High molecular weight triarylamine compound and organic electroluminescent element

Abstract

The purpose of the present invention is to provide a high molecular weight material that exhibits excellent hole injection and transport performance and has electron blocking capabilities, and that has high stability when in the form of a thin film. Another purpose of the present invention is to provide an organic EL element that comprises an organic layer (a thin film) formed from the aforesaid high molecular weight material and has high luminous efficiency and a long service life.　The present invention focused on a high molecular weight triarylamine compound, which contains, in the molecular main chain, a triarylamine structural unit containing a diphenylnaphthalene structure and a diphenylnaphthalene structural unit, and found a high molecular weight compound with a novel structure that has a wide gap in addition to hole injection and transport capabilities.

Description

High molecular weight triarylamine compounds and organic electroluminescent devices

[0001] The present invention relates to a high molecular weight compound suitable for an organic electroluminescence element (organic EL element), which is a self-luminous element suitable for various display devices, and to the element.

[0002] Organic EL elements are self-luminous elements, and therefore are brighter and more visible than liquid crystal elements, and are capable of producing clearer displays, and therefore have been the subject of vigorous research.

[0003] Organic EL elements have a structure in which a thin film (organic layer) of an organic compound is sandwiched between an anode and a cathode. Thin film formation methods are broadly divided into vacuum deposition and coating methods. Vacuum deposition is a technique in which a thin film is formed on a substrate in a vacuum using mainly low-molecular-weight compounds, and is a technology that has already been put to practical use. On the other hand, coating is a technique in which a thin film is formed on a substrate using a solution, such as inkjet printing, mainly using high-molecular-weight compounds. This method is highly efficient in the use of materials and is suitable for larger areas and higher definition, making it an essential technology for future large-area organic EL displays.

[0004] The vacuum deposition method using low-molecular-weight materials has extremely low material utilization efficiency, and as the size increases, the shadow mask bends more, making uniform deposition on large substrates difficult. It also has other problems, such as high manufacturing costs.

[0005] On the other hand, polymer materials can be dissolved in organic solvents and applied to form uniform films even on large substrates, allowing for application methods such as inkjet printing and printing to be used, thereby increasing the efficiency of material use and significantly reducing the manufacturing costs of devices.

[0006] Various organic EL elements using polymer materials have been investigated to date, but there have been problems in that the element characteristics, such as luminous efficiency and life span, are not necessarily sufficient (see, for example, Patent Documents 1 to 5).

[0007] Furthermore, a fluorene polymer called TFB has been known as a typical hole transport material that has been used in polymer organic EL devices (see Patent Documents 6 and 7). However, TFB has insufficient hole transport properties and electron blocking properties, which means that some electrons pass through the light-emitting layer, preventing improvements in luminous efficiency. Furthermore, TFB has poor film adhesion with adjacent layers, preventing the device from having a long life.

[0008] JP 2005-272834 A JP 2007-119763 A JP 2007-162009 A JP 2007-177225 A US7651746 B2 WO 1999 / 054385 WO 2005 / 059951

[0009] The present invention provides a polymer material that has excellent hole injection and transport properties, electron blocking ability, and high stability in a thin film state. Another object of the present invention is to provide an organic EL device that has an organic layer (thin film) formed from the polymer material, has high luminous efficiency, and has a long life.

[0010] The present inventors have focused on the fact that high molecular weight triarylamine compounds containing a naphthalene structural unit and a triarylamine structural unit in the molecular main chain have high hole injection / transport capabilities and can also be expected to have a wide gap. As a result of synthesizing and examining various high molecular weight triarylamine compounds, they have found a high molecular weight compound with a novel structure that not only has hole injection / transport capabilities but also a wide gap, and have completed the present invention.

[0011] According to the present invention, there is provided a high molecular weight compound containing a repeating structural unit represented by the following general formula (3), which consists of a triarylamine structural unit represented by the following general formula (1) and a linking structural unit represented by the following general formula (2).

[0012] Furthermore, according to the present invention, there is provided an organic EL device having an organic layer formed using the high molecular weight compound.

[0013] In the organic EL device of the present invention, the organic layer is preferably a hole transport layer, an electron blocking layer, a hole injection layer or a light emitting layer.

[0014] That is, the present invention is described below.

[0015] [1] A high molecular weight compound containing a repeating structural unit represented by the following general formula (3), which is composed of a triarylamine structural unit represented by the following general formula (1) and a linking structural unit represented by the following general formula (2), and having a weight average molecular weight of 10,000 or more and less than 1,000,000 in terms of polystyrene:

[0016]

[0017]

[0018]

[0019] In the above formula, R １ R each independently represents a hydrogen atom, a deuterium atom, a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group or an alkyloxy group having 1 to 8 carbon atoms, a cycloalkyl group or a cycloalkyloxy group having 5 to 10 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an aryloxy group having 6 to 10 carbon atoms. ２ each independently represents an alkyl group, a cycloalkyl group, or an alkyloxy group having 3 to 40 carbon atoms; X represents a hydrogen atom, an amino group, a monovalent aryl group, or a monovalent heteroaryl group; L represents a divalent phenylene group or a naphthylene group, and n represents an integer of 0 to 3; a, b, and c represent R １ and are the following integers: a = 0, 1, 2, or 3 b = 0, 1, 2, 3, or 4 c = 0 or 1

[0020] [2] The high molecular weight compound according to [1], wherein a, b, and c are 0 in the general formulae (1), (2), and (3).

[0021] [3] In the general formulas (1) and (3), R ２ is an alkyl group having 3 to 40 carbon atoms.

[0022] [4] The high molecular weight compound according to any one of [1] to [3], wherein in the general formulas (2) and (3), X is a hydrogen atom, or an optionally substituted amino group, aryl group, or heteroaryl group.

[0023] [5] The high molecular weight compound according to any one of [1] to [3], wherein in the general formulas (2) and (3), X is a hydrogen atom, a diphenylamino group, a phenyl group, a naphthyl group, a dibenzofuranyl group, a dibenzothienyl group, a phenanthrenyl group, a fluorenyl group, a carbazolyl group, an indenocarbazolyl group, or an acridinyl group.

[0024] [6] The high molecular weight compound according to any one of [1] to [5], which contains a thermally crosslinkable structural unit or a triarylamine structural unit different from the triarylamine structural unit represented by the general formula (1).

[0025] [7] The high molecular weight compound according to [6], wherein the thermally crosslinkable structural unit is a structural unit represented by the following general formulas (4-1) to (4-143):

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034] In the formulas (4-1) to (4-143), the broken lines indicate bonds to adjacent structural units, and the solid lines extending from the rings with free ends indicate that the ends are methyl groups.

[0035] In the formulas (4-1) to (4-143), R each independently represents a hydrogen atom, a deuterium atom, a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or an alkyl group, cycloalkyl group, alkyloxy group, cycloalkyloxy group, alkenyl group, or aryloxy group having 3 to 40 carbon atoms. a and b represent the number of R and are the following integers: a = 0, 1, 2, or 3 b = 0, 1, 2, 3, or 4

[0036] [8] An organic electroluminescence device comprising an organic layer formed using the high molecular weight compound according to any one of [1] to [7].

[0037] [9] The organic electroluminescence device according to [8], wherein the organic layer is a hole transport layer.

[0038]

[10] The organic electroluminescence device according to [8], wherein the organic layer is an electron blocking layer.

[0039]

[11] The organic electroluminescence element according to [8], wherein the organic layer is a hole injection layer.

[0040]

[12] The organic electroluminescence element according to [8], wherein the organic layer is a light-emitting layer.

[0041] The high molecular weight compound of the present invention is a polymer having a repeating structural unit represented by the general formula (3), which consists of a triarylamine structural unit (divalent group) represented by the general formula (1) and a linking structural unit (divalent group) represented by the general formula (2), and preferably has a weight average molecular weight in terms of polystyrene measured by GPC (gel permeation chromatography) in the range of 10,000 or more and less than 1,000,000.

[0042] The high molecular weight compound of the present invention has the following properties: (1) good hole injection characteristics; (2) high hole mobility; (3) wide gap and excellent electron blocking ability; and (4) stable thin film state.

[0043] An organic EL device in which an organic layer formed from such a high molecular weight compound of the present invention, such as a hole transport layer, an electron blocking layer, a hole injection layer, or a light emitting layer, is formed between a pair of electrodes has the following advantages: (1) high luminous efficiency and power efficiency; (2) low practical driving voltage; and (3) long life.

[0044] 1 shows the chemical structures of structural units 1 to 12 suitable as linking structural units represented by general formula (2). 2 shows the chemical structures of structural units 13 to 26 suitable as linking structural units represented by general formula (2). 3 shows an example of the layer configuration of an organic EL device of the present invention. 4 shows an example of the layer configuration of an organic EL device of the present invention. 5 shows the chemical structures of structural units 13 to 26 suitable as linking structural units represented by general formula (2). 6 shows the chemical structures of structural units 13 to 26 suitable as linking structural units represented by general formula (2). 7 shows an example of the layer configuration of an organic EL device of the present invention. 8 shows the chemical structures of structural units 13 to 26 suitable as linking structural units represented by general formula (2). 9 shows the chemical structures of structural units 13 to 26 suitable as linking structural units represented by general formula (2). 10 shows the chemical structures of structural units 13 to 26 suitable as linking structural units represented by general formula (2). 11 shows the chemical structures of structural units 13 to 26 suitable as linking structural units represented by general formula (2). 12 shows the chemical structures of structural units 13 to 26 suitable as linking structural units represented by general formula (2). 13 shows the chemical structures of structural units 13 to 26 suitable as linking structural units represented by general formula (2). 14 shows the chemical structures of structural units 13 to 26 suitable as linking structural units represented by general formula (2). 15 shows the chemical structures of structural units 13 to 26 suitable as linking structural units represented by general formula (2). 16 shows the chemical structures of structural units 13 to 26 suitable as linking structural units represented by general formula (2). 17 shows the chemical structures of structural units 13 to 26 suitable as linking structural units represented by general formula (2). 18 shows the chemical structures of structural units 13 to 26 suitable as linking structural units represented by general formula (2). 19 shows the chemical structures of １ 1 H-NMR chart of high molecular weight compound B synthesized in Example 2. １ FIG. 1 is a H-NMR chart.

[0045] <Triarylamine structural unit and linking structural unit> The triarylamine structural unit and linking structural unit contained in the high molecular weight compound of the present invention are both divalent groups and are represented by the following general formulas (1) and (2), respectively.

[0046]

[0047]

[0048] In the general formulas (1) and (2), R １ each independently represents a hydrogen atom, a deuterium atom, a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group or an alkyloxy group having 1 to 8 carbon atoms, a cycloalkyl group or a cycloalkyloxy group having 5 to 10 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an aryloxy group having 6 to 10 carbon atoms.

[0049] The R １ Examples of the alkyl group, alkyloxy group, cycloalkyl group, cycloalkyloxy group, alkenyl group, and aryloxy group represented by the formula (I) include the following groups.

[0050] Examples of alkyl groups (having 1 to 8 carbon atoms) include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, isohexyl, neohexyl, n-heptyl, isoheptyl, neoheptyl, n-octyl, isooctyl, and neooctyl groups. Examples of alkyloxy groups (having 1 to 8 carbon atoms) include methyloxy, ethyloxy, n-propyloxy, isopropyloxy, n-butyloxy, tert-butyloxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, and n-octyloxy groups. Examples of cycloalkyl groups (having 5 to 10 carbon atoms) include cyclopentyl, cyclohexyl, 1-adamantyl, and 2-adamantyl groups. Examples of cycloalkyloxy groups (having 5 to 10 carbon atoms) include cyclopentyloxy, cyclohexyloxy, cycloheptyloxy, cyclooctyloxy, 1-adamantyloxy, and 2-adamantyloxy groups. Examples of alkenyl groups (having 2 to 6 carbon atoms) include vinyl, allyl, isopropenyl, and 2-butenyl groups. Examples of aryloxy groups (having 6 to 10 carbon atoms) include phenyloxy and tolyloxy groups.

[0051] In the high molecular weight compound of the present invention, when a, b and c are not 0, １ is preferably a deuterium atom. From a synthesis standpoint, it is most preferred that a, b and c are 0.

[0052] In the general formula (1), R ２ each independently represents an alkyl group, a cycloalkyl group, or an alkyloxy group having 3 to 40 carbon atoms.

[0053] R ２ Examples of the alkyl group, cycloalkyl group, and alkyloxy group represented by the formula R １ Examples of the groups include the same groups as those shown in the above.

[0054] In the high molecular weight compound of the present invention, the R２ is preferably an alkyl group having 3 to 40 carbon atoms in order to enhance solubility, and is most preferably an n-hexyl group or an n-octyl group.

[0055] In the general formulas (1) and (2), a, b, and c are R １ and represent the following integers: a = 0, 1, 2, or 3 b = 0, 1, 2, 3, or 4 c = 0 or 1

[0056] In the general formula (2), X represents a hydrogen atom, an amino group, a monovalent aryl group, or a monovalent heteroaryl group.

[0057] Examples of the monovalent aryl group and the monovalent heteroaryl group include the following groups.

[0058] Examples of the aryl group include a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a fluorenyl group, an indenyl group, a pyrenyl group, a perylenyl group, and a fluoranthenyl group.

[0059] Examples of heteroaryl groups include pyridyl, pyrimidinyl, triazinyl, furyl, pyrrolyl, thienyl, quinolyl, isoquinolyl, benzofuranyl, benzothienyl, indolyl, carbazolyl, indenocarbazolyl, benzoxazolyl, benzothiazolyl, quinoxalinyl, benzimidazolyl, pyrazolyl, dibenzofuranyl, dibenzothienyl, naphthyridinyl, phenanthrolinyl, acridinyl, and carbolinyl groups.

[0060] The amino group, aryl group, and heteroaryl group may have a substituent. Examples of the substituent include, in addition to a deuterium atom, a cyano group, and a nitro group, halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom; alkyl groups, particularly those having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, an isohexyl group, a neohexyl group, an n-heptyl group, an isoheptyl group, a neoheptyl group, an n-octyl group, an isooctyl group, and a neooctyl group; alkyloxy groups, particularly those having 1 to 8 carbon atoms, such as a methyloxy group, an ethyloxy group, and a propyloxy group; alkenyl groups, such as a vinyl group and an allyl group; aryloxy groups, such as a phenyloxy group and a tolyloxy group; Examples of suitable aryl groups include phenyl, biphenylyl, terphenylyl, naphthyl, anthracenyl, phenanthrenyl, fluorenyl, indenyl, pyrenyl, perylenyl, fluoranthenyl, and triphenylenyl groups; heteroaryl groups include pyridyl, pyrimidinyl, triazinyl, thienyl, furyl, pyrrolyl, quinolyl, isoquinolyl, benzofuranyl, benzothienyl, indolyl, carbazolyl, indenocarbazolyl, benzoxazolyl, benzothiazolyl, quinoxalinyl, benzimidazolyl, pyrazolyl, dibenzofuranyl, dibenzothienyl, and carbolinyl groups; arylvinyl groups include styryl and naphthylvinyl groups; and acyl groups include acetyl and benzoyl groups.

[0061] These substituents may further have the substituents exemplified above. Furthermore, these substituents preferably exist independently of each other, but these substituents may be bonded to each other via a single bond, a methylene group which may have a substituent, an oxygen atom, or a sulfur atom to form a ring.

[0062] In the present invention, X is preferably a hydrogen atom, a diphenylamino group, a phenyl group, a naphthyl group, a dibenzofuranyl group, a dibenzothienyl group, a phenanthrenyl group, a fluorenyl group, a carbazolyl group, an indenocarbazolyl group, or an acridinyl group, and from the viewpoint of synthesis, a hydrogen atom is particularly preferred.

[0063] For example, the aryl group and heteroaryl group may have a phenyl group as a substituent, and the phenyl group may further have a phenyl group as a substituent, i.e., taking the aryl group as an example, the aryl group may be a biphenylyl group, a terphenylyl group, or a triphenylenyl group.

[0064] In the general formula (1), L represents a divalent phenylene group or naphthylene group, and n represents an integer of 0 to 3. In the present invention, n is preferably 0.

[0065] Furthermore, the above-mentioned L may have a substituent. The substituent is the same as the substituent that the above-mentioned X may have, and these substituents may further have a substituent.

[0066] In the present invention, specific examples of the linking structural unit represented by the above-mentioned general formula (2) are shown in Figures 1 and 2 as structural units 1 to 26. In the chemical formulae shown in Figures 1 and 2, dashed lines indicate bonds to adjacent structural units, and solid lines extending from a ring with a free end indicate that the free end is a methyl group. Although preferred specific examples of the linking structural unit are shown, the linking structural unit used in the present invention is not limited to these structural units.

[0067] <High-Molecular-Weight Compound> The high-molecular-weight compound of the present invention, which contains a repeating unit represented by general formula (3) consisting of the triarylamine structural unit represented by general formula (1) and the linking structural unit represented by general formula (2), has excellent properties such as hole injection characteristics, hole mobility, electron blocking ability, thin-film stability, and heat resistance, as already described above. From the viewpoint of further enhancing these properties and ensuring film-formability, the weight-average molecular weight, measured by GPC in terms of polystyrene, is preferably in the range of 10,000 or more and less than 1,000,000, more preferably 10,000 or more and less than 500,000, and even more preferably 10,000 or more and less than 200,000.

[0068] Furthermore, the high molecular weight compound of the present invention preferably contains other structural units in order to ensure coatability, adhesion to other layers, and durability when applied to form an organic layer in an organic EL device by, for example, coating. Examples of such other structural units include structural units for enhancing thermal crosslinking (thermally crosslinkable structural units) and triarylamine structural units different from the triarylamine structural unit represented by general formula (1).

[0069] Specific examples of the thermally crosslinkable structural unit include the structural units represented by the general formulae (4-1) to (4-143).

[0070] In the general formulas (4-1) to (4-143), the dashed lines indicate bonds to adjacent structural units, and the solid lines extending from the rings with free ends indicate that the ends are methyl groups. In addition, a and b in the formulas are the number of R and are the following integers: a = 0, 1, 2, or 3 b = 0, 1, 2, 3, or 4

[0071] In the general formulae (4-1) to (4-143), R represents a hydrogen atom, a deuterium atom, a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or an alkyl group, alkyloxy group, cycloalkyl group, cycloalkyloxy group, alkenyl group, or aryloxy group having 3 to 40 carbon atoms.

[0072] Examples of the alkyl group, alkyloxy group, cycloalkyl group, cycloalkyloxy group, alkenyl group, and aryloxy group represented by R include R １ Examples of the thermally crosslinkable structural unit include the same groups as those shown in the above. Although preferred specific examples of the thermally crosslinkable structural unit are shown, the thermally crosslinkable structural unit used in the present invention is not limited to these structural units.

[0073] In the high molecular weight compound of the present invention, when the triarylamine structural unit represented by general formula (1) is represented as the "structural unit A," the linking structural unit represented by general formula (2) is represented as the "structural unit B," the thermally crosslinkable structural unit is represented as the "structural unit C," and the triarylamine structural unit different from the triarylamine structural unit represented by general formula (1) is represented as the "structural unit D," the high molecular weight compound preferably contains 1 mol % or more, particularly 20 mol % or more of the structural unit A. Provided that the structural unit A is contained in such an amount, the structural unit B is preferably contained in an amount of 1 mol % or more, particularly 30 to 70 mol %, and further the structural unit C is preferably contained in an amount of 1 mol % or more, particularly 5 to 20 mol %. A terpolymer containing the structural units A, B, and C so as to satisfy these conditions is most suitable for forming an organic layer of an organic EL device.

[0074] The high molecular weight compound of the present invention is synthesized by linking the structural units together through Suzuki polymerization or Hartwig-Buchwald polymerization, respectively, by forming a carbon-carbon bond or a carbon-nitrogen bond. Specifically, the high molecular weight compound of the present invention can be synthesized by preparing a unit compound having each structural unit, appropriately converting this unit compound into a boric acid ester or halogenating it, and then subjecting it to a polycondensation reaction using an appropriate catalyst.

[0075] For example, as a compound for introducing the triarylamine structural unit represented by the general formula (1), a triarylamine derivative represented by the following general formula (1a) can be used.

[0076]

[0077] In the formula (1a), Q is a hydrogen atom or a halogen atom (particularly preferably Br), and R１ , R ２ and L are the same as defined in the general formula (1).

[0078] That is, in the general formula (1a), a compound in which Q is a hydrogen atom is a unit compound for introducing a triarylamine structural unit represented by general formula (1), and a compound in which Q is a halogen atom is a halide used for synthesizing a polymer.

[0079] For example, a copolymer containing 45 mol % of the structural unit A represented by general formula (1), 50 mol % of the structural unit B represented by general formula (2), and 5 mol % of the thermally crosslinkable structural unit C (thermally crosslinkable structural unit represented by general formula (4-5)) is represented by the following general formula (5).

[0080]

[0081] However, it is necessary that the intermediate for introducing the structural unit A and the structural unit C is a borate ester, while the intermediate for introducing the structural unit B is a halogenated product, or that the intermediate for introducing the structural unit A and the structural unit C is a halogenated product, while the intermediate for introducing the structural unit B is a borate ester. In other words, the molar ratio of the halogenated product to the borate ester must be equal.

[0082] The high molecular weight compound of the present invention described above can be dissolved in an aromatic organic solvent such as benzene, toluene, xylene, or anisole to prepare a coating solution, which can then be coated on a predetermined substrate and dried by heating, thereby forming a thin film excellent in properties such as hole injection properties, hole transport properties, and electron blocking properties.

[0083] For example, the high-molecular-weight compound can be used as a constituent material of a hole injection layer and / or a hole transport layer of an organic EL device. The hole injection layer and hole transport layer formed from such a high-molecular-weight compound have higher hole injection properties, higher mobility, and higher electron blocking properties than those formed from conventional materials, and can confine excitons generated in the light-emitting layer. Furthermore, they can improve the probability of hole and electron recombination, thereby achieving high luminous efficiency and reducing the driving voltage, thereby improving the durability of the organic EL device.

[0084] Furthermore, the high molecular weight compound of the present invention having the above-described electrical properties has a wider gap than conventional materials and is effective in confining excitons, and therefore can naturally be suitably used in electron blocking layers and light-emitting layers.

[0085] <Organic EL element> An organic EL element having an organic layer formed using the above-described high molecular weight compound of the present invention has, for example, a structure shown in Fig. 3. That is, a transparent anode 2, a hole injection layer 3, a hole transport layer 4, a light-emitting layer 5, an electron transport layer 6, and a cathode 7 are provided on a glass substrate 1 (any transparent substrate such as a transparent resin substrate).

[0086] The organic EL device to which the high molecular weight compound of the present invention is applied is not limited to the layer structure described above. A hole blocking layer may be provided between the light-emitting layer 5 and the electron transport layer 6, or an electron blocking layer 12 may be provided between the hole transport layer 11 and the light-emitting layer 13, as shown in FIG. 4 . Furthermore, an electron injection layer may be provided between the cathode and the electron transport layer. Furthermore, some layers may be omitted. For example, a simple layer structure may be used in which an anode, a hole transport layer, a light-emitting layer, an electron transport layer, and a cathode are provided on a substrate. A two-layer structure in which layers having the same function are stacked may also be used.

[0087] The high molecular weight compound of the present invention is suitably used as a material for forming an organic layer (e.g., a hole injection layer, a hole transport layer, a light-emitting layer, and an electron blocking layer) provided between the anode and the cathode, taking advantage of its properties such as hole injection property and hole transport property.

[0088] In the organic EL element, the transparent anode may be formed from a known electrode material, and is formed by depositing an electrode material having a large work function, such as ITO or gold, on a substrate (a transparent substrate such as a glass substrate).

[0089] The hole injection layer provided on the transparent anode can be formed using a coating liquid prepared by dissolving the high molecular weight compound of the present invention in an aromatic organic solvent such as toluene, xylene, anisole, etc. For example, the hole injection layer can be formed by coating the transparent anode with this coating liquid by spin coating, inkjet printing, or the like.

[0090] Furthermore, in an organic EL device having an organic layer formed using the high molecular weight compound of the present invention, the hole injection layer can also be formed using conventionally known materials, such as the following materials, without using the high molecular weight compound of the present invention: porphyrin compounds typified by copper phthalocyanine; starburst-type triphenylamine derivatives; arylamines having a structure linked by a single bond or a divalent group not containing a heteroatom (e.g., triphenylamine trimer and tetramer); acceptor heterocyclic compounds such as hexacyanoazatriphenylene; and coating-type polymer materials such as poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(styrenesulfonate) (PSS).

[0091] Layers (thin films) using such materials can be formed by coating methods such as vapor deposition, spin coating, and inkjet printing, etc. The same applies to other layers, and films are formed by vapor deposition or coating depending on the type of film-forming material.

[0092] The hole transport layer provided on the hole injection layer can also be formed using the high molecular weight compound of the present invention by a coating method such as spin coating or ink jet, similar to the hole injection layer.

[0093] Furthermore, in an organic EL device having an organic layer formed using the high molecular weight compound of the present invention, a hole transport layer can also be formed using a conventionally known hole transport material. Representative examples of such hole transport materials include: benzidine derivatives, such as N,N'-diphenyl-N,N'-di(m-tolyl)benzidine (hereinafter abbreviated as TPD); N,N'-diphenyl-N,N'-di(α-naphthyl)benzidine (hereinafter abbreviated as NPD); N,N,N',N'-tetrabiphenylylbenzidine; amine derivatives, such as 1,1-bis[4-(di-4-tolylamino)phenyl]cyclohexane (hereinafter abbreviated as TAPC); various triphenylamine trimers and tetramers; and coating-type polymer materials also used for hole injection layers.

[0094] The compounds for the hole transport layer described above, including the high-molecular-weight compound of the present invention, may be used alone to form a film, or two or more of them may be mixed to form a film. Furthermore, a multilayer film in which multiple layers are formed using one or more of the compounds described above and such layers are stacked may be used as the hole transport layer.

[0095] In an organic EL device having an organic layer formed using the high molecular weight compound of the present invention, the organic layer may also serve as a hole injection layer and a hole transport layer. Such a hole injection / transport layer can be formed by a coating method using a polymer material such as PEDOT.

[0096] In addition, for the hole transport layer (and the hole injection layer), materials typically used for the layer can be doped with P, such as tris(4-bromophenyl)ammoniumylhexachloroantimonate or radialene derivatives (see, for example, WO 2014 / 009310). The hole transport layer (and the hole injection layer) can also be formed using a polymer compound having a TPD basic skeleton.

[0097] Furthermore, an electron blocking layer (which can be provided between the hole transport layer 11 and the light emitting layer 13 as shown in FIG. 4) can also be formed using the high molecular weight compound of the present invention by a coating method such as spin coating or ink jet.

[0098] In an organic EL device having an organic layer formed using the high molecular weight compound of the present invention, the electron blocking layer can also be formed using a known electron blocking compound having an electron blocking effect, such as a carbazole derivative or a compound having a triphenylsilyl group and a triarylamine structure. Specific examples of carbazole derivatives and compounds having a triarylamine structure are as follows: Carbazole derivatives, for example, 4,4',4''-tri(N-carbazolyl)triphenylamine (hereinafter abbreviated as TCTA); 9,9-bis[4-(carbazol-9-yl)phenyl]fluorene; 1,3-bis(carbazol-9-yl)benzene (hereinafter abbreviated as mCP); 2,2-bis(4-carbazol-9-ylphenyl)adamantane (hereinafter abbreviated as Ad-Cz); and compounds having a triarylamine structure, for example, 9-[4-(carbazol-9-yl)phenyl]-9-[4-(triphenylsilyl)phenyl]-9H-fluorene.

[0099] The electron-blocking layer may be formed using a single compound, including the high-molecular-weight compound of the present invention, or a mixture of two or more compounds. Alternatively, a multilayer film formed by laminating multiple layers using one or more of the compounds may be used as the electron-blocking layer.

[0100] In the organic EL device having an organic layer formed using the high molecular weight compound of the present invention, the light emitting layer is ３ The light-emitting element can be formed using light-emitting materials such as metal complexes of quinolinol derivatives including the above; various metal complexes of zinc, beryllium, and aluminum; anthracene derivatives; bisstyrylbenzene derivatives; pyrene derivatives; oxazole derivatives; and polyparaphenylenevinylene derivatives.

[0101] The light-emitting layer can also be composed of a host material and a dopant material. In this case, in addition to the light-emitting materials described above, thiazole derivatives, benzimidazole derivatives, and polydialkylfluorene derivatives can be used as the host material, and the high-molecular-weight compound of the present invention described above can also be used. As the dopant material, quinacridone, coumarin, rubrene, perylene, and derivatives thereof; benzopyran derivatives; rhodamine derivatives; aminostyryl derivatives, etc. can be used.

[0102] Such a light-emitting layer may also have a single layer structure using one or more types of light-emitting materials, or may have a multi-layer structure in which a plurality of layers are laminated.

[0103] Furthermore, a phosphorescent material can be used as the light-emitting material to form the light-emitting layer. As the phosphorescent material, a phosphorescent emitter of a metal complex such as iridium or platinum can be used. For example, Ir(ppy) ３ green phosphorescent emitters such as FIrpic and FIr6; blue phosphorescent emitters such as Btp ２ A red phosphorescent material such as Ir(acac) can be used. These phosphorescent materials are used by doping into a hole-injecting / transporting host material or an electron-transporting host material.

[0104] In order to avoid concentration quenching, the phosphorescent light-emitting material is preferably doped into the host material by co-evaporation in a range of 1 to 30 weight percent based on the entire light-emitting layer.

[0105] Furthermore, materials that emit delayed fluorescence, such as PIC-TRZ, CC2TA, PXZ-TRZ, and CDCB derivatives such as 4CzIPN, can also be used as light-emitting materials (see Appl. Phys. Let., 98, 083302 (2011)).

[0106] By forming an emitting layer by carrying a fluorescent emitter, a phosphorescent emitter, or a material that emits delayed fluorescence, which is called a dopant, on the high molecular weight compound of the present invention, an organic EL device with reduced driving voltage and improved luminous efficiency can be realized.

[0107] In an organic EL device having an organic layer formed using the high-molecular-weight compound of the present invention, the high-molecular-weight compound of the present invention can be used as a hole-injecting / transporting host material. In addition, carbazole derivatives such as 4,4'-di(N-carbazolyl)biphenyl (hereinafter abbreviated as CBP), TCTA, and mCP can also be used.

[0108] In an organic EL device having an organic layer formed using the high molecular weight compound of the present invention, p-bis(triphenylsilyl)benzene (hereinafter abbreviated as UGH2), 2,2′,2″-(1,3,5-phenylene)-tris(1-phenyl-1H-benzimidazole) (hereinafter abbreviated as TPBI), and the like can be used as the electron-transporting host material.

[0109] In an organic EL device having an organic layer formed using the high molecular weight compound of the present invention, the hole-blocking layer (not shown) provided between the light-emitting layer and the electron-transporting layer can be formed using a known compound having hole-blocking properties. Examples of such known compounds having hole-blocking properties include the following: phenanthroline derivatives such as bathocuproine (hereinafter abbreviated as BCP); metal complexes of quinolinol derivatives such as aluminum(III) bis(2-methyl-8-quinolinato)-4-phenylphenolate (hereinafter abbreviated as BAlq); various rare earth complexes; triazole derivatives; triazine derivatives; and oxadiazole derivatives.

[0110] These materials can also be used to form the electron transport layer described below, and can also be used as a hole blocking layer and electron transport layer.

[0111] Such a hole-blocking layer may also have a single layer or a multi-layer laminate structure, and each layer is formed using one or more of the above-mentioned compounds having hole-blocking properties.

[0112] In an organic EL device having an organic layer formed using the high molecular weight compound of the present invention, the electron transport layer is formed using a compound having electron transport properties known per se, for example, Alq ３and BAlq, various metal complexes, pyridine derivatives, pyrimidine derivatives, triazole derivatives, triazine derivatives, oxadiazole derivatives, thiadiazole derivatives, carbodiimide derivatives, quinoxaline derivatives, phenanthroline derivatives, silole derivatives, and benzimidazole derivatives.

[0113] This electron transport layer may also have a single layer or a multi-layer laminate structure, and each layer is formed using one or more of the above-mentioned electron transport compounds.

[0114] Furthermore, in an organic EL device having an organic layer formed using the high molecular weight compound of the present invention, an electron injection layer (not shown in the figure) that is provided as needed can also be formed using a known material, for example, an alkali metal salt such as lithium fluoride or cesium fluoride, an alkaline earth metal salt such as magnesium fluoride, a metal oxide such as aluminum oxide, or an organometallic complex such as lithium quinoline.

[0115] For the cathode of an organic EL device having an organic layer formed using the high molecular weight compound of the present invention, an electrode material having a low work function such as aluminum, or an alloy having an even lower work function such as a magnesium-silver alloy, a magnesium-indium alloy, or an aluminum-magnesium alloy is used.

[0116] As described above, by forming at least one layer selected from the group consisting of a hole injection layer, a hole transport layer, a light-emitting layer, and an electron blocking layer using the high molecular weight compound of the present invention, an organic EL device having high luminous efficiency and power efficiency, a low practical driving voltage, a low light-emission onset voltage, and excellent durability can be obtained. In particular, this organic EL device has high luminous efficiency, a reduced driving voltage, improved current resistance, and an increased maximum luminous brightness.

[0117] The present invention will be described below with reference to the following experimental examples. In the following description, the structural unit represented by general formula (1) contained in the high molecular weight compound of the present invention will be referred to as "structural unit A," the linking structural unit represented by general formula (2) will be referred to as "structural unit B," the thermally crosslinkable structural unit will be referred to as "structural unit C," and the triarylamine structural unit different from general formula (1) will be referred to as "structural unit D."

[0118] The synthesized compounds were purified by column chromatography and / or by crystallization using a solvent, and the compounds were identified by NMR analysis.

[0119] In order to prepare the high molecular weight compounds of the present invention, the following intermediates 1 to 3 were synthesized.

[0120] <Synthesis of Intermediate 1>

[0121]

[0122] The following components were added to a nitrogen-purged reaction vessel, and nitrogen gas was bubbled through for 30 minutes. N,N-bis(4-bromophenyl)-9,9-di-n-octyl-9H-fluoren-2-amine: 16.7 g, bis(pinacolato)diboron: 11.9 g, potassium acetate: 5.7 g, and 1,4-dioxane: 170 ml. Next, 0.19 g of the dichloromethane adduct of {1,1'-bis(diphenylphosphino)ferrocene}palladium(II) dichloride was added, and the mixture was heated and stirred at 100°C for 7 hours. After cooling to room temperature, water and toluene were added, and the organic layer was separated and collected. This organic layer was dehydrated with anhydrous sodium sulfate and then concentrated under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (ethyl acetate / n-hexane = 1 / 20) to obtain 7.6 g of Intermediate 1 as a white powder (yield 40%).

[0123] <Synthesis of Intermediate 2>

[0124]

[0125] The following components were added to a nitrogen-purged reaction vessel, and nitrogen gas was bubbled through for 30 minutes. N,N-bis(4-bromophenyl)-N-(benzocyclobuten-4-yl)amine: 8.0 g, bis(pinacolato)diboron: 9.9 g, potassium acetate: 4.6 g, and 1,4-dioxane: 80 ml. Next, 0.3 g of the dichloromethane adduct of {1,1'-bis(diphenylphosphino)ferrocene}palladium(II) dichloride was added, and the mixture was heated and stirred at 90°C for 11 hours. After cooling to room temperature, water and toluene were added, and the organic layer was separated and collected. This organic layer was dehydrated with anhydrous sodium sulfate and then concentrated under reduced pressure to obtain a crude product. The crude product was recrystallized from a 1 / 2 mixture of toluene and methanol to obtain 3.4 g (35% yield) of a white powder of Intermediate 2.

[0126] <Synthesis of Intermediate 3>

[0127]

[0128] The following components were added to a nitrogen-purged reaction vessel and stirred at -5°C for 0.5 hours. 1-amino-2,4-dibromonaphthalene: 9.5 g, ethanol: 320 mL, concentrated sulfuric acid: 8.5 mL. 52 mL of 1.1 M aqueous sodium nitrite solution was added dropwise and stirred at -5°C for 1 hour. 2 g of copper powder was then added, and 18.5 mL of concentrated sulfuric acid was added dropwise. The mixture was stirred at room temperature for 1 hour and then heated to reflux for 1 hour. The ethanol was distilled off, and extraction was performed with chloroform. The resulting organic layer was dried over sodium sulfate and then evaporated to dryness, and the crude product was subjected to column chromatography using n-hexane as an eluent. The first fraction was collected, and the resulting solid was recrystallized using ethanol to obtain 5.8 g of Intermediate 3 as a white powder (yield 65%).

[0129] <Synthesis of Intermediate 4>

[0130]

[0131] The following components were added to a nitrogen-purged reaction vessel, and nitrogen gas was bubbled through for 30 minutes. N-(benzocyclobuten-4-yl)-3,6-dibromocarbazole: 19.6 g, bis(pinacolato)diboron: 24.5 g, potassium acetate: 13.5 g, and 1,4-dioxane: 120 ml. Next, 0.4 g of the dichloromethane adduct of {1,1'-bis(diphenylphosphino)ferrocene}palladium(II) dichloride was added, and the mixture was heated and stirred at 97°C for 5 hours. After cooling to room temperature, water and toluene were added, and the organic layer was separated and collected. This organic layer was dehydrated with anhydrous sodium sulfate and then concentrated under reduced pressure to obtain a crude product. The crude product was recrystallized from a 1 / 5 mixture of toluene and methanol to obtain 14.5 g of Intermediate 4 as a white powder (yield: 61%).

[0132] Example 1 Synthesis of High Molecular Weight Compound A: The following components were added to a nitrogen-purged reaction vessel, and nitrogen gas was bubbled through for 30 minutes. Intermediate 1: 5.6 g Intermediate 2: 0.4 g Intermediate 3: 2.2 g Tripotassium phosphate: 6.9 g Toluene: 9 ml Water: 5 ml 1,4-dioxane: 27 ml Next, 1.4 mg of palladium(II) acetate and 11.5 mg of tri-o-tolylphosphine were added, and the mixture was heated and stirred at 87°C for 14 hours. After this, 17 mg of phenylboronic acid was added and stirred for 1 hour, followed by 242 mg of bromobenzene and stirring for 1 hour. 50 ml of toluene and 50 ml of a 5 wt % aqueous solution of sodium N,N-diethyldithiocarbamate were added, and the mixture was heated and stirred under reflux for 2 hours. After cooling to room temperature, the organic layer was collected by liquid separation and washed three times with saturated brine. The organic layer was dehydrated over anhydrous sodium sulfate and then concentrated under reduced pressure to obtain a crude polymer. The crude polymer was dissolved in toluene, silica gel was added, and the mixture was purified by adsorption. The mixture was then filtered to remove the silica gel. The resulting filtrate was concentrated under reduced pressure, and 100 ml of toluene was added to the dried product to dissolve it. The resulting solution was added dropwise to 300 ml of n-hexane, and the resulting precipitate was collected by filtration. This procedure was repeated three times, and the resulting mixture was dried to obtain 3.6 g (yield 71%) of high molecular weight compound A.

[0133] The average molecular weight and dispersity of the high molecular weight compound A measured by GPC were as follows: Number average molecular weight Mn (polystyrene equivalent): 60,000 Weight average molecular weight Mw (polystyrene equivalent): 108,000 Dispersity (Mw / Mn): 1.8

[0134] Further, the high molecular weight compound A was subjected to NMR measurement. １ The results of H-NMR measurement are shown in Figure 5. The chemical formula was as follows:

[0135]

[0136] As can be seen from the chemical composition, this high molecular weight compound A contained 45 mol % of structural unit A, 50 mol % of structural unit B, and 5 mol % of structural unit C.

[0137] Example 2 Synthesis of High Molecular Weight Compound B: The following components were added to a nitrogen-purged reaction vessel, and nitrogen gas was bubbled through for 30 minutes. Intermediate 1: 5.4 g Intermediate 3: 2.2 g Intermediate 4: 0.5 g Tripotassium phosphate: 7.4 g Toluene: 9 ml Water: 5 ml 1,4-dioxane: 27 ml Next, 1.5 mg of palladium(II) acetate and 14.4 mg of tri-o-methoxyphenylphosphine were added, and the mixture was heated and stirred at 87°C for 10 hours. After this, 163 mg of phenylboronic acid was added and stirred for 1 hour, followed by 2.1 g of bromobenzene and stirring for 1 hour. 50 ml of toluene and 50 ml of a 5 wt % aqueous solution of sodium N,N-diethyldithiocarbamate were added, and the mixture was heated and stirred under reflux for 2 hours. After cooling to room temperature, the organic layer was collected by liquid separation and washed three times with saturated brine. The organic layer was dehydrated over anhydrous sodium sulfate and then concentrated under reduced pressure to obtain a crude polymer. The crude polymer was dissolved in toluene, and silica gel was added to perform adsorption purification, followed by filtration to remove the silica gel. The resulting filtrate was concentrated under reduced pressure, and 100 ml of toluene was added to the dried product to dissolve it. The mixture was then added dropwise to 300 ml of n-hexane, and the resulting precipitate was collected by filtration. 100 ml of toluene was added to the resulting precipitate to dissolve it. The mixture was then added dropwise to 200 ml of n-hexane, and the resulting precipitate was collected by filtration. This procedure was repeated once more, and the resulting mixture was dried to obtain 3.2 g of high molecular weight compound B (yield 67%).

[0138] The average molecular weight and dispersity of the high molecular weight compound B measured by GPC were as follows: Number average molecular weight Mn (polystyrene equivalent): 73,000 Weight average molecular weight Mw (polystyrene equivalent): 139,000 Dispersity (Mw / Mn): 1.9

[0139] Further, the high molecular weight compound B was subjected to NMR measurement. １ The results of H-NMR measurement are shown in Figure 6. The chemical formula was as follows:

[0140]

[0141] As can be seen from the chemical composition, this high molecular weight compound B contained 44 mol % of structural unit A, 50 mol % of structural unit B, and 6 mol % of structural unit C.

[0142] Example 3 Using the high molecular weight compounds A and B synthesized in Examples 1 and 2, a coating film with a thickness of 80 nm was prepared on an ITO substrate, and the work function was measured using an ionization potential measurement device (PYS-202 model, manufactured by Sumitomo Heavy Industries, Ltd.). The results were as follows: High molecular weight compound A: 5.63 eV High molecular weight compound B: 5.61 eV

[0143] It is clear that the high molecular weight compound A of the present invention exhibits a suitable energy level compared with the work function of 5.4 eV of common hole transport materials such as NPD and TPD, and has good hole transport ability.

[0144] Example 4: Fabrication and Evaluation of Organic EL Device An organic EL device having the layer structure shown in Figure 3 was fabricated by the following method. Specifically, a glass substrate 1 on which a 50 nm thick ITO film had been formed was cleaned with an organic solvent, and then the ITO surface was cleaned by UV / ozone treatment. A 50 nm thick PEDOT / PSS (manufactured by Ossila) film was formed by spin coating so as to cover the transparent anode 2 (ITO) provided on the glass substrate 1, and the film was dried on a hot plate at 200°C for 10 minutes to form a hole injection layer 3.

[0145] A coating solution was prepared by dissolving 0.6 wt % of the high molecular weight compound A obtained in Example 1 in toluene. The substrate on which the hole injection layer 3 had been formed as described above was transferred into a glove box purged with dry nitrogen and dried on a hot plate at 230°C for 10 minutes. Then, a coating layer having a thickness of 25 nm was formed on the hole injection layer 3 by spin coating using the coating solution, and further dried on a hot plate at 220°C for 30 minutes to form a hole transport layer 4.

[0146] The substrate on which the hole transport layer 4 was formed as described above was placed in a vacuum deposition machine, and the pressure was reduced to 0.001 Pa or less. On the hole transport layer 4, a 34 nm-thick light-emitting layer 5 was formed by binary deposition of a blue light-emitting material (EMD-1) having the following structural formula and a host material (EMH-1). In the binary deposition, the deposition rate ratio was EMD-1:EMH-1=4:96.

[0147]

[0148] As electron transport materials, compounds ETM-1 and ETM-2 having the following structural formulas were prepared.

[0149]

[0150] On the light-emitting layer 5 formed above, an electron-transporting layer 6 having a thickness of 20 nm was formed by binary deposition using the electron-transporting materials ETM-1 and ETM-2. In the binary deposition, the deposition rate ratio of ETM-1:ETM-2 was set to 50:50.

[0151] Finally, aluminum was vapor-deposited to a thickness of 100 nm to form a cathode 7. The glass substrate on which the transparent anode 2, hole injection layer 3, hole transport layer 4, light-emitting layer 5, electron transport layer 6, and cathode 7 were formed was moved into a glove box purged with dry nitrogen, and another glass substrate for sealing was attached using a UV-curable resin to form an organic EL device. The characteristics of the fabricated organic EL device were measured in the atmosphere at room temperature. The light-emitting characteristics of the fabricated organic EL device were also measured when a DC voltage was applied. The measurement results are shown in Table 1.

[0152] Comparative Example 1 An organic EL device was produced in the same manner as in Example 4, except that the hole transport layer 4 was formed using a coating solution prepared by dissolving 0.6 wt % of the following TFB (hole transport polymer) in toluene instead of the high molecular weight compound A.

[0153]

[0154] The TFB (hole transport polymer) was poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl))diphenylamine] (American Dye Source, Hole Transport Polymer ADS259BE). The organic EL device of Comparative Example 1 was evaluated for various characteristics in the same manner as in Example 4, and the results are shown in Table 1.

[0155] In the evaluation of various characteristics, the voltage, brightness, luminous efficiency, and power efficiency were measured at a current density of 10 mA / cm ２ The device life is measured when the luminance at the start of light emission (initial luminance) is 700 cd / m ２ When driven at a constant current, the luminance was 560 cd / m ２ The time required for the brightness to decay to 80% (corresponding to 80% when the initial brightness was 100%) was measured.

[0156]

[0157] As shown in Table 1, the current density was 10 mA / cm ２ The luminous efficiency when a current of 1000 cd / A was passed through the organic EL element of Example 4 was 7.83 cd / A, which was a high efficiency, compared to 5.52 cd / A for the organic EL element of Comparative Example 1. Furthermore, the element lifetime (at 80% decay) was 248 hours for the organic EL element of Example 4, which was a long lifetime, compared to 6 hours for the organic EL element of Comparative Example 1.

[0158] Example 5 An organic EL device having the layer structure shown in Fig. 4 was fabricated by the following method. Specifically, a glass substrate 8 on which a 50 nm-thick ITO film had been formed was cleaned with an organic solvent, and then the ITO surface was cleaned by UV / ozone treatment. A 50 nm-thick PEDOT / PSS (manufactured by Ossila) film was formed by spin coating so as to cover a transparent anode 9 (ITO) provided on the glass substrate 8, and the film was dried on a hot plate at 200°C for 10 minutes to form a hole injection layer 10.

[0159] A coating solution was prepared by dissolving 0.4 wt % of a high-molecular-weight compound HTM-1 having the following structural formula in toluene. The substrate on which the hole injection layer 10 had been formed as described above was transferred into a glove box purged with dry nitrogen and dried on a hot plate at 230°C for 10 minutes. Then, a coating layer having a thickness of 15 nm was formed on the hole injection layer 10 by spin coating using the coating solution, and this was further dried on a hot plate at 220°C for 30 minutes to form a hole transport layer 11.

[0160]

[0161] A coating solution was prepared by dissolving 0.4 wt % of the high molecular weight compound A obtained in Example 1 in toluene. A coating layer having a thickness of 15 nm was formed on the hole transport layer 11 by spin coating using the coating solution, and the layer was then dried on a hot plate at 220° C. for 30 minutes to form the electron blocking layer 12.

[0162] The substrate on which the electron-blocking layer 12 had been formed as described above was placed in a vacuum deposition machine, and the pressure was reduced to 0.001 Pa or less. A 34-nm-thick light-emitting layer 13 was formed on the electron-blocking layer 12 by binary deposition of a blue-emitting material (EMD-1) and a host material (EMH-1). The deposition rate ratio for the binary deposition was EMD-1:EMH-1=4:96.

[0163] An electron transport layer 14 having a thickness of 20 nm was formed on the light-emitting layer 13 by binary deposition using electron transport materials ETM-1 and ETM-2. In the binary deposition, the deposition rate ratio of ETM-1:ETM-2 was 50:50.

[0164] Finally, aluminum was vapor-deposited to a thickness of 100 nm to form a cathode 15. The glass substrate on which the transparent anode 9, hole injection layer 10, hole transport layer 11, electron blocking layer 12, light-emitting layer 13, electron transport layer 14, and cathode 15 were formed was moved into a glove box purged with dry nitrogen, and another glass substrate for sealing was attached using a UV-curable resin to form an organic EL device. The characteristics of the fabricated organic EL device were measured in the atmosphere at room temperature. The light-emitting characteristics of the fabricated organic EL device were also measured when a DC voltage was applied. The measurement results are shown in Table 2.

[0165] Example 6 An organic EL device was fabricated in the same manner as in Example 5, except that the electron-blocking layer 12 was formed using a coating liquid prepared by dissolving 0.4 wt % of the high-molecular-weight compound B obtained in Example 2 in toluene instead of the high-molecular-weight compound A. The various properties of the fabricated organic EL device were evaluated in the same manner as in Example 5, and the results are shown in Table 2.

[0166] Comparative Example 2 An organic EL element having the layer structure shown in Fig. 4 was fabricated by the following method. Specifically, a glass substrate 8 on which a 50 nm-thick ITO film had been formed was cleaned with an organic solvent, and then the ITO surface was cleaned by UV / ozone treatment. A 50 nm-thick PEDOT / PSS (manufactured by Ossila) film was formed by spin coating so as to cover a transparent anode 9 (ITO) provided on the glass substrate 8, and the film was dried on a hot plate at 200°C for 10 minutes to form a hole injection layer 10.

[0167] A coating solution was prepared by dissolving 0.6 wt % of the high molecular weight compound HTM-1 in toluene. The substrate on which the hole injection layer 10 had been formed as described above was transferred into a glove box purged with dry nitrogen, and the coating solution was spin-coated onto the hole injection layer 3 to form a coating layer with a thickness of 25 nm. This was then dried on a hot plate at 220°C for 30 minutes to form a hole transport layer 11.

[0168] The substrate on which the hole transport layer 11 was formed as described above was placed in a vacuum deposition machine, and the pressure was reduced to 0.001 Pa or less. An emitting layer 13 having a thickness of 34 nm was formed on the hole transport layer 11 by binary deposition of a blue emitting material (EMD-1) and a host material (EMH-1). In the binary deposition, the deposition rate ratio was EMD-1:EMH-1=4:96.

[0169] On the light-emitting layer 13 thus formed, an electron transport layer 14 having a thickness of 20 nm was formed by binary deposition using electron transport materials (ETM-1) and (ETM-2). In the binary deposition, the deposition rate ratio of ETM-1:ETM-2 was set to 50:50.

[0170] Finally, aluminum was vapor-deposited to a thickness of 100 nm to form a cathode 15. The glass substrate on which the transparent anode 9, hole injection layer 10, hole transport layer 11, light-emitting layer 13, electron transport layer 14, and cathode 15 were formed was moved into a glove box purged with dry nitrogen, and another glass substrate for sealing was attached using a UV-curable resin to form an organic EL device. The characteristics of the fabricated organic EL device were measured in the atmosphere at room temperature. The light-emitting characteristics of the fabricated organic EL device were also measured when a DC voltage was applied. The measurement results are shown in Table 2.

[0171] In the evaluation of various characteristics, the voltage, brightness, luminous efficiency, and power efficiency were measured at a current density of 10 mA / cm ２ The device life is measured when the luminance at the start of light emission (initial luminance) is 700 cd / m ２ When driven at a constant current, the luminance was 560 cd / m ２ The time required for the brightness to decay to 80% (corresponding to 80% when the initial brightness was 100%) was measured.

[0172]

[0173] As shown in Table 2, the current density was 10 mA / cm ２The luminous efficiency when a current of 1000 cd / A was passed was 7.56 cd / A for the organic EL element of Comparative Example 2, and was therefore 8.68 cd / A for the organic EL element of Example 5. Furthermore, the element lifetime (at 80% decay) was 20 hours for the organic EL element of Comparative Example 2, and was 408 hours for the organic EL element of Example 5 and 558 hours for the organic EL element of Example 6, both of which were long lifetimes.

[0174] As described above, it was found that an organic EL element having an organic layer formed using the high molecular weight compound of the present invention can realize an organic EL element with higher luminous efficiency and longer life compared to conventional organic EL elements.

[0175] The high molecular weight compound of the present invention has high hole transport capability, excellent electron blocking capability, and good thermal crosslinkability, making it an excellent compound for use in coating-type organic EL devices. By producing coating-type organic EL devices using the high molecular weight compound of the present invention, high luminous efficiency and power efficiency can be achieved, and durability can be improved. This allows for a wide range of applications, such as in home appliances and lighting.

[0176] 1, 8: Glass substrate 2, 9: Transparent anode 3, 10: Hole injection layer 4, 11: Hole transport layer 5, 13: Light-emitting layer 6, 14: Electron transport layer 7, 15: Cathode 12: Electron blocking layer

Claims

1. A high molecular weight compound containing a repeating structural unit represented by the following general formula (3), which is composed of a triarylamine structural unit represented by the following general formula (1) and a linking structural unit represented by the following general formula (2), and having a weight average molecular weight of 10,000 or more but less than 1,000,000 in terms of polystyrene: A high molecular weight compound in which the linking structural unit represented by the following general formula (2) is a structural unit selected from the following structural units 1 to 26. 【Chemistry 1】 【Chemistry 2】 【Transformation 3】 In the formula, R １ each independently represents a hydrogen atom, a deuterium atom, a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group or an alkyloxy group having 1 to 8 carbon atoms, a cycloalkyl group or a cycloalkyloxy group having 5 to 10 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an aryloxy group having 6 to 10 carbon atoms. R ２ each independently represents an alkyl group, a cycloalkyl group, or an alkyloxy group having 3 to 40 carbon atoms. X represents a hydrogen atom, an amino group, a monovalent aryl group, or a monovalent heteroaryl group. L represents a divalent phenylene group or a divalent naphthylene group, and n represents an integer of 0 to 3. a, b and c are R １ is the number of integers below. a=0, 1, 2 or 3 b=0, 1, 2, 3 or 4 c=0 or 1 【Chemistry 4】 【Transformation 5】 In the structural units 1 to 26, the broken lines indicate bonds to adjacent structural units, and the solid lines extending from the rings with free ends indicate that the free ends are methyl groups.

2. 2. The high molecular weight compound according to claim 1, wherein a, b and c are 0 in the general formulae (1), (2) and (3).

3. In the general formulas (1) and (3), R ２ 2. The high molecular weight compound according to claim 1, wherein is an alkyl group having 3 to 40 carbon atoms.

4. 2. The high molecular weight compound according to claim 1, wherein in the general formulae (2) and (3), X is a hydrogen atom, or an optionally substituted amino group, aryl group, or heteroaryl group.

5. 2. The high molecular weight compound according to claim 1, wherein in the general formulas (2) and (3), X is a hydrogen atom, a diphenylamino group, a phenyl group, a naphthyl group, a dibenzofuranyl group, a dibenzothienyl group, a phenanthrenyl group, a fluorenyl group, a carbazolyl group, an indenocarbazolyl group, or an acridinyl group.

6. 2. The high molecular weight compound according to claim 1, which comprises a thermally crosslinkable structural unit or a triarylamine structural unit different from the triarylamine structural unit represented by the general formula (1).

7. The high molecular weight compound according to claim 6, wherein the thermally crosslinkable structural unit is a structural unit represented by the following general formulas (4-1) to (4-143). 【Transformation 6】 【Transformation 7】 【Transformation 8】 【Chemistry 9】 【Chemistry 10】 【Chemistry 11】 【Chemistry 12】 【Chemistry 13】 In the formula, each R independently represents a hydrogen atom, a deuterium atom, a cyano group, a nitro group, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or an alkyl group, cycloalkyl group, alkyloxy group, cycloalkyloxy group, alkenyl group, or aryloxy group having 3 to 40 carbon atoms. a and b are the numbers of R and are integers below. a=0, 1, 2 or 3 b=0, 1, 2, 3 or 4 In the formulas (4-1) to (4-143), the broken lines indicate bonds to adjacent structural units, and the solid lines extending from the rings with free ends indicate that the ends are methyl groups.

8. An organic electroluminescence device comprising an organic layer formed using the high molecular weight compound according to any one of claims 1 to 7.

9. 9. The organic electroluminescence device according to claim 8, wherein the organic layer is a hole transport layer.

10. 9. The organic electroluminescent device according to claim 8, wherein the organic layer is an electron blocking layer.

11. 9. The organic electroluminescence device according to claim 8, wherein the organic layer is a hole injection layer.

12. The organic electroluminescence device according to claim 8 , wherein the organic layer is a light-emitting layer.

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