JP2005075935A - Ethynylsilane copolymer and hole transport material - Google Patents

Abstract

（式中、Ｒ_１及びＲ_２は、それぞれ独立に、置換基を有していてもよいアルキル基等であり、ｎは、１〜１０の整数であり、Ａｒ^１及びＡｒ^２は、それぞれ独立に、置換基を有していてもよい炭素数１０〜１００のアリーレン基等である。）
で示される繰り返し単位Ｂを有するエチニルシラン共重合体であって、重量平均分子量が５００〜１００，０００であり、且つ該共重合体中に含まれる繰り返し単位Ａの数と繰り返し単位Ｂの数との比であるＢ／Ａが０．０１〜５００であることを特徴とするエチニルシラン共重合体を有機エレクトロルミネッセンス素子用の正孔輸送性材料として使用する。
【選択図】 なし
PROBLEM TO BE SOLVED: To provide a positive hole transporting material excellent in luminous characteristics, high heat resistance, soluble in a solvent and made of a positive film.
The repeating unit A represented by the following formula (1a) and the following formula (1b)
[Chemical 1]

(Wherein, _{R 1} and _{R 2} are each independently an alkyl group or the like may have a substituent, n is an integer from 1 to 10, Ar ¹ and Ar ² are each independently And an arylene group having 10 to 100 carbon atoms which may have a substituent.
An ethynylsilane copolymer having a repeating unit B represented by the formula: wherein the weight average molecular weight is 500 to 100,000, and the number of repeating units A and the number of repeating units B contained in the copolymer; An ethynylsilane copolymer having a B / A ratio of 0.01 to 500 is used as a hole transporting material for an organic electroluminescence device.
[Selection figure] None

Description

  The present invention relates to a novel ethynylsilane copolymer and a hole transporting material comprising the copolymer.

  An organic electroluminescence element (hereinafter referred to as “organic EL element”) is expected to be used as a solid light emitting type inexpensive large-area full-color display element, and is currently being actively developed. In general, an organic EL element is composed of a light emitting layer and a pair of counter electrodes sandwiching the layer. In light emission, when an electric field is applied between both electrodes, electrons are injected from the cathode and holes are injected from the anode. Furthermore, the electrons and holes are recombined in the light emitting layer, and energy is emitted as light when the energy level returns from the conduction band to the valence band.

  As a technique for realizing an organic EL device with low voltage drive, high efficiency, and high brightness, Tang et al. Have a multilayer structure in which a hole transporting compound, a light emitting compound, and an electron transporting compound are stacked in this order on the anode. A device having the same has been proposed. Among these, the hole-transporting compound facilitates the injection of holes from the anode, easily transports holes with a large hole drift mobility, and blocks electrons with a small electron drift mobility, And a function of increasing the recombination probability in the light emitting layer. Therefore, in order to obtain an organic EL device having a low driving voltage, high luminance, and high luminous efficiency, a hole transporting compound having a high hole drift mobility is desired. Currently, arylamine derivatives and hydrazone derivatives are known as hole transporting compounds with high drift mobility, but most of them are low molecular weight compounds. These low molecular weight compounds generally use a method of forming a thin film by vacuum deposition at the time of device preparation, but there is a problem that the workability is not good at the time of manufacturing a large device and the cost is high. Therefore, it is conceivable to disperse these low molecular weight compounds in the resin and thin the film by a coating method such as spin coating. However, when the concentration of the hole transporting compound in the resin is low, the drift mobility is low. On the other hand, when the concentration is increased, there is a problem that the hole transporting compound is easily crystallized and the film forming property is remarkably lowered.

  On the other hand, polysilane compounds having silicon as the main skeleton have been attracting attention as an alternative to low molecular weight hole transporting compounds. Polysilane compounds are not only soluble in organic solvents and excellent in film moldability, but also as semiconductors that conduct holes by delocalized electrons moving through the silicon-silicon bond in the main chain. It is a very promising material because it has In particular, poly (methylphenylsilane) is known to have the highest hole drift mobility as a single polymer material.

  However, the Si skeleton chain of the polysilane has a problem of heat resistance due to structural phase transition from around 80 ° C., and the light emission characteristics are dependent on driving time. Not reached.

  Therefore, for the purpose of improving heat resistance, a hole transporting material made of poly (silanylene-diethynylarylene) has been proposed. This polymer material is excellent in heat resistance and has been shown to give appropriate light emission characteristics (see Non-Patent Document 1). However, further improvement of the light emission characteristics has been demanded.

Sakamaki, five others, Applied Organometallic Chemistry (Appl. Organomet. Chem.), 2001, Vol. 15, p. 604-612

  Accordingly, an object of the present invention is to provide a high-molecular-weight hole-transporting material containing silicon atoms that gives excellent light-emitting properties and has high heat resistance.

  As a result of diligent investigations to solve the above problems, the present inventors have found that an ethynylsilane copolymer having a π-conjugated group having a specific structure has a hole transporting ability that provides high emission characteristics. And it discovered having high heat resistance, and came to provide this invention.

  That is, the present invention provides an ethynylsilane copolymer having a repeating unit A (also referred to as unit A) represented by the following formula (1a) and a repeating unit B (also referred to as unit B) represented by the following formula (1b). The weight average molecular weight is 500 to 100,000, and the ratio of the number of repeating units A and the number of repeating units B contained in the copolymer is B / A of 0.01 to 500. The ethynylsilane copolymer, wherein the ethynylsilane copolymer is 500.

[Wherein, R ₁ and R ₂ each independently represents an alkyl group which may have a substituent, an aryl group which may have a substituent, or a heteroaryl which may have a substituent. Group,
n is an integer of 1 to 10,
Ar ¹ and Ar ² are each independently an arylene group having 15 to 100 carbon atoms, which may have a substituent, and having at least one nitrogen atom in the heterocycle and having 3 to 3 carbon atoms in the heterocycle A substituted or unsubstituted π-excess heteroarylene group having a heterocycle of 100, a substituted or unsubstituted π-excess heteroarylene group having a C8-100 heterocycle having no nitrogen atom in the heterocycle, the following formula It is one group selected from the group consisting of a styreylene group represented by (2), a styreylene group represented by the following formula (3), and a phenylene vinylene group represented by the following formula (4).

{In the formulas (2) and (3), Y represents an arylene group which may have a substituent, and Z ¹ and Z ² may each independently have a substituent. R ^{3 to} R ⁸ are each independently an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or an aryl group which may have a substituent. , An optionally substituted heteroaryl group, amino group or cyano group, and p, q, r, s, t and u are each independently an integer of 0 to 2. }

(In the formula, R ⁹ and R ¹⁰ are each independently an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryl group which may have a substituent, A heteroaryl group optionally having a substituent, an amino group or a cyano group, v and w are each independently 1 or 2, and m is an integer of 1 to 10.)]

  The ethynylsilane copolymer of the present invention is extremely useful as a hole transporting material constituting an organic EL device because the light emission characteristics at high temperatures can be stably obtained.

  The ethynylsilane copolymer of the present invention has a unit A represented by the above formula (1a) and a unit B represented by the following formula (1b).

In the formulas (1a) and (1b), R ¹ and R ² each independently have an alkyl group which may have a substituent, an aryl group which may have a substituent, or a substituent. A heteroaryl group which may be substituted.

The alkyl group which may have a substituent as R ¹ and R ² includes an alkyl group having 1 to 20 carbon atoms and at least one, preferably 1 to 2 hydrogen atoms of the alkyl group. Those substituted with a substituent such as an atom, a hydroxyl group, an alkoxy group, an amino group, a substituted amino group, and a cyano group are preferred. Here, as the substituted amino group, one in which one or two hydrogen atoms of the amino group are substituted with an alkyl group or an aryl group is preferable. Examples of suitable alkyl groups that may have a substituent include methyl, ethyl, propyl, butyl, octyl, stearyl, 3-chloropropyl, 2-hydroxybutyl, and 2 -Ethoxyethyl group, 2- (N, N-dimethyl) ethyl group and the like can be mentioned. Examples of the alkyl group which may have a substituent as R ¹ and R ² include an aryl group having 6 to 36 carbon atoms and at least one of hydrogen atoms of the aryl group, preferably 1 to 2 halogen atoms. Preferred are those substituted with a substituent such as an atom, a hydroxyl group, an alkyl group, an alkoxy group, an amino group, a substituted amino group, a cyano group, and a haloalkyl group, wherein the substituted amino group has the above substituents. It is the same as the case of the alkyl group which may be. Suitable groups as the aryl group which may have a substituent include phenyl, biphenyl, naphthyl, anthryl, phenanthryl, xylyl, tolyl, p-chlorophenyl, 2-hydroxynaphthyl, 3- Ethoxyanthryl group, 3- (N, N-diethyl) -4-ethoxyphenyl group, 4- (N, N-dimethylamino) phenyl group, 4- (N, N-diethylamino) naphthyl group, 3- (N , N-diphenylamino) phenyl group, 3- (N, N-phenyl-naphthylamino) anthryl group, 3-cyanophenyl group, 3-trifluoromethylphenyl group and the like. Examples of the heteroaryl group which may have a substituent as R ¹ and R ² include a triarylamine ring, an oxazole ring, an imidazole ring, a pyrazole ring, a benzimidazole ring, a benzopyrazole ring, a carbazole ring, A monovalent heteroarylene group derived from a thiophene ring, a benzofuran ring, a dibenzothiophene ring, a dibenzofuran ring, or the like can be given. Examples of the substituent that may be substituted on the heteroaryl group include a halogen atom, a hydroxyl group, an alkyl group, an alkoxy group, an amino group, a substituted amino group, a cyano group, and a haloalkyl group. Among these groups, an aryl group substituted with a substituted amino group is particularly preferable because it can increase the HOMO energy level of the molecule and increase the efficiency of hole injection from the anode. Examples of aryl groups substituted with these substituted amino groups include groups represented by the following formulae.

(In the above formula, R ¹¹ , R ¹² , R ¹³ and R ¹⁴ each independently have an alkyl group which may have a substituent, an aryl group which may have a substituent, or a substituent. A heteroaryl group which may be substituted, an alkoxy group which may have a substituent, an amino group or a cyano group, and j, k, l and h are each independently an integer of 0 to 2. )
Regarding R ^{11 to} R ^{14, the} optionally substituted alkyl group, the optionally substituted aryl group and the optionally substituted heteroaryl group include R ¹ and R ¹⁴ , respectively. The same groups as those preferred for R ² can be suitably used. Moreover, as the alkoxy group which may have a substituent, at least one, preferably 1 to 2 of a hydrogen atom of the alkoxy group having 1 to 20 carbon atoms and the alkoxy group is a halogen atom, a hydroxyl group, Those substituted with a substituent such as an alkoxy group are preferred, and suitable groups include methoxy, ethoxy, propoxy, butoxy, octyloxy, isooctyloxy, stearyloxy, 3-chloro. A propyloxy group, 4-hydroxybutyloxy group, 2-ethoxyethoxy group, 6-propyloxyhexyloxy group and the like can be mentioned.

  In the formula (1b), n representing the number of silanylene groups is an integer of 1 to 10, but is preferably an integer of 1 to 6 for ease of synthesis and the like.

The groups represented by Ar ¹ and Ar ² in the formulas (1a) and (1b) are each independently (i) an arylene group having 10 to 100 carbon atoms which may have a substituent, and (ii) at least A substituted or unsubstituted π-excess heteroarylene group having one nitrogen atom in the heterocycle and a heterocycle having 3 to 100 carbon atoms in the heterocycle; (iii) having no nitrogen atom in the heterocycle A substituted or unsubstituted π-excess heteroarylene group having a heterocycle having 8 to 100 carbon atoms, (iv) a styreylene group represented by the formula (2), (v) a styreylene group represented by the formula (3), and ( vi) One group selected from the group consisting of the phenylene vinylene groups represented by the formula (4).

  As the arylene group of the above (i), any known group can be applied as long as it is an arylene group having 10 to 100 carbon atoms, but the light emission characteristics of the resulting copolymer are excellent. Therefore, it is preferable that two or more 5-membered to 7-membered aromatic hydrocarbon rings are divalent arylene groups having 10 to 100 carbon atoms linked by a single bond or condensation. Specific examples of such suitable groups include biphenyl ring, naphthalene ring, anthracene ring, phenanthrene ring, biphenylene ring, fluorene ring, pyrene ring, perylene ring, naphthacene ring, triphenylene ring, picene ring, pentaphen ring, pentacene And a divalent arylene group derived from a ring, a rubicene ring, and the like. In addition, for example, two or more aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a biphenyl ring, and a fluorene ring are connected by a single bond between the same or different types, and the number of carbon atoms is 10 to 10. Groups of 100 can also be used in the present invention. Examples of such groups include 1-phenylnaphthalene-diyl group, 9,10-diphenylanthracene-diyl group, 2,7-diphenylfluorene-diyl group, 9,10-di (2-naphthyl) -anthracene-diyl. Groups and the like. In addition, it is preferable that carbon number of the arylene group of said (i) is the range of 5-35 from the reason that acquisition of a raw material is comparatively easy.

  The π-excess heteroarylene group (ii) is a known π-excess heteroaryl group as long as it is a group having at least one nitrogen atom in the heterocycle and a heterocycle having 3 to 100 carbon atoms in the heterocycle Arylene groups can be applied without any limitation. The π-excess heteroarylene group referred to here means that a lone pair of electrons on the heteroatom participates in the SP2 hybrid orbital to form a 6π electron system that satisfies the Hückel rule {(4n + 2) π rule}, and It means an aromatic ring having fewer atoms constituting the ring than the number of π electrons (this is the same in (iii)). Examples of suitable π-excess heteroarylene groups include divalent heteroarylene groups derived from oxazole rings, imidazole rings, pyrazole rings, benzimidazole rings, benzopyrazole rings, carbazole rings, and the like. Can do. In addition, a heteroarylene group in which these heteroarylene groups are linked by a single bond between the same or different species to have 3 to 100 carbon atoms can also be used in the present invention. Furthermore, a group in which the above-described arylene group and heteroarylene group are linked by a single bond can also be used in the present invention. Specific examples of such a group include 2,5-diphenylpyrrole-diyl group. The π-excess heteroarylene group of (ii) is a divalent π-excess composed of a 5, 9, or 13-membered heterocyclic ring having at least one nitrogen atom because the resulting copolymer has excellent luminescent properties. A divalent π in which two or more of the heteroarylene group, the 5-, 9- or 13-membered heterocyclic ring, or the heterocyclic ring and an aromatic hydrocarbon ring having 5 to 7 carbon atoms are connected by a single bond or condensation Excess heteroarylene groups are preferred.

  The π-excess heteroarylene group of (iii) is the same as (ii) except that it does not have a nitrogen atom in the heterocycle and has 8 to 100 carbon atoms constituting the heterocycle. Examples of the π-excess heteroarylene group (iii) that can be suitably used include a divalent heteroarylene group derived from a benzothiophene ring, a benzofuran ring, a dibenzothiophene ring, a dibenzofuran ring, or the like.

  In addition, when each of the groups (i) to (iii) has a substituent, the substituent includes an alkyl group, an alkoxy group, an aryl group, an amino group, a substituted amino group, a cyano group, a halogen atom, and a hydroxy group. And a haloalkyl group. As an alkyl group, a C1-C20 alkyl group is preferable and a methyl group, an ethyl group, a propyl group, a butyl group, an octyl group, a stearyl group etc. can be mentioned. The alkoxy group is preferably an alkoxy group having 1 to 20 carbon atoms, and specific examples include a methoxy group, an ethoxy group, a propoxy group, a butoxy group, an octyloxy group, an isooctyloxy group, and a stearyloxy group. As the aryl group, a phenyl group having 6 to 36 carbon atoms, a naphthyl group, an anthryl group, a phenanthryl group, a xylyl group, a tolyl group, or the like is preferably used. As the substituted amino group, one in which one or two hydrogen atoms of the amino group are substituted with an alkyl group or an aryl group is preferable. Specific examples of such a substituted amino group include N, N-dimethylamino group, N, N-diethylamino group, N, N-diphenylamino group, N, N-phenyl-naphthylamino group and the like. Can do. As the halogen atom, there can be mentioned a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. Moreover, although a well-known group can be used as a haloalkyl group without a restriction | limiting, a trifluoromethyl group, 3,3,3- trifluoropropyl group etc. can be mentioned as a suitable group.

The groups (iv) and (v) are styreylene groups represented by the formulas (2) and (3), respectively. Y in the formulas (2) and (3) is an arylene group which may have a substituent, and the arylene group is not particularly limited. Suitable arylene groups as Y include divalent groups derived from a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, biphenyl ring, fluorene ring and the like. In the formulas (2) and (3), Z ¹ and Z ² are each independently an aryl group which may have a substituent, and have been described as substituents for the Ar ¹ group and the Ar ² group. A group having the same meaning as the aryl group can be applied. R ^{3 to} R ⁸ in formulas (2) and (3) each independently have an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent. An aryl group which may be substituted, a heteroaryl group which may have a substituent, an amino group or a cyano group. In addition, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryl group which may have a substituent, a heteroaryl group which may have a substituent Is preferably the same group as in R ^{11 to} R ¹⁴ . Furthermore, p, q, r, s, t, and u, each representing the number of bonds of R ^{3 to} R ⁸ , are each independently an integer of 0-2.

  Specific examples of the styreylene group represented by the formulas (2) and (3) include groups represented by the following formulas.

The group (vi) is a phenylene vinylene group represented by the formula (4). R ⁹ and R ¹⁰ in the formula (4) may each independently have an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or a substituent. A good aryl group, a heteroaryl group optionally having a substituent, an amino group, or a cyano group. These groups have the same meanings as in R ^{3 to} R ⁸ . Moreover, v and w in a formula are each independently 1 or 2, and m is an integer of 1-10. Specific examples of groups suitable as the phenylene vinylene group represented by the formula (4) include the following groups.

  The weight average molecular weight of the ethynylsilane copolymer of the present invention is 500 to 100,000. When the weight average molecular weight is less than 500, the uniformity of the coated film may be inferior, and when it exceeds 100,000, the solubility and dispersibility in the coating solvent tend to be inferior. When used as a hole transport material, there is almost no difference in light emission characteristics depending on the molecular weight, but the weight average molecular weight is 1,000 from the viewpoint of excellent film formability and excellent mechanical strength. ˜50,000, particularly 2,000 to 30,000 is preferred.

  Moreover, in the ethynylsilane copolymer of this invention, B / A which is a ratio of the number of units A contained in this copolymer and the number of units B needs to be 0.01-500. When the B / A ratio is out of the above range, there is a tendency that sufficient light emission characteristics are not exhibited. From the viewpoint of effect, B / A is preferably 0.1 to 200. In the ethynylsilane copolymer of the present invention, the bonding sequence of units A and B is arbitrary, and may be a block copolymer or a random copolymer.

  The ethynylsilane copolymer of the present invention generally exists as a colorless or pale yellow solid or a viscous liquid under normal temperature and normal pressure, and the structure thereof can be confirmed by the following means (a) to (d).

(A) By measuring a proton nuclear magnetic resonance spectrum ( ¹ H-NMR), a peak based on an olefinic proton or an aromatic proton is around δ 5.0 to 9.0 ppm, and an alkyl is around δ 1.0 to 4.0 ppm. Peaks based on protons of groups and alkylene groups appear. Moreover, the number of protons of each linking group can be known by relatively comparing the respective spectrum intensities. Further, by comparing the number of protons derived from the unit A and the unit B, the ratio between both units (that is, the B / A value) can be obtained.

  (B) The molecular weight (weight average molecular weight or number average molecular weight) of the obtained polymer can be determined by gel permeation chromatography (GPC) analysis.

  (C) The composition of the corresponding product can be determined by elemental analysis. Further, by comparing the number of protons derived from unit A and unit B, the ratio of B / A can be determined.

(D) By measuring the infrared absorption spectrum (IR), absorption based on a triple bond of a diethynylene group can be observed in the vicinity of 2140 cm ⁻¹ .

  The production method for obtaining the ethynylsilane copolymer of the present invention is not particularly limited, and may be obtained by any synthesis method. For example, it can be suitably produced by the following method.

  That is, the following formula (5)

{In the formula, Ar ¹ has the same meaning as Ar ¹ in formula (1a), and X represents a halogen atom. }
And a compound represented by the following formula (6):

{Wherein, R ₁ and R ₂ have the same meanings as in the formula (1b). }
Can be suitably produced by reacting a compound represented by the formula (also referred to as a unit B precursor) in the presence of a palladium complex catalyst, copper iodide, an amine and water.

  The ratio of the precursors A and B used at this time may be appropriately determined according to the B / A ratio of the ethynylsilane copolymer to be obtained. The reaction temperature is preferably −100 to 120 ° C., and a polar aprotic solvent such as N-methylpyrrolidone, dimethylformamide, toluene, benzene, tetrahydrofuran, diethyl ether or the like can be used as necessary. .

  In the above reaction, the palladium complex catalyst is usually used in the range of 0.01 to 1 mol with respect to 1 mol of the unit A precursor. As the palladium catalyst, dichlorobis (triphenylphosphine) palladium (II) or the like can be suitably used. Moreover, copper iodide is normally used in 0.01-1 mol with respect to 1 mol of unit A precursors. The amine compound is usually used in the range of 1 to 500 parts by weight per 1 part by weight of the unit A precursor. A triethylamine etc. can be used as an amine compound. Water is usually used in the range of 1 to 500 parts by weight per 1 part by weight of the unit A precursor. Although there is no restriction | limiting in particular in the usage-amount of an amine compound and water, Usually, it can use in the range of 1: 100-100: 1. By changing the use ratio of the amine compound and water, the ratio of unit A and unit B in the general formula (1) can be adjusted. In general, the unit B / A ratio can be reduced by increasing the water content. The copolymer of the present invention thus obtained can be purified by performing treatments such as silica gel column purification, recrystallization, and reprecipitation.

  The copolymer of the present invention has the characteristics of exhibiting excellent light emission characteristics and high heat resistance, and can be suitably used as a hole transporting material, and the hole transporting material comprising the copolymer of the present invention is used. Thus, an organic EL element can be created. Regarding the structure of the organic EL device using the hole transporting material comprising the copolymer of the present invention, the hole transporting material of the present invention is disposed between the pair of electrodes, at least one of which is transparent or translucent. Or it will not be restrict | limited especially if it forms in combination with the electric charge transport layer, A well-known structure is employable. For example, the hole transport material of the present invention may be provided on the anode, the light emitting layer may be formed thereon, and the electron transport layer including the electron transporter may be stacked thereon.

  Further, the light emitting layer and the charge transport layer may be a single layer, or a plurality of layers may be combined. Furthermore, a light emitter can be mixed and used in the hole transporting material of the present invention. Further, the hole transporting material of the present invention may be used as a light emitting hole transporting material.

  Known phosphors that can be used together with the hole transporting material of the present invention are not particularly limited, and examples thereof include naphthalene derivatives, anthracene or derivatives thereof, perylene or derivatives thereof, polymethine series, xanthene series, coumarin series, and cyanine series. A dye, a metal complex of 8-hydroxyquinoline or a derivative thereof, an aromatic amine, tetraphenylcyclopentadiene or a derivative thereof, or tetraphenylbutadiene or a derivative thereof can be used. Specifically, for example, known ones such as those described in JP-A-57-51781 and JP-A-59-194393 can be used.

  In addition, examples of known charge transporters that can be used together with the above-described hole transporting material of the present invention include pyrazoline derivatives, arylamine derivatives, stilbene derivatives, triphenyldiamine derivatives and the like. Examples of the electron transporter include oxadiazole derivatives, anthraquinodimethane or derivatives thereof, tetracyanoanthraquinodimethane or derivatives thereof, fluorenone derivatives, diphenoquinone derivatives, or metal complexes of 8-hydroxyquinoline or derivatives thereof. be able to.

  Specific examples of these compounds include JP-A-63-70257, JP-A-63-175860, JP-A-2-135359, JP-A-2-135361, JP-A-2-209998, and JP-A-3-37992. No. 3-152184 and the like.

  Among the charge transporters described above, the hole transporter is preferably a triphenyldiamine derivative, the electron transporter is preferably an oxadiazole derivative, or a metal complex of 8-hydroxyquinoline or a derivative thereof. Is 4,4′-bis (N (3-methylphenyl) -N-phenylamino) biphenyl, and 2- (4-t-butylphenyl) -1,3,4-oxadiazol is the electron transporter. , Benzoquinone, anthraquinone, and tris (8-quinolinol) aluminum are preferred.

  Among these, one or both of a hole transporter and an electron transporter can be used simultaneously. These materials may be used alone or in combination of two or more.

  Moreover, when using the hole transportable material of this invention as a luminescent hole transportable compound, you may mix and use a charge transporter for a luminescent hole transport layer. In this case, the amount of charge transporter used varies depending on the type of compound used and the like, and may be determined as appropriate in consideration of sufficient film forming properties and light emission characteristics. Usually, it is preferably 1 to 40% by weight, more preferably 2 to 30% by weight based on the light-emitting hole transporting material.

  Next, a typical method for manufacturing an organic EL element using the hole transporting material of the present invention will be described. First, an anode is formed on a transparent substrate such as glass or transparent plastic using a transparent or translucent metal oxide or metal thin film. As the material, a conductive metal oxide film, a translucent metal thin film, or the like is used. Specifically, a film (NESA etc.) made of conductive glass made of indium tin oxide (ITO), tin oxide or the like, Au, Pt, Ag, Cu or the like is used. As a manufacturing method, a vacuum deposition method, a sputtering method, a plating method, or the like is used.

  Next, a hole transport layer containing the hole transport material of the present invention is formed on the anode. As a forming method, a spin coating method, a casting method, a dipping method, a bar code method, a roll coating method, a gravure coating method, a flexographic printing method, a spray coating method, an ink jet printing using a melt, solution or mixed solution of these materials. It is particularly preferable to form the film by a coating method such as a method.

  The film thickness of the hole transport layer is preferably 1 nm to 1 μm, more preferably 2 to 500 nm. In order to increase the current density and increase the light emission efficiency, the range of 5 to 200 nm is preferable. In addition, when it thins by the apply | coating method, in order to remove a solvent preferably, it is heat-dried under the pressure of pressure reduction or an inert atmosphere, Preferably it is 30-300 degreeC, More preferably, it is 60-200 degreeC. desirable.

  When a hole injection layer is further provided between the anode and the hole transport layer in order to improve the charge injection efficiency, it may be formed on the anode by the same film forming method as described above, or other known methods After that, the hole transporting material of the present invention is formed by the film forming method described above, and the light emitting layer and the charge transport layer are formed thereon by the same film forming method as described above, or by other known methods. Form.

  There are no particular limitations on the method for forming a film of a known light emitter or charge transporter, but a vacuum deposition method from a powder state, or a spin coating method after being dissolved in a solution, a casting method, a dipping method, a barcode method, a roll coating method A coating method such as a method can be used.

  The light emitting layer or the charge transport layer needs to have a thickness that does not generate pinholes at least. However, if the thickness is too large, the resistance of the device increases and a high driving voltage is required, which is not preferable. Therefore, the thickness of each layer is independently preferably 1 nm to 1 μm, more preferably 2 nm to 500 nm, and particularly preferably 5 nm to 200 nm.

  Next, a cathode is provided. This electrode becomes an electron injection cathode. The material is not particularly limited, but a material having a small ionization energy is preferable. For example, Al, In, Mg, Ca, Li, Mg—Ag alloy, In—Ag alloy, Mg—In alloy, Mg—Al alloy, Mg—Li alloy, Al—Li alloy, Al—Ca alloy, graphite thin film, etc. Is used. As a method for producing the cathode, a vacuum deposition method, a sputtering method, or the like is used.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

Example 1
<Organic EL element material: Synthesis of P1>
Into a 50 ml two-necked eggplant flask equipped with a magnetic stir bar and reflux condenser, 0.1644 g (0.855 mmol) of dibutyldiethynylsilane, 0.2437 g (0.852 mmol) of 1,4-dibromonaphthalene, bis (triphenylphosphine) ) 0.052 g of palladium dichloride, 0.0151 g of copper iodide, 15 ml of triethylamine, and 500 μl of water were added and stirred. After 15 minutes, the reaction temperature was kept at 50 ° C. and the reaction was allowed to proceed for 24 hours. Suction filtration was performed using Hyflo Supercell to remove insoluble components such as catalyst and salt, and then the solvent was distilled off with an evaporator. By repeating reprecipitation twice from chloroform / ethanol, 0.0455 g (19% yield) of the target polymer was obtained.

According to GPC analysis, the obtained solid had a weight average molecular weight (Mw) of 18000, and the ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) was 2.3. ¹ H-NMR measurement was performed to confirm the structure of the compound. FIG. 1 shows a ¹ H-NMR chart. The unit structure of unit A and unit B in the obtained copolymer is shown in the following formula.

Further it was found that from the ratio of the aromatic protons and the alkyl protons in ¹ H-NMR is B / A ratio = 4.2. The results are summarized in Table 1.

Examples 2-6
P2 to P6 were synthesized in the same manner as in Example 1 except that triethylamine and water were used in the amounts shown in Table 1. The results are shown in Table 1.

Example 7
<Synthesis of organic EL element material: P7>
A 50 ml two-necked eggplant flask equipped with a reflux condenser and a magnetic stirrer was charged with diethynyldibutylsilane (0.135 g, 0.695 mmol), 2,7-dibromo-9,9-diethylfluorene (0.266 g, .0. 699 mmol), dichlorobis (triphenylphosphine) palladium (II) (0.052 g, 0.071 mmol), copper (I) iodide (0.015 g, 0.079 mmol), 15 ml of triethylamine, and 1.25 μl of water, The reaction was stirred at 80 ° C. for 24 hours. Thereafter, suction filtration is performed using a high flow supercell to collect soluble matter, and the solvent is distilled off with a rotary evaporator, followed by reprecipitation with chloroform / ethanol to obtain 0.248 g of the target polymer (yield 87%). Got in.

The weight average molecular weight of the obtained solid was 9600 by GPC analysis. Further, the structure of the compound was confirmed by ¹ H-NMR measurement. The unit structure of A unit and B unit in the obtained copolymer is shown in the following formula.

Further, from the results of GPC and ¹ H-NMR, it was found from the same calculation as in Example 1 that B / A ratio = 131.

Examples 8-12
<Synthesis of organic EL element material: 8-12>
P8 to P12 were synthesized in the same manner as in Example 7 except that triethylamine and water were used in the amounts shown in Table 2. The results are shown in Table 2.

Examples 13-15
<Synthesis of organic EL element materials: 13-15>
An ethynylsilane copolymer was synthesized in the same manner as in Example 1 except that the raw materials shown in Table 3 were used, and a polymer having Unit A and Unit B shown in Table 4 was synthesized. The results are shown in Table 5.

Comparative Example 1
<Organic EL element material: Synthesis of R1>
Into a 50 ml two-necked eggplant flask equipped with a magnetic stirring bar and a reflux condenser, 0.1684 g (0.875 mmol) of dibutyldiethynylsilane, 0.2504 g (0.875 mmol) of 1,4-dibromonaphthalene, bis (triphenylphosphine) ) Palladium dichloride 0.0497g, copper iodide 0.0154g, and triethylamine 15ml were added and stirred. After 15 minutes, the reaction temperature was kept at 50 ° C. and the reaction was allowed to proceed for 24 hours. Suction filtration was performed using Hyflo Supercell to remove insoluble components such as catalyst and salt, and then the solvent was distilled off with an evaporator. By repeating reprecipitation twice from chloroform / ethanol, 0.1954 g (71% yield) of the target polymer was obtained.

The weight average molecular weight of the obtained solid was found to be 17600 by GPC analysis. Moreover, it measured from the result of < ¹ > H-NMR and confirmed the structure of the compound.

Example 16
<EL emission characteristics>
A transparent support substrate was obtained by forming an ITO film with a thickness of 600 nm on a glass substrate of 35 mm × 25 mm × 0.8 mm. After etching and washing the transparent support substrate, about 2 g of the above-mentioned 2 wt% chloroform solution of P1 was spin-coated on the substrate surface at a rotational speed of 3000 rpm for 60 seconds using a spin coater 1H-DX2 made by MIKASA. . On top of that, 60 nm of tris (8-quinolinol) aluminum was deposited as an electron transport layer at a deposition rate of 0.1 nm / second using a deposition apparatus manufactured by ULVAC (EBV-6DA). Finally, magnesium: silver = 10: 1 was vapor-deposited with a thickness of 170 nm to 10 mm × 1 mm as a cathode thereon to produce an organic EL device. The degree of vacuum during vapor deposition was 1 × 10 ⁻⁵ Torr or less. When a voltage of 12 V was applied to the device and fluorescence emission was measured using a spectrophotometer (instant multichannel photodetector MCPD1000: manufactured by Otsuka Electronics Co., Ltd.), green fluorescence having a maximum emission wavelength at 520 nm was observed. The emission intensity at this time was 182 cd / m ² . Further, when the P1 compound was subjected to thermogravimetric analysis under a nitrogen stream, no weight reduction was observed up to 200 ° C., and it was confirmed that the compound had high heat resistance.

Example 17
An organic EL device was produced in the same manner as in Example 16 except that the P2 compound was used instead of the P1 compound. When a voltage of 20 V was applied to the device and fluorescence emission was measured using a spectrophotometer (instant multichannel photodetector MCPD1000: manufactured by Otsuka Electronics Co., Ltd.), green fluorescence having a maximum emission wavelength at 520 nm was observed. The emission intensity at this time was 35 cd / m ² . Further, when thermogravimetric analysis was performed in the same manner as in Example 16, no weight reduction was observed up to 200 ° C. even with the P2 compound, and high heat resistance could be confirmed.

Comparative Example 2
An organic EL device was produced in the same manner as in Example 16 except that the R1 compound was used instead of the P1 compound. When a voltage of 20 V was applied to the device and fluorescence emission was measured using a spectrophotometer (instant multichannel photodetector MCPD1000: manufactured by Otsuka Electronics Co., Ltd.), green fluorescence having a maximum emission wavelength at 520 nm was observed. The emission intensity at this time was 28 cd / m ² .

  The copolymer of the present invention can be used as a hole transporting material of an organic electroluminescence element (organic EL element) that is expected to be used as a large-area full-color display element.

2 is a chart of ¹ H-nuclear magnetic resonance spectrum of the ethynylsilane copolymer obtained in Example 1. FIG.

Claims (2)

An ethynylsilane copolymer having a repeating unit A represented by the following formula (1a) and a repeating unit B represented by the following formula (1b), having a weight average molecular weight of 500 to 100,000, The ethynylsilane copolymer, wherein B / A, which is a ratio of the number of repeating units A and the number of repeating units B contained in the coalescence, is 0.01 to 500.

[Wherein, R ₁ and R ₂ each independently represents an alkyl group which may have a substituent, an aryl group which may have a substituent, or a heteroaryl which may have a substituent. Group,
n is an integer of 1 to 10,
Ar ¹ and Ar ² are each independently an arylene group having 10 to 100 carbon atoms which may have a substituent, and at least one nitrogen atom in the heterocyclic ring, and the heterocyclic ring having 3 to 3 carbon atoms. A substituted or unsubstituted π-excess heteroarylene group having a heterocycle of 100, a substituted or unsubstituted π-excess heteroarylene group having a C8-100 heterocycle having no nitrogen atom in the heterocycle, the following formula It is one group selected from the group consisting of a styreylene group represented by (2), a styreylene group represented by the following formula (3), and a phenylene vinylene group represented by the following formula (4).

{In the formulas (2) and (3), Y represents an arylene group which may have a substituent, and Z ¹ and Z ² may each independently have a substituent. R ^{3 to} R ⁸ are each independently an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or an aryl group which may have a substituent. , An optionally substituted heteroaryl group, amino group or cyano group, and p, q, r, s, t and u are each independently an integer of 0 to 2. }

(In the formula, R ⁹ and R ¹⁰ are each independently an alkyl group which may have a substituent, an alkoxy group which may have a substituent, or an aryl group which may have a substituent. A heteroaryl group optionally having a substituent, an amino group, or a cyano group, v and w are each independently 1 or 2, and m is an integer of 1 to 10.) A hole transporting material comprising the ethynylsilane copolymer according to claim 1.

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