JP2018018905A - Photoelectric conversion element and solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell having an appearance color suitable for a use environment of the solar cell by a simple method.SOLUTION: A photoelectric conversion element 107 includes: a pair of electrodes constituted by a lower electrode 101 and an upper electrode 105; an organic active layer 103 between the pair of electrodes; and buffer layers 102 and 104. At least one of the lower electrode 101, the upper electrode 105, and the buffer layers 102 and 104 is a colored layer.SELECTED DRAWING: Figure 1

Description

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

  In recent years, electronic devices using organic semiconductor polymers, especially organic thin film solar cells (OPV), have been actively studied. In particular, a transparent film type organic thin film solar cell is lightweight and can be made flexible, so that it is considered to be installed on a building material or a window. For example, Non-Patent Document 1 describes an organic thin film solar cell having a wide absorption band using two types of organic semiconductor polymers in order to improve the power generation performance of the organic thin film solar cell. In addition, when installing and using organic thin-film solar cells on conspicuous building materials and windows, it is important to improve not only the power generation performance of organic thin-film solar cells but also the design of organic thin-film solar cells. . For example, Patent Document 1 describes a photovoltaic power generation film for window glass in which the photoelectric conversion layer contains a blue or green pigment, and the film thickness of the photoelectric conversion layer is adjusted so as not to interfere with daylighting. Is described.

JP 2012-186310 A

Advanced Energy Materials, 2016, vol. 6 1502109

  As described above, when an organic thin film solar cell is considered to be installed on a building material, a window, or the like, high designability is required. However, in the case of the photovoltaic film described in Patent Document 1, when the film thickness of the photoelectric conversion layer is adjusted, the amount of light absorbed by the photoelectric conversion layer decreases, resulting in a decrease in the conversion efficiency of the photoelectric conversion element. Turned out to be. Moreover, in the case of the photovoltaic film of patent document 1, even if it became possible to adjust transparency by adjusting the film thickness of a photoelectric converting layer, the external color of a photovoltaic film still remains a photoelectric converting layer. Therefore, it was difficult to adjust the appearance color of the photovoltaic power generation film. Further, in Non-Patent Document 1, since the absorption band can be changed by using two kinds of organic semiconductor polymers in the active layer, the active layer is formed using two kinds of organic semiconductor compounds having different absorption spectra. Thus, it is conceivable to adjust the appearance color of the organic thin film solar cell. However, in order to obtain an ideal appearance color while maintaining a high power generation capacity, it is necessary to select an organic semiconductor polymer to be used, and it is extremely difficult to achieve both a high power generation capacity and an ideal appearance color. Have difficulty. This invention solves such a problem, and it aims at providing the solar cell provided with the external color suitable for the use environment of the solar cell by a simple method.

  The present inventors diligently studied to solve the above problems, and found that the above problems can be solved by using at least a part of the layer other than the organic active layer constituting the photoelectric conversion element as a colored layer. Thus, the present invention has been achieved.

That is, the gist of the present invention is as follows.
[1] A photoelectric conversion element having a pair of electrodes composed of a lower electrode and an upper electrode, an organic active layer and a buffer layer between the pair of electrodes, the lower electrode, the upper electrode, and the At least 1 layer is a colored layer among buffer layers, The photoelectric conversion element characterized by the above-mentioned.
[2] The photoelectric conversion element according to [1], wherein the colored layer is any one of layers positioned closer to the non-light-receiving surface than the organic active layer in the photoelectric conversion element.
[3] The photoelectric conversion element according to [1] or [2], wherein the buffer layer is the colored layer.
[4] The photoelectric conversion element according to [3], wherein the buffer layer is a hole extraction layer and contains a conductive polymer compound and a dye.
[5] The photoelectric conversion element according to [4], wherein the dye has a highest occupied molecular orbital (HOMO) energy level lower than a highest occupied molecular orbital (HOMO) energy level of the conductive polymer compound. .
[6] The photoelectric conversion element according to [4] or [5], wherein the content of the dye in the buffer layer is 1% by mass or more and 50% by mass or less.
[7] A solar cell module having the photoelectric conversion element according to any one of [1] to [6].

  According to the present invention, a solar cell module having an appearance color suitable for a use environment can be provided by a simple method.

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 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 includes at least a pair of electrodes, an active layer, and a buffer layer between the pair of electrodes on the element substrate. FIG. 1 shows an embodiment of a photoelectric conversion element according to the present invention. As shown in FIG. 1, one embodiment of a photoelectric conversion device according to the present invention includes a lower electrode 101, a buffer layer 102, an organic active layer 103, a buffer layer 104, and an upper electrode 105 on an element substrate 106. And has a layered structure formed sequentially.

  In the present invention, the lower electrode means an electrode laminated on the element substrate 106 side, and the upper electrode means an electrode laminated above the lower electrode when the element substrate 106 is at 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. Of the pair of electrodes, one electrode is a cathode having a function of collecting electrons generated in the organic active layer 103, and the other electrode collects holes generated in the organic active layer 103. This is an anode having a function. That is, when the lower electrode 101 is a cathode, the upper electrode 105 may be an anode, and when the lower electrode 101 is an anode, the upper electrode 105 may be a cathode.

Further, as described above, the photoelectric conversion element according to the embodiment of FIG. 1 has buffer layers between the lower electrode 101 and the organic active layer 103 and between the upper electrode 105 and the organic active layer 103, respectively. In the present invention, for convenience, the buffer layer 102 between the lower electrode 101 and the active layer 103 may be referred to as a lower buffer layer, and the buffer layer 104 between the upper electrode 105 and the active layer 103 is referred to as an upper buffer. Sometimes referred to as a layer.
One of the lower buffer layer 102 and the upper buffer layer 104 is a hole extraction layer that improves the transport efficiency of holes generated in the organic active layer 103, and the other buffer layer is the organic active layer 103. It is an electron extraction layer that improves the transport efficiency of the generated electrons. Therefore, when the lower electrode 101 is a cathode and the upper electrode is an anode, it is preferable that the lower buffer layer 102 be a hole extraction layer and the upper buffer layer 104 be an electron extraction layer. On the other hand, when the lower electrode 101 is an anode and the upper electrode is a cathode, the lower buffer layer 102 is preferably an electron extraction layer and the upper buffer layer 104 is preferably a hole extraction layer. In the present invention, it is not always necessary to have both the lower buffer layer 102 and the upper buffer layer 104, and only at least one buffer layer may be provided. Moreover, the photoelectric conversion element according to the present invention may optionally have another layer other than the above. Hereinafter, each component of the photoelectric conversion element will be described.

<1-1. Element Substrate 106>

  Each layer constituting the photoelectric conversion element 107 is usually formed on an element substrate 106 serving as a support. There is no particular limitation on the material of the element substrate 106. Preferable examples of the material for the element substrate 106 include inorganic materials such as quartz, glass, sapphire, and titania, and flexible base materials. Specific examples of the flexible substrate include, but are not limited to, polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, fluororesin film, vinyl chloride. Or polyolefin such as polyethylene; organic material (resin substrate) such as cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene, or epoxy resin; paper material such as paper or synthetic paper; stainless steel, Examples thereof include composite materials such as a metal foil such as titanium or aluminum whose surface is coated or laminated in order to impart insulation.

  The film thickness of the element substrate 106 is not particularly limited, but is usually 5 μm or more, preferably 20 μm or more, and is usually 20 mm or less, preferably 10 mm or less. The film thickness of the element substrate is preferably 5 μm or more because the possibility that the strength of the photoelectric conversion element is insufficient is reduced.

  Note that in the solar cell, when the element substrate 106 side is a light receiving surface, the element substrate 106 preferably has a light-transmitting property. In the present invention, having translucency means that the visible light transmittance is 40% or more. Note that it is preferable that the visible light transmittance of the element substrate 106 be 70% or more because more light can reach the photoelectric conversion layer 103. The visible light transmittance of the element substrate 106 can be measured by a method defined in JIS R3106. On the other hand, in the solar cell, in the case where the upper electrode 105 side of the photoelectric conversion element 107 is a light receiving surface, the element substrate 106 may or may not have a light-transmitting property. However, when a solar cell is installed in a window or the like, a see-through solar cell is preferably used. In this case, the element substrate 106 preferably has a light-transmitting property regardless of the light receiving surface.

<1-2. Pair of electrodes (101, 105)>
As described above, the photoelectric conversion element according to the present invention has a pair of electrodes including the lower electrode 101 and the upper electrode 105.

The material for forming the lower electrode 101 and the upper electrode 105 is not particularly limited, and nickel oxide, tin oxide, indium oxide, indium tin oxide (ITO), indium-zirconium oxide (IZO), titanium oxide, indium oxide, or zinc oxide. Metal oxides such as gold, platinum, silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium, sodium,
Examples thereof include metals such as potassium, cesium, calcium, magnesium and cobalt or alloys thereof. Among the above, the anode is preferably formed using a material having a relatively large work function, and the cathode is preferably formed using a material having a relatively small work function. Note that in the case where the photoelectric conversion element includes the lower buffer layer 102 and / or the upper buffer layer 104, the lower electrode 101 and the upper electrode 105 may be formed using the same material by adjusting these buffer layer materials. it can.

  Each of the lower electrode 101 and the upper electrode 105 may have a single layer structure or a laminated structure.

  In addition, at least one of the pair of electrodes preferably has a light-transmitting property. For example, in the case of a sunlight receiving surface on the element substrate 106 side, the lower electrode 101 preferably has a light transmitting property, and the upper electrode 105 may have a light transmitting property. It does not have to have sex. Further, when the upper electrode 105 side is a sunlight receiving surface, the upper electrode 105 is preferably translucent, and the lower electrode 101 may be translucent. It does not have to be light. Note that in the case where the photoelectric conversion element is a see-through type, it is preferable that both the lower electrode 101 and the upper electrode 105 have translucency.

  In the case of using a light-transmitting electrode, the electrode may be formed using the above metal oxide. Moreover, the structure which laminated | stacked the layer containing a metal oxide and the thin metal layer may be sufficient.

  The film thickness of the lower electrode 101 and the upper electrode 105 is not particularly limited, but is usually 5 nm or more, preferably 10 nm or more, more preferably 20 nm or more, while usually 2 μm or less, preferably 1 μm or less, more preferably 500 nm or less.

  The sheet resistance of the 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 a film is formed by applying a coating liquid containing nanoparticles or a precursor.

<1-3. Organic active layer 103>
The organic active layer 103 is a layer that contains a p-type semiconductor compound and an n-type semiconductor compound and undergoes photoelectric conversion. That is, when the photoelectric conversion element 107 receives light, the light is absorbed by the organic active layer 103, electricity is generated at the interface between the p-type semiconductor compound and the n-type semiconductor compound, and the generated electricity is extracted from the anode and the cathode. . The organic active layer 103 is usually colored in order to absorb light.

  As the layer structure of the organic active layer 103, a thin film laminated type in which a layer containing a p-type semiconductor compound and a layer containing an n-type semiconductor compound are laminated, or a layer in which a p-type semiconductor compound and an n-type semiconductor compound are mixed. The bulk hetero type junction type which is (mixed layer) is mentioned. The bulk heterojunction type organic active layer may have a structure in which a layer containing a p-type semiconductor compound and / or a layer containing an n-type semiconductor compound is further laminated in addition to the mixed layer. Among these, since high conversion efficiency can be expected, the organic active layer 103 is preferably a bulk heterojunction type.

The p-type organic semiconductor compound is not particularly limited, and examples thereof include a p-type low-molecular organic semiconductor compound, a p-type organic semiconductor oligomer, and a p-type organic semiconductor polymer.
The p-type low-molecular organic semiconductor compound is not particularly limited, but a porphyrin compound such as tetrabenzoporphyrin, tetrabenzocopper porphyrin, tetrabenzozinc porphyrin; phthalocyanine compound such as phthalocyanine, copper phthalocyanine, zinc phthalocyanine; naphthalocyanine compound; tetracene And pentacene polyacene.
The p-type organic semiconductor oligomer is not particularly limited, and examples thereof include oligothiophenes such as sexithiophene or derivatives containing these compounds as a skeleton.
The p-type organic semiconductor polymer is not particularly limited, but includes polythiophene including poly (3-alkylthiophene), polyfluorene, polyphenylene vinylene, polytriallylamine, polyacetylene, polyaniline, polypyrrole, thiophene ring or thiophene condensed ring. Examples thereof include polymers. More specifically, known p-type semiconductor polymers described in International Publication No. 2011/016430, International Publication No. 2013/180243, Japanese Unexamined Patent Publication No. 2012-191194, and the like can be given.
The n-type semiconductor compound is not particularly limited. For example, a fullerene; a fullerene derivative; a quinolinol derivative metal complex represented by 8-hydroxyquinoline aluminum; a condensed ring such as naphthalenetetracarboxylic acid diimide or perylenetetracarboxylic acid diimide 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, thiadiazoles Derivatives, triazole derivatives, aldazine derivatives, bisstyryl derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, benzoquino Derivatives, bipyridine derivatives, borane derivatives; total fluorides of condensed polycyclic aromatic hydrocarbons such as anthracene, pyrene, naphthacene or pentacene; single-walled carbon nanotubes, n-type polymers (n-type polymer semiconductor materials), etc. .

Among these, fullerene derivatives, 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 More preferred are fullerene derivatives, N-alkyl substituted perylene diimide derivatives, N-alkyl substituted naphthalene tetracarboxylic acid diimides or n-type polymer semiconductor compounds, and fullerene derivatives are particularly preferred. 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.
The thickness of the organic active layer 103 is not particularly limited, but is usually 50 nm or more, preferably 100 nm or more, more preferably 200 nm or more, in order to ensure the uniformity of the film and prevent a short circuit between the electrodes. In order to reduce internal resistance and efficiently perform charge diffusion, the thickness is usually 1000 nm or less, preferably 500 nm or less, and more preferably 400 nm or less.

  The method for forming the organic active layer 103 is not particularly limited, and can be formed by a known method in consideration of the material to be used. Specifically, it can be formed by a vacuum film formation method such as a vapor deposition method or a sputtering method, or a wet film formation method using a coating liquid containing the p-type semiconductor compound and / or n-type semiconductor compound and a solvent. .

As a wet film forming method, there is no particular limitation, spin coating method, reverse roll coating method, gravure coating method, kiss coating method, roll brush method, spray coating method, air knife coating method, wire barber coating method, pipe doctor method, Examples of the method include impregnation / coating and curtain coating.
The solvent is not particularly limited, but for example, aliphatic hydrocarbons such as hexane, heptane, octane, isooctane, nonane, tetralin or decane; aroma such as toluene, xylene, mesitylene, cyclohexylbenzene, chlorobenzene or orthodichlorobenzene Aromatic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, cycloheptane, cyclooctane, tetralin or decalin; lower alcohols such as methanol, ethanol or propanol; acetone, methyl ethyl ketone, cyclopentanone or Aliphatic ketones such as cyclohexanone; aromatic ketones such as acetophenone or propiophenone; esters such as ethyl acetate, butyl acetate or methyl lactate; Arm, methylene chloride, dichloroethane, halogenated hydrocarbons such as trichloroethane or trichlorethylene; ethers such as ethyl ether and tetrahydrofuran or dioxane; or an amide such as dimethylformamide or dimethylacetamide, and the like. In addition, a solvent may use 1 type of solvent independently, and may use arbitrary 2 or more types of solvents together by arbitrary ratios.

  When the organic active layer 103 is a thin film laminated type of a layer containing a p-type semiconductor compound and a layer containing an n-type semiconductor compound, there is no particular limitation, but it is formed by forming each layer by the method described above. do it. When the organic active layer 103 is a bulk heterojunction type, there is no particular limitation, but a coating solution containing a p-type semiconductor compound, an n-type semiconductor compound, and a solvent is prepared, and the coating solution is used. It is preferably formed by a wet film formation method.

<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 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 organic 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 bathocuproine (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 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, polythiophene, polypyrrole, polyacetylene, triphenylenediamine, polyaniline, or the like, a conductive polymer doped with sulfonic acid and / or iodine, a polythiophene derivative having a sulfonyl group as a substituent, or a conductive organic 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 thicknesses of the lower buffer layer 102 and the upper buffer layer 104 are each usually 0.1 nm or more. On the other hand, it is usually 400 nm or less, preferably 200 nm or less. If the thickness of each buffer layer is within the above range, charges can be easily taken out from the active layer 103, and the photoelectric conversion efficiency can be improved.

  There is no limitation on the method of forming the lower buffer layer 102 and the upper buffer layer 104. 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.

  In addition, when forming a buffer layer by the apply | coating method, you may make a coating liquid contain a surfactant further. 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. Colored layer>
As described above, the organic active layer 103 is usually colored. However, in the present invention, as described below, any of the layers other than the organic active layer 103 constituting the photoelectric conversion element is also a colored layer. Preferably there is. That is, at least one of the lower electrode, the upper electrode, and the buffer layer is preferably a colored layer. In the present invention, the colored layer means that the saturation c ^* in the CIE 1976 L ^* a ^* b ^* color space is 0.5 or more. In addition, a ^* value and b ^* value can be calculated | required by the method based on JISZ8722-2000, respectively, and saturation c ^* can be calculated | required by following formula (1).

Among them, the chroma C ^{* of the} colored layer is preferably 1 or more, more preferably 2 or more, more preferably 3 or more, and particularly preferably 5 or more.

  Usually, organic thin-film solar cells are being considered for easy-to-see areas such as building materials and windows, so organic thin-film solar cells are not only suitable for power generation performance but also for their appearance. It is required to have color.

  In general, the organic active layer is colored because it needs to absorb light. On the other hand, layers or members other than the organic active layer constituting the photoelectric conversion element and the solar cell module are usually more than the organic active layer of the organic thin-film solar cell in order to prevent the organic active layer from becoming a light absorption barrier. It is considered that the layer located on the light receiving surface side is preferably colorless and transparent. Therefore, the appearance color of the organic thin film solar cell usually tends to depend on the color of the organic active layer.

  However, as described above, since the appearance color of the organic thin film solar cell tends to depend on the color tone of the organic active layer, even if the power generation performance of the organic thin film solar cell is high, the appearance color of the organic thin film solar cell. Depending on the situation, it may not be suitable for the usage environment. On the other hand, to change the color tone of the organic active layer, it is necessary to change the material itself used for the organic active layer, and in this case, it may be difficult to achieve high conversion efficiency. Therefore, it is an important issue to provide an organic thin-film solar cell that achieves both high conversion efficiency and an appropriate appearance color.

  On the other hand, the present invention makes it possible to adjust the color tone while using a desired organic active layer material by using any one of the layers other than the organic active layer 103 constituting the photoelectric conversion element as a colored layer. Therefore, it is possible to provide an organic thin-film solar cell having an appearance color suitable for the use environment without greatly reducing the conversion efficiency.

  In addition, in order to adjust the external color of a photoelectric conversion element, adding a pigment | dye to an organic active layer is also considered. However, when a dye is added to the organic active layer, there is a concern that the presence of the dye inhibits the formation of a good nano / micro structure in the organic active layer and the photoelectric conversion characteristics are greatly deteriorated. Specifically, in the photoelectric conversion element, when light is absorbed in the organic active layer, exciton moves to the interface between the electron donor material and the electron acceptor material, charge separation at the interface, charge to the buffer layer The photoelectric conversion is performed through a number of processes such as the movement of the substrate, and these are greatly influenced by the nano / micro structure in the organic active layer. For this reason, if a dye is added to the organic active layer, such a nano / micro structure is significantly changed, and it becomes difficult to form a good nano / micro structure. We are anxious about it falling. On the other hand, since the functions of the buffer layer and the electrode are only to transport positive or negative carriers, it is considered that the conversion efficiency is less affected as compared with the organic active layer.

Hereinafter, the colored layer in the present invention will be described.

  As described above, in the present invention, at least one of the lower electrode, the upper electrode, and the buffer layer is preferably a colored layer. More specifically, at least one of the lower electrode 101, the upper electrode 105, the lower buffer layer 102, and the upper buffer layer 104 is preferably a colored layer.

  In the photoelectric conversion element, the layer positioned on the non-light-receiving surface side with respect to the organic active layer 103 is preferably a colored layer. Since the colored layer absorbs sunlight, if the layer located closer to the light-receiving surface than the organic active layer is a colored layer, the amount of sunlight absorbed by the organic active layer decreases, resulting in photoelectric conversion. The conversion efficiency of the element may be reduced. Therefore, if the layer located on the non-light-receiving surface side of the organic conversion layer 103 in the photoelectric conversion element is a colored layer, it is possible to prevent sunlight from being absorbed by the colored layer before being absorbed by the organic active layer. As a result, the appearance color of the photoelectric conversion element can be adjusted without resulting in a significant decrease in conversion efficiency. In the present invention, the layer located on the non-light-receiving surface side of the organic active layer in the photoelectric conversion element is the incident light side through the organic active layer 103 when the photoelectric conversion element is used as a solar cell. The opposite layer is meant.

That is, in the case of a non-transmissive photoelectric conversion element in which one of the pair of electrodes is a transparent electrode and the other electrode is a non-transparent electrode, the layer positioned on the non-light-receiving surface side is a non-transparent electrode. Or the layer located between a non-transparent electrode and an organic active layer is meant. On the other hand, in the case of a see-through photoelectric conversion element in which a pair of electrodes are both transparent electrodes, when the photoelectric conversion element is installed as an organic thin film solar cell, it is opposite to the sunlight receiving side through the organic active layer. It shall mean the layer located. That is, when the lower electrode 101 side is a sunlight receiving surface, the upper buffer layer 1
04 and / or the upper electrode 105 is preferably a colored layer. On the other hand, when the upper electrode 105 side is a sunlight receiving surface, the lower buffer layer 102 and / or the lower electrode 101 are preferably colored layers.

  The color of the colored layer is not particularly limited and may be arbitrarily selected according to the desired hue of the photoelectric conversion element. For example, by using a colored layer having an a * value or / and b * value different from the a * value or / and b * value in the CIE 1976 L * a * b * color space of the organic active layer, the hue of the photoelectric conversion element Can be adjusted. In particular, when a solar cell module is installed on a window or building material, an achromatic one tends to be preferred. Therefore, when it is desired to make the photoelectric conversion element achromatic, when the a * value and the b * value in the CIE1976L * a * b * color space of the organic active layer are x and y, respectively, the CIE1976L * a * b * color space. It is preferable to use a colored layer in which the a * value and b * value in the range of −x ± 3 and −y ± 3, respectively.

  Although there is no special restriction | limiting in the formation method of a colored layer, For example, it can form by making a target layer contain a pigment | dye. That is, when the lower buffer layer 102 and / or the upper buffer layer 104 are colored layers, the above-described <1-4. By using a layer containing the main compound listed in the buffer layer (102, 104)> and a dye, a colored layer maintaining the function as the buffer layer can be obtained. When the lower electrode 101 and / or the upper electrode 105 is a colored layer, <1-2. By forming a layer containing the main compound listed in the pair of electrodes (101, 105)> and a dye, a colored layer maintaining the functions of the lower electrode 101 and / or the upper electrode 105 can be obtained. it can.

  Although there is no special restriction | limiting in a pigment | dye, Dye or a pigment is mentioned.

  The dye is not particularly limited. For example, azo dye, anthraquinone dye, phthalocyanine dye, quinoneimine dye, quinoline dye, nitro dye, carbonyl dye, methine dye, cyanine dye, triaryl Examples thereof include methane dyes, dipyrromethene dyes, and xanthene dyes.

  Examples of the azo dye include C.I. I. Acid Yellow 11, C.I. I. Acid Orange 7, C.I. I. Acid Red 37, C.I. I. Acid Red 180, C.I. I. Acid Blue 29, C.I. I. Direct Red 28, C.I. I. Direct Red 83, C.I. I. Direct Yellow 12, C.I. I. Direct Orange 26, C.I. I. Direct Green 28, C.I. I. Direct Green 59, C.I. I. Reactive Yellow 2, C.I. I. Reactive Red 17, C.I. I. Reactive Red 120, C.I. I. Reactive Black 5, C.I. I. Disperse Orange 5, C.I. I. Disperse thread 58, C.I. I. Disperse blue 165, C.I. I. Basic Blue 41, C.I. I. Basic Red 18, C.I. I. Molded Red 7, C.I. I. Moldant Yellow 5, C.I. I. Examples thereof include Moldant Black 7.

  Examples of anthraquinone dyes include C.I. I. Bat Blue 4, C.I. I. Acid Blue 25, C.I. I. Acid Blue 40, C.I. I. Acid Blue 80, C.I. I. Acid Green 25, C.I. I. Reactive Blue 19, C.I. I. Reactive Blue 49, C.I. I. Disperse thread 60, C.I. I. Disperse Blue 56, C.I. I. Disperse Blue 60 etc. are mentioned.

Other examples of the phthalocyanine dye include C.I. I. Direct Blue 86, C.I. I. Direct Blue 199, C.I. I. Vat Blue 5, those described in JP-A No. 2002-14222, JP-A No. 2005-134759, JP-A No. 2010-191358 and JP-A No. 2011-148950 are examples of quinoneimine dyes such as C .
I. Basic Blue 3, C.I. I. Basic Blue 9 and the like are quinoline dyes such as C.I. I. Solvent Yellow 33, C.I. I. Acid Yellow 3, C.I. I. Disperse Yellow 64 and the like are nitro dyes such as C.I. I. Acid Yellow 1, C.I. I. Acid Orange 3, C.I. I. Disperse Yellow 42 and the like.

Examples of triarylmethane dyes include C.I. I. Acid Blue 86, C.I. I. Acid Blue 88, C.I. I. Acid Blue 108, International Publication No. 2009/107734 Pamphlet, International Publication No. 2011/162217 Pamphlet, and the like.
Furthermore, examples of the cyanine dye include those described in International Publication No. 2011/162217 pamphlet, and preferred embodiments thereof are also the same.

  Examples of dipyrromethene dyes include, for example, JP-A-2008-292970, JP-A-2010-84009, JP-A-2010-84141, JP-A-2010-85454, JP-A-2011-158654, and JP-A-2011-158654. Examples described in JP 2012-158739 A, JP 2012-224852 A, JP 2012-224849 A, JP 2012-224847 A, JP 2012-224846 A, and the like can be given.

  Examples of xanthene dyes include C.I. I. Acid Red 50, C.I. I. Acid Red 52, C.I. I. Acid Red 289, Japanese Patent No. 3387541, Japanese Patent Application Laid-Open No. 2010-32999, Japanese Patent No. 4492760, “Review Synthetic Dye” (Horiguchi Hiroshi, Sankyo Publishing, 1968), pages 326 to 348, etc. Is mentioned.

  Although there is no special restriction | limiting as a pigment, A pigment of various colors, such as a blue pigment, a green pigment, a red pigment, a yellow pigment, a purple pigment, an orange pigment, a brown pigment, can be used. Further, the color tone may be adjusted by combining two or more pigments. In addition to the organic pigments such as azo, phthalocyanine, quinacridone, benzimidazolone, isoindolinone, dioxazine, indanthrene, and perylene as the structure of the pigment, various inorganic pigments are also used. Is possible. Although there is no special restriction | limiting as an inorganic pigment, For example, a metal nanoparticle or a metal oxide nanoparticle is mentioned. Gold, silver, aluminum, nickel, cobalt etc. are mentioned as a metal of these nanoparticles.

  Hereinafter, specific examples of pigments that can be used in the present invention are shown by pigment numbers. Note that terms such as “CI Pigment Red 2” mentioned below mean a color index (CI).

Examples of red pigments include C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 14, 15, 16, 17, 21, 22, 23, 31, 32, 37, 38, 41, 47, 48, 48: 1, 48: 2, 48: 3, 48: 4, 49, 49: 1, 49: 2, 50: 1, 52: 1, 52: 2, 53, 53: 1, 53: 2, 53: 3, 57, 57: 1, 57: 2, 58: 4, 60, 63, 63: 1, 63: 2, 64, 64: 1, 68, 69, 81, 81: 1, 81: 2, 81: 3, 81: 4, 83, 88, 90: 1, 101, 101: 1, 104, 108, 108: 1, 109, 112, 113, 114, 122, 123, 144, 146, 147, 149, 151, 166, 168, 169, 170, 172, 173, 174, 175, 176, 177, 178, 17 , 181, 184, 185, 187, 188, 190, 193, 194, 200, 202, 206, 207, 208, 209, 210, 214, 216, 220, 221, 224, 230, 231, 232, 233, 235 236, 237, 238, 239, 242, 243, 245, 247, 249, 250, 251, 253, 254, 255, 256, 257, 258, 259, 260, 262, 263, 264, 265, 266, 267 268, 269, 270
271, 272, 273, 274, 275, 276. Of these, C.I. I. Pigment Red 48: 1, 122, 168, 177, 202, 206, 207, 209, 224, 242, 254, more preferably C.I. I. Pigment red 177, 209, 224, 254.

  Examples of blue pigments include C.I. I. Pigment Blue 1, 1: 2, 9, 14, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17, 19, 25, 27, 28, 29, 33, 35, 36, 56, 56: 1, 60, 61, 61: 1, 62, 63, 66, 67, 68, 71, 72, 73, 74, 75, 76, 78, 79. Of these, C.I. I. Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, more preferably C.I. I. Pigment blue 15: 6. Examples of green pigments include C.I. I. Pigment green 1, 2, 4, 7, 8, 10, 13, 14, 15, 17, 18, 19, 26, 36, 45, 48, 50, 51, 54, 55. Of these, C.I. I. Pigment Green 7, 36, 58.

  Examples of yellow pigments include C.I. I. Pigment Yellow 1, 1: 1, 2, 3, 4, 5, 6, 9, 10, 12, 13, 14, 16, 17, 24, 31, 32, 34, 35, 35: 1, 36, 36: 1, 37, 37: 1, 40, 41, 42, 43, 48, 53, 55, 61, 62, 62: 1, 63, 65, 73, 74, 75, 81, 83, 87, 93, 94, 95, 97, 100, 101, 104, 105, 108, 109, 110, 111, 116, 117, 119, 120, 126, 127, 127: 1, 128, 129, 133, 134, 136, 138, 139, 142, 147, 148, 150, 151, 153, 154, 155, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 172, 17 174, 175, 176, 180, 181, 182, 183, 184, 185, 188, 189, 190, 191, 191: 1, 192, 193, 194, 195, 196, 197, 198, 199, 200, 202 , 203, 204, 205, 206, 207, 208. Of these, C.I. I. Pigment yellow 83, 117, 129, 138, 139, 150, 154, 155, 180, 185, more preferably C.I. I. Pigment yellow 83, 138, 139, 150, 180.

  Examples of orange pigments include C.I. I. Pigment Orange 1, 2, 5, 13, 16, 17, 19, 20, 21, 22, 23, 24, 34, 36, 38, 39, 43, 46, 48, 49, 61, 62, 64, 65, 67, 68, 69, 70, 71, 72, 73, 74, 75, 77, 78, 79. Of these, C.I. I. And CI pigment oranges 38 and 71.

  Examples of purple pigments include C.I. I. Pigment Violet 1, 1: 1, 2, 2: 2, 3, 3: 1, 3: 3, 5, 5: 1, 14, 15, 16, 19, 23, 25, 27, 29, 31, 32, 37, 39, 42, 44, 47, 49, 50. Of these, C.I. I. Pigment violet 19, 23, more preferably C.I. I. And CI Pigment Violet 23.

  Among these, preferable dyes include azo dyes, anthraquinone dyes, and triarylmethane dyes.

  In addition, when forming a colored layer using a pigment | dye, only 1 type may be used for a pigment | dye and you may use 2 or more types.

  In addition, in order to improve the film-forming property of a colored layer, this pigment | dye may perform a desalting process etc. as needed.

  When the lower buffer layer 102 and / or the upper buffer layer 104 is used as a buffer layer, the lower buffer layer 102 and / or the upper buffer layer 104 preferably contain a dye as described above. Specific examples of the dye used include those described above.

When a dye is used for the buffer layer to form a colored layer, the dye is preferably a dye having an electron orbit that does not trap charge transfer in the buffer layer. That is, in the buffer layer, when the electron extraction layer is a colored layer, the energy level of the lowest unoccupied molecular orbital (LUMO) of the dye is the lowest end of the conduction band of the main compound constituting the electron extraction layer. Preferably it is higher than the energy level or the energy level of the lowest unoccupied molecular orbital (LUMO). That is, when the main compound constituting the electron extraction layer is an organic semiconductor compound, the energy level of the lowest unoccupied molecular orbital (LUMO) of the dye is lower than the energy level of the lowest unoccupied molecular orbital (LUMO) of the organic semiconductor compound. Is preferably high. On the other hand, when the main compound constituting the electron extraction layer is an inorganic compound, the energy level of the lowest unoccupied molecular orbital (LUMO) of the dye may be higher than the lowest energy level of the conduction band of the inorganic compound. preferable. In addition, the main compound which comprises an electron taking-out layer means the compound with most contribution of the wave function to the band used for electron transport, or an electron orbit among the compounds which comprise an electron taking-out layer.
Among the buffer layers, when the hole extraction layer is a colored layer, the energy level of the highest occupied molecular orbital (HOMO) of the dye is the uppermost valence band of the main compound constituting the hole extraction layer. Preferably it is below the energy level or the energy level of the highest occupied molecular orbital (HOMO). That is, when the main compound constituting the electron extraction layer is a conductive polymer compound, the energy level of the highest unoccupied molecular orbital (HOMO) of the dye is the highest unoccupied molecular orbital (HOMO) of the conductive compound. Preferably it is lower than the energy level. Further, when the main compound constituting the hole extraction layer is an inorganic compound, the energy level of the lowest unoccupied molecular orbital (LUMO) of the dye is lower than the energy level at the uppermost end of the valence band of the inorganic compound. It is preferable. Note that the main compound constituting the hole extraction layer is a large compound having the largest contribution of the wave function to the band or electron trajectory used for hole transport among the compounds constituting the hole extraction layer. means.
The energy level of the lowest unoccupied molecular orbital (LUMO), the energy level of the highest occupied molecular orbital (HOMO), the lowest energy level of the conduction band, and the highest energy level of the valence band of each compound and / or dye. Can be determined by cyclic voltammetry, various photoelectron spectroscopy methods represented by photoelectron yield spectroscopy and ultraviolet photoelectron spectroscopy, respectively.

  The buffer layer is <1-4. Although the compound mentioned by buffer layer (102,104)> is contained as a main compound, when making a buffer layer into a colored layer, it is preferable that a buffer layer contains a conductive polymer compound. The reason for this is not clear, but the dye interacts at a molecular level with the conductive polymer compound or its associated polymer compound. It is thought that it can prevent a fall.

When the buffer layer is a colored layer, the amount of the dye contained in the buffer layer is not particularly limited. However, the content of the dye in the buffer layer is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, in order to sufficiently color the buffer layer. It is more preferably 1% by mass or more, particularly preferably 0.5% by mass or more, most preferably 1% by mass or more, while the buffer layer ensures good conductivity. It is preferably 50% by mass or less, more preferably 25% by mass or less, and particularly preferably 20% by mass or less.

  When the lower buffer layer 102 and / or the upper buffer layer 104 are colored layers, the lower buffer layer 102 and / or the upper buffer layer 104 are preferably formed by a wet film forming method in order to disperse the dye well. For example, it can be formed by preparing and applying a coating solution in which a compound and a dye constituting the buffer layer are dissolved or dispersed in a solvent. In addition, what is necessary is just to adjust arbitrarily the quantity of the pigment | dye contained in a coating liquid according to content of the pigment | dye in said buffer layer. The solvent is not particularly limited. However, since the material constituting the organic active layer 103 is usually hydrophobic in many cases, a nonpolar solvent tends to be used for the coating solution for the organic active layer 103. There is. Therefore, when the upper buffer layer 104 and / or the lower buffer layer 104 is applied, a polar solvent such as water or alcohol is used as a main solvent, so that the lower buffer layer 102, the organic active layer 103, and the upper buffer layer 104 are Each layer can be stacked in an orderly manner without being mixed with each other during film formation.

  When the lower electrode 101 and / or the upper electrode 105 are used as a colored layer, the dye contained in the lower electrode 101 and / or the upper electrode 105 is not particularly limited, but the lower electrode and / or the upper electrode is sufficiently colored. Therefore, the content of the dye with respect to the main compound constituting the lower electrode and / or the upper electrode is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and 0.1% by mass. On the other hand, in order to prevent a decrease in the conductivity of the electrode, it is preferably 50% by mass or less, more preferably 20% by mass or less, and further preferably 10% by mass or less. Particularly preferred.

  In addition, when the lower electrode 101 and / or the upper electrode 105 are used as a colored layer, the method for forming the lower electrode 101 and / or the upper electrode 105 is not particularly limited. It is preferable to form by. In addition, what is necessary is just to adjust suitably content of the pigment | dye in the coating liquid for forming a lower electrode and / or an upper electrode, in order to obtain a desired lower electrode and / or upper electrode. Moreover, there is no special restriction | limiting in the solvent used for a coating liquid. However, when the upper electrode is formed as a colored layer by a wet film formation method, it is desirable to use a solvent that does not dissolve the upper buffer layer located below the upper electrode. That is, when the upper buffer layer shows hydrophobicity, it is desirable to use a neutral solvent such as water or alcohol as the coating group for the upper electrode. Conversely, when the upper buffer layer shows hydrophilicity, It is desirable to use a nonpolar solvent such as xylene.

  When forming a colored layer using a dye, there is no particular limitation, but in order to prevent a decrease in the transmittance of the photoelectric conversion element as much as possible, the full width at half maximum of the maximum absorption peak in the visible absorption spectrum of the dye is 60 nm or less. Preferably, it is 40 nm or less, more preferably 30 nm or less. On the other hand, in order to appropriately function as a colored layer, the half-value width of the maximum absorption peak in the visible absorption spectrum is 5 nm or more. preferable.

<1-6. Manufacturing method of photoelectric conversion element>
The photoelectric conversion element 107 having the configuration shown in FIG. 1 is formed on the element substrate 106 on the element substrate 106 in accordance with the above-described method described for each layer, and the upper electrode layer 104, the upper buffer layer 104, and the upper electrode. 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 module>
The photoelectric conversion element according to the above-described embodiment is preferably used as a solar cell module. Note that the solar cell module is preferably sealed with a gas barrier layer or the like in order to prevent the photoelectric conversion element from being deteriorated by water or oxygen. Moreover, it is preferable to have a current collector for taking out the electricity generated by the photoelectric conversion element.

  FIG. 2 is a cross-sectional view schematically showing a configuration of a solar cell module as one embodiment of the present invention. As shown in FIG. 2, the solar cell module includes gas barrier layers 201 and 202, sealing layers 203 and 204, and a current collector 205 in addition to the element substrate 206 and the photoelectric conversion element 207.

  There are no particular restrictions on the materials and stacking methods of the gas barrier layers 201 and 202, the sealing layers 203 and 204, and the current collector 205 that constitute the solar cell module, 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. In addition, the structure of a solar cell module is not limited to the structure of FIG. 2, As long as it can generate electric power with a photoelectric conversion element, what kind of structure may be sufficient as it. In FIG. 2, the element substrate 206 side (gas barrier layer 201 side) is a sunlight incident surface, but the present invention is not limited to this, and the photoelectric conversion element 207 side (gas barrier layer 202 side) is sunlight. It may be a light receiving surface.

  There is no special restriction | limiting in the use of the solar cell module which concerns on this invention, 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.

Especially, it is preferable to affix and use the solar cell module which concerns on this invention on adherends, such as partitions, such as glass, such as a window, a door, a wall surface, or a ceiling, such as a building and a vehicle. In the present invention, when constructing a solar cell module on the wall surface of a window or building material, the colored layer of the photoelectric conversion element absorbs light, thereby preventing the amount of light absorbed by the organic active layer from decreasing. The solar cell module is preferably installed so that the colored layer is positioned closer to the non-light-receiving surface than the organic active layer.

  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 of the present invention 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

(Preparation of coating liquid 1 for organic active layer)
A mixture of an organic semiconductor polymer which is a p-type semiconductor compound and PC ₆₁ BM (phenyl C61 butyric acid methyl ester) and PC ₇₁ BM (phenyl C71 butyric acid methyl ester) which are n-type semiconductor compounds has a mass ratio of 1: 2. It mixed so that it might become. The obtained mixture was dissolved in a solvent in a nitrogen atmosphere so as to be 45 mg with respect to 1 mL of the solvent to prepare an organic active layer coating solution. The solvent used was a mixed solvent of o-xylene and tetralin (volume ratio 9: 1).

(Preparation of coating liquid P1 for hole extraction layer)
Acid R obtained by desalting PEDOT: PSS dispersion with a solid content of 2.3% by mass
2 mg of ed 289 (manufactured by Tokyo Chemical Industry Co., Ltd.) (4.2% by mass with respect to the total solid concentration constituting the hole extraction layer) was added to make 2 g as a whole. Thereafter, ultrasonic treatment was performed for 10 minutes, and then passed through a filter having a diameter of 5 μm to prepare a hole extraction layer coating solution P1.

(Preparation of coating liquid P2 for hole extraction layer)
Except that the amount of Acid Red 289 (manufactured by Tokyo Chemical Industry Co., Ltd.) was 1 mg (2.18% by mass with respect to the total solid concentration constituting the hole extraction layer), the same method as in Example 1 was used. A hole extraction layer coating solution P2 was prepared.

(Preparation of coating liquid P3 for hole extraction layer)
Brilliant Blue R (manufactured by Tokyo Chemical Industry Co., Ltd.) was added to PEDOT: PSS dispersion liquid with a solid content concentration of 2.3% (8% by mass with respect to the total solid content concentration constituting the hole extraction layer). 2 g. Then, ultrasonic treatment was performed for 10 minutes, and the coating solution P2 for hole extraction layer was prepared by passing through a filter having a diameter of 5 μm.

<Example 1: Production and evaluation of solar cell module 1>
A glass substrate (manufactured by Geomatic Co., Ltd.) on which a transparent conductive film made of indium tin oxide (ITO) / Ag / indium tin oxide is patterned is subjected to ultrasonic cleaning with acetone and then ultrasonic cleaning with isopropanol, and then nitrogen. Drying by blow and UV-ozone treatment were performed.

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. Thereafter, this solution was spin-coated on a glass substrate at a speed of 2000 rpm, and heated at 150 ° C. for 5 minutes to form a zinc oxide-containing layer which was an electron extraction layer.

  The glass substrate on which the electron extraction layer is formed is brought into a flow box, heat-treated at 150 ° C. for 3 minutes in a nitrogen atmosphere, and after cooling, the coating solution for organic active layer (0.06 mL) prepared as described above at a speed of 350 rpm. The organic active layer was formed by spin coating. Thereafter, the substrate was heated at 140 degrees for 10 minutes. In addition, as a result of observing the obtained organic active layer visually, the organic active layer was bright yellowish green.

  Further, the hole extraction layer coating liquid P1 was spin-coated at a rate of 300 rpm on the organic active layer, and then heated at 150 ° C. for 10 minutes to form a hole extraction layer as a colored layer.

  Next, an upper electrode is formed on the hole extraction layer by sequentially forming a 30 nm thick IZO film, an 8 nm silver film, and a 40 nm IZO film by vacuum sputtering, and the 5 mm square photoelectric conversion element 1 is formed. Produced.

The photoelectric conversion element 1 conversion efficiency obtained by the above-mentioned method was measured. Moreover, the external appearance color of the obtained photoelectric conversion element was confirmed visually. The obtained results are shown in Table 1.
<Example 2: Production and evaluation of photoelectric conversion element 2>
A photoelectric conversion element 2 was prepared and evaluated in the same manner as in Example 1 except that the hole extraction layer coating solution P2 was used instead of the hole extraction layer coating solution P1. The obtained results are shown in Table 1.

<Example 3: Production and evaluation of photoelectric conversion element 3>
A photoelectric conversion element 3 was prepared and evaluated in the same manner as in Example 1 except that the hole extraction layer coating solution P3 was used instead of the hole extraction layer coating solution P1. The obtained results are shown in Table 1.
<Comparative Example 1: Production / Evaluation of Photoelectric Conversion Element 4>
A photoelectric conversion element was produced in the same manner as in Example 1 except that the hole extraction layer was formed using a PEDOT: PSS dispersion having a solid content of 2.3% instead of the coating liquid 1 for hole extraction layer. 4 was produced and evaluated in the same manner. The obtained results are shown in Table 1.

  The color of the organic active layer visually observed under a white fluorescent lamp is bright yellowish green, and the photoelectric conversion element 3 according to Comparative Example 1 in which no colored layer is provided has the same appearance color as the organic active layer. It was. On the other hand, the appearance color of the photoelectric conversion elements 1 and 2 produced in Examples 1 and 2 using the hole extraction layer as a colored layer is a dark brown color, and the hole extraction layer is colored in the same manner as in Example 1. The appearance color of the photoelectric conversion element 2 produced in Example 3 as a layer was deep blue-green. Furthermore, as shown in Table 1, it is understood that the photoelectric conversion elements 1 to 3 provided with the colored layer have a conversion efficiency equal to or higher than that of the photoelectric conversion element 4 according to Comparative Example 1 in which the colored layer is not provided. . Therefore, it turns out that the external color of a photoelectric conversion element can be adjusted, without reducing conversion efficiency by making layers other than the organic active layer which comprises a photoelectric conversion element into a colored layer.

101 Lower electrode 102 Lower buffer layer 103 Active layer 104 Upper buffer layer 105 Upper electrode 106, 206 Element substrate 107, 207 Photoelectric conversion element 201, 202 Gas barrier layer 203, 204 Sealing layer 205

Claims (7)

A photoelectric conversion element having a pair of electrodes constituted by a lower electrode and an upper electrode, an organic active layer between the pair of electrodes, and a buffer layer,
At least one of the lower electrode, the upper electrode, and the buffer layer is a colored layer.   2. The photoelectric conversion element according to claim 1, wherein the colored layer is any one of layers positioned closer to a non-light-receiving surface than the organic active layer in the photoelectric conversion element.   The photoelectric conversion element according to claim 1, wherein the buffer layer is the colored layer.   The photoelectric conversion element according to claim 3, wherein the buffer layer is a hole extraction layer and contains a conductive polymer compound and a dye.   The photoelectric conversion element according to claim 4, wherein the highest occupied molecular orbital (HOMO) energy level of the dye is lower than the highest occupied molecular orbital (HOMO) energy level of the conductive polymer compound.   6. The photoelectric conversion element according to claim 4, wherein the content of the dye in the buffer layer is 1% by mass or more and 50% by mass or less.   The solar cell module which has a photoelectric conversion element of any one of Claims 1-6.