JP2016184698A - Photoelectric transducer, solar cell, and solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a see-through type solar cell with high light fastness and little reduction in photoelectric conversion efficiency even when being irradiated with light for a long period of time.SOLUTION: The photoelectric transducer includes on a substrate at least a pair of transparent electrodes and an active layer between the pair of transparent electrodes. The active layer contains a p-type organic semiconductor compound, an n-type semiconductor compound, and inorganic nanoparticles.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a photoelectric conversion element, a solar cell, and a solar cell module.

  In recent years, solar cells using solar energy have been actively developed. In particular, as a type of next-generation solar cell following a silicon solar cell, an organic thin-film solar cell having a bulk hetero type active layer in which a p-type organic semiconductor compound such as a conjugated polymer compound and an n-type semiconductor compound are mixed is used. Examples have been reported. In particular, since organic thin film solar cells can be made flexible and lightweight, it is difficult to install conventional solar cells using silicon by using see-through organic thin film solar cells. And application to building materials, etc. are being studied.

  For example, Patent Document 1 describes a see-through type organic thin-film solar cell having transparency that does not interfere with indoor lighting or visibility. Patent Document 2 describes a see-through type organic thin film solar cell in which dielectric multilayer films having different refractive indexes are laminated on an upper electrode in order to prevent water and oxygen from entering the photoelectric conversion layer. .

International Publication 2012/121937 Pamphlet European Patent Application Publication No. 2800161

  In order to put the see-through type organic thin-film solar cell into practical use, in addition to improving the conversion efficiency, it is extremely important to prevent element deterioration with the passage of time. However, according to the study by the present inventors, in the case of a see-through type organic thin film solar cell in which a pair of electrodes constituting the photoelectric conversion element described in Patent Document 1 is a transparent electrode, In comparison, it has been found that conversion efficiency tends to be greatly reduced when an organic thin film solar cell is exposed to light. Further, in the see-through type organic thin-film solar cell described in Patent Document 2, although specific deterioration due to water and oxygen can be suppressed, as in Patent Document 1, the conversion efficiency is greatly increased when exposed to light. It turns out that there is a tendency to decline. In the case of a see-through type organic thin film solar cell, since the active layer and the like constituting the organic thin film solar cell receive light from both the upper electrode side and the lower electrode side, the conversion efficiency greatly decreases with time. It is thought that it will do.

An object of the present invention is to solve the above-described problems, and to provide a see-through solar cell with high light resistance, in which a decrease in photoelectric conversion efficiency is small even when light is irradiated for a long time.

  As a result of intensive studies in view of the above circumstances, the present inventors have found that the above object can be achieved by adding inorganic nanoparticles to the active layer, and have achieved the present invention. That is, the gist of the present invention is as follows.

[1] On a base material, it has at least a pair of transparent electrodes and an active layer between the pair of transparent electrodes. The active layer includes a p-type organic semiconductor compound, an n-type semiconductor compound, and an inorganic material. A photoelectric conversion element comprising nanoparticles.
[2] The photoelectric conversion element according to [1], wherein a ratio of the inorganic nanoparticles to the n-type semiconductor compound in the active layer is 0.5% by mass or more and 20% by mass or less.
[3] The photoelectric conversion element according to [1] or [2], wherein an average primary particle size of the inorganic nanoparticles is 5 nm or more and 100 nm or less.
[4] The photoelectric conversion element according to any one of [1] to [3], wherein the inorganic nanoparticles are zinc oxide particles.
[5] A solar cell having the photoelectric conversion element according to any one of [1] to [4].
[6] A solar cell module having the solar cell according to [5].

  According to the present invention, it is possible to provide a see-through solar cell with high light resistance, in which a decrease in photoelectric conversion efficiency is small even when light is irradiated for a long time.

It is sectional drawing which shows typically the structure of the photoelectric conversion element as one Embodiment of this invention. It is sectional drawing which shows typically the structure of the solar cell as one Embodiment of this invention. It is sectional drawing which shows typically the structure of the solar cell module as one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail. The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not specified in these contents unless it exceeds the gist.

  The photoelectric conversion element according to the present invention has at least a pair of transparent electrodes and an active layer between the pair of transparent electrodes on a substrate. Note that the photoelectric conversion element according to the present invention can be used as a see-through solar cell. Here, the see-through solar cell means a solar cell in which a pair of electrodes constituting the photoelectric conversion element is a transparent electrode, and light is transmitted from both the upper electrode side and the lower electrode side.

  As shown in FIG. 1, one embodiment of the photoelectric conversion element according to the present invention includes a lower electrode 101, a lower buffer layer 102, an active layer 103, an upper buffer layer 104, and an upper electrode on a substrate 106. 105 have a layer structure in which are sequentially formed. In the present invention, the lower electrode means an electrode laminated on the substrate 106 side, and the upper electrode means an electrode laminated above the lower electrode when the substrate 106 is used as the bottom. . In the present invention, the lower electrode 101 and the upper electrode 105 may be collectively referred to as a pair of electrodes. In addition, the lower buffer layer 102 and the upper buffer layer 104 are not essential components, and may be provided arbitrarily, and may include only one of the lower buffer layer 102 and the upper buffer layer 104. Moreover, the photoelectric conversion element may optionally have another layer other than the above. Hereinafter, each component of the photoelectric conversion element will be described.

<1-1. Substrate 106>

  Since the photoelectric conversion element according to the present invention is used as a see-through solar cell, the substrate is preferably a substrate having translucency. In addition, the base material which has translucency refers to the base material which does not absorb in a visible light area | region, and means that visible light transmittance | permeability is 40% or more. Note that the visible light transmittance of the substrate is preferably 70% or more in order to allow more light to reach the photoelectric conversion layer. The visible light transmittance can be measured by a method defined in JIS R3106.

  The substrate 106 is not particularly limited as long as it has translucency, but the material constituting the substrate 106 is an inorganic material such as quartz, glass, sapphire, or titania; polyethylene terephthalate, polyethylene naphthalate , Polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, fluororesin film, polyolefin such as vinyl chloride or polyethylene; cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate And organic materials such as polynorbornene or epoxy resin. In the case of a flexible, flexible film-like substrate, organic materials and composite materials are preferable, organic materials and composite materials are more preferable, and organic materials are particularly preferable.

  Moreover, although there is no restriction | limiting in the film thickness of the base material 106, Usually, it is 5 micrometers or more, Preferably it is 20 micrometers or more, On the other hand, it is 20 mm or less normally, Preferably it is 10 mm or less. The film thickness of the support 3 is preferably 5 μm or more because the possibility that the strength of the photoelectric conversion element is insufficient is reduced. It is preferable that the thickness of the substrate 106 is 20 mm or less because the cost is suppressed and the weight does not increase.

<1-2. Pair of transparent electrodes (lower electrode 101, upper electrode 105)>
The pair of electrodes (the lower electrode 101 and the upper electrode 105) have a function of collecting holes and electrons generated when the active layer 103 absorbs light. Specifically, one electrode of the pair of electrodes needs to be an anode suitable for collecting holes, and the other electrode needs to be a cathode suitable for collecting electrons. That is, when the lower electrode 101 is an anode, the upper electrode 105 needs to be a cathode. On the other hand, when the lower electrode 101 is a cathode, the upper electrode 105 needs to be an anode. Note that one of the lower electrode 101 and the upper electrode 105 may be an anode and the other may be a cathode, or a material may be selected as appropriate in consideration of a work function. For example, when the lower electrode 101 is an anode and the upper electrode 105 is a cathode, the material used for the lower electrode may be a material having a larger work function than the material used for the upper electrode. On the other hand, when the lower electrode 101 is a cathode and the upper electrode 105 is an anode, the material used for the lower electrode 101 is preferably a material having a work function smaller than that of the material used for the upper electrode 105. In the case where the photoelectric conversion element includes the lower buffer layer 102 and / or the upper buffer layer 104, the same material can be used for the lower electrode 101 and the upper electrode 105 by adjusting the buffer layer materials.

  In the present invention, the lower electrode 101 and the upper electrode 105 are transparent electrodes for use as a see-through type organic thin film solar cell. The transparent electrode in the present invention means an electrode having conductivity and a visible light transmittance of 40% or more. Note that the visible light transmittance of the transparent electrode is preferably 70% or more in order to allow more light to reach the photoelectric conversion layer, and there is no upper limit. The visible light transmittance can be measured by a method defined in JIS R3106.

  Examples of the material constituting the transparent electrode include metal oxides such as nickel oxide, tin oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), titanium oxide, and zinc oxide. Zinc oxide doped with aluminum, gallium, alkali metal, alkaline earth metal, or the like may be used, or silver nanowires, carbon nanotubes, graphene, or the like may be used.

  The transparent electrode may be a single layer or a stacked layer. For example, the transparent electrode may be formed by laminating a layer containing the above material and a thin film layer made of a metal such as gold, platinum, silver, aluminum, chromium, cobalt, or an alloy thereof. However, if the thin film layer made of a metal or an alloy thereof is too thick, the translucency of the transparent electrode is lowered. Therefore, it is necessary to arbitrarily adjust the film thickness.

  Among these, from the viewpoint of high translucency, low sheet resistance, film forming processability, etc., a single layer of indium tin oxide (ITO) or indium zinc oxide (IZO), or indium tin oxide (ITO) or indium zinc oxide A laminated structure of (IZO) and a metal thin film layer is preferable.

  The transparent electrode may be a single layer or a laminate. The total film thickness of the transparent electrode is not particularly limited, but is usually 5 nm or more, preferably 10 nm or more, and more preferably 20 nm or more. On the other hand, it is usually 2 μm or less, preferably 1 μm or less, and more preferably 500 nm or less. When the film thickness is 5 nm or more, the sheet resistance is suppressed, and when the film thickness is 2 μm or less, light can be efficiently converted into electricity without lowering the light transmittance. The film thickness must be controlled in a region where both light transmittance and sheet resistance can be achieved.

  The sheet resistance of the transparent electrode is not particularly limited, but is usually 0.1Ω / □ or more, on the other hand, 1000Ω / □ or less, preferably 500Ω / □ or less, more preferably 100Ω / □ or less.

  The formation method of the lower electrode 101 and the upper electrode 105 is not particularly limited, and can be formed by a known method in accordance with a material to be used. For example, a vacuum film forming method such as a vapor deposition method or a sputtering method; or a wet coating method in which an ink containing nanoparticles or a precursor is applied to form a film.

<1-3. Active layer 103>
The active layer 103 is a bulk hetero type mixed layer containing a p-type organic semiconductor compound, an n-type semiconductor compound, and inorganic nanoparticles. As described above, when the active layer 103 absorbs light, electrons and holes are generated at the interface between the p-type organic semiconductor compound and the n-type semiconductor compound, and these charges are extracted from each electrode.

  The p-type organic semiconductor compound is not particularly limited, and examples thereof include a p-type low-molecular organic semiconductor compound or a p-type organic semiconductor polymer. Among these, a p-type semiconductor polymer having an energy band gap of 1.0 eV to 1.8 eV is preferable.

  Specifically, a semiconductor polymer obtained by copolymerization of two or more kinds of monomer units, for example, a polythiophene-thienothiophene copolymer described in Nature Materials, 2006, 5,328, described in International Publication No. 2008/000664 pamphlet. Polythiophene-diketopyrrolopyrrole copolymer, Adv. Mater. , 2007, 4160, polythiophene copolymer such as PCPDTBT described in Nature Materials, 2007, 6,497, and imidothiophene described in WO 2011/028827 pamphlet. And a copolymer of thienothiophene and benzodithiophene described in International Publication No. 2011/011545 pamphlet. Moreover, the conjugated polymer compound as described in international publication 2013/180243 pamphlet, international publication 2013/065855 pamphlet, etc. is also mentioned. In addition, derivatives of these polymers and polymers that can be synthesized by combinations of the monomers listed here can also be used. The substituents of these polymers and monomers can be appropriately selected in order to control solubility, crystallinity, film formability, HOMO energy level, LUMO energy level, and the like.

  The n-type organic semiconductor compound is not particularly limited. Specifically, a fullerene compound; a quinolinol derivative metal complex typified by 8-hydroxyquinoline aluminum; naphthalenetetracarboxylic acid diimide or perylenetetracarboxylic acid diimide Condensed ring tetracarboxylic acid diimides; perylene diimide derivatives, terpyridine metal complexes, tropolone metal complexes, flavonol metal complexes, perinone derivatives, benzimidazole derivatives, benzoxazole derivatives, thiazole derivatives, benzthiazole derivatives, benzothiadiazole derivatives, oxadiazole derivatives , Thiadiazole derivatives, triazole derivatives, aldazine derivatives, bisstyryl derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, benzoquinolines Conductor, bipyridine derivatives, borane derivatives; anthracene, pyrene, total fluoride condensed polycyclic aromatic hydrocarbons such as naphthacene or pentacene; single-walled carbon nanotubes, n-type polymer (n-type polymer semiconductor material), and the like.

  Among these, fullerene compounds, borane derivatives, thiazole derivatives, benzothiazole derivatives, benzothiadiazole derivatives, N-alkyl substituted naphthalene tetracarboxylic acid diimides, N-alkyl substituted perylene diimide derivatives or n-type polymer semiconductor materials. Preferably, fullerene compounds, N-alkyl-substituted perylene diimide derivatives, N-alkyl-substituted naphthalene tetracarboxylic acid diimides or n-type polymer semiconductor compounds are more preferable, and fullerene compounds are particularly preferable. These compounds are not particularly limited, but for example, those described in known literature such as International Publication No. 2011-016430 or Japanese Unexamined Patent Publication No. 2012-191194 can be used. In addition, a kind of compound may be used among the above, and a mixture of a plurality of kinds of compounds may be used.

  In the active layer 103, the ratio of the n-type organic semiconductor compound to the p-type organic semiconductor compound is not particularly limited, but is preferably 100 parts by mass or more, and 150 parts by mass or more in order to promote charge separation. On the other hand, it is preferably 400 parts by mass or less, and particularly preferably 350 parts by mass or less.

  The active layer 103 can improve the light resistance of a photoelectric conversion element by containing an inorganic nanoparticle as above-mentioned. The reason is not clear, but the following reasons are possible.

  According to the study by the present inventors, it has been found that a conventional see-through solar cell that does not contain inorganic nanoparticles in the active layer tends to decrease in conversion efficiency over time when exposed to light. . This is because, in the case of a see-through type organic thin film solar cell, a large amount of light is irradiated from both sides of the organic thin film solar cell as compared with a non-transmissive type organic thin film solar cell. This is thought to be because the morphology of the inside changes and electron traps are likely to occur. On the other hand, when the active layer 103 contains inorganic nanoparticles as in the present invention, an appropriate morphology is formed, and even if the morphology changes due to light, the inorganic nanoparticles function as an electron transport path. Therefore, it can be considered that the generation of an electron trap can be prevented, so that a decrease in conversion efficiency due to light degradation can be suppressed.

  Inorganic nanoparticles are not particularly limited, but include metal oxides such as tin oxide, titanium oxide, and zinc oxide; zinc oxide doped with aluminum, gallium, alkali metal, alkaline earth metal, etc .; copper, indium, selenium And the like. Among these, it is preferable to use inorganic nanoparticles having a conductor bottom band close to the LUMO energy level of the n-type organic semiconductor compound in the active layer 103 in order to function as an assisting electron conduction path. . Specifically, the energy difference between the LUMO energy level of the n-type semiconductor compound and the conductor bottom of the inorganic nanoparticles is preferably 1.0 eV or less, more preferably 0.7 eV or less, and 0.5 eV. It is particularly preferred that Specifically, the inorganic nanoparticles are preferably zinc oxide particles.

  The ratio of the inorganic nanoparticles in the active layer 103 is preferably 0.5% by mass or more based on the n-type semiconductor in order to form a good morphology and function as an electron transport path, and 1.0% by mass. % Or more is more preferable, and 2.5% by mass or more is more preferable. On the other hand, if the ratio of the inorganic nanoparticles to the n-type semiconductor compound is too large, the pn junction interface decreases, which affects charge separation, and when using highly conductive inorganic nanoparticles, the photoelectric conversion element leaks. It tends to be easier. Further, since see-through type organic thin film solar cells are expected to be applied to windows and the like, it is required to improve the appearance. However, if the amount of the inorganic nanoparticles in the active layer is too large, haze (white turbidity) due to scattering by the inorganic nanoparticles occurs, and the appearance tends to be deteriorated. From these viewpoints, the ratio of the inorganic nanoparticles to the n-type semiconductor compound in the active layer 103 is preferably 20% by mass or less, more preferably 17% by mass or less, and 15% by mass or less. Is particularly preferred.

  The average primary particle size of the inorganic nanoparticles is not particularly limited, but is preferably 1 nm or more, and more preferably 5 nm or more so that the inorganic nanoparticles can be dispersed in the active layer 103 and the charge transport ability is not reduced. It is particularly preferably 10 nm or more, on the other hand, preferably 400 nm or less, more preferably 300 nm or less, and particularly preferably 100 nm or less. The average primary particle size can be measured with a dynamic light scattering particle size measuring device, a transmission electron microscope (TEM), or the like.

  Inorganic nanoparticles are preferably dispersed in the active layer in order to function as the morphology of the active layer and function as an electronic conduction path.

  The thickness of the active layer 103 is not particularly limited, but is usually 5 nm or more, preferably 10 nm or more, more preferably 50 nm or more, more preferably 120 nm or more in order to absorb more light. On the other hand, in order to reduce the series resistance, the film thickness of the active layer 103 is usually 600 nm or less, preferably 500 nm or less, more preferably 400 nm or less.

  The method for forming the active layer 103 is not particularly limited, but it is preferably formed by a wet coating method using the composition for forming the active layer. Specifically, by preparing an active layer forming composition containing a p-type organic semiconductor compound, an n-type semiconductor compound, inorganic nanoparticles, and a solvent, and applying this active layer forming composition An active layer 103 can be formed.

  The coating method can be any method, for example, spin coating method, ink jet method, doctor blade method, drop casting method, reverse roll coating method, gravure coating method, kiss coating method, roll brush method, spray coating method, Examples thereof include an air knife coating method, a wire barber coating method, a slit die coating method, a pipe doctor method, an impregnation / coating method, and a curtain coating method.

  Moreover, after apply | coating the composition for active layer formation, you may heat-dry. Heating can promote self-organization of the active layer. The heating temperature is usually 50 ° C. or higher, preferably 80 ° C. or higher, and is usually 300 ° C. or lower, preferably 280 ° C. or lower, more preferably 250 ° C. or lower. The heating time is usually 1 minute or longer, preferably 3 minutes or longer, and usually 3 hours or shorter, preferably 1 hour or shorter.

  If the solvent which the composition for active layer formation contains is a solvent which can melt | dissolve or disperse | distribute a p-type organic-semiconductor compound, an n-type semiconductor compound, and an inorganic nanoparticle, there will be no restriction | limiting in particular. For example, aromatic hydrocarbons such as lobenzene or orthodichlorobenzene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, cycloheptane, cyclooctane, tetralin or decalin; lower alcohols such as methanol, ethanol or propanol Aliphatic ketones such as acetone, methyl ethyl ketone, cyclopentanone or cyclohexanone; aromatic ketones such as acetophenone or propiophenone; esters such as ethyl acetate, butyl acetate or methyl lactate; chloroform, methylene chloride, dichloroethane, Halogen hydrocarbons such as trichloroethane or trichloroethylene; ethers such as ethyl ether, tetrahydrofuran or dioxane; Muamido or amides such as dimethylacetamide and the like.

  Moreover, a solvent may use 1 type of solvent independently, and may use arbitrary 2 or more types of solvents together by arbitrary ratios. When two or more solvents are used in combination, a low boiling point solvent having a boiling point of 60 ° C. or higher and 150 ° C. or lower under normal pressure and a high boiling point solvent having a boiling point of 180 ° C. or higher and 250 ° C. or lower under normal pressure. Is preferred. For example, examples of the high boiling point solvent include tetralin, decalin, and acetophenone, and examples of the low boiling point solvent include toluene, xylene, tetrahydrofuran, and ethyl methyl ketone. When using a combination of a high-boiling solvent and a low-boiling solvent in this way, when forming an active layer, the lower-volatile high-boiling solvent slowly volatilizes, which facilitates the organization of the semiconductor compound. The phase separation structure can be optimized. From the viewpoint of environmental load, these high-boiling solvents and low-boiling solvents are preferably non-halogen solvents.

  The composition for forming an active layer may be prepared by mixing a solution containing a p-type organic semiconductor compound, a solution containing an n-type semiconductor compound, and a dispersion containing inorganic nanoparticles, respectively, A p-type organic semiconductor compound, an n-type semiconductor compound, and inorganic nanoparticles may be simultaneously dissolved or dispersed in one or more kinds of solvents to prepare.

  In addition, a commercial item can also be used for an inorganic nanoparticle dispersion liquid. For example, ZNT15WT% -G0 (Cai Kasei Co., Ltd.), NANOBYKR-3842 (Bic Chemie Co., Ltd.) and the like can be mentioned.

  The ratio of each compound in the composition for forming an active layer is not particularly limited and may be arbitrarily selected according to the desired composition of the active layer 103.

<1-4. Buffer Layer (Lower Buffer Layer 102, Upper Buffer Layer 104)>
As described above, the photoelectric conversion element according to this embodiment includes the lower buffer layer 102 between the lower electrode 101 and the active layer 103, and the upper buffer layer 104 between the upper electrode 105 and the active layer 103. . The lower buffer layer 102 and the upper buffer layer 104 each have a function of improving the electron extraction efficiency from the active layer 103 to the cathode or the hole extraction efficiency from the active layer 103 to the anode. Note that a buffer layer having a function of improving the electron extraction efficiency from the active layer 103 to the cathode is referred to as an electron extraction layer, and a buffer layer having a function of improving the electron extraction efficiency from the active layer 103 to the cathode is referred to as a hole extraction layer. Note that, as described above, the lower buffer layer 102 and the upper buffer layer 104 are not essential components, and the photoelectric conversion element may not include the lower buffer layer 102 and the upper buffer layer 104. Moreover, you may have only any one layer.

  Either of the lower buffer layer 102 and the upper buffer layer 104 may be an electron extraction layer or a hole extraction layer, but when the lower electrode 101 is a cathode and the upper electrode 105 is an anode, the lower buffer layer 102 is an electron extraction layer. The upper buffer layer 104 is preferably a hole extraction layer. On the other hand, when the lower electrode 101 is an anode and the upper electrode 105 is a cathode, the lower buffer layer 102 is preferably a hole extraction layer and the upper buffer layer 104 is preferably an electron extraction layer.

<1-4-1. Electron extraction layer>
The material of the electron extraction layer is not particularly limited as long as it is a material that improves the efficiency of extracting electrons from the active layer 103 to the cathode, and examples thereof include inorganic compounds and organic compounds.

  Examples of inorganic compounds include salts of alkali metals such as Li, Na, K or Cs; n-type semiconductor oxides such as titanium oxide (TiOx) and zinc oxide (ZnO). Among them, the alkali metal salt is preferably a fluoride salt such as LiF, NaF, KF or CsF, and the n-type semiconductor oxide is preferably zinc oxide (ZnO). Although the operation mechanism of such a material is unknown, it is conceivable to reduce the work function of the cathode when combined with a cathode made of Al or the like and increase the voltage applied to the solar cell element.

  Examples of organic compounds include phosphine compounds having a double bond between a phosphorus atom and a group 16 element such as triarylphosphine oxide compounds; substituents such as bathocuproin (BCP) or bathophenanthrene (Bphen) A phenanthrene compound in which the 1-position and the 10-position may be substituted with a heteroatom; a boron compound such as triarylboron; an organometallic such as (8-hydroxyquinolinato) aluminum (Alq3) Oxide; Compound having 1 or 2 ring structure which may have a substituent such as oxadiazole compound or benzimidazole compound; naphthalenetetracarboxylic anhydride (NTCDA) or perylenetetracarboxylic anhydride Such as (PTCDA), such as dicarboxylic anhydride Aromatic compounds having a slip dicarboxylic acid structure.

  The electron extraction layer can be formed using a compound as described above, but in order to reduce the electron extraction barrier, the electron extraction layer contains the same compound as the compound constituting the inorganic nanoparticles in the active layer. It is preferable to do. For example, when the inorganic nanoparticles are composed of a metal oxide, the electron extraction layer preferably also contains the same metal oxide as the metal oxide that constitutes the inorganic nanoparticles. In this case, the metal oxide contained in the electron extraction layer may be doped with a metal element. In particular, the inorganic nanoparticles are preferably composed of zinc oxide, and the electron extraction layer preferably contains zinc oxide which may be doped with a metal element.

  The thickness of the electron extraction layer is usually 0.1 nm or more, preferably 1 nm or more, more preferably 10 nm or more. On the other hand, it is usually 400 nm or less, preferably 200 nm or less. When the film thickness of the electron extraction layer is 0.1 nm or more, it functions as a buffer material. When the film thickness of the electron extraction layer is 400 nm or less, electrons are easily extracted and the photoelectric conversion efficiency is improved. Can improve.

  The LUMO energy level of the material of the electron extraction layer is not particularly limited, but is usually −4.0 eV or more, preferably −3.9 eV or more. On the other hand, it is usually −1.9 eV or less, preferably −2.0 eV or less. It is preferable that the LUMO energy level of the material for the electron extraction layer is −1.9 eV or less because charge transfer can be promoted. It is preferable that the LUMO energy level of the material for the electron extraction layer is −4.0 eV or more in terms of preventing reverse electron transfer to the n-type semiconductor material.

  The HOMO energy level of the material for the electron extraction layer is not particularly limited, but is usually −9.0 eV or more, preferably −8.0 eV or more. On the other hand, it is usually −5.0 eV or less, preferably −5.5 eV or less. The HOMO energy level of the material for the electron extraction layer is preferably −5.0 eV or less from the viewpoint of preventing movement of holes.

  As a method for calculating the LUMO energy level and the HOMO energy level of the material of the electron extraction layer, a cyclic voltammogram measurement method may be mentioned. For example, it can implement with reference to the method as described in the international publication 2011/016430 pamphlet.

  When the material of the electron extraction layer is an organic compound, the glass transition temperature (hereinafter sometimes referred to as Tg) of this compound as measured by the DSC method is not particularly limited, but is not observed, or It is preferable that it is 55 degreeC or more. That the glass transition temperature is not observed by the DSC method means that there is no glass transition temperature. Specifically, the determination is made based on the presence or absence of a glass transition temperature of 400 ° C. or lower. A material in which the glass transition temperature by the DSC method is not observed is preferable in that it has high thermal stability.

  Among the compounds having a glass transition temperature of 55 ° C. or higher as measured by the DSC method, the glass transition temperature is preferably 65 ° C. or higher, more preferably 80 ° C. or higher, more preferably 110 ° C. or higher, particularly preferably. A compound having a temperature of 120 ° C. or higher is desirable. On the other hand, the upper limit of the glass transition temperature is not particularly limited, but is usually 400 ° C. or lower, preferably 350 ° C. or lower, more preferably 300 ° C. or lower. Moreover, it is preferable that the material of an electron taking-out layer is a thing by which the glass transition temperature by DSC method is not observed below 30 degreeC or more and less than 55 degree | times.

  The glass transition temperature in the present specification is defined as a point at which specific heat changes in an amorphous solid, which is a temperature at which local molecular motion is started by thermal energy. When the temperature rises further than Tg, the solid structure changes and crystallization occurs (the temperature at this time is defined as the crystallization temperature (Tc)). When the temperature rises further, it generally melts at the melting point (Tm) and changes to a liquid state. However, these phase transitions may not be observed due to molecular decomposition or sublimation at high temperatures.

  The DSC method is a thermophysical property measurement method (differential scanning calorimetry method) defined in JIS K-0129 “General Rules for Thermal Analysis”. In order to determine the glass transition temperature more clearly, it is desirable to measure after rapidly cooling a sample once heated to a temperature higher than the glass transition temperature. For example, the measurement can be carried out by a method described in a known document (International Publication No. 2011/016430).

  When the glass transition temperature of the compound used for the electron extraction layer is 55 ° C. or higher, the structure of this compound is difficult to change against external stress such as applied electric field, flowing current, stress due to bending or temperature change. It is preferable in terms of durability. Furthermore, since there is a tendency that the crystallization of the thin film of the compound does not proceed easily, the stability of the electron extraction layer is improved by making it difficult for the compound to change between the amorphous state and the crystalline state in the operating temperature range. Therefore, it is preferable in terms of durability. This effect becomes more prominent as the glass transition temperature of the material is higher.

  There is no restriction | limiting in the formation method of an electronic taking-out layer. For example, when a material having sublimation property is used, it can be formed by a vacuum deposition method or the like. Further, for example, when a material soluble in a solvent is used, it can be formed by a wet coating method such as spin coating or inkjet.

  When the electron extraction layer is formed by a coating method, a surfactant may be further contained in the coating solution. By using the surfactant, the occurrence of dents due to adhesion of fine bubbles or foreign matters and / or uneven coating in the drying process is suppressed. Known surfactants (cationic surfactants, anionic surfactants, nonionic surfactants) can be used as the surfactant. Of these, silicon-based surfactants, acetylenic diol-based surfactants, and fluorine-based surfactants are preferable. In addition, as surfactant, only 1 type may be used and 2 or more types may be used together by arbitrary combinations and a ratio.

  Specifically, for example, when an alkali metal salt is used as a material for the electron extraction layer, the electron extraction layer can be formed by using a vacuum film formation method such as vacuum deposition or sputtering. Especially, it is desirable to form an electron taking-out layer by vacuum vapor deposition by resistance heating. By using vacuum deposition, damage to other layers such as an active layer can be reduced.

  On the other hand, when an n-type semiconductor metal oxide is used as the material for the electron extraction layer, a vacuum film formation method such as sputtering can be used. However, the electron extraction layer can be formed by a coating method. desirable. For example, Sol-Gel Science, C.I. J. et al. Brinker, G.M. W. According to the sol-gel method described by Scherer, Academic Press (1990), an electron extraction layer composed of zinc oxide can be formed. In this case, the film thickness is usually 0.1 nm or more, preferably 2 nm or more, more preferably 5 nm or more, and usually 1 μm or less, preferably 100 nm or less, more preferably 50 nm or less. If the electron extraction layer is too thin, the effect of improving the electron extraction efficiency is not sufficient, and if it is too thick, the electron extraction layer tends to deteriorate the characteristics of the device by acting as a series resistance component. Moreover, it can also form by the method as described in the well-known international publication 2013/180230 pamphlet.

<1-4-2. Hole extraction layer>
The material for the hole extraction layer is not particularly limited as long as it is a material capable of improving the efficiency of extracting holes from the active layer 103 to the anode. Specifically, conductive polymers in which polythiophene, polypyrrole, polyacetylene, triphenylenediamine, polyaniline, etc. are doped with sulfonic acid and / or iodine, polythiophene derivatives having a sulfonyl group as a substituent, conductive organics such as arylamine Examples thereof include compounds, copper oxide, nickel oxide, manganese oxide, molybdenum oxide, vanadium oxide, metal oxide such as tungsten oxide, Nafion, and a p-type semiconductor described later. Among them, a conductive polymer doped with sulfonic acid is preferable, and (3,4-ethylenedioxythiophene) poly (styrenesulfonic acid) (PEDOT: PSS) in which a polythiophene derivative is doped with polystyrene sulfonic acid is more preferable. It is. A thin film of metal such as gold, indium, silver or palladium can also be used. A thin film of metal or the like may be formed alone or in combination with the above organic material.

  The film thickness of the hole extraction layer is usually 0.1 nm or more. On the other hand, it is usually 400 nm or less, preferably 200 nm or less. If the film thickness of the hole extraction layer is within the above range, in particular, holes can be easily extracted and the photoelectric conversion efficiency can be improved.

  There is no restriction | limiting in the formation method of a positive hole taking-out layer. For example, when a material having sublimation property is used, it can be formed by a vacuum deposition method or the like. For example, when a material soluble in a solvent is used, it can be formed by a wet coating method such as a spin coating method or an ink jet method. Especially, when using PEDOT: PSS as a material of a hole taking-out layer, it is preferable to form a hole taking-out layer by the method of apply | coating a dispersion liquid. Examples of the dispersion of PEDOT: PSS include CLEVIOSTM series manufactured by Heraeus, ORGACONTM series manufactured by Agfa, and the like.

  When the hole extraction layer is formed by a coating method, a surfactant may be further contained in the coating solution. By using the surfactant, the occurrence of dents due to adhesion of fine bubbles or foreign matters and / or uneven coating in the drying process is suppressed. Known surfactants (cationic surfactants, anionic surfactants, nonionic surfactants) can be used as the surfactant. Of these, silicon-based surfactants, acetylenic diol-based surfactants, and fluorine-based surfactants are preferable. In addition, as surfactant, only 1 type may be used and 2 or more types may be used together by arbitrary combinations and a ratio.

<1-5. Manufacturing method of photoelectric conversion element>
A photoelectric conversion element 107 having the configuration shown in FIG. 1 is formed on a base 106 by a lower electrode 101, a lower buffer layer 102, an active layer 103, an upper buffer layer 104, and an upper electrode in accordance with the method described above for each layer. It can be manufactured by sequentially stacking 105.

  After laminating the lower electrode 101 and the upper electrode 105, the photoelectric conversion element is usually in a temperature range of 50 ° C. or higher, preferably 80 ° C. or higher, usually 300 ° C. or lower, preferably 280 ° C. or lower, more preferably 250 ° C. or lower. It is preferable to heat (this step is referred to as an annealing treatment step).

  Performing the annealing process at a temperature of 50 ° C. or higher improves adhesion between the layers of the photoelectric conversion element, for example, adhesion between the lower buffer layer 102 and the lower electrode 101 and / or the lower buffer layer 102 and the active layer 103. This is preferable because the effect of By improving the adhesion between the layers, the thermal stability and durability of the photoelectric conversion element can be improved. In addition, the self-organization of the active layer can be promoted by the annealing process. It is preferable to set the temperature of the annealing treatment step to 300 ° C. or lower because the possibility that the organic compound in the active layer 103 is thermally decomposed is reduced. In the annealing treatment step, stepwise heating may be performed within the above temperature range.

  The heating time is usually 1 minute or longer, preferably 3 minutes or longer, and usually 3 hours or shorter, preferably 1 hour or shorter. The annealing treatment step is preferably terminated when the open-circuit voltage, the short-circuit current, and the fill factor, which are parameters of the solar cell performance, reach a constant value. Further, the annealing treatment step is preferably performed 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. The heating may be performed batchwise or continuously.

  Each layer constituting the photoelectric conversion element according to the present invention is not particularly limited, and can be formed by a sheet-to-sheet (sheet-fed) method or a roll-to-roll method.

<2. Solar cell>
The photoelectric conversion element according to the above-described embodiment is preferably used as a solar battery, in particular, a solar battery element of a see-through type organic thin film solar battery. The solar cell may have a configuration other than the photoelectric conversion element as shown in FIG.

  FIG. 2 is a cross-sectional view schematically showing the configuration of a thin-film solar cell as one embodiment of the present invention. As shown in FIG. 2, the thin-film solar cell 14 of this 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 photoelectric conversion. The element 6, the sealing material 7, the getter material film 8, the gas barrier film 9, and the back sheet 10 are provided in this order. And a thin film solar cell is normally irradiated with light from the side (downward in the figure) in which the weather-resistant protective film 1 was formed, and the photoelectric conversion element 6 generates electric power. Note that the thin-film solar cell does not need to have all of these constituent members, and each constituent member may be arbitrarily selected and provided.

  There are no particular restrictions on these constituent members constituting the thin-film solar cell and the manufacturing method thereof, and well-known techniques can be used. For example, the thing described in well-known literatures, such as international publication 2011/016430 or Japan Unexamined-Japanese-Patent No. 2012-191194, can be used.

  There is no special restriction | limiting in the use of the solar cell which concerns on this invention, especially the thin film solar cell 14 mentioned above, It can use for arbitrary uses. Examples include solar cells for building materials, solar cells for automobiles, solar cells for spacecrafts, solar cells for home appliances, solar cells for mobile phones, solar cells for toys, and the like.

  The solar cell according to the present invention, particularly a thin-film solar cell, may be used as it is, or for example, a solar cell may be installed on a substrate and used as a solar cell module. For example, as shown in FIG. 3, the solar cell module 13 having the thin film solar cell 14 on the base 12 can be installed and used at a place of use. For the substrate 12, a well-known technique can be used, for example, those described in International Publication No. 2011-016430 or Japanese Unexamined Patent Publication No. 2012-191194. For example, when a building material plate is used as the substrate 12, a solar cell panel can be produced as the solar cell module 13 by providing the thin film solar cell 14 on the surface of the plate.

  Hereinafter, embodiments of the present invention will be described by way of examples. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded. Items described in the examples were measured by the following methods.

(Measurement method of weight average molecular weight and number average molecular weight)
The weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of polystyrene were determined by gel permeation chromatography (GPC). Molecular weight distribution (PDI) represents Mw / Mn.

Gel permeation chromatography (GPC) measurement was performed under the following conditions.
Column: Polymer Laboratories GPC column (PLgel MIXED-B 10 μm, inner diameter 7.5 mm, length 30 cm) connected in series Pump: LC-10AT (manufactured by Shimadzu Corporation) Oven: CTO-10A (Shimadzu Corporation) (Made by company)
Detector: differential refractive index detector (manufactured by Shimadzu Corporation, RID-10A) and UV-vis detector (manufactured by Shimadzu Corporation, SPD-10A)
Sample: 1 μL of 1 mg sample dissolved in chloroform (200 mg)
Mobile phase: Chloroform Flow rate: 1.0 mL / min
Analysis: LC-Solution (manufactured by Shimadzu Corporation)

(Evaluation of photoelectric conversion element)
A 4 mm square metal mask is attached to the photoelectric conversion element, a solar simulator with an air mass (AM) of 1.5 G and an irradiance of 100 mW / cm ² is used as an irradiation light source, and an ITO electrode is connected with a source meter (Keisley, Model 2400). The current-voltage characteristics with the silver electrode were measured. From this measurement result, open circuit voltage Voc (V), short circuit current density Jsc (mA / cm ² ), form factor FF, and photoelectric conversion efficiency PCE (%) were calculated.

Here, the open circuit voltage Voc is a voltage value at a current value = 0 (mA / cm ² ), and the short circuit current density Jsc is a current density at a voltage value = 0 (V). The form factor FF is a factor representing the internal resistance, and is represented by the following expression when the maximum output is Pmax.
FF = Pmax / (Voc × Jsc)
Further, the photoelectric conversion efficiency PCE is given by the following equation when the incident energy is Pin.
PCE = (Pmax / Pin) × 100
= (Voc x Jsc x FF / Pin) x 100

<Synthesis Example 1: Synthesis of copolymer>

  1,3-dibromo-5- (n-octyl) obtained by referring to a method described in a known document (Organic Letters 2004, 6, 3381-3384) as a monomer in a 50 mL two-necked eggplant flask under a nitrogen atmosphere. ) -4H-thieno [3,4-c] pyrrole-4,6- (5H) -dione (compound B1: imidothiophene dibromide), 350 mg, 0.826 mmol), known literature (Polymer, 1990, 31, 1379). -1383), 4,4′-didodecyl-5,5′-bis (trimethylstannyl) -2,2′-bithiophene (compound C1) (342 mg, 0.413 mmol), and WO2013 / 4,4-bis (2-ethylhexyl) -2,6-biphenyl obtained by referring to the method described in 180243 (Trimethyltin) -dithieno [3,2-b: 2 ′, 3′-d] silole (compound A1) (308 mg, 0.413 mmol) was added, and tetrakis (triphenylphosphine) palladium (0) (28. 6 mg, 3 mol%), triphenylphosphine-containing heterogeneous palladium complex catalyst Pd-EnCatTPP30 (Aldrich, 37.2 mg, 3 mol%), toluene (24 mL), and N, N-dimethylformamide (6 mL) The mixture was stirred at 90 ° C. for 1 hour and then at 100 ° C. for 10 hours. After diluting the reaction solution 4 times with toluene and heating and stirring at 100 ° C. for another 0.5 hours, as a terminal treatment, trimethyl (phenyl) tin (0.036 mL) was added and heating and stirring at 100 ° C. for 5 hours. Bromobenzene (8 mL) was further added, and the mixture was heated and stirred at 100 ° C. for 2 hours. The reaction solution was poured into methanol, and the deposited precipitate was collected by filtration. The obtained solid was dissolved in chloroform, diamine silica gel (Fuji Silysia Chemical) was added, and the mixture was stirred for 1 hour at room temperature and passed through a short column of acidic silica gel. The solution was concentrated, recrystallized using chloroform / ethyl acetate as a solvent, and the deposited precipitate was filtered off to obtain the desired copolymer in a yield of 74%. The weight average molecular weight Mw of the obtained copolymer was 37 k, and PDI was 2.1.

<Preparation of composition for forming active layer>

(Preparation of active layer forming composition 1)
A mixture of the copolymer obtained in Synthesis Example 1 as a p-type organic semiconductor compound and PC ₆₁ BM (phenyl C61 butyric acid methyl ester) which is a fullerene compound and PC ₇₁ BM (phenyl C71 butyric acid methyl ester) as an n-type semiconductor compound, It mixed so that mass ratio might be set to 1: 2. Dispersion liquid ZNT15WT% -G0 (manufactured by C-I Kasei Co., Ltd.) containing zinc oxide particles having an average primary particle size of 15 nm, a mixed solvent of o-xylene and tetralin (volume ratio 9: 1) and the mixture are in a mass ratio of 3:92. The mixture was mixed well in a nitrogen atmosphere so that the ratio was 5: 4.5 (the ratio of zinc oxide particles to the n-type semiconductor compound was 15% by mass). PC ₆₁ BM and PC ₇₁ BM were manufactured with reference to Journal of Organic Chemistry, 1995, 60,532. The obtained solution was stirred and mixed on a hot stirrer at a temperature of 80 ° C. for 1 hour. The solution after stirring and mixing was filtered through a 1 μm polytetrafluoroethylene (PTFE) filter to obtain composition 1 for forming an active layer.

(Preparation of active layer forming composition 2)
Instead of ZNT15WT% -G0 (manufactured by CI Kasei Co., Ltd.), a dispersion BYK3842R (manufactured by BYK Chemie) containing zinc oxide particles having an average primary particle diameter of 40 nm is 15% by mass with respect to the n-type semiconductor compound. An active layer forming composition 2 was prepared in the same manner as the active layer forming composition 1 except that the addition was performed as described above.

(Preparation of active layer forming composition 3)
Active layer forming composition 3 was prepared in the same manner as active layer forming composition 1 except that ZNT15WT% -G0 (manufactured by CI Kasei Co., Ltd.) was not added.

(Preparation of active layer forming composition 4)
For forming an active layer by the same method as for the composition 1 for forming an active layer, except that ZNT15WT% -G0 (manufactured by CI Kasei Co., Ltd.) was added so that the ratio of the zinc oxide particles to the n-type semiconductor compound was 3% by mass. Composition 4 was prepared.

(Preparation of active layer forming composition 5)
For forming an active layer by the same method as for composition 1 for forming an active layer, except that ZNT15WT% -G0 (CAI Kasei Co., Ltd.) was added so that the ratio of zinc oxide particles to the n-type semiconductor compound was 6% by mass. Composition 5 was prepared.

(Preparation of active layer forming composition 6)
For forming an active layer by the same method as for the composition 1 for forming an active layer, except that ZNT15WT% -G0 (CAI Kasei Co., Ltd.) was added so that the ratio of zinc oxide particles to the n-type semiconductor compound was 11% by mass. Composition 6 was prepared.

(Preparation of active layer forming composition 7)
For forming an active layer by the same method as the composition 1 for forming an active layer, except that ZNT15WT% -G0 (manufactured by CI Kasei Co., Ltd.) was added so that the ratio of the zinc oxide particles to the n-type semiconductor compound was 23% by mass. Composition 7 was prepared.

<Example 1: Production and evaluation of photoelectric conversion element 1>
A glass substrate (manufactured by Geomatic Co., Ltd.) on which an indium tin oxide (ITO) transparent conductive film is patterned is subjected to ultrasonic cleaning with acetone, followed by ultrasonic cleaning with isopropanol, followed by drying with nitrogen blowing and UV-ozone treatment. went.

  500 mg of zinc acrylate (manufactured by Wako Pure Chemical Industries) was dissolved in 7.77 g of ethanol (manufactured by Wako Pure Chemical Industries), and this solution was stirred for 1 hour. Then, this solution was spin-coated on the glass substrate which performed the said process at the speed of 2000 rotations. This glass substrate was heated at 150 degrees for 5 minutes to form a zinc oxide-containing layer as an electron extraction layer.

  The substrate on which the electron extraction layer was formed was brought into a glove box, heat-treated at 150 ° C. for 3 minutes in a nitrogen atmosphere, and after cooling, the active layer forming composition 1 (0.06 mL) prepared as described above at a speed of 1000 rpm. The active layer was formed by spin coating with Thereafter, the substrate was heated at 140 degrees for 10 minutes.

  Further, a hole extraction layer was formed on the active layer by spin coating a PEDOT: PSS dispersion at a speed of 300 rpm. Thereafter, the substrate was heated at 150 degrees for 10 minutes.

  After forming the hole extraction layer, a 30 nm thick IZO film is sputtered as a transparent electrode layer, then an 8 nm silver film is sputtered by resistance heating vacuum deposition, and a 40 nm IZO film is sequentially sputtered by an upper electrode. Film formation was performed to produce a photoelectric conversion element 1 of 5 mm square.

  The photoelectric conversion element 1 thus produced was measured for conversion efficiency by measuring current-voltage characteristics as described above.

  In order to evaluate the light resistance of the photoelectric conversion element 1, a UV curable resin is applied around the photoelectric conversion element 1 in nitrogen, a glass sealing plate is placed on the upper part, the resin is UV cured, and an irradiation light source As an air mass (AM) 1.5G, irradiance was 100 mW / cm2 solar simulator for 80 hours, and the ratio (maintenance ratio) between the photoelectric conversion efficiency after exposure and the photoelectric conversion efficiency before exposure was determined. The obtained results are shown in Table 1.

<Example 2: Production and evaluation of photoelectric conversion element 2>
A photoelectric conversion element 2 was produced and evaluated by the same method as in Example 1 except that the active layer forming composition 2 was used instead of the active layer forming composition 1. The obtained results are shown in Table 1.

<Comparative example 1: Production and evaluation of photoelectric conversion element 3>
A photoelectric conversion element 3 was produced and evaluated in the same manner as in Example 1 except that the active layer forming composition 3 was used instead of the active layer forming composition 1. The obtained results are shown in Table 1.

<Example 3: Production and evaluation of photoelectric conversion element 4>
As the lower electrode, a PEN substrate on which patterned ITO / Ag / ITO was laminated was prepared. Thereafter, an electron extraction layer, an active layer, a hole extraction layer, and an upper electrode were sequentially formed on the lower electrode by using the active layer forming composition 4 in the same manner as in Example 1 to obtain a photoelectric conversion element. 4 was produced.

  The photoelectric conversion element 4 thus produced was measured for conversion efficiency by measuring current-voltage characteristics as described above.

  In order to evaluate the light resistance of the photoelectric conversion element 4, a gas barrier film is bonded and sealed to the photoelectric conversion element 4 with an adhesive in the atmosphere, and air mass (AM) 1.5G as an irradiation light source, irradiance 100 mW / It exposed for 40 hours below with the solar simulator of cm2, and calculated | required the ratio (maintenance rate) of the photoelectric conversion efficiency after exposure with respect to the photoelectric conversion efficiency before exposure. Moreover, in order to confirm the external appearance of the produced photoelectric conversion element, white turbidity evaluation was performed visually. The obtained results are shown in Table 2.

<Example 4: Production and evaluation of photoelectric conversion element 5>
A photoelectric conversion element 5 was produced in the same manner as in Example 3 except that the active layer forming composition 5 was used instead of the active layer forming composition 4, and the same evaluation as in Example 3 was performed. . The obtained results are shown in Table 2.

<Example 5: Production and evaluation of photoelectric conversion element 6>
A photoelectric conversion element 6 was produced in the same manner as in Example 3 except that the active layer forming composition 6 was used instead of the active layer forming composition 4, and the same evaluation as in Example 3 was performed. . The obtained results are shown in Table 2.

<Example 6: Production and evaluation of photoelectric conversion element 7>
A photoelectric conversion element 7 was produced by the same method as in Example 3 except that the active layer forming composition 1 was used instead of the active layer forming composition 4, and the same evaluation as in Example 3 was performed. . The obtained results are shown in Table 2.

<Reference Example 1: Production and evaluation of photoelectric conversion element 8>
A photoelectric conversion element 8 was produced in the same manner as in Example 3 except that the active layer forming composition 7 was used instead of the active layer forming composition 4, and the same evaluation as in Example 3 was performed. . The obtained results are shown in Table 2.

<Comparative example 2: Production and evaluation of photoelectric conversion element 9>
A photoelectric conversion element 9 was produced in the same manner as in Example 3 except that the active layer forming composition 3 was used instead of the active layer forming composition 4, and the same evaluation as in Example 3 was performed. . The obtained results are shown in Table 2.

  In the column of white turbidity evaluation in Table 2, the case where no white turbidity was visually observed was rated as ◯, and the case where the film surface was clouded was evaluated as x.

  From the results of Table 1 and Table 2, it can be seen that the photoelectric conversion element according to the present invention in which the active layer contains inorganic nanoparticles has high light resistance with little reduction in conversion efficiency even when exposed to light. . Furthermore, it turns out that the photoelectric conversion element for see-through type organic thin-film solar cells excellent in the external appearance with few white turbidity can be provided by making the quantity of an inorganic nanoparticle into a specific range.

DESCRIPTION OF SYMBOLS 101 Lower electrode 102 Lower buffer layer 103 Active layer 104 Upper buffer layer 105 Upper electrode 106 Base material 107 Photoelectric conversion element 1 Weather-resistant protective film 2 UV 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

Claims (6)

On the substrate, at least a pair of transparent electrodes, and an active layer between the pair of transparent electrodes,
The active layer contains a p-type organic semiconductor compound, an n-type semiconductor compound, and inorganic nanoparticles.   The photoelectric conversion element of Claim 1 whose ratio of the said inorganic nanoparticle with respect to the said n-type semiconductor compound in the said active layer is 0.5 mass% or more and 20 mass% or less.   The photoelectric conversion element of Claim 1 or 2 whose average primary particle diameter of the said inorganic nanoparticle is 5 nm or more and 100 nm or less.   The photoelectric conversion element according to claim 1, wherein the inorganic nanoparticles are zinc oxide particles.   The solar cell which has a photoelectric conversion element of any one of Claims 1-4.   A solar cell module comprising the solar cell according to claim 5.

Images