, in an appropriate solvent. In order to shorten the time required for the dissolution step and to keep the solute concentration in the composition uniform, the solute is usually dissolved while stirring the liquid. The dissolution step may be performed at room temperature, but when the dissolution rate is slow, it can be heated and dissolved. After completion of the dissolution step, a filtration step such as filtering may be performed as necessary.

{Properties, properties, etc. of composition for organic electroluminescence device}
<Moisture concentration>
In the case of producing an organic electroluminescent device by forming a layer by a wet film forming method using the composition for organic electroluminescent device of the present invention, if water is present in the composition for organic electroluminescent device to be used, Since moisture is mixed and the uniformity of the film is impaired, the water content in the composition for organic electroluminescent elements of the present invention is preferably as low as possible. In general, since organic electroluminescent devices use many materials such as cathodes that deteriorate significantly due to moisture, when moisture is present in the composition for organic electroluminescent devices, moisture remains in the dried film. However, there is a possibility of deteriorating the characteristics of the element, which is not preferable.

  Specifically, the amount of water contained in the composition for organic electroluminescent elements of the present invention is usually 1% by weight or less, preferably 0.1% by weight or less, more preferably 0.01% by weight or less.

  As a method for measuring the moisture concentration in the composition for organic electroluminescent elements, the method described in Japanese Industrial Standard “Method for Measuring Moisture of Chemical Products” (JIS K0068: 2001) is preferable. For example, the Karl Fischer reagent method (JIS K0211). -1348) and the like.

<Uniformity>
The composition for organic electroluminescent elements of the present invention is preferably in a uniform liquid state at room temperature in order to enhance stability in a wet film forming process, for example, ejection stability from a nozzle in an ink jet film forming method. . The uniform liquid at normal temperature means that the composition is a liquid composed of a uniform phase and does not contain a particle component having a particle size of 0.1 μm or more in the composition.

<Physical properties>
Regarding the viscosity of the composition for organic electroluminescent elements of the present invention, in the case of extremely low viscosity, for example, coating surface non-uniformity due to excessive liquid film flow in the film forming process, nozzle ejection failure in ink jet film formation, etc. are likely to occur. In the case of extremely high viscosity, nozzle clogging or the like in ink jet film formation tends to occur. For this reason, the viscosity at 25 ° C. of the composition of the present invention is usually 1 mPa · s or more, preferably 3 mPa · s or more, more preferably 5 mPa · s or more, and usually 1000 mPa · s or less, preferably 100 mPa · s or less. More preferably, it is 50 mPa · s or less.

  In addition, when the surface tension of the composition for organic electroluminescent elements of the present invention is high, the wettability of the liquid for film formation with respect to the substrate is lowered, the leveling property of the liquid film is poor, and the film formation surface is disturbed during drying. Since the problem of becoming easy occurs, the surface tension at 20 ° C. of the composition of the present invention is usually less than 50 mN / m, preferably less than 40 mN / m.

  Furthermore, when the vapor pressure of the composition for organic electroluminescent elements of the present invention is high, problems such as changes in solute concentration due to evaporation of the solvent tend to occur. For this reason, the vapor pressure at 25 ° C. of the composition of the present invention is usually 50 mmHg or less, preferably 10 mmHg or less, more preferably 1 mmHg or less.

{Storage method of composition for organic electroluminescence device}
The composition for an organic electroluminescent element of the present invention is preferably filled in a container capable of preventing the transmission of ultraviolet rays, for example, a brown glass bottle, and sealed and stored. The storage temperature is usually −30 ° C. or higher, preferably 0 ° C. or higher, and usually 35 ° C. or lower, preferably 25 ° C. or lower.

[Thin film for organic electroluminescence device]
The thin film for an organic electroluminescent device of the present invention formed by a wet film-forming method using the composition for an organic electroluminescent device of the present invention is a film that is difficult to crystallize, has excellent luminescent properties and heat resistance, and is usually organic. Used as a layer between the cathode and anode of the electroluminescent device.

  Here, the wet film-forming method in the present invention refers to a coating composition such as a spin coating method, a spray coating method, a dip coating method, a die coating method, a flexographic printing method, a screen printing method, and an inkjet method. Use to form a film.

  The film thickness of the thin film for organic electroluminescent elements of the present invention is appropriately determined depending on the application. For example, in the case of a light emitting layer of an organic electroluminescent element, as described later, it is usually 10 nm or more, preferably 20 nm or more, usually 300 nm. Below, it is preferably 200 nm or less, or usually 30 nm or more, preferably 50 nm or more, usually 500 nm or less, preferably 300 nm or less.

[Organic electroluminescence device]
The organic electroluminescent element of the present invention has an anode, a cathode, and a light emitting layer provided between the two electrodes, and contains the polymer compound of the present invention between the anode and the cathode. That is, it is preferable to have a layer containing the polymer compound of the present invention. The layer preferably further contains an electron accepting compound. In particular, an organic electroluminescent device having a layer formed by a wet film forming method using the composition for organic electroluminescent devices of the present invention is preferred.

  The layer containing the polymer compound of the present invention between the anode and the cathode is preferably a hole injection layer and / or a hole transport layer. In particular, the polymer compound of the present invention, in a position in contact with the anode, is used as a hole injection layer formed by a wet film-forming method is, is relieved surface roughness of the anode, the short-circuit defects during device fabrication The advantage of this layer that it is effective in preventing is fully utilized, which is preferable. The polymer compound of the present invention has a suitable ionization potential, exhibits high redox stability and high hole injection / transport properties, and is preferable as a hole injection / transport material for organic electroluminescent devices. Of course, you may use the high molecular compound of this invention for a light emitting layer.

  1 to 7 are schematic cross-sectional views showing structural examples suitable for the organic electroluminescence device of the present invention. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a light emitting layer, 5 represents an electron injection layer, and 6 represents a cathode.

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

[2] Anode An anode 2 is provided on the substrate 1. The anode 2 plays a role of hole injection into a layer on the light emitting layer side (such as the hole injection layer 3 or the light emitting layer 4).

  The anode 2 is usually made of metal such as aluminum, gold, silver, nickel, palladium, platinum, metal oxide such as oxide of indium and / or tin, metal halide such as copper iodide, carbon black, or poly It is composed of conductive polymers such as (3-methylthiophene), polypyrrole, and polyaniline.

  The anode 2 is usually formed by sputtering or vacuum deposition. In addition, when forming an anode using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, or conductive polymer fine powder, an appropriate binder resin solution is used. The anode 2 can also be formed by dispersing and coating the substrate 1. Further, in the case of a conductive polymer, a thin film can be directly formed on the substrate 1 by electrolytic polymerization, or the anode 2 can be formed by applying a conductive polymer on the substrate 1 (Appl. Phys. Lett. 60, 2711, 1992).

The anode 2 usually has a single-layer structure, but it can also have a laminated structure made of a plurality of materials if desired.

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

  The surface of the anode is treated with ultraviolet (UV) / ozone, oxygen plasma, or argon plasma for the purpose of removing impurities adhering to the anode and adjusting the ionization potential to improve hole injection. Is preferred.

[3] Hole Injection Layer The hole injection layer 3 is formed on the anode 2 by a wet film forming method or a vacuum deposition method. Since the hole injection layer 3 is a layer that transports holes from the anode 2 to the light emitting layer 4, the hole injection layer 3 preferably contains a hole transporting compound such as the polymer compound of the present invention.

  In particular, it is possible to produce an organic electroluminescent device that can be driven at a low voltage, has high luminous efficiency, and has high heat resistance. Since the generation of non-light-emitting portions (dark spots), short-circuit defects, and the like can be suppressed, the hole injection layer 3 is preferably formed by a wet film forming method using the composition for organic electroluminescent elements of the present invention. Examples of the wet film forming method include spin coating, spray coating, dip coating, die coating, flexographic printing, screen printing, and inkjet method.

  In the hole injection layer 3, a cation radical obtained by removing one electron from an electrically neutral compound accepts one electron from a nearby electrically neutral compound, whereby holes move. When the cation radical compound is not included in the hole injection layer 3 when the element is not energized, the cation radical of the hole transport compound is generated when the hole transport compound gives electrons to the anode 2 during energization, Holes are transported by transferring electrons between the cation radical and an electrically neutral hole transporting compound.

  When the hole injection layer 3 contains a cation radical compound, cation radicals necessary for hole transport are present at a concentration higher than that generated by oxidation by the anode 2, and the hole transport performance is improved. It is preferable that the hole injection layer 3 contains a cation radical compound.

  Here, the cation radical compound is a cation radical that is a chemical species obtained by removing one electron from a hole transporting compound, and an ionic compound composed of a counter anion, and already has holes (free carriers) that are easy to move. Yes.

  In addition, by mixing an electron-accepting compound with a hole-transporting compound such as the polymer compound of the present invention, one-electron transfer from the hole-transporting compound to the electron-accepting compound occurs, and the cation radical compound described above Generate. For this reason, it is preferable that the hole injection layer 3 contains a hole transporting compound such as the polymer compound of the present invention and an electron accepting compound.

  Furthermore, the hole injection layer 3 may contain a binder resin that does not easily trap charges and a coating property improving agent as necessary.

  Alternatively, as the hole injection layer 3, only an electron-accepting compound may be formed on the anode 2 by a wet film forming method, and the organic electroluminescent element composition of the present invention may be directly applied and laminated thereon. Is possible. In this case, when a part of the composition for organic electroluminescent elements of the present invention interacts with the electron accepting compound, a layer excellent in hole injecting property is formed.

[4] Light-Emitting Layer The light-emitting layer 4 is usually formed on the hole injection layer 3 by a wet film forming method or a vacuum deposition method. The light emitting layer 4 is a layer containing a light emitting material, and between the electrodes to which an electric field is applied, holes injected from the anode 2 through the hole injection layer 3 and electrons injected from the cathode 6 through the electron transport layer 5 It is a layer that is excited by recombination and becomes a main light emitting source.

  The light emitting layer 4 preferably contains a light emitting material (dopant) and one or more host materials. The light emitting layer 4 may be a layer produced by a vacuum deposition method or a layer produced by a wet film forming method.

  The light-emitting layer 4 can be made of a polymer light-emitting material such as a polyfluorene derivative or a poly (p-phenylene vinylene) derivative, and of course, the polymer compound of the present invention can also be used.

  The thickness of the light emitting layer 4 is usually 10 nm or more, preferably 20 nm or more, and usually 300 nm or less, preferably 200 nm or less.

The light emitting material mainly refers to a component that emits light, and corresponds to a dopant component in an organic electroluminescent element. Of the amount of light emitted from the organic electroluminescent device (unit: cd / m ² ), usually 10 to 100%, preferably 20 to 100%, more preferably 50 to 100%, most preferably 80 to 100%. When it is identified as light emission from a component material, it is defined as a light emitting material.

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

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

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

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

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

（一般式（VIII−２）中、Ｍ^ｄは金属を表し、Ｔは炭素または窒素を表す。Ｒ⁹²〜Ｒ⁹⁵は、それぞれ独立に置換基を表す。ただし、Ｔが窒素の場合は、Ｒ⁹⁴およびＲ⁹⁵は無い。）

(In General Formula (VIII-2), M ^d represents a metal, T represents carbon or nitrogen. R ^{92 to} R ⁹⁵ each independently represents a substituent. However, when T is nitrogen, R ^d represents R. ⁹⁴ and R ⁹⁵ are not available.)

Hereinafter, the compound represented by formula (VIII-1) will be described first.
In general formula (VIII-1), M represents an arbitrary metal, and specific examples of preferable ones include the metals described above as metals selected from Groups 7 to 11 of the periodic table.
Moreover, the bidentate ligands L and L ′ in the general formula (VIII-1) each represent a ligand having the following partial structure.

As L ′, the followings are particularly preferable from the viewpoint of the stability of the complex.

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

  If the ring A1 and ring A2 has a substituent, examples of preferred substituents, a halogen atom such as a fluorine atom; an alkyl group such as methyl group and ethyl group; alkenyl groups such as vinyl group; a methoxycarbonyl group, an ethoxycarbonyl group, etc. Alkoxycarbonyl groups such as methoxy groups and ethoxy groups; aryloxy groups such as phenoxy groups and benzyloxy groups; dialkylamino groups such as dimethylamino groups and diethylamino groups; diarylamino groups such as diphenylamino groups; carbazolyl groups Acyl groups such as acetyl groups; haloalkyl groups such as trifluoromethyl groups; cyano groups; aromatic hydrocarbon groups such as phenyl groups, naphthyl groups, and phenanthyl groups.

  The compound represented by the general formula (VIII-1), more preferably the following general formula (VIII-1a), (VIII-1b), include compounds represented by (VIII-1c).

（一般式（VIII−１ａ）中、Ｍ^ａはＭと同様の金属を表し、ｗは上記金属の価数を表す。また、環Ａ１は置換基を有していてもよい芳香族炭化水素基を表し、環Ａ２は置換基を有していてもよい含窒素芳香族複素環基を表す。）

(In General Formula (VIII-1a), M ^a represents the same metal as M, w represents the valence of the metal, and ring A1 is an aromatic hydrocarbon group which may have a substituent. Ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

（一般式（VIII−１ｂ）中、Ｍ^ｂはＭと同様の金属を表し、ｗは上記金属の価数を表す。また、環Ａ１は置換基を有していてもよい芳香族炭化水素基または置換基を有していてもよい芳香族複素環基を表し、環Ａ２は置換基を有していてもよい含窒素芳香族複素環基を表す。）

(In the general formula (VIII-1b), M ^b represents the same metal as M, w represents the valence of the metal. Further, the ring A1 is an aromatic optionally substituted hydrocarbon group Or, it represents an aromatic heterocyclic group which may have a substituent, and ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

（一般式（VIII−１ｃ）中、Ｍ^ｃはＭと同様の金属を表し、ｗは上記金属の価数を表す。また、ｊは０、１または２を表す。さらに、環Ａ１および環Ａ１’は、それぞれ独立に、置換基を有していてもよい芳香族炭化水素基または置換基を有していてもよい芳香族複素環基を表す。また、環Ａ２および環Ａ２’は、それぞれ独立に、置換基を有していてもよい含窒素芳香族複素環基を表す。）

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

  In the general formulas (VIII-1a), (VIII-1b), and (VIII-1c), the group of the ring A1 and the ring A1 ′ is preferably, for example, a phenyl group, a biphenyl group, a naphthyl group, an anthryl group, a thienyl group. Group, furyl group, benzothienyl group, benzofuryl group, pyridyl group, quinolyl group, isoquinolyl group, carbazolyl group and the like.

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

  Furthermore, the substituents that the compounds represented by the general formulas (VIII-1a), (VIII-1b), and (VIII-1c) may have include halogen atoms such as fluorine atoms; methyl groups, ethyl groups Alkenyl groups such as vinyl groups; Alkenyl groups such as vinyl groups; Alkoxycarbonyl groups such as methoxycarbonyl groups and ethoxycarbonyl groups; Alkoxy groups such as methoxy groups and ethoxy groups; Aryloxy groups such as phenoxy groups and benzyloxy groups; And dialkylamino groups such as diethylamino group; diarylamino groups such as diphenylamino group; carbazolyl groups; acyl groups such as acetyl group; haloalkyl groups such as trifluoromethyl group; cyano groups and the like.

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

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

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

Further, as M ^a , M ^b , and M ^c in the general formulas (VIII-1a), (VIII-1b), and (VIII-1c), ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, or Gold is mentioned.

  Specific examples of the organometallic complex represented by the general formula (VIII-1), (VIII-1a), (VIII-1b) or (VIII-1c) are shown below, but are not limited to the following compounds. None (in the following, Ph represents a phenyl group).

  Among the organometallic complexes represented by the general formulas (VIII-1), (VIII-1a), (VIII-1b), and (VIII-1c), in particular, the ligand L and / or L ′ is 2- An arylpyridine-based ligand, that is, a compound having 2-arylpyridine, one having an arbitrary substituent bonded thereto, and one obtained by condensing an arbitrary group thereto is preferable.

Next, the compound represented by the general formula (VIII-2) will be described.
In the general formula (VIII-2), M ^d represents a metal, and specific examples include metals described above as the metal to periodic table 7 is selected from Group 11. Among these, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold is preferable, and divalent metals such as platinum and palladium are particularly preferable.

In the general formula (VIII-2), R ⁹² and R ⁹³ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, Represents a carboxyl group, an alkoxy group, an alkylamino group, an aralkylamino group, a haloalkyl group, a hydroxyl group, an aryloxy group, an aromatic hydrocarbon group or an aromatic heterocyclic group.

Further, when T is carbon, R ⁹⁴ and R ⁹⁵ each independently represent a substituent represented by the same examples as R ⁹² and R ⁹³ . Further, as described above, when T is nitrogen, R ⁹⁴ and R ⁹⁵ are absent.

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

  Specific examples (T-1, T-10 to T-15) of the organometallic complex represented by the general formula (VIII-2) are shown below, but are not limited to the following exemplified compounds. In the following, Me represents a methyl group, and Et represents an ethyl group.

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

The phosphorescent material is usually used by mixing with a host material.
Any known material can be applied as the host material, and examples of applicable compounds include the following.

  Examples of carbazole compounds (including triarylamine compounds) include JP-A-63-235946, JP-A-2-285357, JP-A-2-261889, JP-A-3-230584, and JP-A-3230584. JP-A-3-232856, JP-A-5-263073, JP-A-6-312979, JP-A-7-053950, JP-A-8-003547, JP-A-9-157743, JP-A-9- No. 268283, JP-A-9-165573, JP-A-9-249876, JP-A-9-310066, JP-A-10-041069, JP-A-10-168447, European Patent No. 847228 , JP-A-10-208880, JP-A-10-226785, JP-A-10-312 73, JP-A-10-316658, JP-A-10-330361, JP-A-11-144866, JP-A-11-144867, JP-A-11-144873, JP-A-11-149987 Gazette, JP-A-11-167990, JP-A-11-233260, JP-A-11-241662, WO-00 / 70655, U.S. Pat. No. 6,562,982, JP-A-2003-040844, JP-A-2001-313179, JP-A-2001-257076, Japanese Patent Application No. 2003-202925, Japanese Patent Application No. 2003-204940, Japanese Patent Application No. 2003-299512, etc. Compound etc. are mentioned.

  Examples of the phenylanthracene derivative include compounds described as charge transport materials in JP-A No. 2000-344691.

  Furthermore, examples of the starburst type compound of condensed ring arylene include compounds described as charge transport materials in JP-A No. 2001-192651, JP-A No. 2002-324677, and the like.

  Examples of the condensed ring imidazole compound include “Appl. Phys. Lett., 78, 1622, 2001”, JP 2001-335776 A, JP 2002-338579 A, and JP 2002-319491 A. JP-A 2002-367785, JP-A 2002-367786, and the like include compounds described as charge transport materials.

  Furthermore, examples of the azepine-based compound include compounds described as charge transport materials in JP-A No. 2002-2335075 and the like.

  In addition, examples of the condensed triazole-based compound include compounds described as charge transporting materials in JP-A No. 2002-356489 and the like.

  Further, examples of the propeller-type arylene compound include compounds described in JP-A-2003-027048 as charge transport materials.

  Examples of the monotriarylamine type compounds include compounds described as charge transport materials in JP-A No. 2002-17583, JP-A No. 2002-249765, JP-A No. 2002-324676, and the like.

  Furthermore, examples of the arylbenzidine compounds include compounds described as charge transport materials in JP-A No. 2002-329577 and the like.

  Examples of the triaryl boron compound include compounds described as charge transport materials in JP-A Nos. 2003-031367 and 2003-031368.

  Further, examples of the indole compounds include compounds described in JP 2002-305084 A, JP 2003-008866 A, JP 2002-015871 A, and the like as charge transport materials.

  Examples of indolizine compounds include compounds described as charge transport materials in JP-A No. 2000-311787.

  Furthermore, examples of the pyrene compound include compounds described as charge transport materials in JP-A No. 2001-118682 and the like.

  Examples of the dibenzoxazole (or dibenzothiazole) compound include compounds described as charge transport materials in JP-A No. 2002-231453.

  Further, examples of the bipyridyl compounds include compounds described as charge transport materials in JP-A No. 2003-123983 and the like.

  Examples of the pyridine-based compound include compounds described as charge transport materials in JP-A-2005-276801, JP-A-2005-268199, and the like.

  Among these, carbazole compounds (including triarylamine compounds), condensed arylene starburst compounds, condensed imidazole compounds, from the viewpoint of excellent emission characteristics when using an organic electroluminescent device, Propeller type arylene compounds, monotriarylamine type compounds, indole compounds, indolizine compounds, bipyridyl compounds, pyridine compounds and the like are preferable.

  Furthermore, from the viewpoint of driving life when using an organic electroluminescent device, a carbazole compound, a bipyridyl compound, and a pyridine compound are more preferable, and a carbazole compound and a bipyridyl compound are mixed, or It is most preferable to use a mixture of pyridine compounds.

  It is also preferable to employ a compound having both a carbazolyl group and a pyridyl group.

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

  Specific examples of particularly preferable compounds as the charge transport material are shown below. In the following formulae, -N-Cz represents an N-carbazolyl group.

The compound used as the host material has a glass transition point of usually 70 ° C. or higher,
The temperature is preferably 100 ° C or higher, more preferably 120 ° C or higher, further preferably 130 ° C or higher, and most preferably 150 ° C or higher. This is because if the glass transition point is too low, the heat resistance of the organic electroluminescent device may be lowered and the driving life may be shortened.

  The compound used as the host material has a molecular weight of usually 10,000 or less, preferably 5000 or less, more preferably 3000 or less, and usually 100 or more, preferably 300 or more, more preferably 500 or more. When the molecular weight is less than 100, the heat resistance is remarkably lowered, gas generation is caused, the film quality is deteriorated when the film is formed, or the morphology of the organic electroluminescent element is changed due to migration or the like. This is not preferable. When the molecular weight exceeds 10,000, it is not preferable because it is difficult to purify the organic compound or it takes time to dissolve the organic compound in a solvent.

  The compound used as the host material desirably has a band gap of usually 3.0 V or higher, preferably 3.2 V or higher, more preferably 3.5 V or higher. Blue fluorescent light-emitting materials or phosphorescent light-emitting materials, especially green to blue light-emitting materials have a large band gap. When an organic electroluminescent element is produced using this phosphorescent light-emitting material, the host material surrounding the phosphorescent light-emitting material is: This is because, in general, it is preferable that the phosphorescent material has a bandgap that is equal to or larger than that of the phosphorescent material in terms of luminous efficiency and life as an organic electroluminescent element.

  The light emitting layer 4 may further contain other materials and components as long as the performance of the present invention is not impaired.

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

  In the present invention, in addition to the light emitting layer 4, when the organic layer such as the hole injection layer 3 and the electron transport layer 5 described later is provided, the light emitting layer 4 and other organic materials such as the hole injection layer 3 and the electron transport layer 5 are used. The total film thickness combined with the layer is usually 30 nm or more, preferably 50 nm or more, more preferably 100 nm or more, usually 1000 nm or less, preferably 500 nm or less, and more preferably 300 nm or less. In addition, when the conductivity of the hole injection layer 3 other than the light emitting layer 4 and the electron injection layer 5 described later is high, the amount of charge injected into the light emitting layer 4 increases. It is also possible to reduce the drive voltage while increasing the thickness to reduce the thickness of the light emitting layer 4 and maintaining the total thickness to some extent.

  Therefore, the thickness of the light emitting layer 4 is usually 10 nm or more, preferably 20 nm or more, and usually 300 nm or less, preferably 200 nm or less.

[5] Electron Injection Layer The electron injection layer 5 plays a role of efficiently injecting electrons injected from the cathode 6 into the light emitting layer 4. In order to perform electron injection efficiently, the material for forming the electron injection layer 5 is preferably a metal having a low work function, and alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium are used.
The film thickness of the electron injection layer 5 is preferably 0.1 to 5 nm.

Also, an ultrathin insulating film (0.1 to 5 nm) such as LiF, MgF ₂ , Li ₂ O, Cs ₂ CO ₃ may be inserted at the interface between the cathode 6 and the light emitting layer 4 or the electron transport layer 8 described later. This is an effective method for improving the efficiency of the device (Appl. Phys. Lett., 70, 152, 1997; JP-A-10-74586; IEEE Trans. Electron. Devices, 44, 1245, 1997). Year; SID 04 Digest, p. 154).

  Furthermore, organic metal transport materials represented by metal complexes such as nitrogen-containing heterocyclic compounds such as bathophenanthroline and aluminum complexes of 8-hydroxyquinoline described later are doped with alkali metals such as sodium, potassium, cesium, lithium and rubidium. (Described in JP-A-10-270171, JP-A 2002-1000047, JP-A 2002-1000048, and the like) makes it possible to improve electron injection / transport properties and achieve excellent film quality. Therefore, it is preferable. The film thickness in this case is usually 5 nm or more, preferably 10 nm or more, and usually 200 nm or less, preferably 100 nm or less.

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

The alkali metal is deposited using an alkali metal dispenser in which nichrome is filled with an alkali metal chromate and a reducing agent. By heating the dispenser in a vacuum container, the alkali metal chromate is reduced and the alkali metal is evaporated. In the case of co-evaporating the organic electron transport material and the alkali metal, the organic electron transport material is put in a crucible installed in a vacuum vessel, and the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with a suitable vacuum pump. Each crucible and dispenser are heated simultaneously to evaporate to form an electron injection layer on the substrate placed facing the crucible and dispenser.

At this time, co-evaporation is uniformly performed in the film thickness direction of the electron injection layer 5, but there may be a concentration distribution in the film thickness direction.
The electron injection layer 5 may be omitted as shown in FIGS.

[6] Cathode The cathode 6 plays a role of injecting electrons into a layer on the light emitting layer side (such as the electron injection layer 5 or the light emitting layer 4). The material used for the cathode 6 can be the material used for the anode 2, but a metal having a low work function is preferable for efficient electron injection, such as tin, magnesium, indium, calcium, A suitable metal such as aluminum or silver or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

  The film thickness of the cathode 6 is usually the same as that of the anode 2. For the purpose of protecting the cathode made of a low work function metal, further laminating a metal layer having a high work function and stable to the atmosphere on the cathode increases the stability of the device. For this purpose, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used.

[7] Other Constituent Layers While the description has been given centering on the element having the layer constitution shown in FIG. 1, the performance between the anode 2 and the cathode 6 and the light emitting layer 4 in the organic electroluminescent element of the present invention is described. In addition to the layers described above, any layer may be included, and any layer other than the light emitting layer 4 may be omitted.

  Examples of the layer that may be included include the electron transport layer 7. The electron transport layer 7 is provided between the light emitting layer 4 and the electron injection layer 5 as shown in FIG. 2 for the purpose of further improving the light emission efficiency of the device.

The electron transport layer 7 is formed of a compound capable of efficiently transporting electrons injected from the cathode 6 between electrodes to which an electric field is applied in the direction of the light emitting layer 4. As an electron transport compound used for the electron transport layer 7, the electron injection efficiency from the cathode 6 or the electron injection layer 5 is high, and the injected electrons can be efficiently transported with high electron mobility. It must be a compound.
Materials satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, oxadiazole derivatives, Styryl biphenyl derivative, silole derivative, 3- or 5-hydroxyflavone metal complex, benzoxazole metal complex, benzothiazole metal complex, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compound No. 207169), phenanthroline derivatives (Japanese Patent Laid-Open No. 5-331459), 2-t-butyl-9,10-N, N′-dicyanoanthraquinonediimine, n-type hydrogenated amorphous silicon carbide, n-type sulfide Examples include zinc and n-type zinc selenide.

  The lower limit of the thickness of the electron transport layer 7 is usually 1 nm, preferably about 5 nm, and the upper limit is usually about 300 nm, preferably about 100 nm.

  The electron transport layer 7 is formed by laminating on the light emitting layer 4 by a wet film forming method or a vacuum deposition method in the same manner as the hole injection layer 3. Usually, a vacuum deposition method is used.

  In particular, when a phosphorescent material or a blue light emitting material is used as the light emitting substance, it is also effective to provide the hole blocking layer 8 as shown in FIG. The hole blocking layer 8 has a function of confining holes and electrons in the light emitting layer 4 and improving luminous efficiency. That is, the hole blocking layer 8 is generated by blocking the holes moving from the light emitting layer 4 from reaching the electron transport layer 7, thereby increasing the recombination probability with electrons in the light emitting layer 4. There is a role of confining excitons in the light emitting layer 4 and a role of efficiently transporting electrons injected from the electron transport layer 8 toward the light emitting layer 4.

  The hole blocking layer 8 prevents the holes moving from the anode 2 from reaching the cathode 6 and can efficiently transport the electrons injected from the cathode 6 toward the light emitting layer 4. The compound is laminated on the light emitting layer 4 so as to be in contact with the interface of the light emitting layer 4 on the cathode 6 side.

  The physical properties required for the material constituting the hole blocking layer 8 include high electron mobility, low hole mobility, a large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high.

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

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

  The film thickness of the hole blocking layer 8 is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

  The hole blocking layer 8 can also be formed by the same method as the hole injection layer 3, but a vacuum deposition method is usually used.

  The electron transport layer 7 and the hole blocking layer 8 may be appropriately provided as necessary. 1) Only the electron transport layer, 2) Only the hole blocking layer, 3) Lamination of the hole blocking layer / electron transport layer, 4) There are usages such as not using.

  For the same purpose as the hole blocking layer 8, it is also effective to provide an electron blocking layer 9 between the hole injection layer 3 and the light emitting layer 4 as shown in FIG. The electron blocking layer 9 increases the probability of recombination with holes in the light emitting layer 4 by blocking the electrons moving from the light emitting layer 4 from reaching the hole injection layer 3, thereby generating excitons generated. Has a role of confining the light in the light emitting layer 4 and a role of efficiently transporting holes injected from the hole injection layer 3 in the direction of the light emitting layer 4.

  The characteristics required for the electron blocking layer 9 include high hole transportability, a large energy gap (difference between HOMO and LUMO), and a high excited triplet level (T1). Further, when the light emitting layer 4 is formed by a wet film forming method, it is preferable that the electron blocking layer 9 is also formed by a wet film forming method because the device manufacturing becomes easy.

  For this reason, it is preferable that the electron blocking layer 9 also has wet film forming compatibility, and examples of the material used for such an electron blocking layer 9 include dioctyl typified by F8-TFB in addition to the charge transport material of the present invention. And a copolymer of fluorene and triphenylamine (described in WO 2004/084260).

  The structure opposite to that shown in FIG. 1, that is, the cathode 6, the electron injection layer 5, the light emitting layer 4, the hole injection layer 3, and the anode 2 can be laminated on the substrate 1 in this order. It is also possible to provide the organic electroluminescent element of the present invention between two substrates, at least one of which is highly transparent. Similarly, it is also possible to laminate | stack to the structure opposite to the said each layer structure shown in FIGS.

Further, a structure in which a plurality of layers shown in FIG. 1 are stacked (a structure in which a plurality of light emitting units are stacked) may be employed. In that case, instead of the interfacial layer (between the light emitting units) (when the anode is ITO and the cathode is Al, the two layers), for example, V ₂ O ₅ is used as the charge generation layer (CGL). This is more preferable from the viewpoint of luminous efficiency and driving voltage.

  The present invention can be applied to any of an organic electroluminescent element having a single element, an element having a structure arranged in an array, and a structure having an anode and a cathode arranged in an XY matrix.

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

  In the following, the glass transition temperature Tg was determined by DSC measurement. The weight average molecular weight was determined by SEC measurement (developing solvent = THF (tetrahithrofuran)) using polystyrene as a standard sample.

(Synthesis Example 1)
Object 1

  In a nitrogen stream, 3,6-dibromocarbazole (10.2 g), 3-methoxyphenylboronic acid (12.4 g), potassium carbonate (17.4 g), ethylene glycol dimethyl ether (100 ml), and water (50 ml) The mixture was stirred for 15 minutes while heating to 60 ° C., tetrakis (triphenylphosphine) palladium (0) (1.82 g) was added, and the mixture was stirred for 6.5 hours under heating to reflux. After allowing to cool to room temperature, toluene (100 ml) and water (100 ml) were added to the reaction solution, and the mixture was stirred and separated. The aqueous layer was extracted with toluene (100 ml × 2 times), and the organic layers were combined. After drying, it was concentrated. Further, purification by silica gel column chromatography (n-hexane / methylene chloride = 2/1) gave the target product 1 (5.03 g). In the above formula, Me represents a methyl group, and Ph represents a phenyl group (the same applies hereinafter).

Target 2

  In a nitrogen stream, the target compound 1 (4.51 g), iodobenzene (7.28 g), copper (1.14 g), potassium carbonate (4.94 g), and tetraglyme (7 ml) were heated to 155 ° C., Stir for 6.5 hours. After allowing to cool, chloroform (50 ml) was added and stirred, and then insolubles were filtered off and the filtrate was concentrated. Furthermore, the target object 2 (5.22g) was obtained by refine | purifying with silica gel column chromatography (n-hexane / toluene = 1/1).

Target 3

  In a nitrogen stream, the target product 2 (5.22 g) and dichloromethane (40 ml) were cooled to 0 ° C., and a 1M methylene chloride solution of boron tribromide (31 ml) was added dropwise. The mixture was warmed to room temperature and stirred for 2 hours. After adding sodium bicarbonate water, the mixture was extracted with ethyl acetate, dried over magnesium sulfate, and the organic layer was concentrated. Further, purification by silica gel column chromatography (hexane / ethyl acetate = 1/1) gave the target product 3 (4.70 g).

Target 4

  The target compound 3 (4.68 g), 4,4′-difluorobenzophenone (2.38 g), potassium carbonate (9.04 g), and NMP (N-methylpyrrolidone) (110 ml) were heated to 145 ° C. Stir for 5 hours. After allowing to cool, activated clay was added and stirred, insoluble matters were filtered off, and the filtrate was added to methanol (300 ml). The obtained solid was washed with demineralized water (300 ml) and methanol (300 ml), dried under reduced pressure, dissolved in chloroform (300 ml), released into acetone (300 ml) and reprecipitated. Subsequently, by reprecipitation with chloroform (100 ml) / methanol (200 ml), the target compound 4 (P-1) (2.97 g) which is a polymer compound of the present invention was obtained.

  The polymer compound (P-1) had a Tg of 214 ° C., a weight average molecular weight (Mw) of 21,800, and a number average molecular weight (Mn) of 6,100.

  The oxidation potential of the polymer compound (P-1) measured by electrochemical measurement (cyclic voltammetry) is 1.20 V vs. SCE, which is an appropriate value as a hole injection material and a hole transport material of an organic electroluminescence device. Met.

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

Example 1
An organic electroluminescent element having the structure shown in FIG. 7 was produced by the following method.
An indium tin oxide (ITO) transparent conductive film deposited to a thickness of 150 nm on a glass substrate 1 (sputtered film product; sheet resistance 15Ω) is patterned into a 2 mm wide stripe using normal photolithography and hydrochloric acid etching Thus, an anode 2 was formed. The patterned ITO substrate was cleaned in the order of ultrasonic cleaning with acetone, water with pure water, and ultrasonic cleaning with isopropyl alcohol, then dried with nitrogen blow, and finally subjected to ultraviolet ozone cleaning.

Next, the hole injection layer 3 was formed by a wet coating method as follows.
As a material for the hole injection layer 3, a polymer compound having an aromatic amino group represented by the structural formula shown below (P-1 (weight average molecular weight: 21800, number average molecular weight: 6100)) and an electron having the structural formula shown below. Using the accepting compound (A-1), spin coating was performed under the following conditions.

<Spin coating conditions>
Solvent Anisole Coating solution concentration P-1 2.0% by weight
A-1 0.4% by weight
Spinner speed 2000rpm
Spinner rotation time 30 seconds Drying condition 230 ° C. × 3 hours A uniform thin film having a thickness of 30 nm was formed by the above spin coating.

Subsequently, the light emitting layer 4 was formed by a wet coating method as follows.
As a material for the light-emitting layer 4, a compound (E-1) having the structural formula shown below was used together with an iridium complex (D-1) having the structural formula shown below, and spin-coated under the following conditions.

<Spin coating conditions>
Solvent Xylene Coating solution concentration E-1 2.5% by weight
D-1 0.13 wt%
Spinner speed 1500rpm
Spinner rotation time 30 seconds Drying conditions 130 ° C x 60 minutes (under reduced pressure)
A uniform thin film having a thickness of 45 nm was formed by the above spin coating.

Next, a pyridine derivative (HB-1) shown below was laminated as a hole blocking layer 8 at a crucible temperature of 230 to 238 ° C. with a deposition rate of 0.07 to 0.11 nm / second and a film thickness of 5 nm. The degree of vacuum during the deposition was 1.4 × 10 ⁻⁴ Pa (about 1.1 × 10 ⁻⁶ Torr).

Next, an aluminum 8-hydroxyquinoline complex (ET-1) shown below was deposited as an electron transport layer 7 on the hole blocking layer 8 in the same manner. At this time, the crucible temperature of the aluminum 8-hydroxyquinoline complex is controlled in the range of 352 to 338 ° C., the degree of vacuum during the deposition is 1.5 to 1.4 × 10 ⁻⁴ Pa (about 1.1 × 10 ⁻⁶ Torr), and the deposition rate. Was 0.07 to 0.13 nm / sec and the film thickness was 30 nm.

  The substrate temperature during vacuum deposition of the hole blocking layer 8 and the electron transport layer 7 was kept at room temperature.

Here, the element that has been deposited up to the electron transport layer 7 is once taken out from the vacuum deposition apparatus into the atmosphere, and a 2 mm wide striped shadow mask is used as a cathode deposition mask. Installed in a separate vacuum deposition device in close contact with the element at right angles, and the degree of vacuum in the device is 2.6 × 10 ⁻⁶ Torr (about 3.5 × 10 ⁻⁴ Pa) or less in the same manner as the organic layer Was exhausted.

As the cathode 6, first, lithium fluoride (LiF) was deposited at a deposition rate of 0.01 to 0.06 nm / second using a molybdenum boat at a vacuum degree of 2.8 × 10 ⁻⁶ Torr (about 3.7 × 10 ⁻⁴ Pa) and 0.5 nm. The film was formed on the electron transport layer 7 with a film thickness of. Next, aluminum was similarly heated by a molybdenum boat, and the deposition rate was 0.2 to 0.6 nm / second, the degree of vacuum was 5.0 to 9.0 × 10 ⁻⁶ Torr (about 6.7 to 12.0 × 10 ⁻⁴ Pa), and the film thickness was 80 nm. A layer was formed to complete the cathode 6. The substrate temperature at the time of vapor deposition of the above two-layered cathode 6 was kept at room temperature.

As described above, an organic electroluminescent element having a light emitting area portion having a size of 2 mm × 2 mm was obtained. The light emission characteristics of this element are as follows.
Luminance / Current: 24.9 [cd / A] @ 100cd / m ²
Voltage: 5.9 [V] @ 100cd / m ²
Luminous efficiency: 13.4 [1m / w] @ 100cd / m ²

  The maximum wavelength of the emission spectrum of the device was 513 nm, which was identified as from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.308,0.625).

(Comparative Example 1)
An organic electroluminescent element having the structure shown in FIG. 7 was produced by the following method.
An indium tin oxide (ITO) transparent conductive film deposited to a thickness of 150 nm on a glass substrate 1 (sputtered film product; sheet resistance 15Ω) is patterned into a 2 mm wide stripe using normal photolithography and hydrochloric acid etching Thus, an anode 2 was formed. The patterned ITO substrate was cleaned in the order of ultrasonic cleaning with acetone, water with pure water, and ultrasonic cleaning with isopropyl alcohol, then dried with nitrogen blow, and finally subjected to ultraviolet ozone cleaning.

  Next, the hole injection layer 3 was formed by a wet coating method as follows. As a material for the hole injection layer 3, a polymer compound having an aromatic amino group represented by the structural formula shown below (P-2 (weight average molecular weight: 29400, number average molecular weight: 12600)) and an electron having the structural formula shown below. Using the accepting compound (A-1), spin coating was performed under the following conditions.

<Spin coating conditions>
Solvent Ethyl benzoate Coating solution concentration P-2 2.0% by weight
A-1 0.8% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds Drying condition 230 ° C. × 15 minutes A uniform thin film having a thickness of 30 nm was formed by the above spin coating.

Subsequently, the light emitting layer 4 was formed by a wet coating method as follows.
As the material for the light-emitting layer 4, the compound (E-1) used in Example 1 was used together with the iridium complex (D-1) and spin-coated under the following conditions.

<Spin coating conditions>
Solvent Xylene Coating solution concentration E-1 2.0% by weight
D-1 0.11% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds Drying conditions 130 ° C x 60 minutes (under reduced pressure)
A uniform thin film having a thickness of 30 nm was formed by the above spin coating.

Next, as the hole blocking layer 8, the pyridine derivative (HB-1) used in Example 1 was laminated at a crucible temperature of 299 to 305 ° C. with a deposition rate of 0.04 to 0.07 nm / second and a thickness of 5.0 nm. . The degree of vacuum during the deposition was 9.0 × 10 ⁻⁵ Pa (about 1.2 × 10 ⁻⁶ Torr).

Next, the aluminum 8-hydroxyquinoline complex (ET-1) used in Example 1 was deposited on the hole blocking layer 8 in the same manner as the electron transport layer 7. The crucible temperature of the aluminum 8-hydroxyquinoline complex at this time is controlled in the range of 414 to 410 ° C., and the degree of vacuum during the deposition is 9.0 to 8.3 × 10 ⁻⁵ Pa (about 1.2 to 1.1 × 10 ⁻⁶ Torr), The deposition rate was 0.04 to 0.12 nm / second and the film thickness was 30 nm.

  The substrate temperature during vacuum deposition of the hole blocking layer 8 and the electron transport layer 7 was kept at room temperature.

Here, the element that has been deposited up to the electron transport layer 7 is once taken out from the vacuum deposition apparatus into the atmosphere, and a 2 mm wide striped shadow mask is used as a cathode deposition mask. Installed in a separate vacuum deposition device so that they are in close contact with each other at right angles, and the degree of vacuum in the device is 1.4 × 10 ^-6 Torr (about 1.9 × 10 ^-4 Pa) or less in the same manner as the organic layer. Was exhausted.

As the cathode 6, first, lithium fluoride (LiF) is deposited on a molybdenum boat using a molybdenum boat with a deposition rate of 0.012 nm / sec, a vacuum of 1.8 × 10 ⁻⁶ Torr (about 2.4 × 10 ⁻⁴ Pa), and a 0.5 nm film. A film having a thickness was formed on the electron transport layer 7. Next, aluminum was similarly heated by a molybdenum boat, and the deposition rate was 0.05 to 0.5 nm / second, the degree of vacuum was 2.3 to 5.3 × 10 ⁻⁶ Torr (about 3.0 to 7.0 × 10 ⁻⁴ Pa), and the film thickness was 80 nm. A layer was formed to complete the cathode 6. The substrate temperature at the time of vapor deposition of the above two-layered cathode 6 was kept at room temperature.

As described above, an organic electroluminescent element having a light emitting area portion having a size of 2 mm × 2 mm was obtained. The light emission characteristics of this element are as follows.
Luminance / Current: 21.7 [cd / A] @ 100cd / m ²
Voltage: 6.5 [V] @ 100cd / m ²
Luminous efficiency: 10.6 [1m / w] @ 100cd / m ²

  The maximum wavelength of the emission spectrum of the device was 516 nm, and it was identified as that from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.314,0.625).

The device manufactured in Example 1 and Comparative Example 1 is lit by 100 cd / m ² , voltage, current efficiency, luminous efficiency, and normalized luminance halved when driven at a constant current of 2500 cd / m ^2. Table 1 shows the lifetime.

  From the above, it can be seen that the organic electroluminescence device using the polymer compound of the present invention is excellent in efficiency and lifetime.

It is typical sectional drawing which showed an example of the organic electroluminescent element of this invention. It is typical sectional drawing which showed another example of the organic electroluminescent element of this invention. It is typical sectional drawing which showed another example of the organic electroluminescent element of this invention. It is typical sectional drawing which showed another example of the organic electroluminescent element of this invention. It is typical sectional drawing which showed another example of the organic electroluminescent element of this invention. It is typical sectional drawing which showed another example of the organic electroluminescent element of this invention. It is typical sectional drawing which showed another example of the organic electroluminescent element of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Light emitting layer 5 Electron injection layer 6 Cathode 7 Electron transport layer 8 Hole blocking layer 9 Electron blocking layer

Claims (5)

The composition for organic electroluminescent elements containing the high molecular compound containing the repeating unit represented by a following formula ( II-1 ), and an electron-accepting compound.

[In Formula ( II-1 ), Ring A and Ring B each represent a benzene ring that may have a substituent and that constitutes a carbazole ring. Q ¹ and Q ² each independently represent a direct bond, an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. R ¹ represents an alkyl group that may have a substituent, an aromatic hydrocarbon group that may have a substituent, or an aromatic heterocyclic group that may have a substituent. X represents a linking group selected from the group of linkage groups X ¹ below.
<Linking group group ^X 1>

(In the linking group group X ¹ , Ar ^{11 to} Ar ²⁷ are each independently an aromatic hydrocarbon group which may have a substituent, or an aromatic complex which may have a substituent. Represents a cyclic group.)] Formula (II-1) repeating units represented by the composition for organic electroluminescence element according to claim 1, wherein the repeating unit represented by the following formula (II).

(In formula (II), ring C represents an optionally substituted benzene ring. Ring A, ring B, Q ¹ , Q ² and X are as defined in formula ( II-1 ). .) The composition for organic electroluminescent elements according to claim 1 or 2 , wherein the electron-accepting compound is an iodonium salt. The thin film for organic electroluminescent elements formed by the wet film forming method using the composition for organic electroluminescent elements in any one of Claims 1 thru | or 3 . The organic electroluminescent element which has a layer formed by the wet film-forming method using the composition for organic electroluminescent elements in any one of Claim 1 thru | or 3 .

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