JP2022161921A - Electronic device and manufacturing method thereof, coating liquid for forming semiconductor layer and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the durability of an electronic device.

SOLUTION: A coating liquid including an organic semiconductor compound and a dopant for an organic semiconductor compound which is a hypervalent iodine compound is heated to 85°C or higher and/or the coating liquid is irradiated with ultraviolet light, and then the coating liquid is applied so as to form a semiconductor layer.

SELECTED DRAWING: Figure 3

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to an electronic device and its manufacturing method, and a semiconductor layer-forming coating liquid and its manufacturing method.

The performance of a semiconductor device having a semiconductor layer is greatly affected by the properties of the semiconductor layer. For this reason, semiconductor layer improvement has become a major target in research to produce high performance semiconductor devices. For example, Non-Patent Document 1 describes that device reproducibility can be improved by fabricating a perovskite semiconductor layer obtained from methylamine iodide and tin iodide by the LT-VASP method. In addition, in Non-Patent Document 1, poly[bis(4-phenyl)(2,4 ,6-trimethylphenyl)amine] (PTAA) has been used.

T. Yokoyama et al. "Overcoming Short-Circuit in Lead-Free CH3NH3SnI3 Perovskite Solar Cells via Kinetically Controlled Gas-Solid Reaction Film Fabrication Process", J. Phys. Chem. Lett. 2016, 7, 776.

The inventors have found that electronic devices comprising a semiconductor layer comprising a doped semiconductor compound can exhibit a decrease in photoelectric conversion efficiency over time. For example, when PTAA doped with TPFB as described in Non-Patent Document 1 is used as a buffer layer of a photoelectric conversion element, the photoelectric conversion efficiency is high at the initial stage, but when stored under high temperature and high humidity conditions, the photoelectric conversion efficiency is reduced. was found to decline rapidly. For the practical use of photoelectric conversion elements, it is required to increase the durability of the photoelectric conversion efficiency and to make the photoelectric conversion efficiency less likely to decrease.

An object of the present invention is to improve the durability of an electronic device having a semiconductor layer.

The inventors of the present application have found that the durability of an electronic device using this semiconductor compound can be enhanced by performing treatment under specific conditions when doping the semiconductor compound. perfected the invention.

That is, the gist of the present invention resides in the following.
[1] A method for manufacturing an electronic device having a semiconductor layer, wherein a coating liquid containing an organic semiconductor compound and a dopant for the organic semiconductor compound which is a hypervalent iodine compound is heated to 85°C or higher and/or Alternatively, a manufacturing method comprising the step of forming the semiconductor layer by applying the coating liquid after irradiating the coating liquid with ultraviolet rays.
[2] The production method according to [1], wherein the dopant is an organic compound containing trivalent iodine.
[3] The production method according to [1] or [2], wherein the dopant is a diaryliodonium salt.
[4] The production method according to any one of [1] to [3], wherein the organic semiconductor compound is a triarylamine compound.
[5] The electronic device comprises a pair of electrodes composed of a lower electrode and an upper electrode, an active layer containing a perovskite compound between the pair of electrodes, and an active layer between the pair of electrodes and the active layer. and a buffer layer, wherein the semiconductor layer is the buffer layer.
[6] The manufacturing method according to [5], wherein the buffer layer is a hole extraction layer.
[7] The manufacturing method according to [5] or [6], wherein the buffer layer is positioned between the upper electrode and the active layer.
[8] An electronic device manufactured by the manufacturing method according to any one of [1] to [7].
and/ Alternatively, a manufacturing method comprising a step of irradiating the coating liquid with ultraviolet rays.
[10] A coating liquid for forming a semiconductor layer produced by the production method described in [9].
[11] An electronic device comprising a semiconductor layer, wherein the semiconductor layer contains an organic semiconductor compound doped with a dopant, and the amount of unreacted dopant contained in the semiconductor layer has been reacted with the amount of unreacted dopant. An electronic device characterized in that the dopant amount, which is the sum of the dopant amounts, is 80% by mass or less.
[12] The coating liquid for forming a semiconductor layer, wherein the coating liquid for forming a semiconductor layer contains an organic semiconductor compound doped with a dopant, and the amount of unreacted dopant contained in the coating liquid for forming a semiconductor layer is A coating liquid for forming a semiconductor layer, wherein the amount of dopant, which is the sum of the amount of unreacted dopant and the amount of reacted dopant, is 80% by mass or less.

It is possible to improve the durability of an electronic device having a semiconductor layer.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which represents typically the photoelectric conversion element as one Embodiment. 1 is a cross-sectional view schematically showing a solar cell as one embodiment; FIG. 1 is a cross-sectional view schematically showing a solar cell module as one embodiment; FIG.

Embodiments of the present invention are described in detail below. The description of the constituent elements described below is an example (representative example) of the embodiments of the present invention, and the present invention is not limited to these contents as long as it does not exceed the gist of the present invention.

The present invention relates to a method of manufacturing an electronic device with a semiconductor layer. In the production method according to the present invention, a coating liquid containing an organic semiconductor compound and a dopant for the organic semiconductor compound that is a hypervalent iodine compound is heated to 85° C. or higher and/or the coating liquid is irradiated with ultraviolet rays. Afterwards, a step of forming a semiconductor layer by applying a coating liquid is included. The semiconductor layer-forming coating liquid used in the step of forming the semiconductor layer, the method for producing the same, and the electronic device produced by this method will also be described below.

[Organic semiconductor compound]
A semiconducting compound refers to a compound that exhibits semiconducting properties and can be used as a semiconducting material. In this specification, the term "semiconductor" is defined by the magnitude of carrier mobility in a solid state. Carrier mobility, as is well known, is a measure of how fast (or how much) charges (electrons or holes) can be moved. Specifically, the “semiconductor” in this specification preferably has a carrier mobility at room temperature of 1.0×10 ⁻⁶ cm ² /V·s or more, more preferably 1.0×10 ⁻⁵ cm ² /V·s or more. , more preferably 5.0×10 ⁻⁵ cm ² /V·s or more, and particularly preferably 1.0×10 ⁻⁴ cm ² /V·s or more. Note that the carrier mobility can be measured, for example, by measuring IV characteristics of a field effect transistor or by a time-of-flight method.

Although an organic semiconductor compound is used as the semiconductor compound in this embodiment, the type thereof is not particularly limited, and conventionally known compounds can be used, for example. Low-molecular-weight compounds and high-molecular-weight compounds are known as organic semiconductor compounds. Low-molecular-weight organic semiconductor compounds include polycyclic aromatic compounds, and specific examples include acene compounds such as tetracene or pentacene, oligothiophenes, phthalocyanines, perylenes, rubrenes, or thoria. and arylamine compounds such as arylamine compounds. Further, as the high-molecular organic semiconductor compound, polythiophene-based polymer, polyacetylene-based polymer, polyaniline-based polymer, polyphenylene-based polymer, polyphenylene vinylene-based polymer, polyfluorene-based polymer, or conjugated polymer such as polypyrrole-based polymer, or triaryl Arylamine polymers such as amine polymers are included.

The organic semiconductor compound is preferably an arylamine compound, more preferably a triarylamine compound. An arylamine compound is a compound having an arylamine structure (a bond between an aryl group and a nitrogen atom), and includes arylamine polymers. An arylamine polymer is a polymer whose repeating units contain an arylamine structure. A triarylamine compound is a compound having a triarylamine structure (three aryl groups bonded to the same nitrogen atom), and includes triarylamine polymers. A triarylamine polymer is a polymer whose repeating unit contains a triarylamine structure. Such an arylamine compound or triarylamine compound is preferable in that it can be stably oxidized by a dopant and exhibit good semiconductor properties.

Here, the aryl group (or aromatic group) refers to an aromatic hydrocarbon group or an aromatic heterocyclic group, which is a monocyclic group, a condensed ring group, and a monocyclic or condensed ring group. things, including The aromatic group is not particularly limited, but preferably has 30 or less carbon atoms, more preferably 12 or less carbon atoms. Specific examples of aromatic hydrocarbon groups include a phenyl group, a naphthyl group, a biphenyl group, and the like. Specific examples of the aromatic heterocyclic group include thienyl group, furyl group, pyrrolyl group, pyridyl group, imidazolyl group and the like.

The aromatic group may have further substituents. The substituents that the aromatic group may have are not particularly limited, but are halogen atoms, hydroxyl groups, cyano groups, amino groups, carboxyl groups, ester groups, alkylcarbonyl groups, acetyl groups, sulfonyl groups, silyl groups, Boryl group, nitrile group, alkyl group, alkenyl group, alkynyl group, alkoxy group, thio group, seleno group, aromatic hydrocarbon group, aromatic heterocyclic group and the like. A preferred substituent of the aryl group is an amino group or an alkyl group having 1 to 6 carbon atoms. Here, the amino group is preferably a dialkylamino group having 2 to 12 carbon atoms, an alkylarylamino group having 7 to 20 carbon atoms, or a diarylamino group having 12 to 30 carbon atoms.

Preferred examples of organic semiconductor compounds include compounds represented by the following formula (I) or (II).

In formulas (I) and (II), Ar ¹ is a divalent aromatic group and Ar ² is a direct bond or a divalent aromatic group. Ar ¹ and Ar ² may be the same or different. A divalent aromatic group is a substituent obtained by removing one hydrogen atom from the previously described aromatic group. Ar ¹ and Ar ² are each independently preferably a divalent aromatic group having 2 to 20 carbon atoms, more preferably an aromatic hydrocarbon group having 6 to 20 carbon atoms (single ring, condensed ring and those in which single rings or condensed rings are connected). These divalent aromatic groups preferably have no further substituents or carry alkyl groups of 1 to 6 carbon atoms.

In formulas (I) and (II), Ar ³ to Ar ⁵ are aromatic groups which may have a substituent. As the aromatic group, those previously described can be used. Ar ³ to Ar ⁵ may be the same aromatic group or different aromatic groups. Ar ³ to Ar ⁵ are each independently preferably an aromatic group having 2 to 20 carbon atoms, more preferably an aromatic hydrocarbon group having 6 to 20 carbon atoms (monocyclic, condensed ring, and those in which monocyclic or condensed rings are connected). These aromatic groups preferably have no further substituents or carry the abovementioned amino groups or C 1 -C 6 alkyl groups.

Specific examples of organic semiconductor compounds include the following compounds.

[Dopant]
In this embodiment, a hypervalent iodine compound is used as the dopant. Hypervalent iodine compounds act as dopants for organic semiconductor compounds. Hypervalent iodine compounds are known to exhibit electron-accepting properties (that is, act as oxidants). Also, the electron-accepting dopant can improve the conductivity or hole-transporting ability of the semiconductor compound by removing electrons from the semiconductor compound. Thus, hypervalent iodine compounds can improve the charge transport properties of semiconductor compounds used in electronic devices.

A hypervalent iodine compound is a compound containing hypervalent iodine and is defined as a compound containing iodine having an oxidation number of +3 or higher. For example, the dopant can be an iodine (III) compound or an iodine (V) compound. The iodine (V) compound containing pentavalent iodine can be, for example, a periodinane compound such as Dess-Martin periodinane. Examples of iodine (III) compounds containing trivalent iodine include compounds having a structure in which iodobenzene is oxidized, such as (diacetoxyiodo)benzene, and diaryliodonium salts. It is preferable to use a diaryliodonium salt because it exhibits good electron-accepting properties and the reverse reaction is less likely to occur if the molecule is destroyed during the oxidation process.

A diaryliodonium salt is a salt having the [Ar-I ⁺ -Ar]X ^- structure. Here, two Ars each represent an aryl group. The aryl group (aromatic group) is not particularly limited and can be, for example, those already mentioned for the organic semiconductor compounds. X ⁻ represents any anion. X ^- can be, for example, a halide ion, a trifluoroacetate ion, a tetrafluoroborate ion, a tetrakis(pentafluorophenyl)borate ion, or the like. X 1 ⁻ is preferably an anion having a fluorine atom in terms of high solubility and smooth progress of the coating liquid production reaction.

Preferred examples of dopants include those represented by general formula (III). In formula (III), X ^- represents an arbitrary anion, and specific examples are as described above.

In formula (III), R ¹ and R ² are each independently a monovalent organic group. Examples of monovalent organic groups include aliphatic or aromatic groups. Examples of aliphatic groups include aliphatic hydrocarbon groups having 1 to 20 carbon atoms and aliphatic heterocyclic groups having 4 to 20 carbon atoms. For example, the aliphatic group includes an alkyl group including a cycloalkyl group, an alkenyl group, or an alkynyl group, and specific examples include a methyl group, an ethyl group, a butyl group, a cyclohexyl group, a tetrahydrofuryl group, and the like. be done.

Examples of aromatic groups include aromatic hydrocarbon groups having 6 to 20 carbon atoms or aromatic heterocyclic groups having 2 to 20 carbon atoms. For example, aromatic groups include a phenyl group, a naphthyl group, a biphenyl group, a thienyl group, a pyridyl group, and the like.

In addition, said aliphatic group and aromatic group may have a substituent. Substituents which may be present are not particularly limited, but are halogen atoms, hydroxyl groups, cyano groups, amino groups, carboxyl groups, ester groups, alkylcarbonyl groups, acetyl groups, sulfonyl groups, silyl groups, and boryl groups. , nitrile group, alkyl group, alkenyl group, alkynyl group, alkoxy group, thio group, seleno group, aromatic hydrocarbon group, aromatic heterocyclic group and the like.

R ¹ and R ² are preferably aromatic hydrocarbon groups having 6 to 20 carbon atoms, more preferably phenyl groups. Here, the aromatic hydrocarbon group preferably has no substituent or has an alkyl group having 1 to 6 carbon atoms. R ¹ and R ² are particularly preferably phenyl groups having an alkyl group at the para-position.

[Preparation of coating liquid]
In the present embodiment, the coating liquid containing the organic semiconductor compound and the dopant for the organic semiconductor compound which is a hypervalent iodine compound is heated to 85° C. or higher and/or the coating liquid is irradiated with ultraviolet rays, thus A coating liquid for forming a semiconductor layer is prepared. For example, first, a solution containing an organic semiconductor compound and a dopant for the organic semiconductor compound, which is a hypervalent iodine compound, is prepared. Next, the prepared solution is heated above 85° C. and/or the solution is irradiated with ultraviolet light. In this way, a coating liquid for forming a semiconductor layer can be produced.

First, a solution is prepared containing an organic semiconductor compound and a dopant. Specifically, an organic semiconductor compound and a dopant are dissolved in a solvent. However, it is not necessary to completely dissolve these compounds in the solvent, and the compounds may be dissolved in the solvent when heating or irradiating with ultraviolet rays.

A solvent capable of dissolving the semiconductor compound and the dopant is used as the solvent. Also, preferably, a solvent having a boiling point higher than the temperature at which the solution is prepared is used. Examples of solvents include aliphatic hydrocarbons such as heptane, octane, isooctane, nonane or decane; aromatics such as toluene, xylene, mesitylene, cumene, tetralin, cyclohexylbenzene, fluorobenzene, chlorobenzene, bromobenzene or orthodichlorobenzene Alicyclic hydrocarbons such as methylcyclohexane, cycloheptane, cyclooctane or decalin; Aliphatic ketones such as cyclopentanone or cyclohexanone; Aromatic ketones such as acetophenone or propiophenone; Esters such as butyl, methyl lactate, methyl benzoate, ethyl benzoate, isopropyl benzoate, isobutyl benzoate or isoamyl benzoate; halogenated hydrocarbons such as trichlorethylene; or cyclopentyl methyl ether, anisole, diphenyl ether, dimethoxyethane Alternatively, ethers such as dioxane can be used.

The prepared solution is then heated to 85° C. or higher, or the solution is irradiated with ultraviolet light, or both. When heating is performed, the heating method is not particularly limited. For example, a heat source such as a hot plate may be used, or a heating atmosphere such as an oven may be used. Moreover, when irradiating with ultraviolet rays, the irradiation method is not particularly limited, and for example, an ultraviolet lamp can be used. The solution can be stirred during heating or UV irradiation. In the present invention, ultraviolet light means light with a wavelength of 200 nm or more and less than 400 nm.

According to studies by the inventors of the present application, the durability of an electronic device having a semiconductor layer formed using the obtained coating liquid for forming a semiconductor layer is improved by heating to 85° C. or higher or by irradiating with ultraviolet rays. improves. Although the reason for this is not clear, the inventors of the present application believe that heating to 85° C. or higher or ultraviolet irradiation causes a chemical change in the organic semiconductor compound in the solution.

It is known that an electronic device having a semiconductor layer formed using this semiconductor layer-forming coating liquid functions even when the semiconductor layer-forming coating liquid is prepared by heating at 70° C. or lower as in the conventional method. rice field. However, the inventors of the present application have found that the electronic device manufactured in this manner loses its performance in a short period of time in a high-temperature and high-humidity environment. The inventors of the present application believe that the reason for this is that charge transfer from the semiconductor compound to the dopant occurs even in conventional methods, so that although the semiconductor layer initially exhibits charge transport properties, the oxidation state of the semiconductor compound is unstable. It is presumed that the charge of the dopant is likely to return to the semiconductor compound again in a high-temperature and high-humidity environment. As a result, the semiconductor layer becomes electrically neutral, which reduces the conductivity and degrades the performance of the electronic device.

On the other hand, heating to 85° C. or higher or ultraviolet irradiation oxidizes the organic semiconductor compound through a chemical reaction between the dopant and the organic semiconductor compound, so that the organic semiconductor compound becomes stable in an oxidized state. The inventors of the present application presume that the phenomenon in which the charge of the semiconductor layer returns to the dopant again becomes less likely to occur. For example, when a dopant is destroyed at high temperatures and the organic semiconductor compound is oxidized as a result of the generation of an active oxidizing agent, the reaction in which the organic semiconductor compound acquires charge again is unlikely to progress.

In particular, the reaction between the dopant and the organic semiconductor compound can be expected to proceed smoothly by heating to 85° C. or higher or by irradiating with ultraviolet rays, since the reaction generally proceeds easily in a solution state. On the other hand, even if the semiconductor layer is formed by applying the coating liquid for forming the semiconductor layer, and the temperature is raised when drying this, it is expected that the reaction in the solid will not proceed smoothly. In this embodiment, the semiconductor layer is formed by coating at a temperature low enough not to damage the electronic device by heating to 85 ° C. or higher or irradiating ultraviolet rays in a solution state. Also, it is considered that a semiconductor layer having sufficiently high conductivity and being thermodynamically stable was formed.

In one embodiment, the amount of unreacted dopant contained in the coating liquid for forming a semiconductor layer is 80% by mass or less of the amount of dopant. Here, the dopant amount is the sum of the unreacted dopant amount and the reacted dopant amount. An unreacted dopant refers to a dopant that has not undergone a chemical reaction with the organic semiconductor compound and is not destroyed, so that the charge it has can return to the organic semiconductor compound. Also, the term "reacted dopant" refers to a decomposition product of a dopant that has been destroyed through a chemical reaction with an organic semiconductor compound and thus does not have the ability to charge the organic semiconductor compound again. In another embodiment, the dopant amount refers to the amount of dopant used to prepare the semiconductor layer-forming coating liquid.

As described above, if the chemical reaction between the organic semiconductor compound and the dopant progresses to some extent, the phenomenon in which the semiconductor layer loses its charge transport property is less likely to occur, and the chemical reaction between the organic semiconductor compound and the dopant progresses completely. It is considered that a semiconductor layer having higher durability can be obtained by the above. From this point of view, the amount of unreacted dopant contained in the semiconductor layer-forming coating liquid is preferably 60% by mass or less, more preferably 40% by mass or less, and 20% by mass or less of the dopant amount. is more preferred, and substantially absent is particularly preferred. The amount of unreacted dopant can be confirmed by chemical analysis, and can also be estimated by a quantitative method using ultraviolet-visible absorption spectrum.

From the viewpoint of sufficiently advancing the reaction, the temperature of the solution during heating is preferably 90°C or higher, more preferably 95°C or higher, further preferably 100°C or higher, and 115°C. It is more preferably 135° C. or higher, and particularly preferably 150° C. or higher. On the other hand, in order to prevent the decomposition of the compound semiconductor, it is preferably below the thermal decomposition temperature of the semiconductor compound. In the present invention, thermal decomposition temperature means the temperature at which the mass is reduced by 5% as measured by TG-DTA.

From the viewpoint of sufficiently advancing the reaction, the heating time is preferably 10 minutes or longer, more preferably 20 minutes or longer, and even more preferably 30 minutes or longer. Although the upper limit of time is not particularly limited, it can be, for example, 10 hours or less.

When ultraviolet irradiation is performed, the chemical reaction can be sufficiently advanced by irradiating the solution containing the organic semiconductor compound and the dopant with an ultraviolet dose of 0.1 J/cm ² or more. It is more preferably 0.5 J/cm ² or more, still more preferably 1 J/cm ² or more. On the other hand, in order to prevent decomposition of the semiconductor compound, the amount of ultraviolet rays is preferably 1000 J/cm ² or less. It is more preferably 800 J/cm ² or less, still more preferably 500 J/cm ² or less. Although there is no particular limitation on the intensity of ultraviolet rays, for example, ultraviolet rays with an intensity of 5 mW/cm ² or more at 365 nm can be used. Although there are no particular restrictions on the ultraviolet light source, a mercury lamp or a metal halide lamp can be used.

Moreover, both heating to 85° C. or higher and ultraviolet irradiation may be performed on the coating liquid for forming the semiconductor layer. For example, the semiconductor layer-forming coating liquid may be heated to 85° C. or higher and then irradiated with ultraviolet rays, or the semiconductor layer-forming coating liquid may be heated to 85° C. or higher after being irradiated with ultraviolet rays. Alternatively, the coating solution for forming a semiconductor layer may be heated to 85° C. or more and irradiated with ultraviolet rays at the same time. As the reaction conditions in these cases, the above-mentioned conditions can be appropriately adjusted and used so that the reaction between the dopant and the semiconductor compound can proceed smoothly.

The concentrations of the organic semiconductor compound and the dopant in the coating solution are not particularly limited, and can be appropriately set according to the desired thickness of the semiconductor layer. For example, the concentration of the organic semiconductor compound in the coating liquid may be 1.0% by mass or more and may be 10% by mass or less. Moreover, the amount of the dopant in the coating liquid may be 1.0% by mass or more and may be 20% by mass or less with respect to the amount of the organic semiconductor compound in the coating liquid.

[Application of coating liquid]
In this embodiment, the semiconductor layer is formed by applying the coating liquid prepared as described above. Any method can be used as a method for applying the coating liquid, and examples include spin coating, ink jet method, doctor blade method, drop casting method, reverse roll coating method, gravure coating method, kiss coating method, roll brush method, A spray coating method, an air knife coating method, a wire barber coating method, a pipe doctor method, an impregnation/coating method, a curtain coating method, or the like can be used.

Heat drying can be performed after applying the coating liquid. The heating temperature at this time is not particularly limited, but from the viewpoint of sufficiently removing the solvent, it is preferably 60° C. or higher, more preferably 80° C. or higher. On the other hand, in order to suppress damage to the electronic device, the heating temperature is preferably lower than the temperature during preparation of the coating liquid. Specifically, the heating temperature is preferably less than 150°C, more preferably less than 135°C, even more preferably less than 115°C, more preferably less than 100°C, still more preferably less than 95°C, more preferably less than 90°C. Particularly preferably, it is less than 85°C. The heating time is also not particularly limited, but from the viewpoint of sufficiently removing the solvent, it is preferably 1 minute or more, more preferably 3 minutes or more, while from the viewpoint of improving production efficiency, it is preferably 10 hours or less. , and more preferably 1 hour or less. These heatings may be performed under normal pressure or under reduced pressure.

The thickness of the semiconductor layer is not particularly limited, and can be appropriately selected according to the application of the semiconductor layer. As an example, the thickness of the semiconductor layer may be 0.5 nm or more and 500 nm or less.

[Electronic device]
The type of electronic device is not particularly limited. In this specification, the electronic device is a device that has two or more electrodes and controls the current flowing between the electrodes or the voltage generated by electricity, light, magnetism, chemical substances, etc., or between the electrodes A device that generates light, an electric field, a magnetic field, or the like by applying voltage or current. Specific examples include an element that controls current or voltage by applying voltage or current, an element that controls voltage or current by applying a magnetic field, or an element that controls voltage or current by acting a chemical substance. Specific examples of control include rectification, switching, amplification, or oscillation.

Examples of electronic devices include resistors, rectifiers (diodes), switching elements (transistors, thyristors), amplifying elements (transistors), memory elements, chemical sensors, etc., or semiconductors obtained by combining or integrating these elements. device. Further examples of electronic devices include optical elements, which include photodiodes or phototransistors that generate photocurrent, electroluminescent elements that emit light when an electric field is applied, or photoelectric conversion that generates electromotive force due to light. Elements or solar cells are included. As a more specific example of the semiconductor device, S.H. M. Sze, Physics of Semiconductor Devices, 2nd Edition (Wiley Interscience 1981).

The electronic device according to this embodiment includes a semiconductor layer, but its specific configuration is not particularly limited. In one embodiment, an electronic device has a pair of electrodes and a semiconductor layer disposed between the pair of electrodes. The semiconductor layer is obtained by applying the semiconductor layer-forming coating liquid according to the present embodiment. The type of electrode is not particularly limited. Suitable materials can be used to fabricate the electrodes, depending on the type of electronic device.

Preferred examples of electronic devices include electroluminescent devices (LEDs), photoelectric conversion devices, and solar cells. For example, an electroluminescent device (LED) according to one embodiment includes a pair of electrodes, an anode and a cathode, a light-emitting layer disposed between the electrodes, and a semiconductor layer disposed between the light-emitting layer and one of the electrodes. and can be provided. In one embodiment, the semiconductor layer obtained by applying the semiconductor layer-forming coating liquid according to the present embodiment is provided as a hole transport layer between the light emitting layer and the anode.

As described above, in this embodiment, the electronic device is manufactured by a manufacturing method including a step of forming a semiconductor layer by applying the coating liquid prepared as described above. The method for manufacturing the electronic device according to this embodiment is not particularly limited, and can be determined as appropriate according to the configuration of the electronic device. For example, an electronic device can be manufactured by a step of forming a semiconductor layer by applying a coating liquid on a substrate on which an electrode is formed, and a step of forming an electrode on the semiconductor layer.

After forming the semiconductor layer, the electronic device can be heated, for example, after the elements that make up the electronic device are formed. This step is sometimes called an annealing treatment step, and can have the effect of improving the adhesion between elements constituting the electronic device and improving the performance of the electronic device. The heating temperature at this time is not particularly limited, but is preferably 50° C. or higher, more preferably 80° C. or higher, from the viewpoint of obtaining a sufficient effect of improving adhesion. In addition, it is preferable to heat in a temperature range of preferably 300° C. or lower, more preferably 280° C. or lower, and more preferably 250° C. or lower. On the other hand, in order to suppress damage to the electronic device, the heating temperature is preferably lower than the temperature during preparation of the coating liquid. Specifically, the heating temperature is preferably less than 150°C, more preferably less than 135°C, even more preferably less than 115°C, more preferably less than 100°C, even more preferably less than 95°C, more preferably less than 90°C, especially It is preferably less than 85°C. The heating time is also not particularly limited, but from the viewpoint of obtaining a sufficient effect of improving adhesion, it is preferably 1 minute or more, more preferably 3 minutes or more. minutes or less, more preferably 60 minutes or less. These heatings may be performed under normal pressure or under reduced pressure.

A photoelectric conversion element having a semiconductor layer will be described below as a preferred example of the electronic device.

[Photoelectric conversion element]
The photoelectric conversion device according to this embodiment includes a pair of electrodes composed of a lower electrode and an upper electrode, an active layer between the pair of electrodes, and a buffer layer between the pair of electrodes and the active layer. Prepare. In one embodiment, the buffer layer is a semiconductor layer obtained by applying the semiconductor layer-forming coating liquid according to the present embodiment.

FIG. 1 is a cross-sectional view schematically showing one embodiment of a photoelectric conversion element according to the present invention. The photoelectric conversion element shown in FIG. 1 is a photoelectric conversion element used in general thin-film solar cells, but the photoelectric conversion element according to the present invention is not limited to that shown in FIG. A photoelectric conversion element 100 according to one embodiment of the present invention has a layered structure in which a substrate 108, a lower electrode 101, a buffer layer 102, an active layer 103, a buffer layer 105, and an upper electrode 107 are formed in this order. As shown in FIG. 3, when the photoelectric conversion element 100 has a structure in which each layer is laminated on the base material 108, the electrode near the base material 108 is the lower electrode 101, and the electrode far from the base material 108 is the upper electrode 107. can be called respectively. Note that it is not always necessary to provide both the buffer layer 102 and the buffer layer 105 .

Moreover, the photoelectric conversion element 100 may further have other layers. Other layers include a work function tuning layer for adjusting the work function of the lower electrode 101 or the upper electrode 107, an insulator layer, and the like.

The semiconductor layer obtained by applying the semiconductor layer-forming coating liquid according to the present embodiment can exhibit good hole transport properties, and thus can be preferably used as a hole extraction layer. For example, in one embodiment, one of bottom electrode 101 and top electrode 107 is a cathode and the other is an anode. In one embodiment, bottom electrode 101 is the cathode, where buffer layer 102 is the electron extraction layer, buffer layer 105 is the hole extraction layer, and top electrode 107 is the anode. In such a configuration, the buffer layer 105 (hole extraction layer) located between the upper electrode 107 and the active layer 103 is obtained by applying the semiconductor layer forming coating solution according to the present embodiment. It can be a semiconductor layer. Also, in one embodiment, the bottom electrode 101 is the anode, where the buffer layer 102 is the hole extraction layer, the buffer layer 105 is the electron extraction layer, and the top electrode 107 is the cathode. In such a configuration, the buffer layer 102 (hole extraction layer) can be a semiconductor layer obtained by applying the semiconductor layer forming coating liquid according to the present embodiment.

In addition, since the semiconductor layer obtained by applying the semiconductor layer forming coating liquid according to the present embodiment can exhibit high durability, it is located between the upper electrode 107 and the active layer 103 and is not affected by the outside world. It can be preferably used as the susceptible buffer layer 105 .

(1. Active layer 103)
The active layer 103 is a layer in which photoelectric conversion is performed. When the photoelectric conversion element 100 receives light, the light is absorbed by the active layer 103 to generate carriers, which are extracted from the lower electrode 101 and the upper electrode 107 .

The type of the active layer 103 is not particularly limited, and conventionally known ones can be used. For example, the active layer 103 may be a heterojunction active layer including a layer containing a p-type semiconductor compound such as a porphyrin derivative and a layer containing a fullerene derivative n-type semiconductor compound. Also, the active layer 103 may be a bulk hetero-type active layer having a layer (i-layer) in which a p-type semiconductor compound and an n-type semiconductor compound are mixed. Also, the active layer 103 may be a layer containing a perovskite compound.

Preferably, active layer 103 is a layer containing a perovskite compound. A solar cell having such an active layer 103 is known as a perovskite solar cell. In a perovskite semiconductor, a perovskite compound having a perovskite structure forms a crystal. In such crystals, fast charge separation occurs and the diffusion distance of holes and electrons is long, resulting in efficient charge separation. The present invention is particularly effective in manufacturing a photoelectric conversion device using an active layer containing a perovskite compound. The reason for this is that the perovskite compound is usually insoluble in the solvent used in the semiconductor layer-forming coating liquid, and the layer formed from the semiconductor layer-forming coating liquid is a layer containing a perovskite compound. Since it is insoluble in the solvent used to form the layer, it can be laminated by a coating process without deteriorating each layer.

A perovskite compound refers to a semiconductor compound having a perovskite structure. The perovskite compound is not particularly limited, but can be selected from, for example, those listed in Galasso et al. Structure and Properties of Inorganic Solids, Chapter 7 - Perovskite type and related structures. For example, perovskite compounds include those represented by the general _{formula AMX3} or those represented by the general formula _A2MX4 . Here, M denotes a divalent cation, A denotes a monovalent cation, and X denotes a monovalent anion. An appropriate perovskite compound can be selected according to the type of semiconductor device. As the perovskite compound, it is preferable to use a semiconductor compound having an energy bandgap of 1.0 eV or more and 3.5 eV or less.

Although there is no particular limitation on the monovalent cation A, those described in the above-mentioned Galasso can be used. More specific examples include cations containing elements of Groups 1 and 13-16 of the periodic table. Among these, cesium ions, rubidium ions, optionally substituted ammonium ions (including amidinium ions), optionally substituted phosphonium ions, or substituted Good amidinium ions are preferred. Examples of optionally substituted ammonium ions include primary ammonium ions and secondary ammonium ions. There are no particular restrictions on the substituents, either. Specific examples of ammonium ions which may have a substituent include alkylammonium ions, arylammonium ions, amidinium ions, guanidinium ions, and the like. In particular, in order to avoid steric hindrance, a monoalkylammonium ion having a three-dimensional crystal structure is preferable, and from the viewpoint of improving stability, it is preferable to use an alkylammonium ion substituted with one or more fluorine groups. A combination of two or more cations can also be used as the cation A.

Specific examples of the monovalent cation A include methylammonium ion, methylammonium monofluoride ion, methylammonium difluoride ion, methylammonium trifluoride ion, ethylammonium ion, isopropylammonium ion, n-propylammonium ion, and isobutylammonium ion. , n-butylammonium ion, t-butylammonium ion, dimethylammonium ion, diethylammonium ion, phenylammonium ion, benzylammonium ion, phenethylammonium ion, guanidinium ion, formamidinium ion, acetamidinium ion or imidazolium ions and the like.

Although the divalent cation M is not particularly limited, it is preferably a divalent metal cation or metalloid cation. Specific examples include cations of Group 14 elements of the periodic table, and more specific examples include lead cations (Pb ²⁺ ), tin cations (Sn ²⁺ ), and germanium cations (Ge ²⁺ ). A combination of two or more cations can also be used as the cation M. From the viewpoint of obtaining a stable photoelectric conversion device, it is particularly preferable to use lead cations or two or more kinds of cations containing lead cations.

Examples of monovalent anions X include halide ions, acetate ions, nitrate ions, sulfate ions, borate ions, acetylacetonate ions, carbonate ions, citrate ions, sulfur ions, tellurium ions, thiocyanate ions, titanates. ions, zirconate ions, 2,4-pentanedionate ions, silicofluoride ions, and the like. In order to adjust the bandgap, X may be one type of anion or a combination of two or more types of anions. Among them, as X, it is preferable to use a halide ion or a combination of a halide ion and another anion. Examples of halide ions X include chloride ions, bromide ions, iodide ions, and the like.

Preferred examples of perovskite compounds include organic-inorganic perovskite compounds, particularly halide-based organic-inorganic perovskite compounds. _{Specific examples of perovskite compounds include CH3NH3PbI3 , CH3NH3PbBr3 , CH3NH3PbCl3 , CH3NH3SnI3 , CH3NH3SnBr3 , CH3NH3SnCl3 ,} CH3NH3PbI _{(3-x) Clx , CH3NH3PbI ( 3} - _{x )} Brx _{, CH3NH3PbBr} ( ₃ - _{x )} Clx _, CH3NH3Pb _(1-y) Sn _y I ₃ , CH ₃ NH ₃ Pb _(1-y) Sn _y Br ₃ , CH ₃ NH ₃ Pb _(1-y) Sn _y Cl ₃ , CH ₃ NH ₃ Pb _(1-y) Sn _y I _{(3- x)} Cl _x , CH ₃ NH ₃ Pb _(1-y) Sn _y I _(3-x) Br _x , and CH ₃ NH ₃ Pb _(1-y) Sn _y Br _(3-x) Cl _x , and Examples include those using _CFH2NH3 , _{CF2HNH3 , CF3NH3 ,} and _{NH2CH = NH2 instead} of _CH3NH3 in the above compounds. Note that x is 0 or more and 3 or less, and y is any value of 0 or more and 1 or less.

The active layer 103 may contain two or more perovskite compounds. For example, the active layer 103 may contain two or more perovskite compounds in which at least one of A, B and X is different.

The amount of the perovskite compound contained in the active layer 103 is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more so as to obtain good semiconductor characteristics. . There is no particular upper limit.

There is no particular limitation on the thickness of the active layer 103 . The thickness of the active layer 103 is preferably 5 nm or more, more preferably 10 nm or more, more preferably 50 nm or more, and particularly preferably 120 nm or more, in order to absorb more light. On the other hand, the thickness of the active layer 103 is preferably 2000 nm or less, more preferably 1000 nm or less, in order to reduce series resistance.

A method for forming the active layer 103 is not particularly limited, and any method can be used. Specific examples include a coating method and a vapor deposition method (or a co-evaporation method). It is preferable to use the coating method because the active layer 103 can be easily formed.

An example of a method for producing the active layer 103 containing a perovskite compound includes a method of forming a semiconductor layer by applying a coating liquid containing a perovskite compound or its precursor. A perovskite compound precursor refers to a material that can be converted into a perovskite compound after applying a coating liquid. A specific example is a perovskite compound precursor that can be converted into a perovskite compound by heating. For example, by heating a film obtained by applying a coating liquid, a perovskite compound precursor can be converted into a perovskite compound, and a semiconductor layer containing a perovskite compound can be formed. Specific examples of the perovskite compound precursor include a compound represented by the following formula (2) and/or a compound represented by the following formula (3), which can be converted into a perovskite compound represented by the following (1) by heating. compounds that

One example is a method of preparing a coating liquid containing a compound represented by the following formula (2), a compound represented by the following formula (3), and a solvent, and coating the coating liquid. . Such a coating liquid can be prepared by heating and stirring a compound in a solution. According to this method, the active layer 103 containing the compound represented by the following formula (1) can be produced.

AMX ₃ (1)
AX (2)
MX ₂ (3)
The definitions of A, M and X are given above. Specific examples of AX include alkylammonium halide salts, and specific examples of MX ₂ include metal halides. AX and MX ₂ are precursors of the perovskite semiconductor compound AMX ₃ .

As another example, a coating liquid containing the compound represented by the above formula (2) and a solvent and a coating liquid containing the compound represented by the above formula (3) and a solvent are prepared. a method of coating with a brush. For example, first, a layer of the compound represented by formula (3) is formed by applying a coating liquid containing the compound represented by formula (3) and a solvent. By applying a coating liquid containing the compound represented by the above formula (2) and a solvent thereon, the active layer 103 containing the compound represented by the following formula (1) can be produced. . After applying each coating liquid, the layer can be dried and the crystallization of the perovskite semiconductor compound can be promoted by heating. Heating can be performed at, for example, 60° C. or higher or 180° C. or lower.

Solvents are those described in Brandrup, J.; Ed., "Polymer Handbook, 4th Ed.", the solubility parameter (SP value) is preferably 9 or more, particularly preferably 10 or more. Examples include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, pyridine, γ-butyrolactone and the like. As the solvent, a mixed solvent of two or more solvents may be used. Even when a mixed solvent is used, the solubility parameter of at least one of the mixed solvents is preferably 10 or more.

(2. Buffer layers 102 and 105)
Buffer layers can generally be classified as electron-extraction layers and hole-extraction layers. As described above, at least one of the buffer layers included in the photoelectric conversion element 100 can be a semiconductor layer obtained by applying the semiconductor layer forming coating liquid according to the present embodiment. Moreover, such a semiconductor layer is preferably used as a hole extraction layer. Note that the buffer layer 102 may be a hole extraction layer and the buffer layer 105 may be an electron extraction layer, or the buffer layer 102 may be an electron extraction layer and the buffer layer 105 may be a hole extraction layer. The buffer layer is preferably formed by applying the coating liquid for forming the semiconductor layer. The reason for this is that the wettability of the layer formed from the perovskite precursor solution using the semiconductor layer-forming coating liquid tends to decrease, whereas the semiconductor layer-forming composition One of the reasons for this is that it tends to have high wettability with respect to the active layer containing the lobuskite compound. In addition, when the electrode 107 is formed by a sputtering process, the layer formed by the coating liquid for forming the semiconductor layer tends to be difficult to oxidize. Each of the hole extraction layer and the electron extraction layer will be described below. Note that one buffer layer may be composed of a plurality of different films.

The material of the hole extraction layer is not particularly limited as long as it can improve the efficiency of hole extraction from the active layer 103 to the anode. As described above, it is preferable to use the semiconductor layer obtained by applying the semiconductor layer forming coating liquid according to the present embodiment as the hole extraction layer. Another example of the material for the hole extraction layer includes inorganic compounds or organic compounds described in known documents such as International Publication No. 2013/171517, International Publication No. 2013/180230, and JP-A-2012-191194. be done.

For example, inorganic compounds include metal oxides such as copper oxide, nickel oxide, manganese oxide, iron oxide, molybdenum oxide, vanadium oxide, and tungsten oxide. Examples of organic compounds include conductive polymers obtained by doping polythiophene, polypyrrole, polyacetylene, triphenylenediamine, polyaniline, or the like with sulfonic acid and iodine (e.g., PEDOT:PSS or doped P3HT), and sulfonyl groups as substituents. polythiophene derivatives, conductive organic compounds such as arylamines, Nafion, or lithium-doped spiro-OMeTAD.

The thickness of the entire hole extraction layer is not particularly limited, but is preferably 0.5 nm or more. On the other hand, it is preferably 400 nm or less, more preferably 200 nm or less. When the film thickness of the hole extraction layer is 0.5 nm or more, the function as a buffer material is well fulfilled. Photoelectric conversion efficiency can be improved.

There are no restrictions on the method of forming the hole extraction layer. When a sublimable compound is used, it can be formed by a dry film-forming method such as a vacuum deposition method. Moreover, when a compound soluble in a solvent is used, it can be formed by a wet film formation method such as a spin coating method or an inkjet method.

The material of the electron extraction layer is not particularly limited as long as it can improve the efficiency of electron extraction from the active layer 103 to the cathode. Specific examples include inorganic compounds, organic compounds, or organic-inorganic perovskite compounds described in known documents such as WO 2013/171517, WO 2013/180230, and JP-A-2012-191194.

For example, inorganic compounds include salts of alkali metals such as lithium, sodium, potassium, or cesium, and metal oxides such as zinc oxide, titanium oxide, aluminum oxide, indium oxide, or tin oxide. Examples of organic compounds include bathocuproine (BCP), bathophenanthrene (Bphen), (8-hydroxyquinolinato)aluminum (Alq3), boron compounds, oxadiazole compounds, benzimidazole compounds, naphthalenetetracarboxylic anhydride (NTCDA), Examples include perylenetetracarboxylic anhydride (PTCDA), fullerene compounds, and phosphine compounds having a Group 16 element of the periodic table and a double bond, such as phosphine oxide compounds or phosphine sulfide compounds.

There is no particular limitation on the method of forming the electron extraction layer. When a sublimable compound is used as a material, it can be formed by a dry film-forming method such as a vacuum deposition method. When a compound soluble in a solvent is used as a material, it can be formed by a wet film formation method such as a spin coating method or an inkjet method.

The total thickness of the electron extraction layer is not particularly limited, but is preferably 0.5 nm or more, more preferably 1 nm or more, more preferably 5 nm or more, and particularly preferably 10 nm or more. On the other hand, it is preferably 1 μm or less, more preferably 700 nm or less, more preferably 400 nm or less, and particularly preferably 200 nm or less. When the film thickness of the electron extraction layer 105 is within the above range, uniform coating is facilitated, and the electron extraction function can be well exhibited.

(3. Electrodes 101, 107)
The electrode has a function of collecting holes and electrons generated by light absorption. Therefore, as the pair of electrodes, it is preferable to use an anode suitable for collecting holes and a cathode suitable for collecting electrons. Either one of the pair of electrodes may be translucent, or both may be translucent. Having translucency refers to transmitting 40% or more of sunlight. In addition, it is preferable that the transparent electrode has a sunlight transmittance of 70% or more so that more light can pass through the transparent electrode and reach the active layer 103 . The light transmittance can be measured with a spectrophotometer (eg, U-4100 manufactured by Hitachi High-Tech).

The components of the anode and cathode and the manufacturing method thereof are not particularly limited, and well-known techniques can be used. For example, members described in known documents such as International Publication No. 2013/171517, International Publication No. 2013/180230, or Japanese Patent Application Laid-Open No. 2012-191194 and manufacturing methods thereof can be used.

(4. Substrate 108)
The photoelectric conversion element 100 usually has a base material 108 that serves as a support. However, the photoelectric conversion element according to the present invention does not have to have the substrate 108 . The material of the base material 108 is not particularly limited as long as it does not significantly impair the effects of the present invention. can be used.

(5. Method for producing a photoelectric conversion element)
By forming each layer constituting the photoelectric conversion element 100 according to the method described above, the photoelectric conversion element 100 can be manufactured. Moreover, in order to improve durability, the photoelectric conversion element 100 may be further sealed. For example, the photoelectric conversion element 100 can be sealed by further laminating a sealing plate on the upper electrode 107 and fixing the base material 108 and the sealing plate with an adhesive.

There is no particular limitation on the method of forming each layer constituting the photoelectric conversion element 100, and the layers can be formed by a sheet-to-sheet (Manyo) method or a roll-to-roll method. In addition, the roll-to-roll method is a method in which a flexible base material wound in a roll is unwound and processed while being transported intermittently or continuously until it is wound up by a winding roll. be. According to the roll-to-roll method, long substrates on the order of km can be collectively processed, so the roll-to-roll method is more suitable for mass production than the sheet-to-sheet method. On the other hand, when each layer is formed by a roll-to-roll method, the film may be damaged or partially peeled off due to the contact between the film-forming surface and the roll due to its structure.

The size of the roll that can be used in the roll-to-roll method is not particularly limited as long as it can be handled by a roll-to-roll manufacturing apparatus, but the upper limit of the outer diameter is preferably 5 m or less, more preferably 3 m or less, more preferably 3 m or less. 1 m or less. On the other hand, the lower limit is preferably 10 cm or more, more preferably 20 cm or more, and still more preferably 30 cm or more. The upper limit of the outer diameter of the roll core is preferably 4 m or less, more preferably 3 m or less, and even more preferably 0.5 m or less. On the other hand, the lower limit is preferably 1 cm or more, more preferably 3 cm or more, more preferably 5 cm or more, still more preferably 10 cm or more, and particularly preferably 20 cm or more. It is preferable that these diameters are equal to or less than the above upper limit because the handleability of the roll is high. . The lower limit of the width of the roll is preferably 5 cm or more, more preferably 10 cm or more, and still more preferably 20 cm or more. On the other hand, the upper limit is preferably 5 m or less, more preferably 3 m or less, and more preferably 2 m or less. It is preferable that the width is equal to or less than the upper limit because the roll is easy to handle.

Further, after laminating the upper electrode 107, the photoelectric conversion element 100 can be subjected to the above-described annealing process. By performing the annealing process at a temperature of 50° C. or higher, the effect of improving the adhesion between the layers of the photoelectric conversion element 100 can be obtained, which is preferable. By improving the adhesion between each layer, the thermal stability, durability, etc. of the photoelectric conversion element can be improved. Stepwise heating using different temperatures may be performed in the annealing process.

The annealing process is preferably terminated when the open-circuit voltage, short-circuit current, and fill factor, which are parameters of solar cell performance, reach constant values. In order to prevent thermal oxidation of the constituent materials, the annealing process is preferably carried out under normal pressure and in an inert gas atmosphere. As a heating method, the photoelectric conversion element may be placed on a heat source such as a hot plate, or the photoelectric conversion element may be placed in a heating atmosphere such as an oven. Moreover, heating may be performed in a batch system or in a continuous system.

(6. Photoelectric conversion characteristics)
The photoelectric conversion characteristics of the photoelectric conversion element 100 can be obtained as follows. A solar simulator is used to irradiate the photoelectric conversion element 100 with light under AM1.5G conditions at an irradiation intensity of 100 mW/cm ² to measure current-voltage characteristics. From the resulting current-voltage curve, photoelectric conversion characteristics such as photoelectric conversion efficiency (PCE), short-circuit current density (Jsc), open-circuit voltage (Voc), fill factor (FF), series resistance, and shunt resistance can be obtained.

The photoelectric conversion efficiency of the photoelectric conversion element 100 is not particularly limited, but is preferably 1% or higher, more preferably 1.5% or higher, and more preferably 2% or higher. On the other hand, there is no particular upper limit, and the higher the better. The fill factor of the photoelectric conversion element 100 is not particularly limited, but is preferably 0.6 or more, more preferably 0.7 or more, and still more preferably 0.9 or more. On the other hand, there is no particular upper limit, and the higher the better.

The photoelectric conversion element according to this embodiment is characterized by high durability. In one embodiment, the maintenance rate of the photoelectric conversion efficiency is 60% or more, preferably 80% or more, more preferably 90% after being placed in a test environment with a temperature of 60 ° C. and a humidity of 90% for 1 day. 95% or more, particularly preferably 95% or more. For example, the retention rate can be obtained based on the initial photoelectric conversion efficiency immediately after manufacturing the photoelectric conversion element and the photoelectric conversion efficiency after the photoelectric conversion element is placed in a test environment. Further, the retention rate can be measured after sealing the photoelectric conversion element as described above. Here, the retention rate can be calculated as follows based on the photoelectric conversion efficiency before and after placing in the test environment.
Maintenance rate (%) = ((photoelectric conversion efficiency after placing in test environment)/(photoelectric conversion efficiency before placing in test environment)) x 100

In one embodiment, the maintenance rate of the photoelectric conversion efficiency is 40% or more, preferably 60% or more, more preferably 60% or more after being placed in a test environment with a temperature of 60° C. and a humidity of 90% for 96 hours. It is 80% or more, more preferably 90% or more, and particularly preferably 95% or more.

(7. Solar cell)
The photoelectric conversion element 100 according to this embodiment is preferably used as a solar cell element for a solar cell, especially a thin-film solar cell. FIG. 2 is a cross-sectional view schematically showing the configuration of a solar cell according to one embodiment of the present invention, and FIG. 2 shows a thin-film solar cell, which is the solar cell according to one embodiment of the present invention. As shown in FIG. 2, the thin-film solar cell 14 according to the present embodiment includes a weather-resistant protective film 1, an ultraviolet cut film 2, a gas barrier film 3, a getter material film 4, a sealing material 5, and a solar cell. An element 6, a sealing material 7, a getter material film 8, a gas barrier film 9, and a back sheet 10 are provided in this order. The thin-film solar cell 14 according to this embodiment has the photoelectric conversion element according to this embodiment as the solar cell element 6 . Then, light is irradiated from the side where the weather-resistant protective film 1 is formed (lower side in FIG. 2), and the solar cell element 6 generates power. It should be noted that the thin-film solar cell 14 does not need to have all of these constituent members, and necessary constituent members can be arbitrarily selected.

There are no particular restrictions on these constituent members that constitute the thin-film solar cell and the method of manufacturing the same, and well-known techniques can be used. For example, techniques described in known documents such as International Publication No. 2013/171517, International Publication No. 2013/180230, and Japanese Patent Application Laid-Open No. 2012-191194 can be used.

Applications of the solar cell according to the present invention, particularly the thin-film solar cell 14 described above, are not limited and can be used for any application. For example, the solar cell according to one embodiment includes solar cells for building materials, solar cells for automobiles, solar cells for interiors, solar cells for railroads, solar cells for ships, solar cells for airplanes, solar cells for spacecraft, solar cells for home appliances, and so on. It can be used as a battery, a solar cell for mobile phones or a solar cell for toys.

The solar cell according to the present invention, particularly the thin-film solar cell 14 described above, may be used as it is, or may be used as a component of a solar cell module. For example, as shown in FIG. 5, a solar cell module 13 having the solar cell according to the present embodiment, particularly the thin-film solar cell 14 described above, on a substrate 12 is produced, and this solar cell module 13 is installed at a place of use. can be used as A well-known technique can be used for the base material 12. For example, the material for the base material 12 is the material described in International Publication No. 2013/171517, International Publication No. 2013/180230, or Japanese Patent Application Laid-Open No. 2012-191194. can be used. For example, when a building board is used as the base material 12, a solar cell panel for the outer wall of a building can be produced as the solar cell module 13 by providing the thin-film solar cell 14 on the surface of this board.

EXAMPLES Embodiments of the present invention are described below by way of examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

[Preparation of coating liquid]
(Preparation of coating liquid for electron extraction layer)
A 7.5% aqueous tin oxide dispersion was prepared by adding ultrapure water to a 15% aqueous dispersion of tin (IV) oxide (manufactured by Alfa Aesar).

(Preparation of coating solution for active layer)
Lead (II) iodide was weighed into a vial and introduced into the glove box. N,N-dimethylformamide was added as a solvent so that the concentration of lead (II) iodide was 1.3 mol/L, and then the mixture was heated and stirred at 100° C. for 1 hour to prepare active layer coating solution 1. .

Next, formamidine hydroiodide (FAI), methylamine hydrobromide (MABr), and methylamine hydrochloride (MACl) were added to another vial in a mass ratio of 10:1:1. I weighed it out and put it in the glove box. By adding isopropyl alcohol as a solvent thereto, an active layer coating liquid 2 having a total concentration of FAI, MAbr and MACl of 0.49 mol/L was prepared.

(Preparation of Coating Liquid 1 for Hole Extraction Layer)
32 mg of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA, Sigma-Aldrich) and 3.6 mg of 4-isopropyl-4'-methyldiphenyliodonium tetrakis (pentafluoro Phenyl)borate (TPFB, manufactured by TCI) was weighed into a vial and introduced into a glove box. 1.6 mL of chlorobenzene was added thereto as a solvent. Next, the resulting mixed liquid was heated and stirred at 100° C. for 1 hour to prepare a coating liquid 1 for hole extraction layer.

(Preparation of Coating Liquid 2 for Hole Extraction Layer)
For the hole extraction layer, except that 64 mg of PTAA and 3.6 mg of TPFB were weighed into a vial, ortho-dichlorobenzene was used as the solvent, and the resulting mixture was heated and stirred at 150° C. instead of 100° C. for 1 hour. A hole extraction layer coating solution 2 was prepared in the same manner as the coating solution 1 was prepared.

(Preparation of Coating Liquid 3 for Hole Extraction Layer)
Coating solution 3 for hole extraction layer was prepared in the same manner as coating solution 1 for hole extraction layer, except that the obtained mixed solution was heated and stirred at 70° C. instead of 100° C. for 1 hour.

(Preparation of Coating Liquid 4 for Hole Extraction Layer)
A LiTFSI solution was prepared by weighing 170 mg of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) into a vial in a glove box and adding 1 mL of acetonitrile.

Next, 15 mg of PTAA was weighed into another vial bottle in the glove box, and 1 mL of toluene was added thereto as a solvent. 15 μL of the above LiTFSI solution and 7.5 μL of 4-tert-butylpyridine were added to the resulting solution, and the mixture was stirred at room temperature for 1 hour to prepare hole extraction layer coating solution 4.

[Example 1: Production of photoelectric conversion element 1]
A glass substrate (manufactured by Geomatec) having a patterned indium tin oxide (ITO) transparent conductive film was subjected to ultrasonic cleaning using ultrapure water, drying by nitrogen blow, and UV-ozone treatment.

Next, an electron extraction layer having a thickness of about 35 nm was formed by spin-coating the electron extraction layer coating liquid prepared as described above onto the substrate at a speed of 2000 rpm at room temperature. After that, the substrate was heated on a hot plate at 150° C. for 10 minutes.

Next, the substrate was introduced into a glove box, and 150 μL of active layer coating liquid 1 heated to 100° C. was dropped onto the electron extraction layer and spin-coated at a speed of 2000 rpm. Then, the substrate was heat-annealed on a hot plate at 100° C. for 10 minutes to form a lead iodide layer. Next, after the substrate returned to room temperature, the active layer coating liquid 2 (120 μL) was spin-coated on the lead iodide layer at a speed of 2000 rpm and heated at 150° C. for 20 minutes to form an organic/inorganic perovskite active layer. (thickness 650 nm) was formed.

Next, after the substrate returned to room temperature, the hole extraction layer coating solution 1 (200 μL) was spin-coated on the active layer at a speed of 1500 rpm, and further heated on a hot plate at 90° C. for 5 minutes to obtain a positive electrode. A hole extracting layer (170 nm) was formed.

Next, an electrode was formed by depositing a silver film having a thickness of about 100 nm on the hole extracting layer by a resistance heating vacuum deposition method using a patterning mask. Thus, a 50×50 mm square photoelectric conversion element 1 was produced. Further, the photoelectric conversion element 1 was sealed by bonding the glass in which the central portion was dug down and the glass substrate of the photoelectric conversion element 1 with a sealing material (photocurable resin).

[Example 2: Production of photoelectric conversion element 2]
The same method as in Example 1 was used except that instead of spin-coating the hole extraction layer coating liquid 1, the hole extraction layer coating liquid 2 was spin-coated onto the active layer at a speed of 1000 rpm. A conversion element 2 was produced.

[Comparative Example 1: Production of photoelectric conversion element 3]
A photoelectric conversion element 3 was formed in the same manner as in Example 1, except that instead of spin-coating the hole extraction layer coating liquid 1, the hole extraction layer coating liquid 3 was spin-coated onto the active layer. made.

[Reference Example 1: Fabrication of photoelectric conversion element 4]
The same method as in Example 1 was used except that instead of spin-coating the hole extraction layer coating liquid 1, the hole extraction layer coating liquid 4 was spin-coated onto the active layer at a speed of 3000 rpm. A conversion element 4 was produced.

[Evaluation of photoelectric conversion element]
A metal mask of 4 mm square was attached to each of the photoelectric conversion elements 1 to 4 obtained in Examples 1 and 2, Comparative Example 1, and Reference Example 1, and the current-voltage characteristics between the ITO electrode and the silver electrode were measured. did. A source meter (2400 model, manufactured by Keithley) was used for the measurement, and a solar simulator with an air mass (AM) of 1.5 G and an irradiance of 100 mW/cm ² was used as the irradiation light source. From this measurement result, the initial conversion efficiency PCE (%) was calculated for the photoelectric conversion element that was not placed in the durability tester. Next, each of the photoelectric conversion elements 1 to 4 was placed in a high-temperature, high-humidity durability tester set at a temperature of 60° C. and a humidity of 90%, and taken out after one day to measure current-voltage characteristics. Next, each of photoelectric conversion elements 1 to 4 was placed in a high-temperature and high-humidity durability tester and taken out after a long period of time, and the current-voltage characteristics were measured. 1). Table 1 shows the conversion efficiency PCE at each time calculated based on each measurement result. In Table 1, the retention rate indicates the ratio of PCE after the durability test to the initial PCE.

As shown in Table 1, there was no significant difference in the initial conversion efficiency between Examples 1 and 2, Comparative Example 1, and Reference Example 1. On the other hand, looking at the results of the durability test, the conversion efficiency was significantly reduced in Comparative Example 1 and Reference Example 1, whereas in Examples 1 and 2, the conversion efficiency was the same as the initial conversion efficiency even after the durability test. Efficiency maintained. From the above results, it can be seen that the photoelectric conversion elements according to Examples 1 and 2, in which the coating solutions were prepared under conditions of 100° C. or 150° C., have high durability. As described above, it is understood that Comparative Example 1 and Examples 1 and 2 are different in structure although the materials used for forming the buffer layers are the same. Although the reason for this is not necessarily determined at the present time, the inventors of the present application prepared the coating liquid for the hole extraction layer at a high temperature, whereby the oxidation of the organic semiconductor compound (PTAA in this example) proceeded smoothly. It is speculated that this is the reason for the high durability.

In addition, the inventors of the present application measured the absorbance spectrum of the hole extraction layer coating liquid according to Example 2 in order to support the above assumption. A liquid mixture containing PTAA and TPFB was heated and stirred at 150° C. for 10 minutes, and then an absorbance spectrum was measured. As a result, a clear absorption peak was observed at 521 nm. Since PTAA does not have this absorption peak, it is believed that this absorption peak at 521 nm is characteristic of oxidized PTAA. Moreover, the magnitude of this absorption peak hardly increased even after heating and stirring for 1.5 hours. Thus, in the hole extraction layer coating liquid according to Example 2, it is considered that the oxidation reaction by TPFB proceeded almost completely. On the other hand, when the mixed solution containing PTAA and TPFB was heated and stirred for 10 minutes using a lower temperature, the absorption peak at 521 nm tended to hardly increase.

From these results, the inventors of the present application have found that when the temperature is low, the oxidation reaction of the organic semiconductor compound tends to proceed very slowly, and the oxidation state of the organic semiconductor compound is unstable, so that the conductivity is easily lost. By preparing the coating liquid for forming a semiconductor layer under conditions of 85° C. or higher, the oxidation reaction of the organic semiconductor compound proceeds to some extent, so that a stably oxidized organic semiconductor compound is obtained, which is used as a semiconductor layer or an electronic device. It is speculated that this is related to the high durability of

1 weather-resistant protective film 2 ultraviolet cut film 3, 9 gas barrier film 4, 8 getter material film 5, 7 sealing material 6 solar cell element 10 back sheet 12 base material 13 solar cell module 14 thin film solar cell 100 photoelectric conversion element 101 lower part Electrode 102 Buffer layer 103 Active layer 105 Buffer layer 107 Upper electrode 108 Base material

That is, the gist of the present invention resides in the following.
[ 1 ] A method for manufacturing an electronic device having a semiconductor layer, comprising the steps of: irradiating a coating liquid heated to 85° C. or higher with ultraviolet rays, and then applying the coating liquid to form the semiconductor layer. the coating liquid contains an organic semiconductor compound and a dopant for the organic semiconductor compound that is a hypervalent iodine compound; and the electronic device comprises a pair of electrodes composed of a lower electrode and an upper electrode; a solar cell comprising: an active layer containing a perovskite compound between the pair of electrodes; and a buffer layer between the pair of electrodes and the active layer, wherein the semiconductor layer is the buffer layer. A manufacturing method characterized by :
[2] The production method according to [1], wherein the dopant is an organic compound containing trivalent iodine.
[3] The production method according to [1] or [2], wherein the dopant is a diaryliodonium salt.
[4] The production method according to any one of [1] to [3], wherein the organic semiconductor compound is a triarylamine compound.
[5] The manufacturing method according to any one of [1] to [4], wherein the buffer layer is a hole extraction layer.
[6] The manufacturing method according to any one of [1] to [5] , wherein the buffer layer is positioned between the upper electrode and the active layer.
[7] An electronic device manufactured by the manufacturing method according to any one of [1] to [6] .
[8] A method for producing a coating liquid for forming a semiconductor layer, comprising: an organic semiconductor compound ; A manufacturing method, comprising a step of irradiating with ultraviolet rays.
[9] A semiconductor layer-forming coating liquid produced by the production method described in [8].
[10] An electronic device comprising a semiconductor layer, wherein the semiconductor layer contains an organic semiconductor compound doped with a dopant, and the amount of unreacted dopant contained in the semiconductor layer has been reacted with the amount of unreacted dopant. An electronic device characterized in that the dopant amount, which is the sum of the dopant amounts, is 80% by mass or less.
[11] The coating liquid for forming a semiconductor layer, wherein the coating liquid for forming a semiconductor layer contains an organic semiconductor compound doped with a dopant, and the amount of unreacted dopant contained in the coating liquid for forming a semiconductor layer is A coating liquid for forming a semiconductor layer, wherein the amount of dopant, which is the sum of the amount of unreacted dopant and the amount of reacted dopant, is 80% by mass or less.

Claims (12)

A method of manufacturing an electronic device comprising a semiconductor layer, comprising:
After heating a coating liquid containing an organic semiconductor compound and a dopant for the organic semiconductor compound which is a hypervalent iodine compound to 85° C. or higher and/or irradiating the coating liquid with ultraviolet rays, the coating liquid is applied. forming the semiconductor layer by: 2. The manufacturing method according to claim 1, wherein the dopant is an organic compound containing trivalent iodine. 3. The production method according to claim 1, wherein the dopant is a diaryliodonium salt. 4. The manufacturing method according to any one of claims 1 to 3, wherein the organic semiconductor compound is a triarylamine compound. The electronic device comprises a pair of electrodes consisting of a lower electrode and an upper electrode, an active layer containing a perovskite compound between the pair of electrodes, and a buffer layer between the pair of electrodes and the active layer. and a photoelectric conversion element comprising
2. The manufacturing method according to claim 1, wherein said semiconductor layer is said buffer layer. 6. The manufacturing method according to claim 5, wherein said buffer layer is a hole extraction layer. 7. The manufacturing method according to claim 5, wherein said buffer layer is positioned between said upper electrode and said active layer. An electronic device manufactured by the manufacturing method according to any one of claims 1 to 7. A method for producing a coating liquid for forming a semiconductor layer, comprising:
characterized by including a step of heating a coating liquid containing an organic semiconductor compound and a dopant for the organic semiconductor compound which is a hypervalent iodine compound to 85° C. or higher and/or irradiating the coating liquid with ultraviolet rays. manufacturing method. A coating liquid for forming a semiconductor layer produced by the production method according to claim 9 . An electronic device comprising a semiconductor layer,
the semiconductor layer comprises an organic semiconductor compound doped with a dopant;
The electronic device, wherein the amount of unreacted dopant contained in the semiconductor layer is 80% by mass or less of the sum of the amount of unreacted dopant and the amount of reacted dopant. A coating liquid for forming a semiconductor layer,
The semiconductor layer-forming coating liquid contains an organic semiconductor compound doped with a dopant,
The unreacted dopant amount contained in the semiconductor layer forming coating liquid is 80% by mass or less of the dopant amount, which is the sum of the unreacted dopant amount and the reacted dopant amount. coating liquid.

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