JP6250340B2 - Hole transport material, electroluminescence device and thin film solar cell - Google Patents

Description

  The present invention relates to a hole transport material containing a conductive polymer as a constituent material, an electroluminescence element having a hole transport layer composed of the hole transport material, and a thin film solar cell.

  Since conductive polymers have high conductivity, they have been used as solid electrolytes for solid electrolytic capacitors such as tantalum solid electrolytic capacitors and aluminum solid electrolytic capacitors. Recently, utilization as a hole transport material constituting a hole transport layer of an electroluminescence element or a thin film solar cell has been studied by utilizing the high conductivity.

  Therefore, a conductive polymer containing a polymer of 3,4-ethylenedioxythiophene and a polymer anion derived from polystyrene sulfonic acid has been proposed for such applications (Patent Document 1).

  However, the demands on the characteristics of electroluminescent devices and thin film solar cells are increasing, and hole transport is more suitable as a constituent material for the hole transport layer of electroluminescent devices and thin film solar cells than the above-mentioned conductive polymers. The appearance of materials is desired.

JP 2002-12647 A

  In view of the circumstances as described above, the present invention provides a higher-performance electroluminescent element, that is, an electroluminescent element having higher luminance and higher external quantum efficiency, current efficiency, and power efficiency than a conventional product, and a higher The present invention provides a hole transport material suitable for providing a thin-film solar cell having high performance, that is, a thin-film solar cell having a higher open-circuit voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency than conventional products. An object of the present invention is to provide an electroluminescent element and a thin-film solar cell having the above characteristics using a hole transport material.

  The present invention is based on a conductive polymer containing a polymer of a specific thiophene monomer other than 3,4-ethylenedioxythiophene and a polymer anion other than a polymer anion derived from polystyrene sulfonic acid as a dopant. When constructing a hole transport material, the inventors have found that the above problems can be solved, and have completed the present invention.

  That is, the present invention provides a hole containing a conductive polymer containing a polymer of a thiophene monomer represented by the following general formula (1) and a polymer anion derived from the following copolymer functioning as a dopant. It relates to transport materials.

General formula (1):
(In the formula, R ¹ and R ² each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, X represents an oxygen atom or a sulfur atom, provided that both R ¹ and R ² are hydrogen. Except when X is an oxygen atom)

Copolymer:
A copolymer of styrene sulfonic acid and at least one non-sulfonic acid monomer selected from the group consisting of a methacrylic acid ester, an acrylic acid ester, an unsaturated hydrocarbon-containing alkoxysilane compound or a hydrolyzate thereof.

  Moreover, this invention relates to the electroluminescent element and thin film solar cell which have a positive hole transport layer comprised with said hole transport material.

  In the electroluminescence device, the hole transport layer formed of the hole transport material of the present invention combines holes that pass through the hole transport layer with electrons in the light emitting layer with high efficiency. In this case, it is possible to provide an electroluminescence element having higher luminance and higher external quantum efficiency, current efficiency, and power efficiency than the conventional product. Moreover, in the thin film solar cell, the hole transport layer composed of the hole transport material of the present invention can pass the holes generated in the photoelectric conversion layer uniformly, so when compared with the same amount of input light Compared with conventional products, a thin film solar cell having a higher release voltage, short-circuit current density, fill factor, and photoelectric conversion efficiency can be provided.

  The hole transport material of the present invention has the above-described effects in electroluminescence elements and thin film solar cells because the hole transport material of the present invention is a polymer constituting a conductive polymer. Based on the specificity between the polymer anion and the polymer anion, it is possible to form a dense film, and the hole transport layer can be formed into a uniform thin film, so that the hole transport layer is formed. The surface roughness of the material is reduced, thereby reducing the variation in the hole transport rate and the adhesion of the hole transport material of the present invention to the transparent conductive film, light emitting layer, active layer (photoelectric conversion layer), etc. This is considered to be due to the fact that the loss of hole transport at those interfaces is reduced due to the strong nature.

  Since the hole transport material of the present invention is characterized by the polymer and the polymer anion as described above, first, the structure of the polymer will be described.

  The said polymer is comprised with the polymer of the thiophene-type monomer represented by following General formula (1).

General formula (1):
(In the formula, R ¹ and R ² each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, X represents an oxygen atom or a sulfur atom, provided that both R ¹ and R ² are hydrogen. Except when X is an oxygen atom)

Of the thiophene monomers represented by the general formula (1), the most well-known compound is one in which R ¹ and R ² are both hydrogen atoms and X is an oxygen atom (however, the present invention). Therefore, for the reasons described later, a compound in which R ¹ and R ² are both hydrogen atoms and X is an oxygen atom is not used.) This compound is represented by the IUPAC name as “2,3-dihydrothieno [3,4] -B] [1,4] dioxin (2,3-Dihydro-thieno [3,4-b] [1,4] dioxine) ", but this compound is more common than the IUPAC name. The name “3,4-ethylenedioxythiophene” or its “3,4-” part is omitted, and it is often displayed as “ethylenedioxythiophene”. General The portion corresponding to "dihydro over thieno [3,4-b] [1,4] dioxin" of thiophene-based monomer represented by Formula (1) indicated as "ethylenedioxythiophene". In the thiophene-based monomer represented by the general formula (1), one of R ¹ and R ² is a hydrogen atom, the other is an alkyl group, and X is an oxygen atom. Is represented by “2-alkyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin”. In this document, this is simplified to “alkylated ethylenedioxythiophene”. Is displayed.

In the compound in which either ^one of R ¹ and R ² is a hydrogen atom, the other is an alkyl group, and X is an oxygen atom, in the present invention, the alkyl group has 1 to 4 carbon atoms, That is, those having a methyl group, an ethyl group, a propyl group, or a butyl group are used. Specifically, a compound in which the alkyl group is a methyl group can be represented by “2-methyl-2, 3-dihydro-thieno [3,4-b] [1,4] dioxin (2-Methyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxine) " This is simplified and expressed as “methylated ethylenedioxythiophene”. A compound having an alkyl group as an ethyl group can be expressed by the name IUPAC as “2-ethyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin (2-Ethyl-2,3-dihydro). -Thieno [3,4-b] [1,4] dioxine) ", which will be simplified and represented as" ethylated ethylenedioxythiophene "hereinafter. A compound having an alkyl group as a propyl group can be expressed by the name IUPAC as “2-propyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin (2-Propyl-2,3-dihydro). -Thieno [3,4-b] [1,4] dioxine) ", which will be simplified and represented as" propylated ethylenedioxythiophene "hereinafter. A compound in which the alkyl group is a butyl group is represented by the IUPAC name, “2-butyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin (2-Butyl-2,3 -Dihydro-thieno [3,4-b] [1,4] dioxine) ", hereinafter, this is simplified and expressed as" butylated ethylenedioxythiophene ".

In the general formula (1), a thiophene-based monomer in which R ¹ and R ² are both hydrogen atoms and X is a sulfur atom is represented by “THIENO [3,4-b] -1,4” in terms of IUPAC name. -Oxatin ", which is also represented by the general name" 3,4-ethyleneoxythiathiophene ".

In the present invention, regarding the thiophene monomer represented by the general formula (1), in addition to those exemplified above, R ¹ and R ² are both alkyl groups having 1 to 4 carbon atoms, and X is oxygen An atom, or a compound in which X is a sulfur atom, one of R ¹ and R ² is a hydrogen atom, the other is an alkyl group having 1 to 4 carbon atoms, and X is a sulfur atom Either can be used.

  These thiophene monomers represented by the general formula (1) can be used alone or in combination of two or more.

In the present invention, among the thiophene monomers represented by the general formula (1), R ¹ and R ² are both hydrogen atoms and X is a sulfur atom, 3,4-ethyleneoxythiathiophene, R ¹ , R ² is preferably a hydrogen atom, the other is an alkyl group having 1 to 4 carbon atoms, and X is an oxygen atom, preferably an alkylated ethylenedioxythiophene. Among the alkylated ethylenedioxythiophenes, In particular, methylated ethylenedioxythiophene is preferred. In addition, when 3,4-ethyleneoxythiathiophene and alkylated ethylenedioxythiophene are used in combination, the characteristics of the hole transport material are more improved than when they are used alone. When this 3,4-ethyleneoxythiathiophene and alkylated ethylenedioxythiophene are used in combination, the ratio of both is a molar ratio of 3,4-ethyleneoxythiathiophene: 0 of alkylated ethylenedioxythiophene. The range of 1: 1 to 1: 0.1 is preferable, and the range of 0.3: 0.7 to 0.7 to 0.3 is more preferable.

In the present invention, as described above, among the thiophene monomers represented by the general formula (1), R ¹ and R ² are both hydrogen atoms and X is an oxygen atom, 3,4-ethylenedioxythia Thiophene is not used as a monomer for synthesizing a conductive polymer. This is more characteristic of alkylated ethylenedioxythiophene such as 3,4-ethyleneoxythiathiophene and methylated ethylenedioxythiophene than 3,4-ethylenedioxythiophene, as shown in the Examples section below. Because it is good.

  Next, the copolymer in the present invention will be described. This copolymer is selected from the group consisting of styrene sulfonic acid, methacrylic acid ester, acrylic acid ester and unsaturated hydrocarbon-containing alkoxysilane compound or a hydrolyzate thereof. In the conductive polymer, it is present as a polymer anion and functions as a dopant.

  Copolymer of styrene sulfonic acid and at least one non-sulfonic acid monomer selected from the group consisting of methacrylic acid ester, acrylic acid ester and unsaturated hydrocarbon-containing alkoxysilane compound or a hydrolyzate thereof (hereinafter referred to as “non-sulfonic acid monomer”) In some cases, this may be referred to as “a copolymer of styrene sulfonic acid and a non-sulfonic acid monomer”). As a monomer copolymerized with styrene sulfonic acid, methacrylic acid ester, acrylic acid ester and unsaturated At least one selected from the group consisting of a hydrocarbon-containing alkoxysilane compound or a hydrolyzate thereof is used. Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and methacrylic acid. Acid hexyl Stearyl methacrylate, cyclohexyl methacrylate, diphenylbutyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, sodium sulfohexyl methacrylate, glycidyl methacrylate, methyl glycidyl methacrylate, hydroxyalkyl methacrylate, ie hydroxymethyl methacrylate , Hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxyhexyl methacrylate, hydroxy stearyl methacrylate, hydroxyalkyl methacrylate, hydroxypolyoxyethylene methacrylate, methoxyhydroxypropyl methacrylate, ethoxyhydroxypropyl methacrylate , Dihydroxypropyl methacrylate, Dihydroxybutyl tacrylate can be used, and hydroxyalkyl methacrylate having 1 to 4 carbon atoms in the alkyl group such as hydroxymethyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate is particularly preferable. It is preferable in view of characteristics as a dopant when copolymerized with an acid. In addition, those having a glycidyl group such as glycidyl methacrylate and methyl glycidyl methacrylate have a structure containing a hydroxyl group by ring opening of the glycidyl group. Like alkyl, it is preferable from the viewpoint of characteristics as a dopant when copolymerized with styrenesulfonic acid.

  Examples of the acrylate ester include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, stearyl acrylate, cyclohexyl acrylate, diphenylbutyl acrylate, dimethylaminoethyl acrylate, Acrylic acid such as diethylaminoethyl acrylate, sodium sulfohexyl acrylate, glycidyl acrylate, methyl glycidyl acrylate, hydroxyalkyl acrylate, ie hydroxymethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate Hydroxyalkyl and the like can be used, but hydroxymethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, acrylic Acrylic acid hydroxyalkyl having a carbon number 1 to 4 alkyl groups such as hydroxyethyl butyl is preferred from the characteristics as a dopant when the copolymerised with styrene sulfonic acid. In addition, those having a glycidyl group such as glycidyl acrylate and methyl glycidyl acrylate have a structure containing a hydroxyl group by ring opening of the glycidyl group. Like alkyl, it is preferable from the viewpoint of characteristics as a dopant when copolymerized with styrenesulfonic acid.

  Examples of the unsaturated hydrocarbon-containing alkoxysilane compound or a hydrolyzate thereof include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyldimethylmethoxysilane, 3- Methacryloxypropyldimethylethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxymethyldimethoxysilane, 3-acryloxymethyldiethoxysilane, 3-acryloxytriethoxysilane, p-styryltrimethoxysilane, p-styryltriethoxysilane, p-styrylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxy Run, it can be used an unsaturated hydrocarbon containing alkoxysilane compound and a hydrolyzate thereof such as vinyl dimethyl methoxy silane. For example, when the unsaturated hydrocarbon-containing alkoxysilane compound is the above-mentioned 3-methacryloxypropyltrimethoxysilane, the hydrolyzate of the unsaturated hydrocarbon-containing alkoxysilane compound is converted into a hydroxyl group by hydrolysis of the methoxy group. The resulting structure is 3-methacryloxytrihydroxysilane, or silanes are condensed to form an oligomer, and a compound having a structure in which a methoxy group not used in the reaction is converted into a hydroxyl group is obtained. Examples of the unsaturated hydrocarbon-containing alkoxysilane compound include 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, p-styryltrimethoxysilane, vinyltrimethoxysilane, and the like. It is preferable from the standpoint of properties as a dopant when copolymerized.

  Styrene in a copolymer of this styrene sulfonic acid and at least one non-sulfonic acid monomer selected from the group consisting of methacrylic acid esters, acrylic acid esters and unsaturated hydrocarbon-containing alkoxysilane compounds or hydrolysates thereof As a ratio of sulfonic acid and at least one non-sulfonic acid monomer selected from the group consisting of methacrylic acid ester, acrylic acid ester and unsaturated hydrocarbon-containing alkoxysilane compound or a hydrolyzate thereof, It is preferably 1: 0.01 to 0.1: 1.

  A copolymer of the styrene sulfonic acid and at least one non-sulfonic acid monomer selected from the group consisting of a methacrylic acid ester, an acrylic acid ester, an unsaturated hydrocarbon-containing alkoxysilane compound or a hydrolyzate thereof, The molecular weight is preferably about 5,000 to 500,000 in terms of weight average molecular weight from the viewpoint of water solubility and characteristics as a dopant, and more preferably about 40,000 to 200,000 in terms of weight average molecular weight.

  The conductive polymer as the main material in the hole transport material of the present invention can be obtained by oxidative polymerization of the thiophene monomer represented by the general formula (1) in the presence of the copolymer. The reason why the hole transport material is composed of the conductive polymer as the main material as described above is based on the following reason. In other words, for example, when a hole transport layer of an electroluminescence element is formed using a hole transport material composed only of a conductive polymer, the hole transport speed is faster than the electron injection speed from the cathode. In addition, holes and electrons cannot be efficiently combined in the light emitting layer (that is, only some of the holes arriving at the light emitting layer can be combined with electrons), and as a result, light emission is not efficiently performed. Therefore, in order to slow down the hole transport speed of the hole transport layer, a hole transport speed adjusting agent is added to the hole transport material to match the hole transport speed and the electron injection speed. Thus, it is the reason why it is expressed that the addition of the hole transport rate adjusting agent constitutes the hole transport material with the conductive polymer as the main material. However, if the electron injection rate in the electron injection layer is increased in the future, it is not necessary to add a hole transport rate adjusting agent to the hole transport material, so that the hole transport material can be composed of only a conductive polymer. It becomes like this. Therefore, the above hole transport rate adjusting agent is not essential.

  Therefore, when the hole transport material is composed of the conductive polymer as the main material, the hole transport material is composed of only the conductive polymer, and the hole transport speed adjusting agent is added to the conductive polymer. And the case of constituting a hole transport material.

  Next, a method for synthesizing a conductive polymer by oxidative polymerization of the thiophene monomer represented by the general formula (1) in the presence of the copolymer will be described. Copolymer of styrene sulfonic acid and non-sulfonic acid monomer (that is, selected from the group consisting of styrene sulfonic acid, methacrylic acid ester, acrylic acid ester, unsaturated hydrocarbon-containing alkoxysilane compound or hydrolyzate thereof) The copolymer of at least one non-sulfonic acid monomer) is soluble in an aqueous liquid composed of water or a mixture of water and a water-miscible solvent. It is carried out in an aqueous liquid.

  Examples of the water-miscible solvent constituting the aqueous liquid include methanol, ethanol, propanol, acetone, acetonitrile, and the like. The mixing ratio of these water-miscible solvents with water is 50 in the entire aqueous liquid. The mass% or less is preferable.

  As the oxidative polymerization for synthesizing the conductive polymer, either chemical oxidative polymerization or electrolytic oxidative polymerization can be employed.

  For example, persulfate is used as an oxidizing agent in performing chemical oxidative polymerization. Examples of the persulfate include ammonium persulfate, sodium persulfate, potassium persulfate, calcium persulfate, and barium persulfate. Is used.

  In chemical oxidative polymerization, the conditions during the polymerization are not particularly limited, but the temperature during chemical oxidative polymerization is preferably 5 ° C to 95 ° C, more preferably 10 ° C to 30 ° C, and polymerization is also performed. As time, 1 hour-72 hours are preferable, and 8 hours-24 hours are more preferable.

Electrolytic oxidation polymerization is be carried out even at a constant voltage at a constant current, for example, when performing electrolytic oxidation polymerization at a constant current, preferably 0.05mA ^/ cm ² ~10mA ^/ cm 2 as the current value, 0.2 mA / cm more preferably ^{2 ~4mA} / cm ^2, when performing electrolytic oxidation polymerization at a constant voltage, preferably 0.5V~10V as voltage, 1.5V to 5V is more preferable. The temperature during electrolytic oxidation polymerization is preferably 5 ° C to 95 ° C, and particularly preferably 10 ° C to 30 ° C. The polymerization time is preferably 1 hour to 72 hours, more preferably 8 hours to 24 hours. In the electrolytic oxidation polymerization, ferrous sulfate or ferric sulfate may be added as a catalyst.

  The conductive polymer obtained as described above is obtained immediately after polymerization in a state of being dispersed in water or an aqueous liquid, and includes persulfate as an oxidizing agent, iron sulfate used as a catalyst, and decomposition products thereof. Contains. Therefore, it is preferable to remove the metal component with a cation exchange resin after the impurities are dispersed by applying a dispersion of the conductive polymer containing the impurities to a dispersing machine such as an ultrasonic homogenizer, a high-pressure homogenizer, or a planetary ball mill. The particle size of the conductive polymer measured by the dynamic light scattering method at this time is preferably 100 μm or less, more preferably 10 μm or less, 0.01 μm or more, and more preferably 0.1 μm or more. Then, it is preferable to remove what was produced | generated by decomposition | disassembly of an oxidizing agent or a catalyst by ethanol precipitation method, ultrafiltration method, anion exchange resin, etc.

  In the conductive polymer dispersion obtained as described above, the conductive polymer comprises a polymer of a thiophene monomer represented by the general formula (1), the styrene sulfonic acid and the non-sulfonic acid monomer. And a polymer anion derived from the copolymer. That is, the polymer anion derived from the copolymer having a cationic property derived from the thiophene-based monomer represented by the general formula (1) and functioning as a dopant therein is represented by the general formula (1). The polymer of the thiophene monomer represented by) is doped to extract the electrons from the polymer, thereby imparting conductivity to the polymer, thereby forming a conductive polymer.

  At present, the hole transport material is constituted by adding a hole transport rate adjusting agent to the conductive polymer obtained as described above in order to slow the hole transport rate that is too fast. The addition of the hole transport speed adjusting agent is performed by adding the hole transport speed adjusting agent to the dispersion of the conductive polymer, and the hole transport speed adjusting agent is contained in the conductive polymer when dried. What should I do?

  As the hole transport rate adjusting agent, for example, polyvinyl alcohol, polyvinyl acetal, polyvinyl pyrrolidone, water-based polyester resin, acrylic modified polyester resin, phenol sulfonic acid novolak resin and the like that form a film after drying can be used. In addition, the copolymer of the styrene sulfonic acid and the non-sulfonic acid monomer used in the synthesis of the conductive polymer is preferable. That is, the copolymer functions as a dopant in the synthesis of the conductive polymer, but when added to the conductive polymer, the hole transport rate is decreased.

  The amount of the hole transport rate adjusting agent added is determined in accordance with the electron transport rate from the electron injection layer, so an absolutely preferable amount cannot be determined. On the other hand, the hole transport rate modifier is preferably added so that the ratio of the conductive polymer: hole transport rate modifier is 1: 0.1 to 10 in terms of mass ratio.

  The hole transport material of the present invention is used in the construction of a hole transport layer for transporting holes at an appropriate speed in an electroluminescence element or a thin film solar cell, but the hole transport material of the present invention is used. The configured hole transport layer also has an action of blocking the passage of electrons.

  In addition, a binder may be added to the conductive polymer dispersion in a range that does not impair the resistance value in order to increase the film strength of the hole transport layer. Examples of such binder include polyvinyl alcohol, polyurethane, polyester, acrylic resin, polyamide, polyimide, epoxy resin, polyacrylonitrile resin, polymethacrylonitrile resin, polystyrene resin, novolac resin, sulfonated polyallyl, sulfonated polyvinyl, Examples include silane coupling agents.

  In the present invention, the electroluminescent element and the thin-film solar cell may have the same configuration as that of the conventional one except that the hole transport layer is composed of the hole transport material of the present invention.

  The electroluminescence element is composed of, for example, an anode, a hole transport layer composed of the hole transport material of the present invention, a light emitting layer, an electron injection layer, a cathode, and the like.

  The anode is configured, for example, by patterning a transparent conductive film made of indium tin oxide (ITO) on a glass substrate in a stripe shape by photolithography and etching.

  The hole transport layer may be formed by applying the hole transport material of the present invention in a dispersion state by spin coating so that the film thickness after drying is about 20 to 40 nm and drying. preferable.

  The hole transport material of the present invention has a feature that there is little variation (variation) in the surface roughness of a hole transport layer formed using the hole transport material, and the surface roughness is centerline average roughness (Ra). ) Can form a hole transport layer with little variation in thickness of about 0.1 to 0.5 nm.

  Therefore, the hole transport layer formed using the hole transport material of the present invention has a uniform rate of transporting holes over almost the entire surface, and the holes that have passed through the hole transport layer are light emitting layers. It efficiently combines with the electrons that have passed through the electron injection layer to cause the coloring dye to emit light efficiently. Therefore, when compared with the same input power, the electroluminescent element of the present invention has higher luminance and higher external quantum efficiency, current efficiency, and electronic efficiency than the conventional electroluminescent element.

  The light-emitting layer is formed of, for example, polyvinyl carbazole as a hole transport material and 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-as an electron transport material. It comprises oxadiazole and a fluorescent coloring dye.

  The electron injection layer is made of, for example, a lithium fluoride vapor deposition film, and the cathode is made of, for example, an aluminum vapor deposition film.

  A thin film solar cell is comprised by the positive electrode, the positive hole transport layer comprised with the positive hole transport material of this invention, the active layer (photoelectric converting layer), the electron injection layer, and the negative electrode, for example.

  The positive electrode, the hole transport layer, the electron injection layer, and the negative electrode are configured similarly to the case of the electroluminescence element.

  The active layer (photoelectric conversion layer) is obtained, for example, by applying a solution obtained by dissolving poly-3-hexylthiophene as an electron donor and fullerene derivative as an electron acceptor in chlorobenzene by a spin coat method, and drying. It is formed.

  Also in this thin-film solar cell, the hole transport layer composed of the hole transport material of the present invention is uniformly formed even if it is a thin film, so that incident light is almost uniformly transmitted to the active layer. Can be passed. As a result, the incident light is efficiently converted into electricity in the active layer, so that the thin film solar cell of the present invention makes more effective use of the incident light than the conventional thin film solar cell when compared with the same input light quantity. The release voltage, short circuit current density, fill factor, and photoelectric exchange efficiency can be increased.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited only to those illustrated in these examples. In the following examples and the like,% in the case of indicating the concentration and the amount used is% based on mass unless otherwise specified.

  Examples will be described in the order of a hole transport material, an electroluminescence element, and a thin-film solar cell. Prior to the description of these examples, a thiophene-based material used in the production of a conductive polymer that forms the main material of the hole transport material. A monomer production example and a production example of a copolymer of a styrene sulfonic acid and a non-sulfonic acid monomer constituting the conductive polymer dopant will be described first.

Production example 1 of thiophene monomer
In Production Example 1 of this thiophene monomer, production of 3,4-ethyleneoxythiathiophene (that is, thieno [3,4-b] -1,4-oxathiane) will be described. This 3,4-ethyleneoxythiathiophene corresponds to the general formula (1) in which R ¹ and R ² are both hydrogen atoms and X is a sulfur atom.

  Put 433 g (3.0 mol) of 3,4-dimethoxythiophene and 3,400 g of toluene in a reaction vessel equipped with a refluxing vessel, stir for 10 minutes, and add 57 g (3.0 mol) of p-toluenesulfonic acid to it. And mixed.

  While stirring the above mixture, 933 kg (9.0 mol) of 2-mercaptoethanol was added to the mixture, the temperature in the container was kept at 110 ° C., and the mixture was stirred for 12 hours while refluxing. The reaction-terminated liquid was cooled to 70 ° C., 378 g (4.5 mol) of sodium bicarbonate was added, and then cooled to room temperature.

  3,400 g of pure water was added to the reaction-finished solution, and after stirring well, it was allowed to stand for 12 hours to separate the reaction solution into two layers, an aqueous phase and an organic phase. Among them, the organic phase was extracted and toluene was removed by an evaporator to obtain a reddish brown liquid.

  To the obtained reddish brown liquid, 2,000 g of toluene and 2,000 g of pure water were added, stirred well at room temperature, allowed to stand for 12 hours, the organic phase was extracted, toluene was removed with an evaporator, and the reddish brown liquid was removed. Obtained.

  The reddish brown liquid obtained through the above steps is distilled at 20 hPa while gradually raising the temperature to distill water, toluene and the first fraction, and then 373 g of 3,4-ethyleneoxythiathiophene as the main fraction. (2.4 mol) was obtained. The yield was 78%.

Production example 2 of thiophene monomer
In Production Example 2 of this thiophene monomer, a production example of methylated ethylenedioxythiophene (that is, 2-methyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin) will be described. .

This methylated ethylenedioxythiophene corresponds to the general formula (1) in which one of R ¹ and R ² is a hydrogen atom, the other is a methyl group, and X is an oxygen atom. . The methylated ethylenedioxythiophene is produced through the following synthesis steps (1) to (3).

(1) Synthesis of propane-1,2-diyl-bis (4-methylbenzenesulfonate) Under ice cooling, 7.86 kg (40 mol) of tosyl chloride and 7 kg of 1,2-dichloroethane were placed in a reaction vessel. The mixture was stirred until the temperature reached 10 ° C., and 5.11 kg (50 mol) of triethylamine was dropped therein.

  While stirring the above mixture, 1.55 kg (20 mol) of 1,2-propanediol was carefully added dropwise to the mixture over 60 minutes while keeping the temperature in the container not exceeding 40 ° C. The mixture was stirred for 6 hours while maintaining at 40 ° C.

The reaction completion liquid was cooled to room temperature, 4 kg of water was added and stirred, and then allowed to stand. The reaction-terminated liquid was divided into two layers, an aqueous phase and an organic phase, and the organic phase was concentrated to obtain a black-red oily product.
Under ice-cooling, 500 g of methanol was added to the reaction vessel and stirred, and the black-red oily substance obtained as described above was added dropwise to the reaction vessel and stirred, and the precipitated white solid was collected by filtration. The white solid was washed with a small amount of methanol and dried to obtain 3.87 kg of propane-1,2-diyl-bis (4-methylbenzenesulfonate) as a product.

(2) Synthesis of 2-methyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin-5,7-dicarboxylic acid Disodium-2,5-bis (alkoxy) in a reaction vessel Carbonyl) thiophene-3,4-diolate 508 g (1.67 mol), propane-1,2-diyl-bis (4-methylbenzenesulfonate) 960 g (2.5 mol) obtained in (1) above, 46 g (0.33 mol) of potassium carbonate and 2.5 kg of dimethylformamide were added, and the mixture was stirred for 4 hours while maintaining the temperature in the container at 120 ° C.

The reaction-terminated liquid was concentrated, 3.7 kg of 5% aqueous sodium hydrogen carbonate solution was added to the remaining brown solid, stirred at room temperature for 15 minutes, and the brown solid was collected by filtration. A brown solid collected by filtration and 2.47 kg of a 7% aqueous sodium hydroxide solution were added to the reaction vessel, and the mixture was stirred for 2 hours while maintaining the temperature in the vessel at 80 ° C.
The container is cooled to room temperature, 98% sulfuric acid (759 g) is carefully added dropwise to the reaction end solution while keeping the temperature in the container not exceeding 30 ° C., and the temperature in the container is kept at 80 ° C. for 2 hours. Stir.

  The container was cooled with stirring until it reached room temperature, and the precipitated gray solid was collected by filtration. Further, the reaction completion liquid was cooled and a gray solid was collected by filtration. These gray solids were washed with a small amount of water and then dried to give 2-methyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin-5,7-di as a product. 310 g of carboxylic acid was obtained.

(3) Synthesis of methylated ethylenedioxythiophene (2-methyl-2,3-dihydro-thieno [3,4-b] [1,4] dioxin) 2-methyl-2 obtained in (2) above 880 g (3.6 mol) of 3-dihydro-thieno [3,4-b] [1,4] dioxin-5,7-dicarboxylic acid was added to 3 kg of polyethylene glycol 300 (Hayashi Junyaku Kogyo Co., Ltd.) 176 g of copper oxide, and the mixture is distilled at an internal pressure of 20 hPa while gradually raising the temperature to distill water and the first distillate, and 400 g of water is added to the main distillate containing polyethylene glycol 300. Stir and let stand.
The solution separated into two layers was separated, and 345 g of the lower yellow transparent liquid was obtained as the product methylated ethylenedioxythiophene.

  Next, an example of producing a copolymer of styrene sulfonic acid and a non-sulfonic acid monomer used for producing a conductive polymer will be described. This copolymer produces a polymer anion that functions as a dopant in the conductive polymer.

Production Example 1 of Copolymer
[Production of copolymer (styrenesulfonic acid: hydroxyethyl methacrylate = 9: 1)]
In Production Example 1, the production of a copolymer in which the monomer at the start of use is styrene sulfonic acid and hydroxyethyl methacrylate as a methacrylic acid ester and the ratio thereof is 9: 1 will be described. Also in the following copolymer production examples, the copolymer composition is indicated by the mass ratio of the monomer at the start of use.

  1 L of pure water was added to a 2 L separable flask equipped with a stirrer, and 201.5 g of sodium styrenesulfonate (180 g as styrenesulfonic acid) and 20 g of hydroxyethyl methacrylate were added thereto. And 1g of ammonium persulfate was added to the solution as an oxidizing agent, and the polymerization reaction of styrenesulfonic acid and hydroxyl methacrylate was performed for 12 hours.

  Thereafter, 100 g of a cation exchange resin [Amberlite 120B (trade name)] manufactured by Organo Corporation was added to the reaction solution, and the mixture was stirred for 1 hour with a stirrer. The mixture was filtered through 131, and the treatment with this cation exchange resin and filtration were repeated three times to remove all cation components in the liquid.

  The obtained copolymer of styrene sulfonic acid and hydroxyethyl methacrylate was subjected to HPLC (High performance liquid) using a GPC (Gel Permeation Chromatography: Gel Filtration Chromatography, but only “GPC” hereinafter) column. As a result of analysis using a system (high-performance liquid chromatography, which will be referred to only as “HPLC” hereinafter), the weight average molecular weight estimated using dextran of the copolymer as a standard was 100,000. there were.

Copolymer production example 2
[Production of copolymer (styrenesulfonic acid: hydroxyethyl acrylate = 8: 2)]
In Production Example 2, production of a copolymer having a mass ratio of styrene sulfonic acid to hydroxyethyl acrylate of 8: 2 will be described.

  1 L of pure water was added to a 2 L separable flask equipped with a stirrer, and 173.5 g of sodium styrenesulfonate (155 g as styrenesulfonic acid) and 33 g of hydroxyethyl acrylate were added thereto. Then, 1 g of ammonium persulfate was added to the solution, and a polymerization reaction between styrene sulfonic acid and hydroxyethyl acrylate was performed for 12 hours.

  Thereafter, 100 g of a cation exchange resin [Amberlite 120B (trade name)] manufactured by Organo Corporation was added to the reaction solution, and the mixture was stirred for 1 hour with a stirrer. The mixture was filtered through 131, and the treatment with this cation exchange resin and filtration were repeated three times to remove all cation components in the liquid.

  As a result of analyzing the obtained copolymer of styrene sulfonic acid and hydroxyethyl acrylate using an HPLC system using a GPC column, the weight average molecular weight estimated using dextran of the copolymer as a standard was 90,000.

Copolymer Production Example 3
[Production of copolymer (styrenesulfonic acid: 3-methacryloxypropyltrimethoxysilane = 9: 1)]
In Production Example 3, production of a copolymer having a mass ratio of 9: 1 between styrenesulfonic acid and 3-methacryloxypropyltrimethoxysilane will be described.

  1 L of pure water was added to a 2 L separable flask equipped with a stirrer, and 201.5 g of sodium styrenesulfonate (180 g as styrenesulfonic acid) and 20 g of 3-methacryloxypropyltrimethoxysilane were added thereto. Then, 1 g of ammonium persulfate was added to the solution, and a polymerization reaction of styrenesulfonic acid and 3-methacryloxypropyltrimethoxysilane was performed for 12 hours.

  Thereafter, 100 g of a cation exchange resin [Amberlite 120B (trade name)] manufactured by Organo Corporation was added to the reaction solution, and the mixture was stirred for 1 hour with a stirrer. The mixture was filtered through 131, and the treatment with this cation exchange resin and filtration were repeated three times to remove all cation components in the liquid.

  As a result of analyzing the obtained copolymer of styrenesulfonic acid and 3-methacryloxypropyltrimethoxysilane using an HPLC system using a GPC column, the copolymer dextran was estimated as a standard product. The weight average molecular weight was 70,000.

Copolymer Production Example 4
[Production of copolymer (styrenesulfonic acid: 3-acryloxypropyltrimethoxysilane = 8: 2)]
In this Production Example 4, production of a copolymer having a mass ratio of styrenesulfonic acid and 3-acryloxypropyltrimethoxysilane of 9: 1 will be described.

  1 L of pure water was added to a 2 L separable flask equipped with a stirrer, and 201.5 g of sodium styrenesulfonate (180 g as styrenesulfonic acid) and 20 g of 3-acryloxypropyltrimethoxysilane were added thereto. Then, 1 g of ammonium persulfate was added to the solution, and a polymerization reaction of styrenesulfonic acid and vinyltrimethoxysilane was performed for 12 hours.

  Thereafter, 100 g of a cation exchange resin [Amberlite 120B (trade name)] manufactured by Organo Corporation was added to the reaction solution, and the mixture was stirred for 1 hour with a stirrer. The mixture was filtered through 131, and the treatment with this cation exchange resin and filtration were repeated three times to remove all cation components in the liquid.

  The copolymer of styrene sulfonic acid and 3-acryloxypropyltrimethoxysilane thus obtained was analyzed using an HPLC system using a GPC column, and as a result, dextran of the copolymer was estimated as a standard product. The weight average molecular weight was 80,000.

  Next, examples of the hole transport material will be described in Examples 1 to 24. This hole transport material is manufactured in the state of a dispersion, and only the surface resistance and surface roughness of this hole transport material are used. Measured in the example of the transport material, and other characteristics are constituted by using the hole transport material to constitute a hole transport layer of an electroluminescence element or a thin film solar cell, and the electroluminescence using the hole transport layer. The characteristics of the device and thin film solar cell are evaluated.

Example 1
600 g of a 4% aqueous solution of a copolymer having a mass ratio of 9: 1 of styrene sulfonic acid and hydroxyethyl methacrylate obtained in Production Example 1 of the copolymer was placed in a stainless steel container having an internal volume of 1 L, and the catalyst was placed there. As a solution, 0.3 g of ferrous sulfate heptahydrate was added and dissolved. 4 mL of 3,4-ethyleneoxythiathiophene produced in Production Example 1 for thiophene monomer was slowly dropped therein. The mixture was stirred with a stainless steel stirring spring, an anode was attached to the container, a cathode was attached to the stirring spring, and electrolytic oxidation polymerization was performed at a constant current of 1 mA / cm ² for 18 hours to synthesize a conductive polymer. After the electrolytic oxidation polymerization, the mixture was diluted 4 times with water, and then subjected to a dispersion treatment for 30 minutes with an ultrasonic homogenizer [manufactured by Nippon Seiki Co., Ltd., US-T300 (trade name)].

  Thereafter, 100 g of Organo Cation Exchange Resin [Urbanlite 120B (trade name)] was added and stirred with a stirrer for 1 hour. The mixture was filtered through 131, and the treatment with this cation exchange resin and filtration were repeated three times to remove all cation components in the liquid.

  The treated liquid is passed through a filter having a pore size of 1 μm, and the passing liquid is treated with an ultrafiltration device (Saltorius Vivaflow 200 (trade name), molecular weight fraction 50,000) to give free low molecular components in the liquid. Was removed. The liquid after this treatment was diluted with water to adjust the concentration of the conductive polymer to 1.5% to obtain a dispersion having a concentration of 1.5% of the conductive polymer.

  Copolymer used as a dopant in the synthesis of the above conductive polymer as a hole transport rate adjusting agent for adjusting the hole transport rate when used as a hole transport material in this conductive polymer dispersion And a copolymer having a mass ratio of styrene sulfonic acid and hydroxyethyl methacrylate of 9: 1 and a mixing ratio of conductive polymer: copolymer = 1: 3. After adding and mixing as described above, it was diluted with pure water until the solid content concentration became 0.8% to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds), and then dried at 130 ° C. for 5 minutes, so that the thickness of the hole transport material was 30 nm. A thin film was formed. The surface resistance of this hole transporting material film was measured by Hirester UP [MCP-HT450 type, ring probe (URS)] manufactured by Mitsubishi Chemical Analytech Co., Ltd. and found to be 2.1 × 10 ¹⁰ Ω. The surface roughness (Ra) measured with (VN-8000 manufactured by Keyence Corporation) was 0.4 nm. The “surface roughness (Ra)” indicates that the surface roughness is due to the centerline average roughness. Moreover, the thickness of the hole transport material film formed in the following Examples 2 to 12 and Comparative Examples 1 to 4 is 30 nm as in Example 1, and the surface resistance and the surface roughness (Ra) are measured. The temperature of the hour is 25 ° C. in all cases.

Example 2
The same as Example 1 except that methylated ethylenedioxythiophene produced in Production Example 2 of thiophene monomer was used instead of 3,4-ethyleneoxythiathiophene produced in Production Example 1 of thiophene monomer. Thus, a hole transport material dispersion was obtained.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 2.8 × 10 ¹⁰ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.5 nm.

Example 3
Manufactured in Production Example 2 of 3,4-ethyleneoxythiathiophene and thiophene monomer produced in Production Example 1 of thiophene monomer instead of 3,4-ethyleneoxythiathiophene produced in Production Example 1 of thiophene monomer A hole transport material dispersion was obtained in the same manner as in Example 1 except that a monomer solution in which the methylated ethylenedioxythiophene was mixed at a molar ratio of 1: 1 was used.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 1.5 × 10 ¹⁰ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.4 nm.

Example 4
Instead of the copolymer having a mass ratio of 9: 1 of styrene sulfonic acid and hydroxyethyl methacrylate obtained in Production Example 1 of the copolymer, styrene sulfonic acid and acrylic acid obtained in Production Example 2 of the copolymer Except that a copolymer having a mass ratio with hydroxyethyl of 8: 2 was used, the same operation as in Example 1 was performed to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 3.6 × 10 ¹⁰ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.4 nm.

Example 5
Instead of the copolymer having a mass ratio of 9: 1 of styrene sulfonic acid and hydroxyethyl methacrylate obtained in Production Example 1 of the copolymer, styrene sulfonic acid and acrylic acid obtained in Production Example 2 of the copolymer Except that a copolymer having a mass ratio to hydroxyethyl of 8: 2 was used, the same operation as in Example 2 was performed to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 3.1 × 10 ¹⁰ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.5 nm.

Example 6
Instead of the copolymer having a mass ratio of 9: 1 of styrene sulfonic acid and hydroxyethyl methacrylate obtained in Production Example 1 of the copolymer, styrene sulfonic acid and acrylic acid obtained in Production Example 2 of the copolymer Except that a copolymer having a mass ratio to hydroxyethyl of 8: 2 was used, the same operation as in Example 3 was performed to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 2.2 × 10 ¹⁰ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.4 nm.

Example 7
Instead of the copolymer having a mass ratio of styrene sulfonic acid and hydroxyethyl methacrylate of 9: 1 obtained in Copolymer Production Example 1, styrene sulfonic acid obtained in Copolymer Production Example 3 and 3- Except for using a copolymer having a mass ratio of 9: 1 with methacryloxypropyltrimethoxysilane, all operations were performed in the same manner as in Example 1 to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 4.4 × 10 ¹⁰ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.5 nm.

Example 8
Instead of the copolymer having a mass ratio of styrene sulfonic acid and hydroxyethyl methacrylate of 9: 1 obtained in Copolymer Production Example 1, styrene sulfonic acid obtained in Copolymer Production Example 3 and 3- Except for using a copolymer having a mass ratio of 9: 1 with methacryloxypropyltrimethoxysilane, all operations were performed in the same manner as in Example 2 to obtain a hole transport material dispersion.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 2.7 × 10 ¹⁰ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.4 nm.

Example 9
Instead of the copolymer having a mass ratio of styrene sulfonic acid and hydroxyethyl methacrylate of 9: 1 obtained in Copolymer Production Example 1, styrene sulfonic acid obtained in Copolymer Production Example 3 and 3- Except that a copolymer having a mass ratio of 9: 1 with methacryloxypropyltrimethoxysilane was used, the same operation as in Example 3 was carried out to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 2.0 × 10 ¹⁰ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.4 nm.

Example 10
Instead of the copolymer having a mass ratio of styrene sulfonic acid and hydroxyethyl methacrylate obtained in Copolymer Production Example 1 of 9: 1, styrene sulfonic acid obtained in Copolymer Production Example 4 and 3- Except for using a copolymer having a mass ratio of 8: 2 with acryloxypropyltrimethoxysilane, all operations were performed in the same manner as in Example 1 to obtain a hole transport material dispersion.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 3.9 × 10 ¹⁰ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.4 nm.

Example 11
Instead of the copolymer having a mass ratio of 9: 1 of the styrene sulfonic acid and hydroxyethyl methacrylate obtained in Production Example 1 of copolymer polymer anion, the styrene sulfonic acid obtained in Production Example 4 of the copolymer and Except that a copolymer having a mass ratio of 3-acryloxypropyltrimethoxysilane of 8: 2 was used, the same operation as in Example 2 was performed to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 1.9 × 10 ¹⁰ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.5 nm.

Example 12
Instead of the copolymer having a mass ratio of styrene sulfonic acid and hydroxyethyl methacrylate obtained in Copolymer Production Example 1 of 9: 1, styrene sulfonic acid obtained in Copolymer Production Example 4 and 3- A hole transport material dispersion was obtained in the same manner as in Example 3 except that a copolymer having a mass ratio with acryloxypropyltrimethoxysilane of 8: 2 was used.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 2.7 × 10 ¹⁰ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.4 nm.

Comparative Example 1
600 g of 4% aqueous solution of polystyrene sulfonic acid having a weight average molecular weight of 100,000 manufactured by Teika Co., Ltd. is put into a stainless steel container having an internal volume of 1 L, and 0.3 g of ferrous sulfate heptahydrate is added thereto as a catalyst. And dissolved. 4 mL of 3,4-ethylenedioxythiophene was slowly dropped therein. The mixture was stirred with a stainless steel stirring spring, an anode was attached to the container, a cathode was attached to the stirring spring, and electrolytic oxidation polymerization was performed at a constant current of 1 mA / cm ² for 18 hours to synthesize a conductive polymer. After the electrolytic oxidation polymerization, the mixture was diluted 4 times with water, and then subjected to a dispersion treatment for 30 minutes with an ultrasonic homogenizer [manufactured by Nippon Seiki Co., Ltd., US-T300 (trade name)].

  Thereafter, 100 g of a cation exchange resin [Urbanlite 120B (trade name)] manufactured by Organo Co., Ltd. was added and stirred with a stirrer for 1 hour. The mixture was filtered through 131, and the treatment with this cation exchange resin and filtration were repeated three times to remove all cation components in the liquid.

  The treated liquid is passed through a filter having a pore size of 1 μm, and the passing liquid is treated with an ultrafiltration device (Saltorius Vivaflow 200 (trade name), molecular weight fraction 50,000) to give free low molecular components in the liquid. Was removed. The liquid after this treatment was diluted with water to adjust the concentration of the conductive polymer to 0.8% to obtain a dispersion having a concentration of the conductive polymer of 0.8%.

  Polystyrene sulfonic acid is added to the dispersion of the conductive polymer in a mass ratio so that the ratio of conductive polymer: polystyrene sulfonic acid is 1: 3, and is mixed until the solid content concentration becomes 0.8%. Dilution with water gave a dispersion of the hole transport material.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 1.3 × 10 ¹⁰ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.8 nm.

Comparative Example 2
In place of 3,4-ethylenedioxythiophene, the same operation as in Comparative Example 1 was carried out except that 3,4-ethyleneoxythiathiophene produced in Production Example 1 of thiophene monomer was used. A transport material dispersion was obtained.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 5.6 × 10 ¹⁰ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.8 nm.

Comparative Example 3
In place of 3,4-ethylenedioxythiophene, the same procedure as in Comparative Example 1 was performed except that the methylated ethylenedioxythiophene produced in Production Example 2 of the thiophene monomer was used. A dispersion was obtained.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 1.5 × 10 ¹⁰ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.7 nm.

Comparative Example 4
The same procedure as in Example 1 was performed except that 3,4-ethylenedioxythiophene was used in place of 3,4-ethyleneoxythiathiophene produced in Production Example 1 of thiophene monomer, and holes were formed. A transport material dispersion was obtained.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (3,000 rpm, 60 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 1.1 × 10 ¹⁰ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.7 nm.

The surface resistance values and surface roughness values of the hole transport materials of Examples 1 to 12 and Comparative Examples 1 to 4 are shown in Table 1 together with the types of monomers and polymer anions. However, monomers are abbreviated as follows because of space limitations.
EOST: 3,4-ethyleneoxythiathiophene MeEDOT: methylated ethylenedioxythiophene EDOT: 3,4-ethylenedioxythiophene

  The polymer anion is indicated by the type of the polymer (copolymer, polystyrene sulfonic acid), and in these cases as well, in Table 1, the copolymer used in the examples is a production example. Numbers are given after the copolymer, and polystyrenesulfonic acid is abbreviated as “PSSA”.

  As shown in Table 1, the hole transport materials of Examples 1 to 12 have a smaller surface roughness and higher surface uniformity of the formed thin film than the hole transport materials of Comparative Examples 1 to 4. It showed that.

  The hole transport materials of Examples 1 to 12 and Comparative Examples 1 to 4 are used in the configuration of the hole transport layer of the electroluminescent element shown in Examples 25 to 36 and Comparative Examples 9 to 12 described later. In Examples 13 to 24 and Comparative Examples 5 to 8 below, dispersion of the hole transport material used in the construction of the hole transport layer of the thin film solar cell shown in Examples 37 to 48 and Comparative Examples 13 to 16 described later The production of the liquid will be described.

Example 13
The same operation as in Example 1 was performed to obtain a dispersion having a conductive polymer concentration of 1.5%. The same copolymer (a copolymer having a 9: 1 mass ratio of styrene sulfonic acid and hydroxyethyl methacrylate) as that used in Example 1 was electrically conductive in this conductive polymer dispersion. Polymer and copolymer were added and mixed so that the ratio was 1: 1, and diluted with pure water until the solid content concentration became 0.8% to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion was applied to a 6 cm × 6 cm glass substrate by spin coating (2000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a thin film having a hole transport material thickness of 35 nm. Formed. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 6.1 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.5 nm. In addition, also in the following Examples 14-24 and Comparative Examples 5-8, the thickness of the positive hole transport material film | membrane formed is 35 nm.

Example 14
Example 13 is the same as Example 13 except that methylated ethylenedioxythiophene produced in Production Example 2 of thiophene monomer was used instead of 3,4-ethyleneoxythiathiophene produced in Production Example 1 of thiophene monomer. Thus, a hole transport material dispersion was obtained.

The obtained hole transport material dispersion is applied to a 6 cm × 6 cm glass substrate by spin coating (2,000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 5.7 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.3 nm.

Example 15
Manufactured in Production Example 2 of 3,4-ethyleneoxythiathiophene and thiophene monomer produced in Production Example 1 of thiophene monomer instead of 3,4-ethyleneoxythiathiophene produced in Production Example 1 of thiophene monomer Except that a monomer solution in which the methylated ethylenedioxythiophene was mixed at a molar ratio of 1: 1 was used, the same operation as in Example 13 was performed to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion is applied to a 6 cm × 6 cm glass substrate by spin coating (2,000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 4.1 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.4 nm.

Example 16
Instead of the copolymer having a mass ratio of 9: 1 of styrene sulfonic acid and hydroxyethyl methacrylate obtained in Production Example 1 of the copolymer, styrene sulfonic acid and acrylic acid obtained in Production Example 2 of the copolymer Except that a copolymer having a mass ratio with hydroxyethyl of 8: 2 was used, the same operation as in Example 13 was performed to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion is applied to a 6 cm × 6 cm glass substrate by spin coating (2,000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 3.8 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.3 nm.

Example 17
Instead of the copolymer having a mass ratio of 9: 1 of styrene sulfonic acid and hydroxyethyl methacrylate obtained in Production Example 1 of the copolymer, styrene sulfonic acid and acrylic acid obtained in Production Example 2 of the copolymer Except that a copolymer having a mass ratio to hydroxyethyl of 8: 2 was used, the same operation as in Example 14 was performed to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion is applied to a 6 cm × 6 cm glass substrate by spin coating (2,000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 6.2 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.5 nm.

Example 18
Instead of the copolymer having a mass ratio of 9: 1 of styrene sulfonic acid and hydroxyethyl methacrylate obtained in Production Example 1 of the copolymer, styrene sulfonic acid and acrylic acid obtained in Production Example 2 of the copolymer Except that a copolymer having a mass ratio to hydroxyethyl of 8: 2 was used, the same operation as in Example 15 was performed to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion is applied to a 6 cm × 6 cm glass substrate by spin coating (2,000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 7.5 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.4 nm.

Example 19
Instead of the copolymer having a mass ratio of 9: 1 between the styrene sulfonic acid and hydroxyethyl methacrylate obtained in Copolymer Production Example 1, the styrene sulfonic acid obtained in Copolymer Production Example 3 and 3- Except for using a copolymer having a mass ratio of 9: 1 with methacryloxypropyltrimethoxysilane, all operations were performed in the same manner as in Example 13 to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion is applied to a 6 cm × 6 cm glass substrate by spin coating (2,000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 4.3 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.5 nm.

Example 20
Instead of the copolymer having a mass ratio of styrene sulfonic acid and hydroxyethyl methacrylate of 9: 1 obtained in Copolymer Production Example 1, styrene sulfonic acid obtained in Copolymer Production Example 3 and 3- Except for using a copolymer having a mass ratio of 9: 1 with methacryloxypropyltrimethoxysilane, all operations were carried out in the same manner as in Example 14 to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion is applied to a 6 cm × 6 cm glass substrate by spin coating (2,000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 7.4 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.5 nm.

Example 21
Instead of the copolymer having a mass ratio of styrene sulfonic acid and hydroxyethyl methacrylate of 9: 1 obtained in Copolymer Production Example 1, styrene sulfonic acid obtained in Copolymer Production Example 3 and 3- Except that a copolymer having a mass ratio of 9: 1 with methacryloxypropyltrimethoxysilane was used, the same operation as in Example 15 was performed to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion is applied to a 6 cm × 6 cm glass substrate by spin coating (2,000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 5.9 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.5 nm.

Example 22
Instead of the copolymer having a mass ratio of 9: 1 between the styrene sulfonic acid and hydroxyethyl methacrylate obtained in Copolymer Production Example 1, the styrene sulfonic acid obtained in Copolymer Production Example 4 and 3- Except that a copolymer having a mass ratio of 9: 1 with acryloxypropyltrimethoxysilane was used, all operations were performed in the same manner as in Example 13 to obtain a dispersion liquid of a hole transport material.

The obtained hole transport material dispersion is applied to a 6 cm × 6 cm glass substrate by spin coating (2,000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 6.8 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.5 nm.

Example 23
Instead of the copolymer having a mass ratio of 9: 1 between the styrene sulfonic acid and hydroxyethyl methacrylate obtained in Copolymer Production Example 1, the styrene sulfonic acid obtained in Copolymer Production Example 4 and 3- Except for using a copolymer having a mass ratio of 9: 1 with acryloxypropyltrimethoxysilane, all operations were performed in the same manner as in Example 14 to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion is applied to a 6 cm × 6 cm glass substrate by spin coating (2,000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 5.3 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.5 nm.

Example 24
Instead of the copolymer having a mass ratio of 9: 1 between the styrene sulfonic acid and hydroxyethyl methacrylate obtained in Copolymer Production Example 1, the styrene sulfonic acid obtained in Copolymer Production Example 4 and 3- Except that a copolymer having a mass ratio of 9: 1 with acryloxypropyltrimethoxysilane was used, all operations were performed in the same manner as in Example 15 to obtain a dispersion of a hole transport material.

The obtained hole transport material dispersion is applied to a 6 cm × 6 cm glass substrate by spin coating (2,000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 6.3 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.4 nm.

Comparative Example 5
Similarly to Comparative Example 1, 3,4-ethylenedioxythiophene was polymerized in the presence of polystyrene sulfonic acid to obtain a dispersion having a conductive polymer concentration of 1.5%.

  Polystyrene sulfonic acid is added to the dispersion of the conductive polymer in a mass ratio so that the ratio of conductive polymer: polystyrene sulfonic acid is 1: 1, and the solid content concentration becomes 0.8%. The solution was diluted with pure water until a hole transport material dispersion was obtained.

The obtained hole transport material dispersion is applied to a 6 cm × 6 cm glass substrate by spin coating (2,000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 2.8 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.8 nm.

Comparative Example 6
Except that 3,4-ethylenedioxythiophene was replaced with 3,4-ethylenethiathiophene produced in Production Example 1 of a thiophene monomer, all operations were performed in the same manner as in Comparative Example 5 to transport holes. A dispersion of the material was obtained.

The obtained hole transport material dispersion is applied to a 6 cm × 6 cm glass substrate by spin coating (2,000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 4.0 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.7 nm.

Comparative Example 7
In place of 3,4-ethylenedioxythiophene, the same operation as in Comparative Example 5 was performed except that the methylated ethylenedioxythiophene produced in Production Example 2 of the thiophene monomer was used. A dispersion was obtained.

The obtained hole transport material dispersion is applied to a 6 cm × 6 cm glass substrate by spin coating (2,000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 3.1 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.8 nm.

Comparative Example 8
The same operation as in Example 13 was carried out except that 3,4-ethylenedioxythiophene was used in place of 3,4-ethyleneoxythiathioene produced in Production Example 1 of the thiophene monomer. A dispersion of pore transport material was obtained.

The obtained hole transport material dispersion is applied to a 6 cm × 6 cm glass substrate by spin coating (2,000 rpm, 80 seconds) and then dried at 130 ° C. for 5 minutes to form a hole transport material thin film. did. When the surface resistance of this hole transport material film was measured in the same manner as in Example 1, it was 2.2 × 10 ⁸ Ω, and the surface roughness (Ra) measured with a nanoscale hybrid microscope (VN-8000 manufactured by Keyence Corporation). ) Was 0.7 nm.

  The surface resistance values and surface roughness values of the hole transport materials of Examples 13 to 24 and Comparative Examples 5 to 8 are shown in Table 2 in the same manner as in Table 1.

  As shown in Table 2, the hole transport materials of Examples 13 to 24 have smaller surface roughness and higher surface uniformity of the formed thin film than the hole transport materials of Comparative Examples 5 to 8. It showed that.

  Next, electroluminescent devices having hole transport layers constructed using the hole transport materials of Examples 1 to 12 are shown in Examples 25 to 36, and the electroluminescent devices to be compared with these are comparative examples. 9-12.

Example 25
A 150 nm thick indium tin oxide (ITO) transparent conductive film deposited on a glass substrate [manufactured by Sanyo Vacuum Co .; Was patterned into a stripe having a width of 5 mm using a normal photolithography technique and zinc-hydrochloric acid etching to form an anode. After cleaning with zinc-hydrochloric acid, the patterned ITO substrate was cleaned in the order of ultrasonic cleaning with chloroform, cleaning with neutral detergent, water cleaning with pure water, ultrasonic cleaning with ethanol and acetone, and Soxhlet cleaning with isopropyl alcohol. Dry with nitrogen blow. Finally, after surface hydrophilization by ozone treatment, it was placed in a spin coater.

  The positive electrode transport layer having a thickness of 30 nm was formed by spin-coating the dispersion liquid of the hole transport material obtained in Example 1 on the transparent conductive film of the anode. The above spin coating was performed at 25 ° C. for 2 seconds at a rotation speed of 1500 rotations / minute and then for 60 seconds at a rotation speed of 3000 rotations / minute.

  Next, 69.7% of PVCz (that is, polyvinylcarbazole) as a hole transport material and PBD as an electron transport material [that is, 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole] at 30%, Compound 1 [that is, tris (2-phenylpyridinato) iridium (III) complex] as a fluorescent coloring dye at a concentration of 0.3% in toluene A toluene solution for forming a light-emitting layer containing them was spin-coated on the hole transport layer to form a light-emitting layer having a thickness of 120 nm. Further, lithium fluoride was vapor-deposited to a thickness of 0.5 nm on the light-emitting layer to form an electron injection layer, and then aluminum was vapor-deposited to a thickness of 200 nm to form a reflective electrode as a cathode to produce an electroluminescent device. Produced.

The vapor deposition of lithium fluoride and the vapor deposition of aluminum were performed in a vacuum of 10 ⁻⁴ Pa. At that time, the deposition rate and the film thickness of the vapor deposition material were controlled using a film deposition monitor CRTM-8000 (manufactured by ULVAC, Inc.) using a crystal resonator attached in the vapor deposition machine.

Examples 26-36
An electroluminescent device was prepared in the same manner as in Example 25 except that the hole transport material dispersions of Examples 2 to 12 were used instead of the hole transport material dispersion of Example 1. Was made.

Comparative Examples 9-12
An electroluminescent device was prepared in the same manner as in Example 25 except that the hole transport material dispersions in Comparative Examples 1 to 4 were used in place of the hole transport material dispersion in Example 1. Was made.

  The maximum luminance, external quantum efficiency, current efficiency and power efficiency of the obtained electroluminescent elements of Examples 25 to 36 and Comparative Examples 9 to 12 were measured using a C9920-11 luminance orientation characteristic measuring device manufactured by Hamamatsu Photonics Co., Ltd. did. The results are shown in Table 3.

  The numerical values shown in Table 3 are evaluated for each of the five samples of the electroluminescent elements of Examples 25 to 36 and Comparative Examples 9 to 12, and the maximum luminance is the unit of the light emitter. The maximum value of brightness per area is displayed, the external quantum efficiency is displayed as a percentage of the number of photons generated with respect to the number of electrons injected from the outside into the device, the current efficiency is displayed as the luminance with respect to the unit current amount, and the power efficiency is The efficiency of the light source is displayed as the total luminous flux per unit power. The numerical values in parentheses below the respective measured values indicate how many volts the voltage is when the measured values are the best.

  As shown in Table 3, the electroluminescent elements of Examples 25 to 36 have a larger maximum luminance and higher external quantum efficiency, current efficiency, and power efficiency than the electroluminescent elements of Comparative Examples 9 to 12, The characteristics as an electroluminescence element were excellent.

  Next, examples of thin film solar cells having a hole transport layer constituted by using the dispersion liquids of the hole transport materials of Examples 13 to 24 are shown in Examples 37 to 48, and should be compared with them. Thin film solar cells are shown in Comparative Examples 13-16.

Example 37
A 150 nm thick indium tin oxide (ITO) transparent conductive film deposited on a glass substrate [(Sanyo Vacuum Co., Ltd .; sheet resistance 10Ω, 20 mm (horizontal) × 25 mm (vertical) × 0.7 mm (glass film thickness) ] Was patterned into a 2 mm wide stripe using ordinary photolithography and zinc-hydrochloric acid etching, and after washing with zinc-hydrochloric acid, the patterned ITO substrate was subjected to ultrasonic cleaning with chloroform, neutrality Cleaning with detergent, water with pure water, ultrasonic cleaning with ethanol and acetone, Soxhlet cleaning with isopropyl alcohol, followed by drying with nitrogen blow, and finally surface hydrophilization by ozone treatment, spin coater Installed inside.

  A hole transport layer having a thickness of 35 nm was formed by spin-coating the dispersion liquid of the hole transport material of Example 13 on the transparent conductive film. This spin coating was performed at 25 ° C. for 80 seconds at a rotation speed of 2000 rotations / minute.

Subsequently, 5 mg of poly-3-hexylthiophene (manufactured by Aldrich, average molecular weight 15,000-45,000, head to tail:> 95%) and 5 mg of fullerene derivative (PC ₆₁ BM, manufactured by Aldrich) A mixed solution dissolved in chlorobenzene was applied onto the hole transport layer by a spin coating method to form an active layer having a thickness of 70 nm. Further thereon, 0.3 nm of lithium fluoride was vapor-deposited to form an electron injection layer, and then 150 nm of aluminum was vapor-deposited to form a reflective electrode as a negative electrode to produce a thin film solar cell.

  The spin coating for forming the active layer is performed at 25 ° C. under the condition of 80 seconds at a rotation speed of 1000 rotations / minute, and the deposition of lithium fluoride and aluminum is the same as in the case of the electroluminescence element. went.

Examples 38-48
A thin film solar cell was prepared by performing the same operations as in Example 37 except that the hole transport material dispersions of Examples 14 to 24 were used instead of the hole transport material dispersion of Example 13, respectively. Was made.

Comparative Examples 13-16
A thin film solar cell was prepared by performing the same operations as in Example 37 except that the hole transport material dispersions of Comparative Examples 9 to 12 were used in place of the hole transport material dispersion of Example 1. Was made.

  The open-circuit voltage, short-circuit current density, fill factor and photoelectric conversion rate of the thin film solar cells of Examples 37 to 48 and Comparative Examples 13 to 16 obtained were measured using a spectral sensitivity measuring device CEP-2000 manufactured by Spectrometer Co., Ltd. did. The results are shown in Table 4.

  The relationship between the release voltage, the short-circuit current density, the fill factor, and the photoelectric conversion efficiency and their significance are as follows.

Short-circuit current density: Current voltage obtained when bias voltage (voltage applied to make a biased signal non-biased) is not applied. Voltage is applied in a direction that makes current difficult to flow from the short-circuit current density, and the current is zero. The voltage at the point becomes the open circuit voltage.
Curve factor: Value obtained by dividing the point at which the product of current and voltage (output power) is maximum divided by the ideal maximum output (open-circuit voltage x short-circuit current density).
Photoelectric conversion efficiency (energy conversion efficiency): The maximum output (voltage x current) divided by the energy of the incident light and made into%. In measurement, since a light source of 100 mW / cm ² is often used, PCE = (current at maximum output × voltage at maximum output) ÷ 100 × 100.

The above measurement is performed for each sample for five samples, and in each case, the numerical values shown in Table 4 are obtained by calculating an average value of the five measured values and rounding off to the second decimal place.

  As shown in Table 4, the thin film solar cells of Examples 37 to 48 have a higher release voltage, a larger short circuit current density, a higher fill factor, and higher photoelectric conversion efficiency than the thin film solar cells of Comparative Examples 13 to 16. The characteristics as a thin film solar cell were high.

Claims (6)

A hole comprising: a polymer of a thiophene monomer represented by the following general formula (1); and a conductive polymer including a polymer anion derived from the following copolymer functioning as a dopant: Transport material.
General formula (1):

(In the formula, R ¹ and R ² each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, X represents an oxygen atom or a sulfur atom, provided that both R ¹ and R ² are hydrogen. Except when X is an oxygen atom)
Copolymer:
At least one non-sulfonic acid selected from the group consisting of styrene sulfonic acid and hydroxyalkyl methacrylate, glycidyl methacrylate, hydroxyalkyl acrylate, glycidyl acrylate and unsaturated hydrocarbon-containing alkoxysilane compound or a hydrolyzate thereof Copolymer with monomer. The hole according to claim 1, wherein the thiophene monomer represented by the general formula (1) is a thiophene monomer in which R ¹ and R ² in the general formula (1) are both hydrogen atoms and X is a sulfur atom. Transport material. The thiophene monomer represented by the general formula (1) is a thiophene monomer in which one of R ¹ and R ^{2 in} the general formula (1) is a hydrogen atom, the other is a methyl group, and X is an oxygen atom. The hole transport material according to claim 1, which is a monomer. The polymer of the thiophene monomer represented by the general formula (1) is a thiophene monomer in which R ¹ and R ² in the general formula (1) are both hydrogen atoms and X is a sulfur atom, and R ¹ , R ^2. The hole transport material according to claim 1, which is a copolymer with a thiophene monomer in which any one of ² is a hydrogen atom, the other is a methyl group, and X is an oxygen atom.   An electroluminescent device comprising a hole transport layer composed of the hole transport material according to claim 1.   A thin-film solar cell comprising a hole transport layer composed of the hole transport material according to claim 1.