JP5125480B2 - Hole transport material, polymer compound obtained by polymerizing the hole transport material, composition for organic electroluminescence device, and organic electroluminescence device - Google Patents

Description

  The present invention relates to a hole transport material composed of an organic compound having a crosslinking group, which can be formed by a wet film formation method, a polymer compound obtained by polymerizing the hole transport material, and the hole transport material. The present invention relates to an organic electroluminescent device having a composition containing an organic electroluminescent device and a layer containing the polymer compound, having high luminous efficiency and excellent driving stability.

In recent years, an electroluminescent element (organic electroluminescent element) using an organic thin film has been developed. Examples of the method for forming the organic thin film in the organic electroluminescence device include a vacuum deposition method and a wet film formation method.
Since the vacuum deposition method can be laminated, it has an advantage that the charge injection from the anode and / or the cathode is improved and the exciton light-emitting layer can be easily contained. The wet film formation method does not require a vacuum process, is easy to increase in area, and has an advantage that it is easy to mix a plurality of materials having various functions into one layer (coating liquid). .

  However, since the wet film forming method is difficult to stack, the driving stability is inferior to that of the element by the vacuum vapor deposition method, and the present state is that it has not reached a practical level except for a part. In particular, the layering by the wet film forming method can be performed by stacking two layers by using an organic solvent and an aqueous solvent, but it is difficult to stack three or more layers.

  In order to solve such problems in lamination, for example, in Patent Document 1, a film is formed using a diamine compound having an epoxy group.

Patent Document 2 proposes an aromatic amine compound having the following crosslinking group.

In the above compound, all the p-positions of the amine are substituents having a strong electron donating property, so that they are very easily oxidized and have a problem in storage stability.
JP-A-7-85973 Japanese Unexamined Patent Publication No. 7-114987

An object of the present invention is to provide a hole transport material suitable for a wet film-forming method, in particular, a hole transport material having a high effect of confining electrons and excitons on the light emitting layer side and excellent in storage stability.
Another object of the present invention is to provide an organic electroluminescent device having high luminous efficiency and high driving stability.

  As a result of intensive studies to solve the above problems, the present inventors have found that an organic compound having a crosslinking group having the following specific structure has high hole transport ability, high electron and exciton blocking ability, and is preserved. It has been found that the compound is excellent in stability and suitable for a wet film-forming method, and has reached the present invention.

［式中、Ｒ^１〜Ｒ^７は、各々独立に、水素原子、連結基Ｚ^１への直接結合または１価の基を表す。
ｎは、２〜４の整数を表す。
連結基Ｚ^１は、直接結合、エーテル基または２価の芳香族基を表す。
Ａ^１は、水素原子または架橋基を表す。
但し、一分子中において、少なくとも１つのＡ^１は架橋基である。
一分子内の複数のＡ^１同士あるいはＲ^１〜Ｒ^７同士は、それぞれ同一であっても異なっていてもよい。］ [1] A hole transport material represented by the following general formula (I) and having a molecular weight of 300 to 5,000.

[Wherein, R ^{1 to} R ⁷ each independently represents a hydrogen atom, a direct bond to the linking group Z ¹ or a monovalent group.
n represents an integer of 2 to 4.
Linking groups Z ¹ represents a direct bond, an ether group or a divalent aromatic group.
A ¹ represents a hydrogen atom or a bridging group.
However, in one molecule, at least one A ¹ is a crosslinking group.
A plurality of A ¹ or R ^{1 to} R ⁷ in one molecule may be the same or different. ]

[ 2 ] The hole transport material according to [1 ], wherein n is 2 .

[ 3 ] The hole transport material according to [1] or [ 2], wherein the number of crosslinking groups in one molecule is 1, 2 or 3.

［式中、Ｒ^１、Ｒ^５〜Ｒ^７、Ｚ^１、ｎおよびＡ^１は、それぞれ式（Ｉ）におけるものと同義である。また、Ｒ^９〜Ｒ^１１は、各々独立に、Ｒ^１〜Ｒ^７と同義である。］ [ 4 ] The hole transport material according to any one of [1] to [ 3 ], wherein the formula (I) is represented by the following general formula (II).

[Wherein, R ¹ , R ^{5 to} R ⁷ , Z ¹ , n and A ¹ have the same meanings as in formula (I), respectively. Moreover, R < ⁹ > -R < ¹¹ > is synonymous with R < ¹ > -R < ⁷ > each independently. ]

（式中、Ｒ^１５〜Ｒ^１８は、各々独立に、水素原子またはアルキル基を表す。Ａｒ^１は置換基を有してもよい芳香族炭化水素基または置換基を有してもよい芳香族複素環基を表す。）］ [ 5 ] The hole transport material according to any one of [1] to [ 4 ], wherein the crosslinking group is represented by the following formula (Ia).
-GJ (Ia)
[In the formula, G is formed by linking 1 to 30 groups selected from an —O— group, a —C (═O) — group, or an optionally substituted —CH ₂ — group. Represents a valent group, and J represents a group selected from the following cross-linking group group T.
<Crosslinking group T>

(Wherein R ^{15 to} R ¹⁸ each independently represents a hydrogen atom or an alkyl group. Ar ¹ is an aromatic hydrocarbon group which may have a substituent or an aromatic group which may have a substituent. Represents a heterocyclic group.]]

[ 6 ] A composition for an organic electroluminescence device comprising the hole transport material according to any one of [1] to [ 5 ] and a solvent.

[ 7 ] The composition for organic electroluminescent elements according to [ 6 ], wherein the composition contains two or more hole transport materials.

[ 8 ] A polymer compound obtained by polymerizing the hole transport material according to any one of [1] to [ 5 ].

[ 9 ] An organic electroluminescent element having an anode, a cathode, and an organic light emitting layer provided between both electrodes on a substrate, characterized in that it has a layer containing the polymer compound described in [ 8 ]. Organic electroluminescent device.

[ 10 ] The organic electroluminescent element as described in [ 9 ], wherein the organic light emitting layer is formed by a wet film forming method.

[ 11 ] The organic electroluminescent element as described in [ 9 ] or [ 10 ], wherein the layer containing a polymer compound is a hole transport layer.

  The hole transport material of the present invention has high hole transport ability, high electron and exciton blocking ability, and is excellent in storage stability. Moreover, this hole transport material is suitable for a wet film-forming method, and an organic layer of an organic electroluminescent element can be laminated by the wet film-forming method using this hole transport material.

Moreover, the organic electroluminescent element formed by the wet film-forming method using the composition for organic electroluminescent elements containing this hole transport material can be enlarged in area.
It is also possible to form an organic thin film insoluble in an organic solvent using the composition for organic electroluminescence device containing the hole transport material, and it is easy to stack the organic electroluminescence device by a wet film forming method. It becomes.
Furthermore, according to the organic electroluminescent device having a layer containing a polymer compound obtained by polymerizing the hole transport material of the present invention, it is possible to emit light with high efficiency, and the stability of the device, particularly driving. Stability is improved.
In addition, the hole transport material of the present invention has excellent film-forming properties, charge transport properties, light emission characteristics, and heat resistance, so that a hole injection material, a hole transport material, a light emitting material, and a host are used according to the layer structure of the device. It can also be applied as a material, an electron injection material, an electron transport material, and the like.

An organic electroluminescent device having a layer containing a polymer compound obtained by polymerizing the hole transport material of the present invention is a flat panel display (for example, for OA computers or wall-mounted televisions), an in-vehicle display device, a mobile phone display, It can be applied to light sources (for example, light sources for copying machines, backlight sources for liquid crystal displays and instruments), display panels, and marker lamps that make use of the characteristics of surface emitters, and their technical value is great. .
In addition, since the hole transport material of the present invention has excellent redox stability, it is useful not only for organic electroluminescence devices but also for electrophotographic photoreceptors.

  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.

［式中、Ｒ^１〜Ｒ^７は、各々独立に、水素原子、連結基Ｚ^１への直接結合または１価の基を表す。
ｎは、１〜４の整数を表す。
連結基Ｚ^１は、ｎ＝１であるときは、存在せず、ｎが２以上であるときは、直接結合またはｎ価の連結基を表す。
Ａ^１は、水素原子または架橋基を表す。
但し、一分子中において、少なくとも１つのＡ^１は架橋基である。
一分子内の複数のＡ^１同士あるいはＲ^１〜Ｒ^７同士は、それぞれ同一であっても異なっていてもよい。］ [Hole transport material]
The hole transport material of the present invention is represented by the following general formula (I) and has a molecular weight of 300 to 5,000.

[Wherein, R ^{1 to} R ⁷ each independently represents a hydrogen atom, a direct bond to the linking group Z ¹ or a monovalent group.
n represents an integer of 1 to 4.
The linking group Z ¹ does not exist when n = 1, and when n is 2 or more, it represents a direct bond or an n-valent linking group.
A ¹ represents a hydrogen atom or a bridging group.
However, in one molecule, at least one A ¹ is a crosslinking group.
A plurality of A ¹ or R ^{1 to} R ⁷ in one molecule may be the same or different. ]

[1] Structural features The hole transport material of the present invention has an N- (4-biphenyl) skeleton having no substituent at a position where the planarity of the biphenyl skeleton can be hindered as a partial structure. In addition, it has excellent electrical oxidation resistance, and since it has no bridging group or other substituent at the 4′-position of the skeleton, it also has excellent electrical reduction resistance. Further, because of the asymmetry of the partial structure, the amorphous structure is excellent and the melting point and the glass transition point when unpolymerized are low, so that a high degree of polymerization can be obtained by polymerization at a high temperature. As a result, it is possible to reduce unreacted residues, so that a film formed by a wet film formation method can be made insoluble in an organic solvent under mild conditions. Excellent resistance to mechanical damage.

[2] Molecular Weight Range The molecular weight of the hole transport material of the present invention is usually 5000 or less, preferably 2500 or less, and usually 300 or more, preferably 500 or more. If the molecular weight exceeds this upper limit, the solubility is lowered, and wet film formation becomes difficult, so that it may be necessary to additionally take a solubility improving means. Further, purification may become difficult due to the high molecular weight of impurities. Also, if the molecular weight is below this lower limit value, the ratio of charge transporting groups to the cross-linking group decreases, so the charge transportability may decrease, or the ratio of unreacted residues may increase, impairing electrical resistance. There is. Further, since the glass transition temperature, the melting point, the vaporization temperature and the like are lowered, the heat resistance may be significantly impaired.

[3] R ^{1 to} R ⁷
R ^{1 to} R ⁷ each independently represents a hydrogen atom, a direct bond to the linking group Z ¹ or a monovalent group. Monovalent group may be those bound to the linking group Z ^1. Examples of the monovalent group of R ^{1 to} R ⁷ include the following.

<Specific examples of monovalent groups>
An alkyl group which may have a substituent (preferably a linear or branched alkyl group having 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, 2-propyl, n-butyl, isobutyl, tert, -A butyl group etc. are mentioned.)
An alkenyl group which may have a substituent (preferably an alkenyl group having 2 to 9 carbon atoms, such as vinyl, allyl, 1-butenyl group, etc.).
An alkynyl group which may have a substituent (preferably an alkynyl group having 2 to 9 carbon atoms, such as ethynyl and propargyl groups).
An aralkyl group which may have a substituent (preferably an aralkyl group having 7 to 15 carbon atoms, such as a benzyl group).
An alkoxy group which may have a substituent (preferably an alkoxy group having 1 to 8 carbon atoms which may have a substituent, such as methoxy, ethoxy and butoxy groups).
An aryloxy group which may have a substituent (preferably an aromatic hydrocarbon group having 6 to 12 carbon atoms, such as phenyloxy, 1-naphthyloxy, 2-naphthyloxy group and the like. .)
A heteroaryloxy group which may have a substituent (preferably has a 5- or 6-membered aromatic heterocyclic group, and examples thereof include a pyridyloxy and thienyloxy group).
An acyl group which may have a substituent (preferably an acyl group having 2 to 10 carbon atoms which may have a substituent, such as formyl, acetyl and benzoyl groups).
An alkoxycarbonyl group which may have a substituent (preferably an alkoxycarbonyl group having 2 to 10 carbon atoms which may have a substituent, such as methoxycarbonyl and ethoxycarbonyl groups).
An aryloxycarbonyl group which may have a substituent (preferably an aryloxycarbonyl group having 7 to 13 carbon atoms which may have a substituent, such as a phenoxycarbonyl group).
An alkylcarbonyloxy group which may have a substituent (preferably an alkylcarbonyloxy group having 2 to 10 carbon atoms which may have a substituent, such as an acetoxy group).
Halogen atoms (especially fluorine or chlorine atoms),
Carboxy group Cyano group Hydroxyl group Mercapto group Alkylthio group which may have a substituent (preferably an alkylthio group having 1 to 8 carbon atoms, such as methylthio group and ethylthio group).
An arylthio group which may have a substituent (preferably an arylthio group having 6 to 12 carbon atoms, such as a phenylthio group and a 1-naphthylthio group).
A sulfonyl group which may have a substituent (for example, a mesyl group, a tosyl group, etc.).
A silyl group which may have a substituent (for example, a trimethylsilyl group, a triphenylsilyl group, etc.).
An optionally substituted boryl group (eg, a dimesitylboryl group).
A phosphino group which may have a substituent (for example, a diphenylphosphino group).
An aromatic hydrocarbon group which may have a substituent (for example, benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, fluoranthene ring, etc. And monovalent groups derived from 5- or 6-membered monocyclic rings or 2 to 5 condensed rings.)
An aromatic heterocyclic group which may have a substituent (for example, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrrolo) Imidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, Pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, benzimidazole ring,
And monovalent groups derived from a 5- or 6-membered monocyclic ring or a 2-4 condensed ring, such as a perimidine ring and a quinazoline ring. )

Among these, R ^{1 to} R ⁷ are preferably a hydrogen atom, an alkoxy group, an aryloxy group, an aromatic hydrocarbon group, or an aromatic heterocyclic group. Most preferred is an aromatic hydrocarbon group.
R ^{1 to} R ⁷ may have a substituent, and specific examples thereof are the same as those exemplified as the monovalent group of R ^{1 to} R ⁷ . Moreover, as a monovalent group, the crosslinking group illustrated below may be sufficient.

[4] n
n represents an integer of 1 to 4. n is preferably 1 or 2.

[5] Z ¹
Z ¹ is not present when n = 1, and represents a direct bond or an n-valent linking group when n is 2 or more.
Examples of the n-valent linking group include a divalent group and an ether group corresponding to the above <specific example of monovalent group>.
When n is an integer of 2 to 4, Z ¹ is preferably a direct bond, an ether group or a divalent aromatic group (aromatic hydrocarbon group or aromatic heterocyclic group).

[6] A ¹
A ¹ represents a hydrogen atom or a bridging group. However, the number of crosslinking groups in one molecule is 1 or more and 12 or less, preferably an integer of 1 to 3.

The cross-linking group for A ¹ is not particularly limited as long as it can form a bond with each other by application of energy such as heat and light, but a group containing an unsaturated double bond, cyclic ether, benzocyclobutane, or the like is preferable.

（式中、Ｒ^１５〜Ｒ^１８は、各々独立に、水素原子またはアルキル基を表す。Ａｒ^１は置換基を有してもよい芳香族炭化水素基または置換基を有してもよい芳香族複素環基を表す。）］ A ¹ is particularly preferably represented by the following formula (Ia).
-GJ (Ia)
[In the formula, G is formed by linking 1 to 30 groups selected from an —O— group, a —C (═O) — group, or an optionally substituted —CH ₂ — group. Represents a valent group, and J represents a group selected from the following cross-linking group group T.
<Crosslinking group T>

(Wherein R ^{15 to} R ¹⁸ each independently represents a hydrogen atom or an alkyl group. Ar ¹ is an aromatic hydrocarbon group which may have a substituent or an aromatic group which may have a substituent. Represents a heterocyclic group.]]

The alkyl group of R ^{15 to} R ¹⁸ is preferably a linear or branched alkyl group having 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, 2-propyl, n-butyl, isobutyl, Examples thereof include a tert-butyl group. The alkyl group may have a substituent, and examples of the substituent include the groups exemplified as the monovalent groups of R ^{1 to} R ⁷ .

Examples of the aromatic hydrocarbon group which may have a substituent of Ar ¹ include a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, and a triphenylene ring. , Monovalent groups derived from a 5- or 6-membered monocyclic ring or a 2-5 condensed ring, such as a fluoranthene ring. Examples of the aromatic heterocyclic group that may have a substituent include a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, an oxadiazole ring, an indole ring, Carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring , Pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, benzimidazole ring, perimidine ring, quinazoline ring, etc. Examples of monovalent groups That.
Examples of the substituent that each of the groups may have include the groups exemplified as the monovalent group of R ^{1 to} R ⁷ .

A ¹ is particularly preferably a group in which J in the formula (Ia) is a group selected from the following cross-linking group group T ′ because of excellent electrochemical durability.

<Crosslinking group T '>

[7] Preferred Structure The hole transport material of the present invention represented by the general formula (I) is particularly preferably represented by the following general formula (II).

［式中、Ｒ^１、Ｒ^５〜Ｒ^７、Ｚ^１、ｎおよびＡ^１は、それぞれ式（Ｉ）におけるものと同義である。また、Ｒ^９〜Ｒ^１１は、各々独立に、Ｒ^１〜Ｒ^７と同義である。］

[Wherein, R ¹ , R ^{5 to} R ⁷ , Z ¹ , n and A ¹ have the same meanings as in formula (I), respectively. Moreover, R < ⁹ > -R < ¹¹ > is synonymous with R < ¹ > -R < ⁷ > each independently. ]

[8] Illustrative Examples Preferred specific examples of the hole transport material of the present invention are shown below, but the present invention is not limited thereto.
First, specific examples of the compound represented by the general formula (I) are shown. In the following specific examples, A ^{11 to} A ¹³ are respectively synonymous with A ¹ in the general formula (I).

  Among these, the following are preferable.

Next, specific examples of the crosslinking group A (A ^{11 to} A ¹³ in the above exemplary compounds) will be shown, but the present invention is not limited thereto.

  Preferred examples of the crosslinking group A include the following.

Specific examples of preferable combinations of the skeleton and the crosslinking group A (A ^{11 to} A ¹³ in the above exemplary compounds) are shown below as the hole transport material of the present invention represented by the general formula (I).

The ratio of the molecular weight of the hole transport material of the present invention to the number of crosslinking groups (molecular weight / number of crosslinking groups) is usually 200 to 4000, preferably 300 to 3500, and most preferably 500 to 3000.
If the ratio of molecular weight / number of crosslinkable groups is less than 200, unreacted crosslinkable groups remain during the polymerization reaction, and the electrical durability of the formed film is lowered or the degree of crosslinking is excessively increased. This is not preferable because cracking occurs, charge transportability is lowered, and excitation levels are lowered.
On the other hand, if the ratio of molecular weight / number of cross-linking groups exceeds 4000, the formed film is hardly insolubilized or heat resistance is lowered, which is not preferable.

[9] Synthesis Method The hole transport material of the present invention can be synthesized using a known method by selecting raw materials according to the structure of the target compound.
A typical synthesis scheme is shown below.

Here, X ^{1 to} X ¹⁰ represent a leaving group (for example, Br, I, —B (OH) _2, etc.).
Y ^{1 to} Y ² are A ²¹ precursors (for example, a vinyl group precursor is a —CHO group, and a —O— (CH ₂ ) ₄ —O—CH ₂ -methyloxetane group precursor is — Represents an OH group) or a leaving group (for example, Br, I, -B (OH) _{2 and the} like).
R ^{21 to} R ²⁶ represent a group having the same meaning as R ^{2 to} R ⁷ .
A ²¹ represents a cross-linking group having the same meaning as A ¹ .

Each raw material compound can be appropriately obtained as a reagent, and the reaction can be easily realized using a known coupling method.
In the reaction of synthesizing an Ar ₂ NH-based compound (eg, compound b, c, h) from an ArNH ₂ -based compound (eg, compound a, e), it is once acylated to form an ArNHAc form, and then Ar ₂ It is also possible to select to obtain an NAc form and then deacetylate to obtain an Ar ₂ NH form. Here, Ar independently represents an arbitrary monovalent aromatic hydrocarbon group, and Ac represents an acetyl group.

  Methods for purifying compounds include “Separation and Purification Technology Handbook” (1993, edited by The Chemical Society of Japan), “Advanced separation of trace components and difficult-to-purify substances by chemical conversion method” (1988, IP Corporation). Issued by C.), or the methods described in the section “Separation and purification” of “Experimental Chemistry Course (4th edition) 1” (1990, edited by The Chemical Society of Japan) can be used. It is. Specifically, extraction (including suspension washing, boiling washing, ultrasonic washing, acid-base washing), adsorption, occlusion, melting, crystallization (including recrystallization from solvent, reprecipitation), distillation (atmospheric pressure) Distillation, vacuum distillation), evaporation, sublimation (atmospheric pressure sublimation, vacuum sublimation), ion exchange, dialysis, filtration, ultrafiltration, reverse osmosis, pressure osmosis, zone lysis, electrophoresis, centrifugation, flotation separation, sedimentation separation, Magnetic separation, various chromatography (shape classification: column, paper, thin layer, capillary, mobile phase classification: gas, liquid, micelle, supercritical fluid. Separation mechanism: adsorption, distribution, ion exchange, molecular sieve, chelate, gel filtration , Exclusion, affinity) and the like.

  Product confirmation and purity analysis methods include gas chromatograph (GC), high performance liquid chromatograph (HPLC), high speed amino acid analyzer (organic compound), capillary electrophoresis measurement (CE), size exclusion chromatograph (SEC). , Gel permeation chromatography (GPC), cross-fractionation chromatography (CFC), mass spectrometry (MS, LC / MS, GC / MS, MS / MS), nuclear magnetic resonance apparatus (NMR (1HNMR, 13CNMR)), Fourier transform Infrared spectrophotometer (FT-IR), UV-visible near-infrared spectrophotometer (UV.VIS, NIR), electron spin resonance apparatus (ESR), transmission electron microscope (TEM-EDX), electron beam microanalyzer (EPMA), Metal element analysis (ion chromatography, inductively coupled plasma-emission spectroscopy (ICP-AES) atomic absorption) Analysis (AAS), fluorescent X-ray analyzer (XRF)), nonmetal element analysis, trace analysis (ICP-MS, GF-AAS, optionally a GD-MS), etc., it is applicable.

[Polymer compound]
The polymer compound of the present invention is obtained by polymerizing the hole transport material of the present invention. For example, in the production of the organic electroluminescent element of the present invention described later, the composition for an organic electroluminescent element of the present invention is used. It is contained in the organic layer formed using.

  When the polymer compound of the present invention is thermosetting, the degree of crosslinking is preferably 10% or more, more preferably 50% or more, and most preferably 80% or more. Here, the gel fraction means that it remained undissolved when immersed in a specific solvent (the hole transport material of the present invention indicates a solvent that can be dissolved by 0.5% by weight or more when uncrosslinked). The portion is a gel (the cross-linked portion remains as a gel), and refers to the ratio (percentage) between the weight of the gel portion and the weight before dissolving with a solvent.

  On the other hand, when the polymer compound of the present invention is thermoplastic, the weight average molecular weight obtained from a measurement method using a known means such as GPC is at least three times the molecular weight of the hole transport material before crosslinking. It is preferably 5 times or more, more preferably 10 times or more.

[Composition for organic electroluminescence device]
The composition for organic electroluminescent elements of the present invention is usually used as a coating solution for forming an organic layer by a wet film-forming method in an organic electroluminescent element having an organic layer sandwiched between an anode and a cathode. . It is preferable that the composition for organic electroluminescent elements of the present invention is used for forming a hole transport layer in the organic layer.

  Here, when there is one layer between the anode and the light emitting layer in the organic electroluminescent element, this is referred to as a “hole transport layer”, and when there are two or more layers, the layer in contact with the anode is The “hole injection layer” and the other layers are collectively referred to as “hole transport layer”. In addition, layers provided between the anode and the light emitting layer may be collectively referred to as a “hole injection / transport layer”.

The composition for organic electroluminescent elements of the present invention comprises the hole transport material of the present invention and a solvent.
The solvent is preferably a solvent that dissolves the hole transport material of the present invention, and is usually a solvent that dissolves 0.05% by weight or more, preferably 0.5% by weight or more, more preferably 1% by weight or more of an organic compound. is there.
In addition, the composition for organic electroluminescent elements of the present invention may contain only one kind of the hole transport material of the present invention or may contain two or more kinds, but the crosslinking group As the unreacted residue, it is easy to reduce the ratio of remaining in the film, and since improvement in amorphousness is expected, two or more hole transport materials, for example, 2 to 4 are used. It is preferable to include seeds.

  The composition for organic electroluminescent elements of the present invention preferably contains 0.01% by weight or more of the hole transport material of the present invention, more preferably 0.05% by weight or more, and more preferably 0.1% by weight. The content is particularly preferably 90% by weight or less, more preferably 70% by weight or less, and particularly preferably 50% by weight or less.

  In addition, the composition for an organic electroluminescent device of the present invention may reduce the solubility of an electron-accepting compound and a hole transport layer described later, if necessary, and apply another layer on the hole transport layer. An additive such as an additive for accelerating the cross-linking reaction that enables the reaction may be included. In this case, a solvent that dissolves both the hole transport material and the additive of the present invention by 0.05% by weight or more, preferably 0.5% by weight or more, more preferably 1% by weight or more is used as the solvent. It is preferable.

  Additives that promote the crosslinking reaction of the hole transport material of the present invention contained in the composition for organic electroluminescent elements of the present invention include alkylphenone compounds, acylphosphine oxide compounds, metallocene compounds, oxime ester compounds, and azo compounds. And photoinitiators such as polymerization initiators and polymerization accelerators such as onium salts, condensed polycyclic hydrocarbons, porphyrin compounds, and diaryl ketone compounds. These may be used alone or in combination of two or more.

  However, the composition for organic electroluminescent elements of the present invention usually has sufficiently excellent polymerizability, and it is preferable not to contain a polymerization initiator from the viewpoint of not impairing electrical resistance. In addition, regarding the technique of holding a polymerization initiator in the underlayer when forming the composition and promoting the polymerization from the vicinity of the interface with the underlayer, it is an example of a preferable polymerization acceleration technique.

  Moreover, as an electron-accepting compound contained in the composition for organic electroluminescent elements of this invention, it is 1 type or 2 of what was mentioned later as an electron-accepting compound contained in the positive hole injection layer of the organic electroluminescent element of this invention. More than seeds can be used.

  The solvent contained in the composition for organic electroluminescent elements of the present invention is not particularly limited, but preferably, since it is necessary to dissolve the hole transport material of the present invention, toluene, xylene, Aromatic compounds such as methicylene and cyclohexylbenzene; halogen-containing solvents such as 1,2-dichloroethane, chlorobenzene and o-dichlorobenzene; ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA), etc. Aliphatic ether, 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethyl Anisole Ether solvents such as aromatic ethers; aliphatic esters such as ethyl acetate, n-butyl acetate, ethyl lactate and n-butyl lactate; phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, isopropyl benzoate, Examples thereof include organic solvents such as ester solvents such as propyl benzoate and n-butyl benzoate. These may be used alone or in combination of two or more.

  The concentration of the solvent contained in the composition for organic electroluminescent elements of the present invention is usually 10% by weight or more, preferably 50% by weight or more, more preferably 80% by weight or more.

  In addition, it is widely known that moisture may promote deterioration of the performance of the organic electroluminescent element, particularly brightness reduction during continuous driving, in order to reduce moisture remaining in the coating film as much as possible. Among these solvents, those having a water solubility at 25 ° C. of 1% by weight or less are preferred, and solvents having a solubility of 0.1% by weight or less are more preferred.

  Examples of the solvent contained in the composition for organic electroluminescent elements of the present invention include a solvent having a surface tension at 20 ° C. of less than 40 dyn / cm, preferably 36 dyn / cm or less, more preferably 33 dyn / cm or less.

  That is, when a layer containing a polymer compound obtained by polymerizing the hole transport material of the present invention is formed by a wet film forming method, the affinity with the base is important. The uniformity of the film quality greatly affects the uniformity and stability of the light emission of the organic electroluminescence device. Therefore, the coating solution used in the wet film-forming method has a surface that can form a uniform coating film with higher leveling properties. Low tension is required. By using such a solvent, a uniform layer containing a polymer compound obtained by polymerizing the hole transport material of the present invention can be formed.

  Specific examples of such a low surface tension solvent include the aforementioned aromatic solvents such as toluene, xylene, methicylene and cyclohexylbenzene, ester solvents such as ethyl benzoate, ether solvents such as anisole, trifluoromethoxy, and the like. Anisole, pentafluoromethoxybenzene, 3- (trifluoromethyl) anisole, ethyl (pentafluorobenzoate) and the like can be mentioned.

  The concentration of these solvents in the composition is usually 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more.

  Examples of the solvent contained in the composition for organic electroluminescence device of the present invention include a solvent having a vapor pressure at 25 ° C. of 10 mmHg or less, preferably 5 mmHg or less and usually 0.1 mmHg or more. By using such a solvent, it is possible to prepare a composition suitable for a process for producing an organic electroluminescent device by a wet film-forming method and suitable for the properties of the hole transport material of the present invention. Specific examples of such a solvent include the above-mentioned aromatic solvents such as toluene, xylene and methicylene, ether solvents and ester solvents. The concentration of these solvents in the composition is usually 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more.

  As a solvent contained in the composition for organic electroluminescent elements of the present invention, the vapor pressure at 25 ° C. is 2 mmHg or more, preferably 3 mmHg or more, more preferably 4 mmHg or more (however, the upper limit is preferably 10 mmHg or less). A mixed solvent of a certain solvent and a solvent having a vapor pressure at 25 ° C. of less than 2 mmHg, preferably 1 mmHg or less, more preferably 0.5 mmHg or less. By using such a mixed solvent, a homogeneous layer containing the hole transport material of the present invention and further an electron accepting compound can be formed by a wet film forming method. The concentration of the mixed solvent in the composition is usually 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more.

  Since the organic electroluminescent element is formed by laminating a plurality of layers made of organic compounds, it is very important that the film quality is uniform. When a layer is formed by a wet film formation method, a known film formation method such as a coating method such as a spin coating method or a spray method, or a printing method such as an ink jet method or a screen method can be adopted depending on the material and properties of the base. . For example, since the spray method is effective for forming a uniform film on a surface with unevenness, it is preferable when a layer made of an organic compound is provided on a surface where unevenness due to a patterned electrode or a partition between pixels remains. In the case of coating by the spray method, it is preferable that the coating liquid droplets sprayed from the nozzle to the coating surface be as small as possible because uniform film quality can be obtained. For that purpose, a solvent with high vapor pressure is mixed with the coating liquid, and a part of the solvent is volatilized from the sprayed coating droplet in the coating atmosphere, so that fine droplets are generated immediately before adhering to the substrate. Is preferred. Also, in order to obtain a more uniform film quality, it is necessary to secure time for the liquid film generated on the substrate to be leveled immediately after coating. In order to achieve this purpose, a slower drying solvent, that is, a vapor A technique in which a solvent having a low pressure is contained to some extent is used.

  Specific examples of the solvent whose vapor pressure at 25 ° C. is 2 mmHg or more and 10 mmHg or less include xylene, anisole, cyclohexanone, toluene and the like. Examples of the solvent having a vapor pressure of less than 2 mmHg at 25 ° C. include ethyl benzoate, methyl benzoate, tetralin, and phenetole.

  The ratio of the mixed solvent is such that the solvent whose vapor pressure at 25 ° C. is 2 mmHg or more is 5% by weight or more, preferably 25% by weight or more, but less than 50% by weight, and the vapor pressure at 25 ° C. is 25% by weight. The solvent which is less than 2 mmHg is 30% by weight or more, preferably 50% by weight or more, particularly preferably 75% by weight or more, but less than 95% by weight in the total mixed solvent.

  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. In the case of forming a layer by a wet film forming method, moisture may be mixed into the coating solution (composition) for forming the layer, so that moisture may be mixed into the coating film and the uniformity of the film may be impaired. It is preferable that the water content is as low as possible. Specifically, the amount of water contained in the organic electroluminescent element composition is preferably 1% by weight or less, more preferably 0.1% by weight or less, and still 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 solution include nitrogen gas sealing, use of a desiccant, dehydration of the solvent in advance, use of a solvent with low water solubility, and the like. Among these, the use of a solvent having low water solubility is preferable because the solution coating film can prevent whitening by absorbing moisture in the atmosphere during the coating process.
From such a viewpoint, the composition for organic electroluminescent elements of the present invention contains, for example, a solvent having a water solubility at 25 ° C. of 1% by weight or less (preferably 0.1% by weight or less) in the composition. It is preferable to contain 10% by weight or more. The solvent satisfying the above solubility condition is more preferably 30% by weight or more, and particularly preferably 50% by weight or more.

In addition, as a solvent contained in the composition for organic electroluminescent elements to which this embodiment is applied, various other solvents may be included as necessary in addition to the solvents described above. Examples of such other solvents include amides such as N, N-dimethylformamide and N, N-dimethylacetamide; dimethyl sulfoxide and the like.
Moreover, the composition for organic electroluminescent elements of this invention may contain various additives, such as coating property improving agents, such as a leveling agent and an antifoamer.

[Film formation method]
As described above, since the organic electroluminescent element is formed by laminating a plurality of layers made of organic compounds, it is very important that the film quality is uniform. When a layer is formed by a wet film formation method, a known film formation method such as a coating method such as a spin coating method or a spray method, or a printing method such as an ink jet method or a screen method can be adopted depending on the material and properties of the base. .

When using a wet film-forming method, the hole transport material of the present invention and other components used as necessary (electron-accepting compounds, additives that promote crosslinking reaction, coatability improvers, etc.) are used in an appropriate solvent. The organic electroluminescent element composition is prepared by dissolving in an organic electroluminescent element. The composition containing the hole transport material of the present invention is formed by applying this composition onto a layer corresponding to the lower layer of the layer to be formed by a method such as spin coating or dip coating, and drying. .
Usually, the layer formed using the composition for organic electroluminescent elements of the present invention is used as a hole transport layer. Therefore, this layer is usually formed on the hole injection layer or on the anode.

  In addition, in order to form a light emitting layer subsequent to the layer formed using the composition for organic electroluminescent elements of the present invention, the formed hole transport layer is dissolved in the coating composition for forming the light emitting layer. Preferably not. For this reason, after film-forming the composition for organic electroluminescent elements of the present invention, the hole transport material of the present invention undergoes a crosslinking reaction by heating and / or irradiation with electromagnetic energy such as light, and the solubility of the film after the reaction Is preferably reduced.

  The heating method is not particularly limited, and examples thereof include heat drying and reduced pressure drying. As a condition in the case of heat drying, the layer formed using the composition for organic electroluminescent elements of the present invention is usually heated to 120 ° C. or higher, preferably 400 ° C. or lower. The heating time is usually 1 minute or longer, preferably 24 hours or shorter. Although it does not specifically limit as a heating means, Means, such as mounting the laminated body which has the formed layer on a hotplate, or heating in oven, is used. For example, conditions such as heating on a hot plate at 120 ° C. or more for 1 minute or more can be used.

  In the case of irradiation with electromagnetic energy such as light, a method of irradiating directly using an ultraviolet / visible / infrared light source such as an ultra-high pressure mercury lamp, a high-pressure mercury lamp, a halogen lamp or an infrared lamp, or the above-mentioned light source is incorporated. Examples include a mask aligner and a method of irradiation using a conveyor type light irradiation device. In electromagnetic energy irradiation other than light, for example, there is a method of irradiation using a device that irradiates a microwave generated by a magnetron, a so-called microwave oven.

  As the irradiation time, it is preferable to set conditions necessary for reducing the solubility of the film, but irradiation is usually performed for 0.1 seconds or longer, preferably 10 hours or shorter.

  Heating and irradiation of electromagnetic energy such as light may be performed individually or in combination. When combined, the order of implementation is not particularly limited.

  In order to reduce the amount of moisture contained in the layer and / or moisture adsorbed on the surface after implementation, the electromagnetic energy irradiation including heating and light is preferably performed in an atmosphere containing no moisture such as a nitrogen gas atmosphere. For the same purpose, when combined with heating and / or irradiation with electromagnetic energy such as light, it is particularly preferable to perform at least the step immediately before the formation of the organic light emitting layer in an atmosphere containing no moisture such as a nitrogen gas atmosphere.

[Organic electroluminescence device]
The organic electroluminescent element of the present invention has a laminated structure in which an anode and a cathode are provided on a substrate, and a plurality of organic layers are laminated between the anode and the cathode. Any one of the plurality of organic layers, preferably the hole transport layer, is a layer containing a polymer compound obtained by polymerizing the hole transport material of the present invention, and this layer Is formed using, for example, the composition for organic electroluminescent elements containing the above-described hole transport material of the present invention.

  FIG. 1 is a cross-sectional view schematically showing an example of the structure of the organic electroluminescent element of the present invention. The organic electroluminescent device shown in FIG. 1 includes an anode 2, a hole injection layer 3, a hole transport layer 4, an organic light emitting layer 5, a hole blocking layer 6, an electron transport layer 7, and an electron injection layer on a substrate 1. 8 and the cathode 9 are laminated in this order. In the case of this configuration, the hole transport layer 4 usually corresponds to a layer made of a polymer compound obtained by polymerizing the above hole transport material.

[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 The anode 2 plays the role of hole injection into a layer (hole injection layer 3 or organic light emitting layer 5) on the organic light emitting layer side described later. This anode 2 is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum, a metal oxide such as an oxide of indium and / or tin, a metal halide such as copper iodide, carbon black, or A conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline is used. In general, the anode 2 is often formed by sputtering, vacuum deposition, or the like. Further, in the case of metal fine particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, and conductive polymer fine powders, they are dispersed in an appropriate binder resin solution and placed on the substrate 1. It is also possible to form the anode 2 by applying to. 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 (Applied Physics Letters, 1992). Year, Vol.60, pp.2711). The anode 2 can also be formed by stacking different materials.

  The thickness of the anode 2 varies depending on the required transparency. When transparency is required, it is desirable that the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness is usually 5 nm or more, preferably 10 nm or more, Usually, it is 1000 nm or less, preferably 500 nm or less. If opaque, 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.

  In addition, 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 the hole injection property. Is preferred. In addition, a known anode buffer layer is inserted between the hole injection layer 3 and the anode 2 for the purpose of further improving the efficiency of hole injection and improving the adhesion of the entire organic layer to the anode. Also good.

[3] Hole Injection Layer The hole injection layer 3 is a layer that transports holes from the anode 2 to the organic light emitting layer 5. Usually, this hole injection layer 3 is formed on the anode 2. Therefore, the hole injection layer 3 is preferably configured to contain a hole injection compound and an electron accepting compound. Furthermore, the hole injection layer 3 may contain other components without departing from the spirit of the present invention.

  Examples of the method for forming the hole injection layer 3 on the anode 2 include a wet film formation method and a vacuum deposition method. As described above, a uniform and defect-free thin film can be easily obtained. The wet film-forming method is preferable from the viewpoint that the time required for the preparation is short. In addition, ITO (indium tin oxide), which is generally used as the anode 2, has a surface roughness (Ra) of about 10 nm in addition to its surface, and often has local protrusions. There was a problem that defects were easily generated. Forming the hole injection layer 3 on the anode 2 by the wet film formation method reduces the occurrence of device defects due to the unevenness of the surface of the anode 2 as compared with the case of forming by the vacuum deposition method. It also has advantages.

  As the aromatic amine compound as the hole-injecting compound, a compound having a triarylamine structure is preferable, and a compound selected from compounds conventionally used as a material for forming a hole-injecting layer in an organic electroluminescent device is appropriately selected. Also good. As an aromatic amine compound, the binaphthyl type compound represented by following General formula (1) is mentioned, for example.

In the general formula (1), Ar ^{a to} Ar ^d are each independently a 5- or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic monocyclic group or condensed ring group which may have a substituent. Ar ^a and Ar ^b , Ar ^c and Ar ^d may be bonded to each other to form a ring. W1 and W2 each represent an integer of 0 to 4, and W1 + W2 ≧ 1. X ¹¹ and X ¹² each independently represent a direct bond or a divalent linking group. Further, a naphthalene ring in the general formula ^{(1), - (X 11 NAr a Ar} b) and ^- in addition to the ^{(X 12 NAr c Ar d)} , may have an arbitrary substituent.

In the general formula (1), as the monocyclic group or condensed ring group of a 5- or 6-membered aromatic hydrocarbon ring or aromatic heterocyclic ring which may have a substituent of Ar ^{a to} Ar ^d , respectively. Independently, for example, a 5- or 6-membered monocyclic ring or a 2-3 condensed ring, specifically, a group derived from an aromatic hydrocarbon ring such as a phenyl group, a naphthyl group, an anthryl group; a pyridyl group, a thienyl group A group derived from an aromatic heterocycle such as Any of these may have a substituent.

As the substituent that Ar ^{a to} Ar ^d may have, those described later as the substituent that Ar ^{e to} Ar ^l may have, and an arylamino group (that is,-(NAr ^e Ar ^f ) described later, -(Corresponding to NAr ^g Ar ^h )).

Ar ^a and Ar ^b and / or Ar ^c and Ar ^d may be bonded to each other to form a ring. In this case, specific examples of the ring to be formed include a carbazole ring, a phenoxazine ring, an iminostilbene ring, a phenothiazine ring, an acridone ring, an acridine ring, an iminodibenzyl ring and the like that may have a substituent. Of these, a carbazole ring is preferred.

  In the general formula (1), W1 and W2 each represent an integer of 0 to 4, and W1 + W2 ≧ 1. Particularly preferred are W1 = 1 and W2 = 1. The arylamino groups in the case where W1 and / or W2 is 2 or more may be the same or different.

X ¹¹ and X ¹² each independently represent a direct bond or a divalent linking group. Although there is no restriction | limiting in particular as a bivalent coupling group, For example, what is shown below etc. are mentioned. As X ¹¹ and X ¹² , a direct bond is particularly preferable.

In addition to — (X ¹¹ NAr ^a Ar ^b ) and — (X ¹² NAr ^c Ar ^d ), the naphthalene ring in the general formula (1) has one or more arbitrary substituents at an arbitrary position. It may be. Preferred examples of such a substituent include a halogen atom, a hydroxyl group, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, and an alkenyl group which may have a substituent. , One or more substituents selected from the group consisting of optionally substituted alkoxycarbonyl groups. Of these, an alkyl group is particularly preferred.

  Moreover, as a high molecular compound which has a positive hole transport site | part in a molecule | numerator used as a hole injectable compound, the high molecular compound which contains an aromatic tertiary amino group in a main skeleton as a structural unit is mentioned, for example. Specific examples thereof include a hole injecting compound having a structure represented by the following general formula (2) as a repeating unit.

（式（２）中、Ａｒ^４４〜Ａｒ^４８は、各々独立して置換基を有していてもよい２価の芳香族環基を示し、Ｒ^３１〜Ｒ^３２は、各々独立して置換基を有していてもよい１価の芳香族環基を示し、Ｑは直接結合、または下記の連結基から選ばれる。なお、「芳香族環基」とは、「芳香族炭化水素環由来の基」および「芳香族複素環由来の基」の両方を含む。）

（式（３）中、Ａｒ^４９は置換基を有していてもよい２価の芳香族環基を示し、Ａｒ^５０は置換基を有していてもよい１価の芳香族環基を示す。）

(In the formula (2), Ar ^{44 to} Ar ⁴⁸ each independently represents a divalent aromatic ring group which may have a substituent, and R ^{31 to} R ³² each independently represents a substituent. And Q is selected from a direct bond or the following linking group, wherein “aromatic ring group” means “derived from an aromatic hydrocarbon ring” Including "group" and "group derived from an aromatic heterocycle")

(In formula (3), Ar ⁴⁹ represents a divalent aromatic ring group which may have a substituent, and Ar ⁵⁰ represents a monovalent aromatic ring group which may have a substituent. .)

In the general formula (2), Ar ^{44 to} Ar ⁴⁸ are each preferably a group derived from a divalent benzene ring, naphthalene ring, anthracene ring or biphenyl group which may each independently have a substituent, A group derived from a benzene ring is preferred. Examples of the substituent include a halogen atom; a linear or branched alkyl group having 1 to 6 carbon atoms such as a methyl group and an ethyl group; an alkenyl group such as a vinyl group; and a C 2-7 such as a methoxycarbonyl group and an ethoxycarbonyl group. A linear or branched alkoxycarbonyl group of 1 to 6 carbon atoms such as a methoxy group or an ethoxy group; an aryloxy group of 6 to 12 carbon atoms such as a phenoxy group or a benzyloxy group; And a dialkylamino group having an alkyl chain having 1 to 6 carbon atoms such as a diisopropylamino group. Of these, an alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group is particularly preferable. Most preferably, Ar ^{44 to} Ar ⁴⁸ are each an unsubstituted aromatic ring group.

R ³¹ and R ³² are preferably each independently a phenyl group, naphthyl group, anthryl group, pyridyl group, triazyl group, pyrazyl group, quinoxalyl group, thienyl group, or biphenyl group, which may have a substituent. Preferably a phenyl group, a naphthyl group or a biphenyl group, more preferably a phenyl group. Examples of the substituent include a group in which an aromatic ring in Ar ⁴⁴ to Ar ⁴⁸ may have include the same groups as previously described.

In the general formula (3), Ar ⁴⁹ is a divalent aromatic ring group which may have a substituent, preferably an aromatic hydrocarbon ring group from the viewpoint of hole transportability. Includes an optionally substituted divalent benzene ring, naphthalene ring, anthracene ring-derived group, biphenylene group, and terphenylene group. Further, examples of the substituent include a group in which an aromatic ring may have at Ar ⁴⁴ to Ar ^48, include the same groups as previously described. Of these, an alkyl group having 1 to 3 carbon atoms is preferable, and a methyl group is particularly preferable.

Ar ⁵⁰ is an aromatic ring group which may have a substituent, preferably an aromatic hydrocarbon ring group from the viewpoint of hole transportability, and specifically, phenyl which may have a substituent. Group, naphthyl group, anthryl group, pyridyl group, triazyl group, pyrazyl group, quinoxalyl group, thienyl group, biphenyl group and the like. As this substituent, the group similar to the group mentioned above is mentioned as a group which the aromatic ring in Ar < ⁴⁴ > -Ar < ⁴⁸ > of General formula (2) may have.

In the general formula (3), it is most preferable that Ar ⁴⁹ and Ar ⁵⁰ are both unsubstituted aromatic ring groups.

  Examples of the hole-injecting compound containing an aromatic tertiary amino group as a side chain include compounds having a repeating unit having a structure represented by the following general formulas (4) and (5).

（式（４）中、Ａｒ^５１は置換基を有していてもよい２価の芳香族環基を示し、Ａｒ^５２〜Ａｒ^５３は、各々独立して置換基を有していてもよい１価の芳香族環基を示し、Ｒ^３３〜Ｒ^３５は、各々独立して水素原子、ハロゲン原子、アルキル基、アルコキシ基、置換基を有していてもよい１価の芳香族環基を示す。）

(In formula (4), Ar ⁵¹ represents a divalent aromatic ring group which may have a substituent, and Ar ^{52 to} Ar ⁵³ may each independently have a substituent 1. R ^{33 to} R ³⁵ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a monovalent aromatic ring group which may have a substituent. .)

（式（５）中、Ａｒ^５４〜Ａｒ^５８は、各々独立して置換基を有していてもよい２価の芳香族環基を示し、Ｒ^３６およびＲ^３７は、各々独立して置換基を有していてもよい芳香族環基を示し、Ｙは直接結合、または下記の連結基から選ばれる。）

(In the formula (5), Ar ^{54 to} Ar ⁵⁸ each independently represent a divalent aromatic ring group which may have a substituent, and R ³⁶ and R ³⁷ each independently represent a substituent. And Y is selected from a direct bond or the following linking group.)

In the general formula (4), Ar ⁵¹ is preferably a divalent benzene ring, a naphthalene ring, a group derived from an anthracene ring, or a biphenylene group each optionally having a substituent. For example, examples of the group that the aromatic ring in Ar ^{44 to} Ar ⁴⁸ in the general formula (2) described above may have include the same groups as those described above, and preferred groups are also the same.

Ar ⁵² and Ar ⁵³ are preferably each independently a phenyl group, a naphthyl group, an anthryl group, a pyridyl group, a triazyl group, a pyrazyl group, a quinoxalyl group, a thienyl group, and a biphenyl group, and these include a substituent group. May have. Examples of the substituent include the same groups as those described above as the group that the aromatic ring in Ar ^{44 to} Ar ⁴⁸ of the general formula (2) may have, and preferred groups are also the same.

R ^{33 to} R ³⁵ are preferably each independently a hydrogen atom; a halogen atom; a linear or branched alkyl group having 1 to 6 carbon atoms such as a methyl group or an ethyl group; a carbon such as a methoxy group or an ethoxy group. A linear or branched alkoxy group of 1 to 6; a phenyl group; or a tolyl group.

In the general formula (5), Ar ^{54 to} Ar ⁵⁸ are preferably a divalent benzene ring, a naphthalene ring, a group derived from an anthracene ring, or a biphenylene group, each of which may have a substituent. A group derived from a benzene ring. Examples of the substituent include the same groups as those described above as the groups that the aromatic ring in Ar ^{44 to} Ar ⁴⁸ of formula (2) may have, and preferred groups are also the same.

R ³⁶ and R ³⁷ are each preferably a phenyl group, a naphthyl group, an anthryl group, a pyridyl group, a triazyl group, a pyrazyl group, a quinoxalyl group, a thienyl group, or a biphenyl group, each of which may have a substituent. . Examples of the substituent include the same groups as those described above as the groups that the aromatic ring in Ar ^{44 to} Ar ⁴⁸ of formula (2) may have, and preferred groups are also the same.

  Preferred examples of the structures represented by the general formulas (2) to (5) are shown below, but are not limited thereto.

  The hole injecting compound which is a polymer compound having a hole transporting site in the molecule is most preferably a homopolymer having a structure represented by any one of the general formulas (2) to (5). It may be a copolymer (copolymer) with any monomer. When it is a copolymer, it is preferable to contain 50 mol% or more, especially 70 mol% or more of the structural units represented by the general formulas (2) to (5). In addition, the hole injectable material which is a high molecular compound may contain multiple types of structures represented by the general formulas (2) to (5) in one compound. Moreover, you may use in combination of multiple types of the compound containing the structure represented by General formula (2)-(5). Of the general formulas (2) to (5), a homopolymer composed of a repeating unit represented by the general formula (2) is particularly preferable.

  Examples of the hole injecting material containing the polymer compound further include conjugated polymers. For this purpose, polyfluorene, polypyrrole, polyaniline, polythiophene, polyparaphenylene vinylene are preferred.

Next, the electron accepting compound will be described.
Examples of the electron accepting compound contained in the hole injection layer include triaryl boron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, arylamines and Lewis acids. And one or more compounds selected from the group consisting of salts with These electron-accepting compounds are used by mixing with a hole-injecting material, and the conductivity of the hole-injecting layer can be improved by oxidizing the hole-injecting material.

  Examples of the triarylboron compound as the electron-accepting compound include boron compounds represented by the following general formula (6). The boron compound represented by the general formula (6) is preferably a Lewis acid. The electron affinity of the boron compound is usually 4 eV or more, preferably 5 eV or more.

In the general formula (6), preferably, Ar ^{101 to} Ar ¹⁰³ are each independently a monocyclic 5- or 6-membered ring such as a phenyl group, a naphthyl group, an anthryl group, or a biphenyl group that may have a substituent, Or an aromatic hydrocarbon ring group formed by condensing and / or directly bonding 2 to 3 of these; or 5 or 6 such as a thienyl group, pyridyl group, triazyl group, pyrazyl group, quinoxalyl group, etc., which may have a substituent. It represents a single-membered ring or an aromatic heterocyclic group formed by condensing 2 or 3 of these and / or directly bonding them.

Examples of the substituent that Ar ^{101 to} Ar ¹⁰³ may have include a halogen atom; an alkyl group; an alkenyl group; an alkoxycarbonyl group; an alkoxy group; an aryloxy group; an acyl group; a haloalkyl group;

In particular, at least one of Ar ^{101 to} Ar ¹⁰³ is preferably a substituent having a positive Hammett constant (σ _m and / or σ _p ), and Ar ^{101 to} Ar ¹⁰³ are all Hammet constants (σ It is particularly preferred that _m and / or σ _p ) is a substituent showing a positive value. By having such an electron-withdrawing substituent, the electron acceptability of these compounds is improved. Ar ^{101 to} Ar ¹⁰³ are more preferably an aromatic hydrocarbon group or an aromatic heterocyclic group substituted with a halogen atom.

  Although the preferable specific example of the boron compound represented by General formula (6) is shown to the following 6-1 to 6-17, it is not limited to these.

  Of these, the following compounds are particularly preferred.

  Examples of the electron-accepting compound include onium salts described in WO2005 / 089024, and preferred examples thereof are the same, but the following compounds are particularly preferred.

  The thickness of the hole injection layer 3 is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less.

  The content of the electron-accepting compound in the hole-injecting layer 3 with respect to the hole-injecting compound is usually 0.1 mol% or more, preferably 1 mol% or more. However, it is usually 100 mol% or less, preferably 40 mol% or less.

[4] Hole transport layer The hole transport layer 4 has a function of injecting holes injected in the order of the anode 2 and the hole injection layer 3 into the organic light emitting layer 5, and electrons from the light emitting layer 5 are anode 2. It has a function of suppressing a decrease in luminous efficiency caused by being injected into the side.

  In order to exhibit this function, the hole transport layer 4 is preferably a layer containing a polymer compound obtained by polymerizing the hole transport material of the present invention.

The hole transport layer 4 is preferably formed by the method described in [Film Forming Method] using the composition for organic electroluminescent elements of the present invention.
The film thickness is usually in the range of 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less.

[5] Organic Light-Emitting Layer The organic light-emitting layer 5 is usually provided on the hole transport layer 4. The organic light-emitting layer 5 includes holes injected from the anode 2 through the hole injection layer 3 and the hole transport layer 4 between the electrodes to which an electric field is applied, and from the cathode 9 to the electron injection layer 8 and the hole blocking layer 6. It is a layer that is excited by recombination with electrons injected through and becomes a main light emitting source.

  The organic light emitting layer 5 contains at least a material having a light emitting property (light emitting material), and preferably has a material having a hole transporting property (hole transporting compound) or an electron transporting property. Material (electron transporting compound). Furthermore, the organic light emitting layer 5 may contain other components without departing from the spirit of the present invention. As these materials, from the viewpoint of forming the organic light emitting layer 5 by a wet film formation method as described later, it is preferable to use any low molecular weight materials.

  Any known material can be applied as the light emitting material. For example, a fluorescent material or a phosphorescent material may be used, but a phosphorescent material is preferable from the viewpoint of internal quantum efficiency.

  In order to improve the solubility in a solvent, it is also important to reduce the symmetry and rigidity of the molecules of the luminescent material, 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. Red fluorescent dyes include DCM (4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran) compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, azabenzothioxanthene, etc. Can be mentioned.

  As the phosphorescent material, for example, a long-period type periodic table (hereinafter referred to as a long-period type periodic table when referred to as “periodic table” unless otherwise specified) is selected from the seventh to eleventh groups. And an organometallic complex containing a metal.

  Preferred examples of the metal selected from Groups 7 to 11 of the periodic table contained in the phosphorescent organometallic complex include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. Preferred examples of these organometallic complexes include compounds represented by the following formula (III) or formula (IV).

ML _(q−j) L ′ _j (III)
(In formula (III), M represents a metal, q represents the valence of the metal, L and L ′ represent a bidentate ligand, and j represents a number of 0, 1 or 2. )

（式（IV）中、Ｍ^７は金属を表し、Ｔは炭素原子または窒素原子を表す。Ｒ^９２〜Ｒ^９５は、それぞれ独立に置換基を表す。但し、Ｔが窒素原子の場合は、Ｒ^９４およびＲ^９５は無い。）

(In the formula (IV), M ⁷ represents a metal, T represents a carbon atom or a nitrogen atom. R ^{92 to} R ⁹⁵ each independently represents a substituent. However, when T is a nitrogen atom, R 7 ⁹⁴ and R ⁹⁵ are not.)

Hereinafter, the compound represented by the formula (III) will be described first.
In formula (III), M represents an arbitrary metal, and specific examples of preferable ones include the metals described above as metals selected from Groups 7 to 11 of the periodic table.

（上記Ｌの部分構造において、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芳香族複素環基を表す。） Moreover, in formula (III), the bidentate ligand L shows the ligand which has the following partial structures.

(In the partial structure of L, ring A1 represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.)

  Examples of the aromatic hydrocarbon group include a 5- or 6-membered monocyclic ring or a 2-5 condensed ring. Specific examples include monovalent groups derived from a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluoranthene ring, fluorene ring, etc. Is mentioned.

  Examples of the aromatic heterocyclic group include a 5- or 6-membered monocyclic ring or a 2-4 condensed ring. Specific examples include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, Thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring , Sinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, monovalent group derived from an azulene ring, and the like.

  In the partial structure of L, ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

  Examples of the nitrogen-containing aromatic heterocyclic group include groups derived from a 5- or 6-membered monocyclic ring or a 2-4 condensed ring. Specific examples include pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, furopyrrole ring, thienofuran ring, benzoisoxazole ring. , Benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone Examples thereof include a monovalent group derived from a ring.

  Examples of the substituent that each of ring A1 and ring A2 may have include a halogen atom; an alkyl group; an alkenyl group; an alkoxycarbonyl group; an alkoxy group; an aryloxy group; a dialkylamino group; Acyl group; haloalkyl group; cyano group; aromatic hydrocarbon group and the like.

  In the formula (III), the bidentate ligand L ′ represents a ligand having the following partial structure. However, in the following formulae, “Ph” represents a phenyl group.

  Among these, as L ′, the following ligands are preferable from the viewpoint of the stability of the complex.

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

（式（IIIａ）中、Ｍ^４は、Ｍと同様の金属を表し、ｗは、上記金属の価数を表し、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 formula (IIIa), M ⁴ represents the same metal as M, w represents the valence of the metal, and ring A1 represents an aromatic hydrocarbon group which may have a substituent. Ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

（式（IIIｂ）中、Ｍ^５は、Ｍと同様の金属を表し、ｗは、上記金属の価数を表し、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 formula (IIIb), M ⁵ represents the same metal as M, w represents the valence of the metal, and ring A1 represents an aromatic hydrocarbon group or aromatic group which may have a substituent. Represents a heterocyclic group, and ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.)

（式（IIIｃ）中、Ｍ^６は、Ｍと同様の金属を表し、ｗは、上記金属の価数を表し、ｊは、０、１または２を表し、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芳香族複素環基を表し、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 formula (IIIc), M ⁶ represents the same metal as M, w represents the valence of the metal, j represents 0, 1 or 2, and ring A1 and ring A1 ′ each represent Independently represents an optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group, and ring A2 and ring A2 ′ are each independently a nitrogen-containing aromatic optionally having a substituent. Represents a heterocyclic group.)

In the above formulas (IIIa), (IIIb) and (IIIc), preferred examples of ring A1 and ring A1 ′ include phenyl group, biphenyl group, naphthyl group, anthryl group, thienyl group, furyl group, benzothienyl group, benzofuryl group. Group, pyridyl group, quinolyl group, isoquinolyl group, carbazolyl group and the like.

  In the above formulas (IIIa) to (IIIc), preferred examples of ring A2 and ring A2 ′ include pyridyl group, pyrimidyl group, pyrazyl group, triazyl group, benzothiazole group, benzoxazole group, benzimidazole group, quinolyl group, An isoquinolyl group, a quinoxalyl group, a phenanthridyl group, and the like can be given.

  Examples of the substituent that the compounds represented by the formulas (IIIa) to (IIIc) may have include a halogen atom; an alkyl group; an alkenyl group; an alkoxycarbonyl group; an alkoxy group; an aryloxy group; A diarylamino group; a carbazolyl group; an acyl group; a haloalkyl group; a cyano group, and the like.

  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 include a 7,8-benzoquinoline group.

  Among these, as a substituent for ring A1, ring A1 ′, ring A2 and ring A2 ′, an alkyl group, alkoxy group, aromatic hydrocarbon group, cyano group, halogen atom, haloalkyl group, diarylamino group, carbazolyl are more preferable. Groups.

In addition, preferable examples of M ^{4 to} M ⁶ in the formulas (IIIa) to (IIIc) include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, or gold.

  Specific examples of the organometallic complexes represented by the above formulas (III) and (IIIa) to (IIIc) are shown below, but are not limited to the following compounds.

  Among the organometallic complexes represented by the above formula (III), in particular, as the ligand L and / or L ′, a 2-arylpyridine-based ligand, that is, 2-arylpyridine, there is an optional substituent. The compound which has what was couple | bonded and the thing formed by arbitrary groups condensing to this is preferable.

  The compounds described in International Patent Publication No. 2005/019373 can also be used as the light emitting material.

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

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

Further, when T is carbon ^{atom, R 94} and ^{R 95} each independently ^represents a substituent represented by the same exemplary compounds and ^{R 92} and ^{R 93.} Also, if T is a nitrogen ^{atom, R 94} and ^{R 95} is not.

R ^{92 to} R ⁹⁵ may further have a substituent. When it has a substituent, there is no restriction | limiting in particular in the kind, Arbitrary groups can be made into a substituent.
Further, any two or more groups of R ^{92 to} R ⁹⁵ may be connected to each other to form a ring.

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

  In the present invention, the molecular weight of the compound used as the light emitting material is usually 10,000 or less, preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less, and usually 100 or more, preferably 200 or more, more preferably 300 or more. More preferably, the range is 400 or more. If the molecular weight is less than 100, the heat resistance is remarkably reduced, gas is generated, 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. If 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 light emitting layer may contain any one of the various light emitting materials described above alone, or may contain two or more kinds in any combination and ratio.

  Examples of the low molecular weight hole transporting compound include various compounds exemplified as the hole transporting compound of the hole transporting layer, and 4,4′-bis [N- (1-naphthyl)- N-phenylamino] biphenyl, an aromatic diamine containing two or more tertiary amines and having two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234811), 4,4 An aromatic amine compound having a starburst structure such as', 4 "-tris (1-naphthylphenylamino) triphenylamine (Journal of Luminescence, 1997, Vol.72-74, pp.985), Spiro compounds such as aromatic amine compounds comprising tetramers (Chemical Communications, 1996, pp. 2175), 2,2 ′, 7,7′-tetrakis- (diphenylamino) -9,9′-spirobifluorene (Synthetic Metals, 1 997, Vol.91, pp.209).

  Examples of low molecular weight electron transport compounds include 2,5-bis (1-naphthyl) -1,3,4-oxadiazole (BND) and 2,5-bis (6 ′-(2 ′). , 2 "-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy), bathophenanthroline (BPhen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline ( BCP, bathocuproine), 2- (4-biphenylyl) -5- (p-tertiarybutylphenyl) -1,3,4-oxadiazole (tBu-PBD), 4,4′-bis (9-carbazole) ) -Biphenyl (CBP) and the like.

  These hole transporting compounds and electron transporting compounds are preferably used as host materials in the light-emitting layer, but specifically, the following compounds can be used as host materials.

  Examples of the method for forming the organic light emitting layer 5 include a wet film forming method and a vacuum evaporation method. As described above, a homogeneous and defect-free thin film can be easily obtained, and the time for formation is short. The wet film-forming method is preferable from the viewpoint that the effect of insolubilization of the hole transport layer 4 by the organic compound of the present invention can be enjoyed. When the organic light emitting layer 5 is formed by a wet film formation method, the above-described material is dissolved in an appropriate solvent to prepare a coating solution, which is applied and formed on the hole transport layer 4 after the above formation. And drying to remove the solvent. The formation method is the same as the formation method of the hole transport layer.

  The film thickness of the organic light emitting layer 5 is usually 3 nm or more, preferably 5 nm or more, and usually 200 nm or less, preferably 100 nm or less.

[6] Hole blocking layer In FIG. 1, the hole blocking layer 6 is provided between the organic light emitting layer 5 and the electron transport layer 7, but the hole blocking layer 6 may be omitted.
The hole blocking layer 6 is laminated on the organic light emitting layer 5 so as to be in contact with the interface of the organic light emitting layer 5 on the cathode 9 side, but the holes moving from the anode 2 reach the cathode 9. And a compound capable of efficiently transporting electrons injected from the cathode 9 toward the organic light emitting layer 5.

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

  As hole blocking materials satisfying such conditions, mixed materials such as bis (2-methyl-8-quinolinolato), (phenolato) aluminum, bis (2-methyl-8-quinolinolato), (triphenylsilanolato) aluminum, etc. Ligand complexes, metal complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinato) aluminum binuclear metal complexes, and 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, compounds having at least one pyridine ring substituted at the 2,4,6-position described in International Publication No. 2005-022962 are also preferable as the hole blocking material.

Specific examples include the compounds described below.

  Similarly to the hole injection layer 3 and the organic light emitting layer 5, the hole blocking layer 6 can also be formed by a wet film formation method, but is usually formed by a vacuum deposition method. The details of the procedure of the vacuum deposition method are the same as those of the electron injection layer 8 described later.

  The film thickness of the hole blocking layer 6 is usually 0.5 nm or more, preferably 1 nm or more, and usually 100 nm or less, preferably 50 nm or less.

[7] Electron Transport Layer The electron transport layer 7 is provided between the hole blocking layer 6 and the electron injection layer 8 for the purpose of further improving the light emission efficiency of the device.

The electron transport layer 7 is formed of a compound that can efficiently transport electrons injected from the cathode 9 between electrodes to which an electric field is applied in the direction of the light emitting layer 5. The electron transporting compound used for the electron transport layer 7 is a compound that has high electron injection efficiency from the electron injection layer 8 and has high electron mobility and can efficiently transport injected electrons. It is necessary.
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.

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

  Further, organic electron transport materials represented by metal complexes such as nitrogen-containing heterocyclic compounds such as bathophenanthroline and aluminum complexes of 8-hydroxyquinoline described later are doped with alkali metals such as sodium, potassium, cesium, lithium and rubidium. (Described in 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 in the range of 5 nm or more, preferably 10 nm or more, and usually 200 nm or less, preferably 100 nm or less.

  The electron injection layer 8 is formed by laminating on the organic light emitting layer 5 or the hole blocking layer 6 thereon by a wet film formation method or a vacuum deposition method.

Details of the wet film forming method are the same as those of the hole injection layer 3 and the organic light emitting layer 5.
On the other hand, in the case of the vacuum vapor deposition method, the vapor deposition source is put into a crucible or a metal boat installed in the 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 The boat is heated and evaporated to form an electron injection layer 8 on the organic light-emitting layer 5 or the hole blocking layer 6 or the electron transport layer 7 on the substrate placed facing the crucible or the metal boat.

The alkali metal as the electron injection layer is deposited by 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 simultaneously heated and evaporated to form the electron injection layer 8 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 8, but there may be a concentration distribution in the film thickness direction.

[8] Cathode The cathode 9 plays a role of injecting electrons into a layer (such as the electron injection layer 8 or the organic light emitting layer 5) on the organic light emitting layer 5 side. As the material of the cathode 9, the material used for the anode 2 can be used. However, in order to perform electron injection efficiently, a metal having a low work function is preferable, and 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 9 is usually the same as that of the anode 2.

  For the purpose of protecting the cathode made of a low work function metal, it is preferable to further stack a metal layer having a high work function and stable to the atmosphere because the stability of the device is increased. For this purpose, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used.

[9] Others Although the organic electroluminescent element having the layer configuration shown in FIG. 1 has been described above, the organic electroluminescent element of the present invention has another configuration without departing from the gist thereof. Also good. For example, as long as the performance is not impaired, an arbitrary layer may be provided between the anode 2 and the cathode 9 in addition to the layers described above, and an arbitrary layer may be omitted. .

  In the present invention, by using the organic compound of the present invention for the hole transport layer 4, the hole injection layer 3, the hole transport layer 4 and the organic light emitting layer 5 are all laminated by a wet film formation method. be able to. This makes it possible to manufacture a large area display.

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

[Synthesis example]
The synthesis example of the hole transport material of the present invention is shown below.
In the following synthesis examples, the glass transition temperature was determined by DSC measurement, the weight loss starting temperature was determined by TG-DTA measurement, and the melting point was determined by DSC measurement or TG-DTA measurement.

(Synthesis Example 1)
<Synthesis of Target 1>

  In a nitrogen stream, 3-ethyl-3-oxetanemethanol (10.1 g), water (80 ml), and sodium hydroxide (20.88 g) were stirred at room temperature for 30 minutes, to which p-tosyl chloride (21.56 g) was added. ) In tetrahydrofuran (80 ml) was added dropwise and reacted at room temperature for 3 hours. Water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was dried over magnesium sulfate and concentrated to give the desired product 1 (23.11 g) as a transparent oil.

¹ H NMR (CDCl ₃ , 400 MHz)
δ 7.81 (d, 2H), 7.37 (d, 2H), 4.36 (d, 2H), 4.30 (d, 2H), 4.15 (s, 2H), 1.74 (m , 2H), 2.51 (s, 3H), 0.83 (t, 3H)

<Synthesis of Target 2>

  Potassium fluoride (20.68 g) was warmed with a dryer under vacuum to remove moisture, and then under a nitrogen stream, 3-hydroxyphenylboronic acid (21.15 g), tris (4-bromophenyl) amine (17.35 g) And tris (dibenzylideneacetone) dipalladium (0) chloroform complex (0.559 g) were added, tetrahydrofuran (70 ml) and tri-t-butylphosphine (0.262 g) were added, and the mixture was stirred at room temperature for 7 hours. . Water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with 1N hydrochloric acid, dried over anhydrous magnesium sulfate, and concentrated. The residue was purified by silica gel column chromatography (hexane / ethyl acetate = 3/2) and reprecipitation (ethyl acetate / toluene) to give the intended product 2 (10.3 g).

<Synthesis of Target 3>

  In a nitrogen stream, dimethyl sulfoxide (40 ml) and pulverized potassium hydroxide (2.16 g) were stirred at room temperature, and the target product 2 (4.02 g) was added thereto and dissolved completely. The target product 1 (6.46 g) was added dropwise thereto and reacted at room temperature for 3 hours. Methanol (7 ml) was added thereto, and the mixture was heated at 50 ° C. for 1 hour to decompose excess target product 3. Further, water was added and the mixture was extracted with ethyl acetate. The organic layer was dried over magnesium sulfate and concentrated. did. The obtained oily component was purified by silica gel column chromatography (methylene chloride: ethyl acetate) and reprecipitated with methylene chloride / hexane to obtain the desired product 3 (2.71 g) as white crystals.

The glass transition temperature of this product was 53 ° C., no melting point was observed, and the weight loss starting temperature under a nitrogen stream was 419 ° C.
¹ H NMR (CDCl ₃ , 400 MHz)
δ 7.52 (d, 6H), 7.35 (t, 6H), 7.23 to 7.17 (m, 9H), 6.91 (m, 3H), 4.60 (d, 6H), 4 .50 (d, 6H), 4.15 (d, 6H), 1.90 (m, 6H), 0.96 (t, 9H)

(Synthesis Example 2)
<Synthesis of Target 4>

  In a nitrogen atmosphere, the target compound 2 (4.0 g) was dissolved in tetrahydrofuran (50 ml), cooled to 0 ° C. with ice, triethylamine (4.66 g) was added, and cinnamoyl chloride (7.66 g) was added to tetrahydrofuran (7.66 g). A solution dissolved in 20 ml) was dropped into the system. After 20 minutes, the ice bath was removed and the mixture was stirred at room temperature for 2 hours. The insoluble material was removed by filtration, concentrated, and then added dropwise to methanol. The precipitated crystals were collected by filtration, dissolved in ethyl acetate (20 ml), and reprecipitated in 300 ml of methanol. This reprecipitation operation was repeated twice, followed by reprecipitation with methylene chloride / methanol to obtain pale yellow crystals (5.87 g) of the target product 4.

The glass transition temperature of this product was 79 ° C.
It was confirmed to be the target product 4 by DEI-MS (m / z = 911 (M ⁺ )).

窒素気流中、目的物２（５．０ｇ）、ｐ−フルオロベンズアルデヒド（３．６９ｇ）、炭酸カリウム（３．９８ｇ）、およびＮ，Ｎ−ジメチルホルムアミド（５０ｍｌ）を、３．５時間加熱還流し、室温まで放冷した。反応混合物に２０重量％メタノール水溶液を加え、不溶物を濾別した。得られた粗結晶を８０重量％メタノール水溶液で懸洗し、目的物５（７．５３ｇ）を得た。 (Synthesis Example 3)
<Synthesis of Target 5>

In a nitrogen stream, target product 2 (5.0 g), p-fluorobenzaldehyde (3.69 g), potassium carbonate (3.98 g), and N, N-dimethylformamide (50 ml) were heated to reflux for 3.5 hours. And allowed to cool to room temperature. 20% by weight aqueous methanol solution was added to the reaction mixture, and insoluble matters were filtered off. The obtained crude crystals were washed with an 80 wt% aqueous methanol solution to obtain the desired product 5 (7.53 g).

<Synthesis of Target 6>

  To a target 5 (8.45 g), methyltriphenylphosphine iodide (12.7 g) and dehydrated tetrahydrofuran (170 ml) in a nitrogen stream, t-butoxypotassium (3.53 g) was added little by little under ice cooling. It was. After stirring at that temperature for 2.5 hours, water was added to the reaction mixture and extracted with ethyl acetate. The organic layer was washed with water, concentrated, purified by silica gel column chromatography (hexane / ethyl acetate, second time toluene), and washed with methanol to obtain the desired product 6 (3.09 g).

It was confirmed to be the target product 6 by DEI-MS (m / z = 828 (M ⁺ )).
The glass transition temperature of this product was not clearly observed, the melting point was 187 ° C., and the weight loss starting temperature was 516 ° C.

(Synthesis Example 4)
<Synthesis of Target 7>

The synthesis of intermediate 1 is described in Polymer, 41, 5125-5136 (2000).
A few drops of 1,2-dibromoethane were added to an anhydrous ether solution (100 mL) of magnesium (1.15 g, 47.4 mmol) at 30 ° C. under a nitrogen stream, and intermediate 1 (10 g) was added so that the ether was gently refluxed. An anhydrous ether solution (100 mL) was added dropwise. After completion of dropping, the mixture was stirred at 30 ° C. for 1 hour, and the solution was cooled to −78 ° C. While stirring vigorously, an anhydrous ether solution (50 mL) of trimethoxyborane (22.2 g, 118 mmol) was slowly added dropwise, followed by stirring at −78 ° C. for 1 hour and stirring at room temperature for 1 hour. The reaction mixture was poured into water, adjusted to pH = 1 with 1N hydrochloric acid, stirred for 30 minutes, and the organic layer was separated. The aqueous layer was extracted with methylene chloride (50 mL × twice), combined with the previous organic layer, washed with a saturated aqueous sodium chloride solution (100 mL), dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The residue was subjected to silica gel column chromatography to obtain 2.4 g of the target product 7.

<Synthesis of Target 8>

  Under a nitrogen atmosphere, the target compound 7 (1.5 g, 6.88 mmol), tris (p-iodophenyl) amine (1.3 g, 2.08 mmol), tris (dibenzylideneacetone) dipalladium (18 mg, 31.2 μmol) And tri-t-butylphosphine (15 mg, 74.9 μmol) was added dropwise to a solution of potassium fluoride (1.2 g, 20.59 mmol) in tetrahydrofuran (10 mL). The reaction mixture was stirred at room temperature for 72 hours, poured into water and extracted with methylene chloride (2 × 50 mL). The organic layer was washed with a saturated aqueous sodium chloride solution (20 mL × 3 times) and dried over anhydrous magnesium sulfate, and then the solvent was distilled off under reduced pressure. The residue was subjected to silica gel column chromatography to obtain the intended product 8 (0.121 g, yield: 8%).

From DEI-MS (m / z = 761M ⁺ )), it was confirmed to be the target product 8.

(Synthesis Example 5)
<Synthesis of Target 9>

  Dimethyl sulfoxide (150 ml) was added to pulverized potassium hydroxide (4.304 g), and the mixture was stirred at room temperature for 30 minutes, and then target product 2 (8 g) was added. Further, after stirring for 30 minutes, t-butyl (4-iodobutoxy) dimethylsilane (15.91 g) was added, and the mixture was stirred at room temperature for 6 and a half hours. The reaction mixture was placed in ice water and filtered. The filtered product was extracted by dissolving in methylene chloride, and the organic layer was washed with saturated brine, dried over magnesium sulfate, and concentrated. The residue was purified by silica gel column chromatography (hexane / methylene chloride mixed solution) to obtain the desired product 9 (7.46 g).

It was confirmed to be the target product 9 by DEI-MS (m / z = 1079 (M ⁺ )).

<Synthesis of Target Product 10>

  In a nitrogen stream, target product 9 (7.35 g), tetrabutylammonium fluoride hydrate (10.67 g), and tetrahydrofuran (35 ml) were added, and the mixture was stirred at room temperature for 6 and a half hours. Water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with water, dried over magnesium sulfate, and concentrated. The residue was purified by silica gel column chromatography (ethyl acetate / methylene chloride = 10/1) to obtain the desired product 10 (4.73 g).

<Synthesis of Target 11>

  The target product 10 (4.6 g), tetra-n-butylammonium bromide (0.603 g), and methylene chloride (98 ml) were added, and the mixture was stirred with a DC stirrer under ice-cooling, and then 30% by weight aqueous potassium hydroxide solution (130 ml). ) Was added. While further stirring vigorously, a solution of cinnamoyl chloride (4.36 g) in methylene chloride (32 ml) was added dropwise and stirred for 3 hours under ice cooling. The reaction mixture was extracted with methylene chloride, and the organic layer was washed three times with water, dried over magnesium sulfate, and concentrated. The residue was purified by silica gel column chromatography (ethyl acetate / methylene chloride = 1/30) to obtain the desired product 11 (6.68 g).

The glass transition temperature of this product was 19 ° C., no melting point was observed, and the weight loss starting temperature under a nitrogen stream was 388 ° C.
It was confirmed to be the target product 11 by DEI-MS (m / z = 1127 (M ⁺ )).

(Synthesis Example 6)
<Synthesis of Target 12>

  In a nitrogen stream, tetrahydrofuran (60 ml) was added to compound 2 (6.26 g) and stirred while cooling to 0 ° C. in an ice bath. Triethylamine (5.46 g) was added, and then methacrylic acid chloride (5.64 g). ) Was added dropwise and reacted at room temperature for 3 hours. Insoluble matter was filtered off, the filtrate was concentrated, reprecipitated with methanol, and purified by silica gel column chromatography (hexane: methylene chloride = 1: 3) and reprecipitation from methylene chloride and methanol. Compound 12 (4.00 g) was obtained.

The glass transition temperature of this product was 58 ° C., the melting point was 155 ° C., and the weight reduction starting temperature under a nitrogen stream was 438 ° C.
The compound 12 was confirmed by DEI-MS (m / z = 725 (M ⁺ )).

(Synthesis Example 7)
<Synthesis of Target Product 13>

  While stirring 1,4-pentadien-3-ol (4.21 g) and dehydrated pyridine (20 ml) under a nitrogen atmosphere, 6-bromohexanoic acid chloride (7.5 ml) was added under ice cooling. Then, the mixture was stirred at room temperature for 3.3 hours. Ethyl acetate (150 ml) was added to the resulting solution, followed by washing with an aqueous sodium hydrogen carbonate solution (100 ml) and then brine (100 ml), and the organic layer was concentrated. The obtained extract was purified by silica gel column chromatography (ethyl acetate solvent) and silica gel column chromatography (ethyl acetate / n-hexane = 3/7 solvent) to obtain the desired product 13 (9.9 g).

From CI-MS (m / z = 278 (M + NH ₄ ) ⁺ ), it was confirmed to be the target product 13.

  <Synthesis of Target Product 14>

In a nitrogen stream, target product 13 (6.22 g) was added to a mixed solution of target product 2 (2.07 g), potassium carbonate (2.20 g), and dehydrated N, N-dimethylformamide (100 ml). The mixture was stirred in an oil bath at 9.5 hours for 9.5 hours. Subsequently, the target product 13 (1 g) was further added and then stirred in an oil bath at 60 ° C. for 3 hours. Further, the target product 13 (1 g) was further added and then stirred in an oil bath at 80 ° C. for 7.5 hours. . Distilled water was added to the resulting solution, and the mixture was extracted with ethyl acetate, washed with brine, dried over anhydrous magnesium sulfate, filtered, and the filtrate was concentrated to obtain a crude product of target product 14. .
From DEI-MS (m / z = 1061 (M ⁺ )), it was confirmed to be the target product 14.

[Production of organic electroluminescence device]
Example 1
An organic electroluminescent element having the structure shown in FIG. 1 was produced by the following method.

  An indium tin oxide (ITO) transparent conductive film deposited on a glass substrate 1 having a thickness of 150 nm (sputtered film; sheet resistance 15 Ω) 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: 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 Application environment Air Solvent Ethyl benzoate Coating solution concentration P-1 2.0% by weight
A-1 0.8% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds Drying conditions 230 ° C. × 3 hours A uniform thin film having a thickness of 30 nm was formed by the above spin coating.

Subsequently, the hole transport layer 4 was formed by a wet coating method as follows.
As a material for the hole transport layer 4, a solution obtained by mixing the following hole transport material (H-1) of the present invention (target product 3 synthesized in Synthesis Example 1) and the electron accepting compound (A-1). Was spin-coated under the following conditions.

Spin coating conditions Application environment Air Solvent Xylene Coating solution concentration H-1 2% by weight
A-1 0.1% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds The above-described spin coat film was heated in air at 120 ° C. for 1 hour to obtain a uniform thin film having a thickness of 35 nm.

Subsequently, the light emitting layer 5 was formed by a wet coating method as follows.
As the material for the light emitting layer 5, the following compounds (E-1) and (E-2) were used together with an iridium complex (D-1) having the structural formula shown below and spin-coated under the following conditions.

Spin coating conditions Application environment Nitrogen glove box Solvent Xylene Coating solution concentration E-1 1.0% by weight
E-2 1.0% by weight
D-1 0.1% 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 40 nm was formed by the above spin coating.

The substrate on which the light emitting layer 5 was formed was carried into a multi-chamber vacuum deposition apparatus connected to a nitrogen glove box without exposure to the atmosphere, and the inside of the apparatus was evacuated to a vacuum degree of 3.8 × 10 ⁻⁵ Pa. The hole blocking layer 6 and the electron transport layer 7 were formed by a vacuum deposition method.

As the hole blocking layer 6, a pyridine derivative (HB-1) shown below was laminated with a film thickness of 5 nm at a deposition rate of 0.07 to 0.1 nm / second. The degree of vacuum at the time of vapor deposition was 3.5 × 10 ⁻⁵ Pa.

Subsequently, an aluminum 8-hydroxyquinoline complex (ET-1) shown below was deposited as an electron transport layer 7 on the hole blocking layer 6 in the same manner. The degree of vacuum during deposition was 3.1 to 3.2 × 10 ⁻⁵ Pa, the deposition rate was 0.09 to 0.11 nm / sec, and the film thickness was 30 nm.

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

Here, the element on which the electron transport layer 7 has been deposited is transported in vacuum from the organic layer deposition chamber on which the electron transport layer has been deposited to the metal deposition chamber, and a 2 mm wide striped shadow is used as a mask for cathode deposition. After the mask was brought into close contact with the element so as to be orthogonal to the ITO stripe of the anode 2 and evacuated until the degree of vacuum in the apparatus was 4.0 × 10 ⁻⁵ Pa or less, the electron injection layer 8 and the cathode 9 A two-layer cathode was formed by vacuum evaporation. As the electron injection layer 8, first, lithium fluoride (LiF) is deposited at a deposition rate of 0.015 to 0.014 nm / second and a degree of vacuum of 4.9 to 5.2 × 10 ⁻⁵ Pa using a molybdenum boat. A film having a thickness of 0.5 nm was formed on the electron transport layer 7. Next, aluminum is similarly heated by a molybdenum boat to form an aluminum layer having a film thickness of 85 nm at a deposition rate of 0.1 to 1.3 nm / second and a degree of vacuum of 7.5 to 9.1 × 10 ⁻⁵ Pa. Thus, the cathode 9 was completed. The substrate temperature during the deposition of the electron injection layer 8 and the cathode 9 was kept at room temperature.

  The element on which the vapor deposition was performed up to the cathode was applied in a nitrogen atmosphere with an ultraviolet curable resin (sealing agent 3124 for FPD manufactured by ThreeBond Co., Ltd.) with a width of about 1 mm on the outer periphery, and a hygroscopic agent (Organic EL manufactured by Dynic Co., Ltd.) at the center. The glass plate on which the moisture getter agent HD-S050914W-40) was affixed together with the hygroscopic agent affixing surface and the element deposition surface being inward. Thereafter, the resin was cured by irradiating ultraviolet light only around the ultraviolet curable resin application part.

  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: 25.1 [cd / A] @ 100 cd / m ²
Voltage: 7.6 [V] @ 100 cd / m ²
Luminous efficiency: 10.4 [1 m / W] @ 100 cd / m ²
The maximum wavelength of the emission spectrum of the device was 513 nm, which was identified as from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.31, 0.63).

(Example 2)
An organic electroluminescent element was produced in the same manner as in Example 1 except that the hole transport layer 4 was formed by the following method.
On the ITO substrate on which the hole injection layer 3 was formed in the same manner as in Example 1, the hole transport material (H-1) of the present invention and the electron accepting compound (A- The solution containing 1) was spin-coated under the following conditions.

Spin coating conditions Application environment In nitrogen glove box Solvent Xylene Coating solution concentration H-1 2% by weight
A-1 0.1% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds

The spin coat film was heated and dried at 120 ° C. for 1 hour in a nitrogen glove box to obtain a uniform thin film having a thickness of 30 nm.
Then, the organic electroluminescent element was produced in the same procedure as Example 1.

  The light emission characteristics of the organic electroluminescence device having a light emission area portion of 2 mm × 2 mm obtained in this way are shown below.

Luminance / current: 31.7 [cd / A] @ 100 cd / m ²
Voltage: 7.5 [V] @ 100 cd / m ²
Luminous efficiency: 25.9 [1 m / W] @ 100 cd / m ²
The maximum wavelength of the emission spectrum of the device was 515 nm, which was identified as that from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.31, 0.63).

(Example 3)
An organic electroluminescent element was produced in the same manner as in Example 1 except that the hole transport layer 4 was formed by the following method.
A solution of the hole transport material (H-1) of the present invention shown below as a material for the hole transport layer 4 on the ITO substrate on which the hole injection layer 3 was formed by the same method as in Example 1 was used as follows. Spin coat under conditions.

Spin coating conditions Application environment In nitrogen glove box Solvent Xylene Coating solution concentration H-1 2% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds

The spin coat film was heated in a nitrogen glove box at 230 ° C. for 1 hour to obtain a uniform thin film of 30 nm.
Then, the organic electroluminescent element was produced in the same procedure as Example 1.

  The light emission characteristics of the organic electroluminescence device having a light emission area portion of 2 mm × 2 mm obtained in this way are shown below.

Luminance / current: 32.3 [cd / A] @ 100 cd / m ²
Voltage: 9.2 [V] @ 100 cd / m ²
Luminous efficiency: 11.1 [1 m / W] @ 100 cd / m ²
The maximum wavelength of the emission spectrum of the device was 515 nm, which was identified as that from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.31, 0.63).

Example 4
An organic electroluminescent element was produced in the same manner as in Example 1 except that the hole transport layer 4 was formed by the following method.
On the ITO substrate on which the hole injection layer 3 was formed in the same manner as in Example 1, the hole transport material (H-2) of the present invention shown below as the material of the hole transport layer 4 (in Synthesis Example 2) The synthesized solution of the object 4) was spin-coated under the following conditions.

Spin coating conditions Application environment Air Solvent Xylene Coating concentration H-2 1% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds

The spin coat film was irradiated with UV light with an integrated light amount of 5 J / cm ² (energy value of 365 nm light) using a high-pressure mercury lamp in the atmosphere. Then, a uniform thin film having a film thickness of 16 nm was obtained by heating at 230 ° C. for 1 hour in a nitrogen glove box.
Then, the organic electroluminescent element was produced in the same procedure as Example 1.

  The light emission characteristics of the organic electroluminescence device having a light emission area portion of 2 mm × 2 mm obtained in this way are shown below.

Luminance / current: 19.0 [cd / A] @ 100 cd / m ²
Voltage: 9.0 [V] @ 100 cd / m ²
Luminous efficiency: 6.6 [1 m / W] @ 100 cd / m ²
The maximum wavelength of the emission spectrum of the device was 513 nm, which was identified as from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.31, 0.62).

(Example 5)
An organic electroluminescent element was produced in the same manner as in Example 1 except that the hole transport layer 4 was formed by the following method.
On the ITO substrate on which the hole injection layer 3 was formed by the same method as in Example 1, the hole transport material (H-3) of the present invention shown below as the material of the hole transport layer 4 (in Synthesis Example 3) The synthesized solution of the target product 6) was spin-coated under the following conditions.

Spin coating conditions Application environment In nitrogen glove box Solvent Toluene Coating solution concentration H-3 1% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds

The spin coat film was heated in a nitrogen glove box at 180 ° C. for 30 minutes to obtain a uniform thin film having a thickness of 30 nm.
Then, the organic electroluminescent element was produced in the same procedure as Example 1.

  The light emission characteristics of the organic electroluminescence device having a light emission area portion of 2 mm × 2 mm obtained in this way are shown below.

Luminance / current: 30.7 [cd / A] @ 100 cd / m ²
Voltage: 8.0 [V] @ 100 cd / m ²
Luminous efficiency: 12.1 [1 m / W] @ 100 cd / m ²
The maximum wavelength of the emission spectrum of the device was 514 nm, which was identified as that from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.32, 0.62).

(Example 6)
An organic electroluminescent element was produced in the same manner as in Example 1 except that the hole transport layer 4 was formed by the following method.
On the ITO substrate on which the hole injection layer 3 was formed in the same manner as in Example 1, the hole transport material (H-4) of the present invention shown below as the material of the hole transport layer 4 (in Synthesis Example 4) The synthesized solution of the target product 8) was spin-coated under the following conditions.

Spin coating conditions Application environment Air Solvent Xylene Coating concentration H-4 2% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds

The spin coat film was heated in the atmosphere at 200 ° C. for 1 hour to obtain a uniform thin film having a thickness of 30 nm.
Then, the organic electroluminescent element was produced in the same procedure as Example 1.

  The light emission characteristics of the organic electroluminescence device having a light emission area portion of 2 mm × 2 mm obtained in this way are shown below.

Luminance / current: 17.2 [cd / A] @ 100 cd / m ²
Voltage: 8.0 [V] @ 100 cd / m ²
Luminous efficiency: 6.7 [1 m / W] @ 100 cd / m ²
The maximum wavelength of the emission spectrum of the device was 512 nm, which was identified as that from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.30, 0.63).

(Example 7)
An organic electroluminescent element was produced in the same manner as in Example 1 except that the hole transport layer 4 was formed by the following method.
On the ITO substrate on which the hole injection layer 3 was formed in the same manner as in Example 1, the hole transport material (H-5) of the present invention shown below as the material of the hole transport layer 4 (in Synthesis Example 6) The synthesized solution of the target product 12) was spin-coated under the following conditions.

Spin coating conditions Application environment Nitrogen glove box Solvent Xylene Coating solution concentration H-5 0.7% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds

The spin coat film was irradiated with UV light at an integrated light amount of 5 J / cm ² (energy value of 365 nm light) using a high-pressure mercury lamp in a nitrogen glove box. Then, a uniform thin film having a thickness of 17 nm was obtained by heating at 150 ° C. for 1 hour in a nitrogen glove box. Then, the organic electroluminescent element was produced in the same procedure as Example 1.

  The light emission characteristics of the organic electroluminescence device having a light emission area portion of 2 mm × 2 mm obtained in this way are shown below.

Luminance / current: 23.3 [cd / A] @ 100 cd / m ²
Voltage: 7.0 [V] @ 100 cd / m ²
Luminous efficiency: 10.4 [1 m / W] @ 100 cd / m ²
The maximum wavelength of the emission spectrum of the device was 512 nm, which was identified as that from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.30, 0.62).

(Comparative Example 1)
An organic electroluminescent element was produced in the same manner as in Example 1 except that the hole transport layer 4 was formed by the following method.
The following compound (H-6) and electron-accepting compound (A-1) as materials for the hole transport layer 4 are formed on the ITO substrate on which the hole injection layer 3 is formed in the same manner as in Example 1. The mixed solution was spin-coated under the following conditions.

Spin coating conditions Application environment In the atmosphere Solvent Toluene: Diglyme Weight ratio 1: 2 Mixed solvent Coating solution concentration H-6 1% by weight
A-1 0.05% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds

The spin coat film was heated in the atmosphere at 120 ° C. for 1 hour to obtain a uniform thin film having a thickness of 18 nm.
Then, the organic electroluminescent element was produced in the same procedure as Example 1.
Table 1 shows the light emission characteristics of the organic electroluminescence device having a light emission area portion of 2 mm × 2 mm obtained in this manner.

  The maximum wavelength of the emission spectrum of the device was 512 nm, which was identified as that from the iridium complex (D-1). The chromaticity was CIE (x, y) = (0.32, 0.62).

(Comparative Example 2)
An organic electroluminescent element was produced in the same manner as in Example 1 except that the hole transport layer 4 was formed by the following method.
A solution of the following compound (H-7) as a material for the hole transport layer 4 was spin-coated on the ITO substrate on which the hole injection layer 3 was formed in the same manner as in Example 1 under the following conditions.

Spin coating conditions Application environment Air Solvent Xylene Coating concentration H-7 0.7% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds

The spin coat film was heated in the atmosphere at 120 ° C. for 1 hour to obtain a uniform thin film having a thickness of 18 nm.
Then, the organic electroluminescent element was produced in the same procedure as Example 1.

Table 1 shows the light emission characteristics of the organic electroluminescence device having a light emission area portion of 2 mm × 2 mm obtained in this manner.
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) = (0.30, 0.63).

(Comparative Example 3)
An organic electroluminescent element was produced in the same manner as in Example 1 except that the hole transport layer 4 was formed by the following method.
A solution of the following compound (H-8) as a material for the hole transport layer 4 was spin-coated on the ITO substrate on which the hole injection layer 3 was formed in the same manner as in Example 1 under the following conditions.

Spin coating conditions Application environment In nitrogen glove box Solvent Xylene Coating solution concentration H-8 1% by weight
Spinner speed 1500rpm
Spinner rotation time 30 seconds

The spin coat film was heated in a nitrogen glove box at 150 ° C. for 1 hour to obtain a uniform thin film having a thickness of 26 nm.
Then, the organic electroluminescent element was produced in the same procedure as Example 1.

Table 1 shows the light emission characteristics of the organic electroluminescence device having a light emission area portion of 2 mm × 2 mm obtained in this manner.
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) = (0.30, 0.62).

  Table 1 summarizes the characteristics of the organic electroluminescent device produced as described above.

(Driving life test)
The elements produced in Example 2, Example 4 to Example 7 and Comparative Example 2 to Comparative Example 3 were continuously lit by applying a direct current having an electric current density of 10 mA / cm ^2, and the luminance after 10 hours. And the ratio to the luminance at the start of the test was examined. The results are shown in Table 2.

  As can be seen from Tables 1 and 2, the organic electroluminescent device produced using the hole transport material of the present invention can achieve both high luminous efficiency and long life.

  The present invention relates to various fields in which organic electroluminescent elements are used, for example, light sources (for example, light sources of copiers, flat panel displays (for example, for OA computers and wall-mounted televisions) and surface light emitters). It can be suitably used in the fields of liquid crystal displays and backlights of instruments), display panels, indicator lamps and the like.

It is sectional drawing which shows typically an example of the structure of the organic electroluminescent element of this invention.

Explanation of symbols

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

Claims (11)

A hole transport material represented by the following general formula (I) and having a molecular weight of 300 to 5,000.

[Wherein, R ^{1 to} R ⁷ each independently represents a hydrogen atom, a direct bond to the linking group Z ¹ or a monovalent group.
n represents an integer of 2 to 4.
Linking groups Z ¹ represents a direct bond, an ether group or a divalent aromatic group.
A ¹ represents a hydrogen atom or a bridging group.
However, in one molecule, at least one A ¹ is a crosslinking group.
A plurality of A ¹ or R ^{1 to} R ⁷ in one molecule may be the same or different. ] 2. The hole transport material according to claim 1, wherein n is 2 . The hole transport material according to claim 1 or 2 , wherein the number of crosslinking groups in one molecule is 1, 2 or 3. The hole transport material according to any one of claims 1 to 3 , wherein the formula (I) is represented by the following general formula (II).

[Wherein, R ¹ , R ^{5 to} R ⁷ , Z ¹ , n and A ¹ have the same meanings as in formula (I), respectively. Moreover, R < ⁹ > -R < ¹¹ > is synonymous with R < ¹ > -R < ⁷ > each independently. ] The hole transport material according to any one of claims 1 to 4 , wherein the crosslinking group is represented by the following formula (Ia).
-GJ (Ia)
[In the formula, G is formed by linking 1 to 30 groups selected from an —O— group, a —C (═O) — group, or an optionally substituted —CH ₂ — group. Represents a valent group, and J represents a group selected from the following cross-linking group group T.
<Crosslinking group T>

(Wherein R ^{15 to} R ¹⁸ each independently represents a hydrogen atom or an alkyl group. Ar ¹ is an aromatic hydrocarbon group which may have a substituent or an aromatic group which may have a substituent. Represents a heterocyclic group.]] An organic electroluminescent element composition comprising the hole transport material according to any one of claims 1 to 5 and a solvent. The composition for organic electroluminescent elements according to claim 6 , comprising two or more hole transport materials. Hole transport material is polymerized polymer obtained according to any one of claims 1 to 5. 9. An organic electroluminescent device comprising an organic electroluminescent device having an anode, a cathode, and an organic light emitting layer provided between both electrodes on a substrate, wherein the organic electroluminescent device comprises the layer containing the polymer compound according to claim 8. element. The organic electroluminescent device according to claim 9 , wherein the organic light emitting layer is formed by a wet film forming method. The organic electroluminescent element according to claim 9 or 10 , wherein the layer containing a polymer compound is a hole transport layer.

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