JP2014207321A - Organic thin film solar cell element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic thin film solar cell element that is transparent and is excellent in durability.SOLUTION: The organic thin film solar cell element includes sequentially at least on a transparent substrate: a lower transparent electrode; an organic photoelectric conversion layer; and an upper transparent electrode. The upper transparent electrode is made to be a translucent multilayer film electrode containing a metal layer and a transparent conductive oxide layer.

Description

  The present invention relates to an organic thin film solar cell element.

  Since organic thin film solar cells are thin and light and have excellent design properties, applications utilizing these features, such as attaching organic thin film solar cells to windows of buildings, etc., have been devised. For example, Patent Document 1 discloses a solar power generation film having translucency that does not interfere with visibility and indoor lighting while maintaining high power generation efficiency.

JP 2012-186310 A

In order to obtain an organic thin-film solar cell element having translucency, it is necessary to use an opaque metal electrode that is usually used as an electrode on the non-light-receiving surface side as an electrode having translucency.
ITO, a conductive polymer, or the like is known as a light-transmitting electrode. However, when ITO is used, the surface resistance of the electrode is higher than that of a metal electrode, and the performance of the solar cell is lowered. Although the surface resistance can be reduced by increasing the thickness of ITO or performing high-temperature film formation or heat treatment, there are problems such as a decrease in flexibility and the occurrence of cracks due to an increase in film stress. Furthermore, the formed organic photoelectric conversion layer may be deteriorated by heating. In addition, a material having a low surface resistance when a conductive polymer is formed into a thin film is not known.

Therefore, in Patent Document 1, grid electrodes provided in a lattice shape are formed by a gravure printing method or the like. However, the grid electrode described in Patent Document 1 has a line of about 10 μm to about 50 μm installed at a distance between the grids of about 200 μm to about 300 μm, and there is a problem of reduction of the daylighting area and cost increase due to printing. .
This invention solves these problems, and makes it a subject to provide the organic thin-film solar cell element excellent in electric power generation performance and lighting property.

The present inventors have studied to form an electrode having translucency by thinning the metal electrode. However, when the metal electrode is thinned, the initial output of the organic thin film solar cell obtained through the sealing step is reduced. I found that there was a problem of decline.
The reason why the initial output of the organic thin-film solar cell is lowered is not clear, but the metal constituting the metal electrode is crystallized or aggregated by heat by heating the entire organic thin-film solar cell in the sealing process, and as a result, This is thought to be because the continuity of the metal electrode is lost and electrical conduction is interrupted.

Therefore, the present inventors have found that the above-mentioned problems can be solved by further laminating a transparent conductive oxide layer on the thinned metal layer, and have completed the present invention.
The outline of the present invention is as follows.
[1] In an organic thin film solar cell element having at least a lower transparent electrode, an organic photoelectric conversion layer, and an upper transparent electrode in this order on a transparent substrate, the upper transparent electrode includes a metal layer and a transparent conductive oxide layer. An organic thin film solar cell element which is a multilayer electrode.
[2] The organic thin-film solar cell element according to [1], which has an adhesive layer and a gas barrier layer sequentially on the upper transparent electrode.
[3] The organic thin-film solar cell element according to [1] or [2], wherein the metal of the metal layer is silver.
[4] The organic thin-film solar cell element according to any one of [1] to [3], wherein the metal layer has a thickness of 30 nm or less.
[5] The organic thin-film solar cell element according to any one of [1] to [4], wherein the conductive oxide of the transparent conductive oxide layer is a compound containing indium oxide.
[6] The organic thin-film solar cell element according to any one of [2] to [5], wherein the adhesive layer is a thermosetting resin layer.
[7] The organic thin film solar cell element according to any one of [1] to [6], wherein the transparent substrate is an organic resin film.

  According to the present invention, it is possible to obtain an organic thin-film solar cell element that has high initial output and weather resistance and that does not reduce the daylighting area.

It is a conceptual diagram which shows the one aspect | mode of an organic thin-film solar cell element. It is a figure which shows typically the structure of the organic thin film solar cell using the organic thin film solar cell element of this invention. It is a conceptual diagram which shows typically the structure of the organic thin film solar cell module using the organic thin film solar cell element of this invention.

Hereinafter, the organic thin film solar cell element of the present invention will be described.
1. Organic thin-film solar cell element The organic thin-film solar cell element of the present invention sequentially has at least a lower transparent electrode, an organic photoelectric conversion layer, and an upper transparent electrode on a transparent substrate.
FIG. 1 shows one embodiment of an organic thin film solar cell element. The organic thin film solar cell element shown in FIG. 1 is an organic thin film solar cell element used for a general organic thin film solar cell. The configuration of the organic thin film solar cell element according to the present invention is the same as that shown in FIG. It is not limited. The organic thin film solar cell element 107 as one embodiment of the present invention includes a transparent substrate 106, a lower transparent electrode 101, an electron extraction layer 102, an organic photoelectric conversion layer 103 (a layer containing a p-type semiconductor compound and an n-type semiconductor material). , A hole extraction layer 104 and an upper transparent electrode 105 are sequentially formed.

1-1. Buffer layer (electron extraction layer 102, hole extraction layer 104)
The organic thin film solar cell element 107 includes an electron extraction layer 102 between the lower transparent electrode 101 and the organic photoelectric conversion layer 103. The organic thin-film solar cell element 107 has a hole extraction layer 104 between the organic photoelectric conversion layer 103 and the upper transparent electrode 105. In the organic thin-film solar cell element according to the present invention, the electron extraction layer 102 and the hole extraction layer 104 are not essential and can be arbitrarily provided.

The electron extraction layer 102 and the hole extraction layer 104 are preferably disposed so as to sandwich the organic photoelectric conversion layer 103 between the pair of transparent electrodes (101, 105). That is, when the organic thin film solar cell element 107 includes both the electron extraction layer 102 and the hole extraction layer 104, the upper transparent electrode 105, the hole extraction layer 104, the organic photoelectric conversion layer 103, the electron extraction layer 102, and the lower transparent The electrodes 101 can be arranged in this order. When the organic thin film solar cell element 107 includes the electron extraction layer 102 but does not include the hole extraction layer 104, the electrode 105, the organic photoelectric conversion layer 103, the electron extraction layer 102, and the lower transparent electrode 101 may be arranged in this order. it can. The stacking order of the electron extraction layer 102 and the hole extraction layer 104 may be reversed, or at least one of the electron extraction layer 102 and the hole extraction layer 104 may be formed of a plurality of different films.

1-1-1. Electron extraction layer (102)
The material of the electron extraction layer 102 is not particularly limited as long as it is a material that improves the efficiency of extracting electrons from the organic photoelectric conversion layer 103 to the lower transparent electrode 101, and examples thereof include inorganic compounds and organic compounds.
Examples of the material of the inorganic compound 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, the work function of the lower transparent electrode 101 is reduced when combined with the lower transparent electrode 101 made of Al or the like, and the voltage applied to the solar cell element is reduced. It can be raised.

  Examples of organic compound materials include, for example, phosphine compounds having a double bond between a phosphorus atom and a group 16 element such as triarylphosphine oxide compounds; bathocuproin (BCP) or bathophenanthrene (Bphen), A phenanthrene compound which may have a substituent and may be substituted at the 1-position and the 10-position with a heteroatom; a boron compound such as triarylboron; and (8-hydroxyquinolinato) aluminum (Alq3) Organometallic 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 acid Of dicarboxylic anhydrides, such as anhydrides (PTCDA) Aromatic compounds having Unachijimigo dicarboxylic acid structure.

  The LUMO energy level of the material of the electron extraction layer 102 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 of the electron extraction layer 102 is −1.9 eV or less because charge transfer can be promoted. It is preferable that the LUMO energy level of the material of the electron extraction layer 102 is −4.0 eV or more because reverse electron transfer to the n-type semiconductor material can be prevented.

  The HOMO energy level of the material of the electron extraction layer 102 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 of the electron extraction layer 102 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 102, a cyclic voltammogram measurement method can be given. For example, it can implement with reference to the method as described in well-known literature (International Publication 2011/016430).
When the material of the electron extraction layer 102 is an organic compound, the glass transition temperature (hereinafter sometimes referred to as Tg) of this compound when measured by a 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. Compounds that are 120 ° C. or higher are 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. The material of the electron extraction layer 104 is preferably a material whose glass transition temperature by DSC method is not observed to be 30 ° C. or higher and lower than 55 ° C.

  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.

  The thickness of the electron extraction layer 102 is not particularly limited, but is usually 0.01 nm or more, preferably 0.1 nm or more, more preferably 0.5 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 102 is 0.01 nm or more, it functions as a buffer material. When the film thickness of the electron extraction layer 102 is 400 nm or less, electrons are easily extracted, and photoelectric conversion is performed. Efficiency can be improved.

When an alkali metal salt is used as a material for the electron extraction layer 102, the electron extraction layer 102 can be formed using a vacuum film formation method such as vacuum evaporation or sputtering. In particular, it is desirable to form the electron extraction layer 102 by vacuum deposition using resistance heating. By using vacuum deposition, damage to other layers such as the organic photoelectric conversion layer 103 can be reduced. As for the metal oxide of the n-type semiconductor, for example, when zinc oxide ZnO is used as the material of the electron extraction layer 102, a vacuum film formation method such as a sputtering method can be used. It is desirable to form the layer 102. 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), the electron extraction layer 102 made of zinc oxide can be formed. 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 102 is too thin, the effect of improving the electron extraction efficiency is not sufficient, and if it is too thick, the electron extraction layer 102 acts as a series resistance component and tends to impair the characteristics of the element. When the material of the electron extraction layer 102 is an organic compound, in general, when a material having sublimation properties is used, a vacuum film formation method such as a vacuum evaporation method can be used. In addition, when a material soluble in a solvent is used, a wet coating method such as spin coating or ink jet can be used.

  When the electron extraction layer 102 is formed by a coating method, a surfactant may be further included 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.

1-1-2. Hole extraction layer (104)
The material of the hole extraction layer 104 is not particularly limited as long as it is a material capable of improving the efficiency of extracting holes from the organic photoelectric conversion layer 103 to the upper transparent electrode 105. 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 thickness of the hole extraction layer 104 is not particularly limited, but is usually 0.2 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 hole extraction layer 104 is 0.2 nm or more, it functions as a buffer material, and when the film thickness of the hole extraction layer 104 is 400 nm or less, holes are easily extracted. The photoelectric conversion efficiency can be improved.

  There is no limitation on the formation method of the hole extraction 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 the case of using a semiconductor material for the hole extraction layer 104, the precursor may be converted into a semiconductor compound after the layer is formed using the precursor, similarly to the low-molecular organic semiconductor compound of the organic organic photoelectric conversion layer described later. Good.

Especially, when using PEDOT: PSS as a material of the hole taking-out layer 104, it is preferable to form the hole taking-out layer 104 by the method of apply | coating a dispersion liquid. PEDOT: The dispersion of PSS, and CLEVIOS ^TM series of Heraeus, Inc., include Agfa Corp. of ORGACON ^TM series and the like.
When the hole extraction layer 104 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.

1-2. Organic photoelectric conversion layer (103)
The organic photoelectric conversion layer 103 refers to a layer in which photoelectric conversion is performed, and usually includes a p-type semiconductor compound and an n-type semiconductor compound. The p-type semiconductor compound is a compound that works as a p-type semiconductor material, and the n-type semiconductor compound is a compound that works as an n-type semiconductor material. When the organic thin film solar cell element 107 receives light, the light is absorbed by the organic photoelectric conversion 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 transmitted from the electrodes 101 and 105. It is taken out.

As the material of the organic photoelectric conversion layer 103, either an inorganic compound or an organic compound may be used, but a layer that can be formed by a simple coating process is preferable. More preferably, the organic photoelectric conversion layer 103 is an organic photoelectric conversion layer made of an organic compound. Below, the organic photoelectric converting layer 103 is demonstrated as what is an organic photoelectric converting layer.
The layer structure of the organic photoelectric conversion layer 103 includes a thin film stack type in which a p-type semiconductor compound layer and an n-type semiconductor compound layer are stacked, and a bulk heterojunction type having a layer in which a p-type semiconductor compound and an n-type semiconductor compound are mixed. , A p-type semiconductor compound layer, a layer in which a p-type semiconductor compound and an n-type semiconductor compound are mixed (i-layer), and an n-type semiconductor compound layer are stacked. Among these, a bulk heterojunction type having a layer in which a p-type semiconductor compound and an n-type semiconductor compound are mixed is preferable.

  The film thickness of the organic photoelectric conversion layer 103 is not particularly limited, but is usually 10 nm or more, preferably 50 nm or more, while usually 1000 nm or less, preferably 500 nm or less, more preferably 400 nm or less, still more preferably 300 nm or less, particularly preferably. 200 nm or less. When the thickness of the organic photoelectric conversion layer 103 is equal to or more than the lower limit, the uniformity of the film is maintained, and a short circuit is hardly caused. Moreover, it is preferable in that it is less than the upper limit in that the internal resistance is reduced, and the electrodes 101 and 105 are not separated too much and the charge diffusion is good. Moreover, it is preferable at the point which can maintain the translucency of an organic photoelectric converting layer.

  Although there is no restriction | limiting in particular as a preparation method of the organic photoelectric converting layer 103, The application | coating method is preferable. As the coating method, any method can be used, for example, 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, Examples include the pipe doctor method, the impregnation / coating method, and the curtain coating method.

  For example, the p-type semiconductor compound layer and the n-type semiconductor compound layer can be produced by applying a coating liquid containing a p-type semiconductor compound or an n-type semiconductor compound. Moreover, the layer in which the p-type semiconductor compound and the n-type semiconductor compound are mixed can be prepared by applying a coating solution containing the p-type semiconductor compound and the n-type semiconductor compound. As will be described later, the semiconductor compound precursor may be converted into a semiconductor compound after the coating liquid containing the semiconductor compound precursor is applied.

1-2-1. The p-type semiconductor compound included in the organic photoelectric conversion layer 103 is not particularly limited, and examples thereof include a low-molecular organic semiconductor compound and a high-molecular organic semiconductor compound.
1-2-1-1. Low molecular organic semiconductor compound The molecular weight of the low molecular organic semiconductor compound is not particularly limited both at the upper limit and the lower limit, but is usually 5000 or less, preferably 2000 or less, and is usually 100 or more, preferably 200 or more.

Further, the low molecular organic semiconductor compound preferably has crystallinity. The p-type semiconductor compound having crystallinity has a strong intermolecular interaction, and holes generated at the interface between the p-type semiconductor compound and the n-type semiconductor compound in the organic photoelectric conversion layer 103 are efficiently transferred to the upper transparent electrode 105. Can be transported.
In the present specification, crystallinity is a property of a compound that takes a three-dimensional periodic arrangement with uniform orientation due to intermolecular interaction or the like. Examples of the crystallinity measuring method include an X-ray diffraction method (XRD) and a field effect mobility measuring method. In particular, in the field effect mobility measurement, the hole mobility is preferably 1.0 × 10 ⁻⁵ cm ² / Vs or more, and more preferably 1.0 × 10 ⁻⁴ cm ² / Vs or more. On the other hand, the hole mobility is usually preferably 1.0 × 10 ⁴ cm ² / Vs or less, more preferably 1.0 × 10 ³ cm ² / Vs or less, and 1.0 × 10 ² cm. More preferably, it is ² / Vs or less.

  The low-molecular organic semiconductor compound is not particularly limited as long as it can function as a p-type semiconductor material. Specifically, condensed aromatic hydrocarbons such as naphthacene, pentacene, or pyrene; α-sexithiophene, etc. Oligothiophenes containing 4 or more thiophene rings; including at least one of thiophene ring, benzene ring, fluorene ring, naphthalene ring, anthracene ring, thiazole ring, thiadiazole ring and benzothiazole ring, and a total of 4 or more linked A phthalocyanine compound and a metal complex thereof, or a porphyrin compound such as tetrabenzoporphyrin and a macrocycle such as a metal complex thereof. Preferably, they are a phthalocyanine compound and its metal complex, or a porphyrin compound and its metal complex.

  Examples of the method for forming a low molecular organic semiconductor compound include a vapor deposition method and a coating method. The latter is preferred because of the process advantage that coating can be formed. When the coating method is used, there is a method of converting a low molecular organic semiconductor compound precursor into a low molecular organic semiconductor compound after coating. A method using a semiconductor compound precursor is more preferable in that coating film formation is easier.

(Low molecular organic semiconductor compound precursor)
A low molecular organic semiconductor compound precursor is a compound that changes its chemical structure and is converted into a low molecular organic semiconductor compound by applying an external stimulus such as heating or light irradiation. The low molecular organic semiconductor compound precursor is preferably excellent in film formability. In particular, in order to be able to apply the coating method, it is preferable that the precursor itself can be applied in a liquid state, or the precursor is highly soluble in some solvent and can be applied as a solution. For this reason, the solubility with respect to the solvent of a low molecular organic-semiconductor compound precursor is usually 0.1 weight% or more, Preferably it is 0.5 weight% or more, More preferably, it is 1 weight% or more. On the other hand, the upper limit is not particularly limited, but is usually 50% by weight or less, preferably 40% by weight or less.

The type of the solvent is not particularly limited as long as it can uniformly dissolve or disperse the semiconductor precursor compound. For example, aliphatic hydrocarbons such as hexane, heptane, octane, isooctane, nonane or decane; toluene, xylene , Aromatic hydrocarbons such as cyclohexylbenzene, chlorobenzene or orthodichlorobenzene; lower alcohols such as methanol, ethanol or propanol; ketones such as acetone, methyl ethyl ketone, cyclopentanone or cyclohexanone; ethyl acetate, butyl acetate or methyl lactate Esters such as: Chloroform, methylene chloride, dichloroethane, trichloroethane, trichloroethylene, and other halogen hydrocarbons; Ethyl ether, tetrahydrofuran, dioxane, and other ethers; Dimethyl Formamide or amides such as dimethylacetamide and the like. Of these, aromatic hydrocarbons such as toluene, xylene, cyclohexylbenzene, chlorobenzene, or orthodichlorobenzene; ketones such as acetone, methyl ethyl ketone, cyclopentanone, or cyclohexanone; chloroform, methylene chloride, dichloroethane, trichloroethane, or trichloroethylene Halogen hydrocarbons; ethers such as ethyl ether, tetrahydrofuran or dioxane. More preferably, non-halogen aromatic hydrocarbons such as toluene, xylene or cyclohexylbenzene; non-halogen ketones such as cyclopentanone or cyclohexanone; non-halogen aliphatic ethers such as tetrahydrofuran or 1,4-dioxane is there. Particularly preferred are non-halogen aromatic hydrocarbons such as toluene, xylene or cyclohexylbenzene. In addition, 1 type of solvent may be used independently and 2 or more types of solvents may be used together by arbitrary combinations and a ratio.

  Furthermore, it is preferable that the low molecular organic semiconductor compound precursor can be easily converted into a semiconductor compound. In the step of converting a low molecular organic semiconductor compound precursor to a semiconductor compound, which will be described later, what kind of external stimulus is given to the semiconductor precursor is arbitrary, but usually heat treatment or light treatment is performed. Preferably, it is heat treatment. In this case, the low-molecular organic semiconductor compound precursor preferably has a solvophilic group with respect to a predetermined solvent, which can be eliminated by a reverse Diels-Alder reaction as a part of the skeleton.

  Moreover, it is preferable that a low molecular organic-semiconductor compound precursor is converted into a semiconductor compound with a high yield through a conversion process. At this time, the yield of the semiconductor compound obtained by conversion from the low molecular organic semiconductor compound precursor is arbitrary as long as the performance of the organic thin film solar cell element is not impaired, but the low molecular organic obtained from the molecular organic semiconductor compound precursor The yield of the semiconductor compound is usually 90 mol% or more, preferably 95 mol% or more, more preferably 99 mol% or more.

The low molecular organic semiconductor compound precursor is not particularly limited as long as it has the above characteristics, and specifically, compounds described in JP-A-2007-324587 can be used.
The low molecular organic semiconductor compound precursor may have a structure in which positional isomers exist, and in that case, it may be a mixture of a plurality of positional isomers. A mixture of a plurality of positional isomers is preferable because it has a higher solubility in a solvent than a low-molecular organic semiconductor compound precursor composed of a single positional isomer component, and is easy to form a coating film. The reason why the solubility of the mixture of multiple positional isomers is high is that the detailed mechanism is not clear, but the crystallinity of the compound itself is potentially retained, but the mixture of multiple isomers is mixed in the solution. It is assumed that three-dimensional regular intermolecular interaction becomes difficult. The solubility of the mixture of a plurality of regioisomers in a non-halogen solvent is usually 0.1% by weight or more, preferably 1% by weight or more, more preferably 5% by weight or more. Although there is no restriction | limiting in an upper limit, Usually, it is 50 weight% or less, More preferably, it is 40 weight% or less.

1-2-1-2. High-molecular organic semiconductor compound There is no particular limitation on the high-molecular organic semiconductor compound, and a conjugated polymer semiconductor such as polythiophene, polyfluorene, polyphenylene vinylene, polythienylene vinylene, polyacetylene, or polyaniline; an alkyl group or other substituent is substituted Polymer semiconductors such as oligothiophene; and the like. Moreover, the semiconductor polymer which copolymerized 2 or more types of monomer units is also mentioned. The conjugated polymers, ^{e.g., Handbook of Conducting Polymers, 3 rd} Ed. (2 volumes), 2007, Materials Science and Engineering, 2001, 32, 1-40, Pure Appl. Chem. Use polymers that can be synthesized by a combination of polymers described in known literature such as 2002, 74, 2031-3044, Handbook of THIOPHENE-BASED MATERIALS (2 volumes), 2009, and derivatives thereof, and combinations of the described monomers. Can do. The polymer organic semiconductor compound used as the p-type semiconductor compound may be a single compound or a mixture of a plurality of compounds.

The monomer skeleton and monomer substituent of the polymer organic semiconductor compound can be selected to control the solubility, crystallinity, film-forming property, HOMO energy level, LUMO energy level, and the like. Moreover, it is preferable that the polymer organic semiconductor compound is soluble in an organic solvent in that the organic photoelectric conversion layer 103 can be formed by a coating method when a photoelectric conversion element is produced.
Among the p-type semiconductor compounds, the low-molecular organic semiconductor compound is preferably a condensed aromatic hydrocarbon such as naphthacene, pentacene, or pyrene, a phthalocyanine compound and a metal complex thereof, or a porphyrin compound such as tetrabenzoporphyrin (BP) and The metal complex and the polymer organic semiconductor compound is a conjugated polymer semiconductor such as polythiophene. The p-type semiconductor compound used in the organic photoelectric conversion layer 103 may be one kind of compound or a mixture of plural kinds of compounds.

The low-molecular organic semiconductor compound and / or the high-molecular organic semiconductor compound may have some self-organized structure in the film-formed state, or may be in an amorphous state.
The HOMO (highest occupied molecular orbital) energy level of the p-type semiconductor compound is not particularly limited, and can be selected according to the type of the n-type semiconductor compound described later. In particular, when a fullerene compound is used as an n-type semiconductor compound, the HOMO energy level of the p-type semiconductor compound is usually −5.7 eV or more, more preferably −5.5 eV or more, on the other hand, usually −4.6 eV or less. Preferably it is -4.8 eV or less. When the HOMO energy level of the p-type semiconductor compound is −5.7 eV or more, the characteristics as a p-type semiconductor are improved, and when the HOMO energy level of the p-type semiconductor compound is −4.6 eV or less, Stability is improved and the open circuit voltage (Voc) is also improved.

  The LUMO (lowest unoccupied molecular orbital) energy level of the p-type semiconductor compound is not particularly limited, but can be selected according to the type of the n-type semiconductor compound described later. In particular, when a fullerene compound is used as an n-type semiconductor compound, the LUMO energy level of the p-type semiconductor compound is usually −3.7 eV or more, preferably −3.6 eV or more. On the other hand, it is usually −2.5 eV or less, preferably −2.7 eV or less. When the LUMO energy level of the p-type semiconductor is −2.5 eV or less, the band gap is adjusted, light energy having a long wavelength can be effectively absorbed, and the short-circuit current density is improved. When the LUMO energy level of the p-type semiconductor compound is −3.7 eV or more, electron transfer to the n-type semiconductor compound is likely to occur and the short-circuit current density is improved.

1-2-2. n-type semiconductor compound The n-type semiconductor compound is not particularly limited, but specifically, a fullerene compound, a quinolinol derivative metal complex represented by 8-hydroxyquinoline aluminum; naphthalene tetracarboxylic acid diimide or perylene tetracarboxylic acid diimide Condensed ring tetracarboxylic acid diimides such as: perylene diimide derivatives, terpyridine metal complexes, tropolone metal complexes, flavonol metal complexes, perinone derivatives, benzimidazole derivatives, benzoxazole derivatives, thiazole derivatives, benzthiazole derivatives, benzothiadiazole derivatives, oxadi Azole derivatives, thiadiazole derivatives, triazole derivatives, aldazine derivatives, bisstyryl derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline derivatives, ben Examples thereof include total fluorides of condensed polycyclic aromatic hydrocarbons such as zoquinoline derivatives, bipyridine derivatives, borane derivatives, anthracene, pyrene, naphthacene or pentacene; single-walled carbon nanotubes and the like.

  Among them, fullerene compounds, borane derivatives, thiazole derivatives, benzothiazole derivatives, benzothiadiazole derivatives, N-alkyl-substituted naphthalenetetracarboxylic acid diimides and N-alkyl-substituted perylene diimide derivatives are preferable, and fullerene compounds, N- Alkyl substituted perylene diimide derivatives and N-alkyl substituted naphthalene tetracarboxylic acid diimides are more preferred. One of the above compounds may be used, or a mixture of a plurality of compounds may be used. Examples of the n-type semiconductor compound include an n-type polymer semiconductor compound.

  The LUMO energy level of the n-type semiconductor compound is not particularly limited. For example, the value with respect to the vacuum level calculated by the cyclic voltammogram measurement method is usually −3.85 eV or more, preferably −3.80 eV or more. . In order to efficiently transfer electrons from a p-type semiconductor compound to an n-type semiconductor compound, the relative relationship of LUMO energy levels between the p-type semiconductor compound and the n-type semiconductor compound is important. Specifically, the LUMO energy level of the p-type semiconductor compound is above the LUMO energy level of the n-type semiconductor compound by a predetermined value, in other words, the electron affinity of the n-type semiconductor compound is p-type semiconductor compound. It is preferable that a predetermined energy is larger than the electron affinity. Since the open circuit voltage (Voc) depends on the difference between the HOMO energy level of the p-type semiconductor compound and the LUMO energy level of the n-type semiconductor compound, increasing the LUMO of the n-type semiconductor compound tends to increase the Voc. On the other hand, the LUMO value is usually −1.0 eV or less, preferably −2.0 eV or less, more preferably −3.0 eV or less, and still more preferably −3.3 eV or less. By lowering the LUMO energy level of the n-type semiconductor compound, electrons tend to move and the short circuit current (Jsc) tends to increase.

  As a method for calculating the LUMO energy level of an n-type semiconductor compound, there are a theoretically calculated method and a method of actually measuring. Theoretically calculated methods include semi-empirical molecular orbital methods and non-empirical molecular orbital methods. Examples of the actual measurement method include an ultraviolet-visible absorption spectrum measurement method and a cyclic voltammogram measurement method. Among them, the cyclic voltammogram measurement method is preferable.

  The HOMO energy level of the n-type semiconductor compound is not particularly limited, but is usually −5.0 eV or less, preferably −5.5 eV or less. On the other hand, it is usually −7.0 eV or more, preferably −6.6 eV or more. It is preferable that the HOMO energy level of the n-type semiconductor compound is −7.0 eV or more because light absorption of the n-type semiconductor compound can also be used for power generation. The HOMO energy level of the n-type semiconductor compound is preferably −5.0 eV or less from the viewpoint of preventing reverse movement of holes.

The electron mobility of the n-type semiconductor compound is not particularly limited, but is usually 1.0 × 10 ⁻⁶ cm ² / Vs or more, preferably 1.0 × 10 ⁻⁵ cm ² / Vs or more. 0 × 10 ⁻⁵ cm ² / Vs or more is more preferable, and 1.0 × 10 ⁻⁴ cm ² / Vs or more is more preferable. On the other hand, it is usually 1.0 × 10 ³ cm ² / Vs or less, preferably 1.0 × 10 ² cm ² / Vs or less, and more preferably 5.0 × 10 ¹ cm ² / Vs or less. When the electron mobility of the n-type semiconductor compound is 1.0 × 10 ⁻⁶ cm ² / Vs or more, effects such as improvement of the electron diffusion rate, short circuit current, and conversion efficiency of the organic thin film solar cell element can be obtained. This is preferable. As a method for measuring electron mobility, there is a field effect transistor (FET) method, which can be carried out by a method described in a known document (Japanese Patent Laid-Open No. 2010-045186).

  The solubility of the n-type semiconductor compound in toluene at 25 ° C. is usually 0.5% by weight or more, preferably 0.6% by weight or more, and more preferably 0.7% by weight or more. On the other hand, it is usually preferably 90% by weight or less, more preferably 80% by weight or less, and further preferably 70% by weight or less. When the solubility of the n-type semiconductor compound in toluene at 25 ° C. is 0.5% by weight or more, the dispersion stability of the n-type semiconductor compound in the solution is improved, and aggregation, sedimentation, separation, and the like are less likely to occur. Therefore, it is preferable.

1-3. Transparent substrate (106)
The organic thin film solar cell element 107 has a transparent substrate 106 serving as a support. That is, the electrodes 101 and 105 and the organic photoelectric conversion layer 103 are formed on the transparent substrate.
The material of the transparent substrate 106 is not particularly limited as long as the effects of the present invention are not significantly impaired. Suitable examples of the material for the transparent substrate 106 include inorganic materials such as quartz, glass, sapphire, and titania; polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, and ethylene vinyl alcohol copolymer. Polyolefins such as fluororesin, vinyl chloride or polyethylene; organic resins such as cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene or epoxy resin; paper materials such as paper or synthetic paper And organic resins are preferred.

Examples of the glass include soda glass, blue plate glass, and non-alkali glass. Among these, alkali-free glass is preferable in that there are few eluted ions from the glass.
There is no restriction | limiting in the shape of the transparent substrate 106, For example, things, such as plate shape, a film form, or a sheet form, can be used. Moreover, although there is no restriction | limiting in the film thickness of the transparent substrate 106, it is 5 micrometers or more normally, 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. It is preferable that the film thickness of the transparent substrate is 5 μm or more because the possibility that the strength of the organic thin film solar cell element is insufficient is reduced. The film thickness of the transparent substrate is preferably 20 mm or less because the cost is suppressed and the weight does not increase. When the material of the transparent substrate 106 is glass, the film thickness is usually 0.01 mm or more, preferably 0.1 mm or more, and is usually 1 cm or less, preferably 0.5 cm or less. It is preferable for the film thickness to be equal to or more than the lower limit because mechanical strength increases and cracking is difficult. Moreover, it is preferable that it is below the said upper limit since a weight does not become heavy.

1-4. Electrode (lower transparent electrode 101, upper transparent electrode 105)
In the present invention, an electrode closer to the substrate than the organic photoelectric conversion layer is referred to as a lower transparent electrode, and an electrode opposite to the substrate in the organic photoelectric conversion layer is referred to as an upper transparent electrode.
The electrodes (lower transparent electrode 101 and upper transparent electrode 105) have a function of collecting holes and electrons generated by light absorption. Therefore, in FIG. 1, an upper transparent electrode 105 suitable for collecting holes (hereinafter sometimes simply referred to as an upper transparent electrode) and a lower transparent electrode 101 suitable for collecting electrons (hereinafter simply referred to as an upper transparent electrode). May be described as a lower transparent electrode).
Both the lower transparent electrode 101 and the upper transparent electrode 105 have translucency. To have translucency means that sunlight passes through 40% or more. In addition, the sunlight transmittance of the lower transparent electrode and the upper transparent electrode is preferably 70% or more in order to allow the light to reach the organic photoelectric conversion layer 103 through the transparent electrode. The light transmittance can be measured with a normal spectrophotometer.

1-4-1. Upper transparent electrode (105)
The upper transparent electrode 105 is generally made of a conductive material whose work function is higher than that of the lower transparent electrode, and has a function of smoothly extracting holes generated in the organic photoelectric conversion layer 103.
In the present invention, the upper transparent electrode 105 is a translucent multilayer film electrode including a metal layer and a transparent conductive oxide layer, so that both the stability of the electroconductivity and the translucency of the electrode are compatible and the durability is excellent. An organic thin film solar cell element can be provided. As the laminated structure of the light-transmitting multilayer film electrode, a structure in which metal / transparent conductive oxide or transparent conductive oxide / metal / transparent conductive oxide is laminated in this order is preferable.

Among the constituent materials of the upper transparent electrode 105, examples of the metal include metals such as gold, platinum, silver, copper, aluminum, chromium, and cobalt, or alloys thereof, and silver is preferable. Examples of the transparent conductive oxide include nickel oxide, tin oxide, indium oxide, indium tin oxide (ITO), zinc oxide, titanium oxide, and indium-zinc oxide (IZO).
, Aluminum-zinc oxide (AZO), gallium-zinc oxide (GZO), indium-gallium-zinc oxide (IGZO), indium-tungsten oxide (IWO), and the like. Among these, it is preferable to use a compound containing indium oxide, zinc oxide or tin oxide, and a compound containing indium oxide is particularly preferable.

The film thickness of the upper transparent electrode 105 is not particularly limited as long as necessary transparency is ensured, but is usually 10 nm or more, preferably 20 nm or more, and more preferably 50 nm or more. On the other hand, it is usually 10 μm or less, preferably 1 μm or less, more preferably 500 nm or less.
When the film thickness of the upper electrode 105 is equal to or greater than the above lower limit, sheet resistance is suppressed, and when the film thickness of the upper electrode 105 is equal to or less than the upper limit, light is efficiently converted into electricity without reducing light transmittance. can do. It is necessary to select a film thickness that can achieve both light transmittance, sheet resistance, and film strength.

  The film thickness of the metal layer forming the upper transparent electrode 105 is usually 30 nm or less, preferably 20 nm or less, more preferably 15 nm or less, and usually 1 nm or more, preferably 2 nm or more, more preferably 3 nm or more. When the film thickness of the metal layer is not more than the above upper limit, it can have transparency, and when it is not less than the above lower limit, the sheet resistance of the upper transparent electrode 105 can be lowered.

The sheet resistance of the upper transparent electrode 105 is not particularly limited, but is usually 1Ω / □ or more, on the other hand, 1000Ω / □ or less, preferably 500Ω / □ or less, more preferably 100Ω / □ or less.
As a method for forming the upper transparent electrode 105, a vacuum film forming method such as an evaporation method or a sputtering method can be used.

1-4-2. Lower transparent electrode (101)
The lower transparent electrode 101 is generally an electrode made of a conductive material having a low work function, and has a function of smoothly extracting electrons generated in the organic photoelectric conversion layer 103. The lower transparent electrode 101 is adjacent to the electron extraction layer 102.
Examples of the material of the lower transparent electrode 101 include, for example, metals such as platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium, sodium, potassium, cesium, calcium, and magnesium, and alloys thereof; Examples include inorganic salts such as lithium fluoride and cesium fluoride; metal oxides such as nickel oxide, aluminum oxide, lithium oxide, and cesium oxide. These materials are preferable because they are materials having a low work function. Similarly to the upper transparent electrode 105, the lower transparent electrode 101 can be made of a material having a high work function by using an n-type semiconductor such as titania having conductivity as the electron extraction layer 102. From the viewpoint of electrode protection, the material of the lower transparent electrode 101 is preferably a metal such as platinum, gold, silver, copper, iron, tin, aluminum, calcium or indium, or an alloy using these metals such as indium tin oxide. It is.

  The film thickness of the lower transparent electrode 101 is not particularly limited, but is usually 10 nm or more, preferably 20 nm or more, and more preferably 50 nm or more. On the other hand, it is usually 10 μm or less, preferably 1 μm or less, more preferably 500 nm or less. When the film thickness of the lower transparent electrode 101 is 10 nm or more, the sheet resistance is suppressed, and when the film thickness of the lower transparent electrode 101 is 10 μm or less, the light is efficiently transferred without reducing the light transmittance. Can be converted. For the lower transparent electrode 101, it is necessary to select a film thickness that achieves both light transmittance and sheet resistance.

The sheet resistance of the lower transparent electrode 101 is not particularly limited, but is usually 1000Ω / □ or less, preferably 500Ω / □ or less, and more preferably 100Ω / □ or less. Although there is no restriction on the lower limit, it is usually 1Ω / □ or more.
As a method for forming the lower transparent electrode 101, there are a vacuum film forming method such as an evaporation 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.

Furthermore, characteristics (electric characteristics, wetting characteristics, etc.) may be improved by performing surface treatment on the upper transparent electrode 105 and the lower transparent electrode 101.
After laminating the upper transparent electrode 105 and the lower transparent electrode 101, the organic thin film solar cell element is usually 50 ° C. or higher, preferably 80 ° C. or higher, and usually 300 ° C. or lower, preferably 280 ° C. or lower, more preferably 250 ° C. or lower. It is preferable to heat in this temperature range (this step may be referred to as an annealing treatment step). By performing the annealing process at a temperature of 50 ° C. or higher, the adhesion between each layer of the organic thin film solar cell element, for example, the electron extraction layer 102 and the lower transparent electrode 101 and / or the electron extraction layer 102 and the organic photoelectric conversion layer 103 This is preferable because an effect of improving adhesion can be obtained. By improving the adhesion between the layers, the thermal stability and durability of the organic thin film solar cell element can be improved. It is preferable to set the temperature of the annealing treatment step to 300 ° C. or lower because the organic compound in the organic photoelectric conversion layer 103 is less likely to be thermally decomposed. 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 organic thin film solar cell element may be placed on a heat source such as a hot plate, or the organic thin film solar cell element may be placed in a heating atmosphere such as an oven. The heating may be performed batchwise or continuously.
1-5. Film-like member The organic thin-film solar cell element of this invention can provide a film-like member on the surface. The film-like member protects the organic thin-film solar cell element from the device installation environment such as temperature change, humidity change, oxygen, water, light, or wind, and prevents deterioration.

Moreover, since the film-like member is located on the outermost layer of the organic thin film solar cell element, the surface covering material of the organic thin film solar cell element such as weather resistance, heat resistance, transparency, water repellency, contamination resistance, mechanical strength, etc. It is preferable to have a property suitable for the above and to maintain it for a long period of time in outdoor exposure.
Furthermore, since the organic thin film solar cell element is often heated by receiving light, it is preferable that the film-like member also has heat resistance. From this viewpoint, the melting point of the constituent material of the film-like member is usually 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower, more preferably It is 300 degrees C or less. By increasing the melting point, it is possible to reduce the possibility that the film-like member melts and deteriorates when the solar cell element is used.

  The material which comprises a film-like member is arbitrary. Examples of the material include polyethylene resin, polypropylene resin, cyclic polyolefin resin, AS (acrylonitrile-styrene) resin, ABS (acrylonitrile-butadiene-styrene) resin, polyvinyl chloride resin, fluorine resin, polyethylene terephthalate, polyethylene Examples thereof include polyester resins such as naphthalate, phenol resins, polyacrylic resins, polyamide resins such as various nylons, polyimide resins, polyamide-imide resins, polyurethane resins, cellulose resins, silicone resins, and polycarbonate resins.

Note that the film-like member may be formed of one type of material or may be formed of two or more types of materials. The film-like member may be formed of a single layer film, but may be a laminated film including two or more layers.
The thickness of the film-like member is usually 5 μm or more, preferably 10 μm or more, more preferably 20 μm or more, and usually 200 μm or less, preferably 100 μm or less, more preferably 50 μm or less. Increasing the thickness tends to increase mechanical strength, and decreasing the thickness tends to increase flexibility. For this reason, it is desirable to set it as the said range as a range which has both advantages.

Further, the film-like member may be subjected to surface treatment such as corona treatment or plasma treatment in order to improve adhesiveness with other films.
In addition, ultraviolet rays, heat rays, antifouling properties, hydrophilicity, hydrophobicity, antifogging properties, abrasion resistance, electrical conductivity, antireflection, antiglare properties, light diffusion, light scattering, wavelength conversion, gas barrier are applied to film-like members. You may give functions, such as sex.
In particular, since an organic layer included in an organic thin-film solar cell element such as an organic photoelectric conversion layer may be deteriorated by water or oxygen, the organic photoelectric conversion layer is effective for effectively suppressing the influence of water or oxygen. It is preferable to form a gas barrier layer by installing a film-like member having gas barrier properties so as to be close to each other.

As a film-like member having such a function, a known film-like member can be used. A film-like member in which a layer of the material and a layer imparting a function are laminated, or a material that exhibits a function is dissolved and dissolved. Examples thereof include a film-like member that is contained by being dispersed. As a film-like member having gas barrier properties, a film-like member obtained by laminating a layer of the material and an inorganic layer is preferable. Examples thereof include a film obtained by vacuum-depositing SiO _x on a base film such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN).

  The method of laminating the film-like member on the organic thin-film solar cell element is not particularly limited, and examples thereof include a method of heat-pressing by a thermal laminating method, a method of laminating via an adhesive layer, etc. A method of laminating through layers is preferred. The material of the adhesive layer is not particularly limited and may be a thermoplastic resin or a thermosetting resin. However, in the case of forming a gas barrier layer by installing a film-like member having gas barrier properties, the thermosetting resin is used from the viewpoint of durability. Is preferred.

Examples of the thermoplastic resin include an ethylene-vinyl acetate copolymer (EVA) resin, a polyvinyl butyral (PVB) resin, a modified polyethylene resin modified with maleic acid or silane, and a modified polypropylene resin. Examples of the thermosetting resin include materials such as an epoxy adhesive, a urethane adhesive, and an acrylic adhesive. The thickness of the adhesive layer is preferably 1 μm or more, and more preferably 5 μm or more. On the other hand, the upper limit is preferably 100 μm or less, and more preferably 40 μm or less.
Gas barrier Further, the film-like member and the adhesive layer are preferably those that transmit visible light from the viewpoint of not preventing light absorption. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 75% or more, preferably 80% or more, more preferably 85% or more, further preferably 90% or more, and particularly preferably 95% or more. Particularly preferably, it is 97% or more.

1-6. Photoelectric conversion characteristic The photoelectric conversion characteristic of the organic thin-film solar cell element 107 can be obtained as follows. The photoelectric conversion element 107 is irradiated with light having an AM1.5G condition at an irradiation intensity of 100 mW / cm ^{2 using a} solar simulator, and current-voltage characteristics are measured. From the obtained current-voltage curve, photoelectric conversion characteristics such as photoelectric conversion efficiency (PCE), short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), series resistance, and shunt resistance can be obtained.

Although there is no special restriction | limiting, the photoelectric conversion efficiency of the organic thin-film solar cell element which concerns on this invention is 1% or more normally, Preferably it is 1.5% or more, More preferably, it is 2% or more. On the other hand, there is no particular limitation on the upper limit, and the higher the better.
Moreover, as a method for measuring the durability of the organic thin film solar cell element, there is a method for obtaining a maintenance rate of photoelectric conversion efficiency before and after the organic thin film solar cell element is exposed to the atmosphere.
(Maintenance rate) = (Photoelectric conversion efficiency after N hours of atmospheric exposure) / (Photoelectric conversion efficiency immediately before atmospheric exposure)
In order to put an organic thin-film solar cell element into practical use, it is important to have high photoelectric conversion efficiency and high durability in addition to simple and inexpensive manufacture. From this viewpoint, the maintenance rate of photoelectric conversion efficiency before and after exposure to the atmosphere for one week is preferably 60% or more, more preferably 80% or more, and the higher the better.

2. Organic thin film solar cell using organic thin film solar cell element of the present invention The organic thin film solar cell element (hereinafter also referred to as solar cell element) according to the present invention is used as a solar cell element of an organic thin film solar cell.
FIG. 2 is a cross-sectional view schematically showing a configuration of an organic thin film solar cell as an example of use of the organic thin film solar cell element of the present invention. As shown in FIG. 2, the organic thin film solar cell 14 (hereinafter also referred to as 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, and a getter material film 4. The sealing material 5, the solar cell 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 light is irradiated from the side (downward in the figure) where the weather-resistant protective film 1 is formed, and the solar cell element 6 generates power.

  In addition, since the solar cell element 6 of the present invention itself has a sealing structure, the getter material film 8 and / or the gas barrier film 9 may not be used. Further, even when the getter material film 8 and / or the gas barrier film 9 is used, these films can be made thinner and have lower performance than conventional solar cell elements. Thin film and flexibility can be improved.

  Further, even in applications where gas barrier properties are particularly required, the getter material film 8 and / or the gas barrier film 9 may not be used when a highly waterproof sheet is used as the back sheet 10 described later.

2-1. Weatherproof protective film (1)
The weather-resistant protective film 1 is a film that protects the solar cell element 6 from weather changes. By covering the solar cell element 6 with the weather-resistant protective film 1, the solar cell element 6 and the like are protected from weather changes and the power generation capacity is kept high. Since the weather resistant protective film 1 is located on the outermost layer of the thin film solar cell 14, the surface covering material of the thin film solar cell 14 such as weather resistance, heat resistance, transparency, water repellency, stain resistance and / or mechanical strength is provided. It is preferable to have a property suitable for the above and to maintain it for a long period of time in outdoor exposure.

  Moreover, it is preferable that the weather-resistant protective film 1 transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is preferably 80% or more, and the upper limit is not limited. Furthermore, since the thin-film solar cell 14 is often heated by receiving light, it is preferable that the weather-resistant protective film 1 also has heat resistance. From this viewpoint, the melting point of the constituent material of the weather-resistant protective film 1 is usually 100 ° C. or higher and 350 ° C. or lower.

The material which comprises the weather-resistant protective film 1 is arbitrary as long as it can protect the solar cell element 6 from a weather change. Examples of the material include polyethylene resin, polypropylene resin, cyclic polyolefin resin, AS (acrylonitrile-styrene) resin, ABS (acrylonitrile-butadiene-styrene) resin, polyvinyl chloride resin, fluorine resin, polyethylene terephthalate, polyethylene Examples thereof include polyester resins such as naphthalate, phenol resins, polyacrylic resins, polyamide resins such as various nylons, polyimide resins, polyamide-imide resins, polyurethane resins, cellulose resins, silicon resins, and polycarbonate resins.

In addition, the weather-resistant protective film 1 may be formed with 1 type of material, and may be formed with 2 or more types of materials. Moreover, although the weather-resistant protective film 1 may be formed with the single layer film, the laminated | multilayer film provided with the film of two or more layers may be sufficient as it.
The thickness of the weather-resistant protective film 1 is not particularly defined, but is usually 10 μm or more and 200 μm or less.

Moreover, you may perform surface treatment, such as a corona treatment and / or a plasma treatment, for the weather-resistant protective film 1 in order to improve the adhesiveness with another film.
The weatherproof protective film 1 is preferably provided on the outer side as much as possible in the thin-film solar cell 14. This is because more of the constituent members of the thin-film solar cell 14 can be protected.

2-2. UV cut film (2)
The ultraviolet cut film 2 is a film that prevents the transmission of ultraviolet rays. The ultraviolet cut film 2 is provided in the light receiving portion of the thin-film solar cell 14, and the ultraviolet cut film 2 covers the light receiving surface 6a of the solar cell element 6, so that the solar cell element 6 and, if necessary, the gas barrier films 3 and 9 are exposed to ultraviolet rays. The power generation capacity can be maintained at a high level.

  The degree of the ability to suppress the transmission of ultraviolet rays required for the ultraviolet cut film 2 is preferably such that the transmittance of ultraviolet rays (for example, wavelength of 300 nm) is 50% or less, and there is no limit on the lower limit. Moreover, it is preferable that the ultraviolet cut film 2 transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is preferably 80% or more, and the upper limit is not limited.

Furthermore, since the thin film solar cell 14 is often heated by receiving light, the ultraviolet cut film 2 preferably has heat resistance. From this viewpoint, the melting point of the constituent material of the ultraviolet cut film 2 is usually 100 ° C. or higher and 350 ° C. or lower.
Moreover, it is preferable that the ultraviolet cut film 2 is high in flexibility, has good adhesion to an adjacent film, and can cut water vapor and oxygen.

  The material which comprises the ultraviolet cut film 2 is arbitrary if the intensity | strength of an ultraviolet-ray can be weakened. Examples of the material include films formed by blending an ultraviolet absorber with an epoxy, acrylic, urethane, or ester resin. Further, a film in which a layer of an ultraviolet absorbent dispersed or dissolved in a resin (hereinafter referred to as “ultraviolet absorbing layer” as appropriate) is formed on a base film may be used.

  Examples of the ultraviolet absorber that can be used include salicylic acid-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based ones. In addition, a ultraviolet absorber may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio. As described above, a film in which an ultraviolet absorbing layer is formed on a base film can also be used as the ultraviolet absorbing film. Such a film can be produced, for example, by applying a coating solution containing an ultraviolet absorber on a substrate film and drying it.

Although the material of a base film is not specifically limited, For example, polyester is mentioned at the point from which the balance of heat resistance and a softness | flexibility is obtained.
Examples of specific products of the ultraviolet cut film 2 include cut ace (MKV Plastic Co., Ltd.). In addition, the ultraviolet cut film 2 may be formed with 1 type of material, and may be formed with 2 or more types of materials.

Further, the ultraviolet cut film 2 may be formed of a single layer film, but may be a laminated film including two or more layers. The thickness of the ultraviolet cut film 2 is not particularly limited, but is usually 5 μm or more and 200 μm or less.
Although the ultraviolet cut film 2 should just be provided in the position which covers at least one part of the light-receiving surface 6a of the solar cell element 6, Preferably it is provided in the position which covers all the light-receiving surfaces 6a of the solar cell element 6. FIG. However, the ultraviolet cut film 2 may be provided at a position other than the position covering the light receiving surface 6 a of the solar cell element 6.

2-3. Gas barrier film (3)
The gas barrier film 3 is a film that prevents permeation of water and oxygen. By covering the solar cell element 6 with the gas barrier film 3, the solar cell element 6 can be protected from water and oxygen, and the power generation capacity can be kept high.
Although the degree of moisture-proof capability required for the gas barrier film 3 varies depending on the type of the solar cell element 6 and the like, the water vapor transmission rate per unit area (1 m ² ) per day is usually 1 × 10 ^−1. It is preferable that it is below g / m < ² > / day, and there is no restriction | limiting in a minimum.

Although the degree of oxygen permeability required for the gas barrier film 3 varies depending on the type of the solar cell element 6 and the like, the oxygen permeability per unit area (1 m ² ) per day is usually 1 × 10 ^−. It is preferably ¹ cc / m ² / day / atm or less, and the lower limit is not limited.
Moreover, it is preferable that the gas barrier film 3 transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, and there is no upper limit.

Furthermore, since the thin film solar cell 14 is often heated by receiving light, it is preferable that the gas barrier film 3 also has heat resistance. From this viewpoint, the melting point of the constituent material of the gas barrier film 3 is usually 100 ° C. or higher and 350 ° C. or lower.
The specific configuration of the gas barrier film 3 is arbitrary as long as the solar cell element 6 can be protected from water. However, since the manufacturing cost increases as the amount of water vapor or oxygen that can permeate the gas barrier film 3 increases, it is preferable to use an appropriate film considering these points comprehensively.

Particularly suitable gas barrier film 3 includes, for example, a film obtained by vacuum-depositing SiO _x on a base film such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN).
In addition, the gas barrier film 3 may be formed with 1 type of material, and may be formed with 2 or more types of materials. The gas barrier film 3 may be formed of a single layer film, but may be a laminated film including two or more layers.

The thickness of the gas barrier film 3 is not particularly defined, but is usually 5 μm or more and 200 μm or less.
As long as the gas barrier film 3 covers the solar cell element 6 and can be protected from moisture and oxygen, the formation position is not limited. However, the front surface of the solar cell element 6 (surface on the light receiving surface side, lower surface in FIG. 2) and It is preferable to cover the back surface (the surface opposite to the light receiving surface; the upper surface in FIG. 2). This is because the front and back surfaces of the thin film solar cell 14 are often formed in a larger area than the other surfaces. In this embodiment, the gas barrier film 3 covers the front surface of the solar cell element 6, and a gas barrier film 9 described later covers the back surface of the solar cell element 6.

2-4. Getter material film (4)
The getter material film 4 is a film that absorbs moisture and / or oxygen. By covering the solar cell element 6 with the getter material film 4, the solar cell element 6 and the like are protected from moisture and / or oxygen, and the power generation capacity is kept high. Here, unlike the gas barrier film 3 as described above, the getter material film 4 does not prevent moisture permeation but absorbs moisture. By using a film that absorbs moisture, the getter material film 4 captures moisture that slightly enters the space formed by the gas barrier films 3 and 9 when the solar cell element 6 is covered with the gas barrier film 3 or the like. The influence of moisture on the solar cell element 6 can be eliminated.

The degree of moisture absorption capacity of the getter material film 4 is usually 0.1 mg / cm ² or more, and although there is no upper limit, it is usually 10 mg / cm ² or less. Further, when the solar cell element 6 is covered with the gas barrier films 3 and 9 or the like by the getter material film 4 absorbing oxygen, the oxygen that slightly enters the space formed by the gas barrier films 3 and 9 is obtained as the getter material. The film 4 can capture and eliminate the influence of oxygen on the solar cell element 6.

Furthermore, it is preferable that the getter material film 4 transmits visible light from the viewpoint of not preventing the solar cell element 6 from absorbing light. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, and there is no upper limit.
Furthermore, since the thin film solar cell 14 is often heated by receiving light, the getter material film 4 preferably has heat resistance. From this viewpoint, the melting point of the constituent material of the getter material film 4 is usually 100 ° C. or higher and 350 ° C. or lower.

  The material constituting the getter material film 4 is arbitrary as long as it can absorb moisture and / or oxygen. Examples of the material include alkali metal, alkaline earth metal or alkaline earth metal oxides; alkali metal or alkaline earth metal hydroxides; silica gel, zeolitic compounds, magnesium sulfate. And sulfates such as sodium sulfate and nickel sulfate; and organometallic compounds such as aluminum metal complexes and aluminum oxide octylates. Specifically, examples of the alkaline earth metal include Ca, Sr, and Ba. Examples of the alkaline earth metal oxide include CaO, SrO, and BaO. In addition, Zr-Al-BaO and aluminum metal complexes are also included. Specific product names include, for example, OleDry (Futaba Electronics).

Examples of the substance that absorbs oxygen include activated carbon, silica gel, activated alumina, molecular sieve, magnesium oxide, and iron oxide. In addition, Fe, Mn, Zn, and inorganic salts such as sulfates, chlorides, and nitrates of these metals are also included.
In addition, the getter material film 4 may be formed of one type of material or may be formed of two or more types of materials. The getter material film 4 may be formed of a single layer film, but may be a laminated film including two or more layers.

The thickness of the getter material film 4 is not particularly specified, but is usually 5 μm or more and 200 μm or less.
The formation position of the getter material film 4 is not limited as long as it is in the space formed by the gas barrier films 3 and 9, but the front surface of the solar cell element 6 (the surface on the light receiving surface side, the lower surface in FIG. 2). And it is preferable to cover the back surface (surface opposite to the light receiving surface; upper surface in FIG. 2). This is because, in the thin film solar cell 14, the front and back surfaces are often formed in a larger area than the other surfaces, and therefore moisture and oxygen tend to enter through these surfaces. From this viewpoint, the getter material film 4 is preferably provided between the gas barrier film 3 and the solar cell element 6. In this embodiment, the getter material film 4 covers the front surface of the solar cell element 6, a getter material film 8 described later covers the back surface of the solar cell element 6, and the getter material films 4 and 8 are respectively the solar cell element 6 and the gas barrier film 3. , 9 are located between them. In addition, when using a highly waterproof sheet | seat as the back sheet | seat 10 mentioned later, the getter material film 8 and / or the gas barrier film 9 do not need to be used according to a use.

2-5. Sealing material (5)
The sealing material 5 is a film that reinforces the solar cell element 6. Since the solar cell element 6 is thin, the strength is usually weak, and thus the strength of the thin film solar cell tends to be weak. However, the strength can be maintained high by the sealing material 5.
Moreover, it is preferable that the sealing material 5 has high strength from the viewpoint of maintaining the strength of the thin-film solar cell 14. The specific strength is related to the strength of the weatherproof protective film 1 other than the sealing material 5 and the strength of the back sheet 10 and is generally difficult to define, but the thin film solar cell 14 as a whole has good bending workability. However, it is desirable to have a strength that does not cause peeling of the bent portion.

Moreover, it is preferable that the sealing material 5 permeate | transmits visible light from a viewpoint which does not prevent the light absorption of the solar cell element 6. FIG. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, and there is no upper limit.
The thickness of the sealing material 5 is not particularly specified, but is usually 2 μm or more and 700 μm or less.
The T-type peel adhesion strength of the sealing material 5 to the substrate is usually 1 N / inch or more and usually 2000 N / inch or less. It is preferable that the T-type peel adhesion strength is 1 N / inch or more in terms of ensuring the long-term durability of the organic thin film solar cell. It is preferable that the T-type peel adhesive strength is 2000 N / inch or less in that the base material, the barrier film, and the adhesive can be separated and discarded when the solar cell is discarded. The T-type peel adhesion strength is measured by a method according to JIS K6854.

The constituent material of the sealing material 5 is not particularly limited as long as it has the above characteristics, but sealing of organic / inorganic solar cells, sealing of organic / inorganic LED elements, sealing of electronic circuit boards, etc. In general, a sealing material generally used can be used.
Specifically, a thermosetting resin composition or a thermoplastic resin composition and an active energy ray curable resin composition can be mentioned. The active energy ray-curable resin composition is, for example, a resin that is cured by ultraviolet rays, visible light, electron beams, or the like. More specifically, an ethylene-vinyl acetate copolymer (EVA) resin composition, a hydrocarbon resin composition, an epoxy resin composition, a polyester resin composition, an acrylic resin composition, and a urethane resin composition. Or a silicon-based resin composition, etc., depending on the main chain, branched chain, terminal chemical modification of each polymer, adjustment of molecular weight, additives, etc., thermosetting, thermoplastic and active energy ray curable, etc. The characteristics are expressed.

Moreover, since the thin film solar cell 14 is often heated by receiving light, it is preferable that the sealing material 5 also has heat resistance. From this viewpoint, the melting point of the constituent material of the sealing material 5 is usually 100 ° C. or higher and 350 ° C. or lower.
The density of the constituent material for sealing material in the sealing material 5 is preferably 0.80 g / cm ³ or more, and there is no upper limit. The measurement and evaluation of density can be performed by a method based on JIS K7112.

Although there is no restriction | limiting in the position which provides the sealing material 5, Usually, it provides so that the solar cell element 6 may be inserted | pinched. This is for reliably protecting the solar cell element 6. In this embodiment, the sealing material 5 and the sealing material 7 are provided on the front surface and the back surface of the solar cell element 6, respectively.
2-6. Solar cell element (6)
The solar cell element 6 is the same as the above-described solar cell element (organic thin film solar cell element). That is, the thin film solar cell 14 can be manufactured using a solar cell element (organic thin film solar cell element).

Although only one solar cell element 6 may be provided for each thin film solar cell 14, usually two or more solar cell elements 6 are provided. The specific number of solar cell elements 6 may be set arbitrarily. When a plurality of solar cell elements 6 are provided, the solar cell elements 6 are often arranged in an array.
When a plurality of solar cell elements 6 are provided, the solar cell elements 6 are usually electrically connected to each other, and electricity generated from the connected group of solar cell elements 6 is taken out from a terminal (not shown). At this time, the solar cell elements are usually connected in series in order to increase the voltage.

  Thus, when connecting the solar cell elements 6, it is preferable that the distance between the solar cell elements 6 is small, and the clearance between the solar cell element 6 and the solar cell element 6 is preferably narrow. This is because the light receiving area of the solar cell element 6 is widened to increase the amount of received light, and the amount of power generated by the thin film solar cell 14 is increased.

2-7. Sealing material (7)
The sealing material 7 is a film similar to the sealing material 5 described above, and the same material as the sealing material 7 can be used in the same manner except that the arrangement position is different.

2-8. Getter material film (8)
The getter material film 8 is the same film as the getter material film 4 described above, and the same material as the getter material film 4 can be used as necessary, except for the arrangement position.

2-9. Gas barrier film (9)
The gas barrier film 9 is the same film as the gas barrier film 3 described above, and the same material as the gas barrier film 9 can be used as necessary except that the arrangement position is different.

2-10. Back sheet (10)
The back sheet 10 is the same film as the weather-resistant protective film 1 described above, and the same material as the weather-resistant protective film 1 can be used in the same manner except that the arrangement position is different. In addition, if the back sheet 10 is difficult to permeate water and oxygen, the back sheet 10 can also function as a gas barrier layer.

2-11. Dimensions etc. The thin film solar cell 14 of the present embodiment is usually a thin film member. Thus, by forming the thin film solar cell 14 as a film-like member, the thin film solar cell 14 can be easily installed in a building material, an automobile, an interior, or the like. The thin-film solar cell 14 is light and difficult to break, and thus a highly safe solar cell can be obtained and can be applied to a curved surface, so that it can be used for more applications. Since it is thin and light, it is preferable in terms of distribution such as transportation and storage. Furthermore, since it is in the form of a film, it can be manufactured in a roll-to-roll manner, and a significant cost cut can be achieved.
Although there is no restriction | limiting in the specific dimension of the thin film solar cell 14, The thickness is usually 300 micrometers or more and 3000 micrometers or less.

2-12. 2. Manufacturing Method Although there is no restriction | limiting in the manufacturing method of the thin film solar cell 14, For example, as a manufacturing method of the solar cell of the form of FIG. 2, the method of performing a lamination sealing process after creating the laminated body shown in FIG. Can be mentioned. Since the solar cell element of this embodiment is excellent in heat resistance, it is preferable in that deterioration due to the laminate sealing step is reduced.

  The laminate shown in FIG. 2 can be created using a known technique. The method of the laminate sealing step is not particularly limited as long as the effects of the present invention are not impaired, but for example, wet lamination, dry lamination, hot melt lamination, extrusion lamination, coextrusion molding lamination, extrusion coating, photocuring adhesive Laminate, thermal laminate, etc. are mentioned. Among them, a laminating method using a photo-curing adhesive having a proven record in organic EL device sealing, a hot melt laminate or a thermal laminate having a proven record in solar cells is preferable, and a hot melt laminate or a thermal laminate is a sheet-like sealing material. It is more preferable at the point which can be used.

  The heating temperature in the laminate sealing step is usually 130 ° C or higher, preferably 140 ° C or higher, and is usually 180 ° C or lower, preferably 170 ° C or lower. The heating time in the laminate sealing step is usually 10 minutes or longer, preferably 20 minutes or longer, and is usually 100 minutes or shorter, preferably 90 minutes or shorter. The pressure in the laminate sealing step is usually 0.001 MPa or more, preferably 0.01 MPa or more, and usually 0.2 MPa or less, preferably 0.1 MPa or less. By setting the pressure within this range, sealing can be performed reliably, and the reduction of the film thickness due to the protrusion of the sealing materials 5 and 7 from the end portion and overpressurization can be suppressed, thereby ensuring dimensional stability. In addition, what connected two or more solar cell elements 6 in series or in parallel can be manufactured similarly to the above.

2-13. Use There is no restriction | limiting in the use of the organic thin-film solar cell element of this invention, It can use for arbitrary uses. Examples of fields to which organic thin film solar cells are applied include building material solar cells, automotive solar cells, interior solar cells, railroad solar cells, marine solar cells, airplane solar cells, spacecraft solar cells, A solar cell for home appliances, a solar cell for mobile phones, a solar cell for toys, and the like.

  The organic thin film solar cell according to the present invention may be used as it is, or may be used as a solar cell module by installing a solar cell on a substrate. For example, as schematically shown in FIG. 3, a solar cell module 13 including a thin film solar cell 14 on a base material 12 is prepared and used at a place of use. That is, the solar cell module 13 can be manufactured using the thin film solar cell 14. As a specific example, when a building material plate is used as the base material 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 material.

  The substrate 12 is a support member that supports the thin film solar cell 14. Examples of the material for forming the substrate 12 include inorganic materials such as glass, sapphire, and titania; polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, fluorine. Examples thereof include organic materials such as resin, vinyl chloride, polyethylene, cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, and polynorbornene; paper materials such as paper and synthetic paper.

In addition, 1 type may be used for the material of a base material, and 2 or more types may be used together by arbitrary combinations and a ratio. Moreover, carbon fiber may be included in these organic materials or paper materials to reinforce the mechanical strength.
Although there is no restriction | limiting in the shape of the base material 12, Usually, a board | plate material is used. Moreover, what is necessary is just to set the material of the base material 12, a dimension, etc. arbitrarily according to the use environment. This solar cell module can be installed on the outer wall of a building.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, it cannot be overemphasized that this invention is not limited only to a following example.
In the examples, the evaluation of the organic thin-film solar cell element was performed by the following method.

<Initial output (photoelectric conversion efficiency)>
After irradiating the light-receiving surface of the organic thin-film solar cell element with sunlight having an insolation intensity of 500 mW / m ² or more for 1 hour, within 3 hours from the irradiation of sunlight, JIS C 8935 (amorphous solar cell module output measurement method) Based on this, the photoelectric conversion efficiency of the organic thin film solar cell element was measured.

<Durability test>
The organic thin-film solar cell element was held without performing light irradiation under an environmental condition of a temperature of 85 ° C. and a relative humidity of 85% using a constant temperature and humidity chamber PR-1KP manufactured by ESPEC CORP. The photoelectric conversion efficiency of the organic thin-film solar cell element at 100 hours and 200 hours after the start of the test was measured based on JIS C 8935 (amorphous solar cell module output measurement method), and the relative photoelectricity before the test was started. Conversion efficiency was determined.

<Example 1>
A polyethylene naphthalate (PEN) film having a thickness of 125 μm was used as a base material, and ITO (40 nm), Ag (10 nm), and ITO (40 nm) were sputter-deposited in this order as lower transparent electrodes thereon. After patterning the lower transparent electrode with a laser, the ZnO nanoparticle dispersion was applied with a slit die coating apparatus and dried at 100 ° C. for 30 minutes to form an electron extraction layer having a thickness of 120 nm. Under a nitrogen atmosphere, a P3HT / PCBM mixed solution was applied on the electron extraction layer by slit die coating, and then dried at 120 ° C. for 30 minutes to form an organic photoelectric conversion layer having a thickness of 180 nm. A dispersion of PEDOT: PSS was applied on the organic photoelectric conversion layer by slit die coating and dried at 120 ° C. for 30 minutes to form a 180 nm thick hole extraction layer. An upper transparent electrode was formed on the hole extraction layer by sputtering with Ag (10 nm) and ITO (40 nm) in this order using a sputtering apparatus. A current collector is attached to the obtained element, a gas barrier film is laminated through a thermosetting epoxy resin layer, heated at 80 ° C. for 6 minutes, and then heated at 120 ° C. for 1 hour with a vacuum laminator to form an adhesive layer As a result, an organic thin-film solar cell element sealed with a gas barrier film having a thickness of about 100 μm was obtained through a thermosetting epoxy resin layer having a thickness of about 50 μm.

<Example 2>
An organic thin-film solar cell element was obtained in the same manner as in Example 1 except that ITO (20 nm), Ag (10 nm), and ITO (40 nm) were formed by sputtering in this order as the upper transparent electrode.

<Comparative Example 1>
An organic thin-film solar cell element was obtained in the same manner as in Example 1 except that Ag (10 nm) was formed by sputtering as the upper transparent electrode.

  Table 1 shows initial outputs of the organic thin-film solar cell elements obtained in Examples 1 and 2 and Comparative Example 1.

  Table 2 shows the results of the high-temperature and high-humidity test of the organic thin-film solar cell elements obtained in Examples 1 and 2.

  From the above results, the organic thin-film solar cell element of Comparative Example 1 did not obtain an initial output, whereas in Examples 1 and 2 which are the organic thin-film solar cell elements of the present invention, the initial output was high and excellent. It can be seen that it has high durability.

DESCRIPTION OF SYMBOLS 101 Lower transparent electrode 102 Electron extraction layer 103 Organic photoelectric converting layer 104 Hole extraction layer 105 Upper electrode 106 Transparent substrate 107 Organic thin-film solar cell element 1 Weather-resistant protective film 2 Ultraviolet cut film 3, 9 Gas barrier film 4, 8 Getter material film 5, 7 Encapsulant 6 Organic thin film solar cell element (solar cell element)
DESCRIPTION OF SYMBOLS 10 Back sheet 12 Base material 13 Organic thin film solar cell module 14 Organic thin film solar cell

Claims (7)

  An organic thin film solar cell element having at least a lower transparent electrode, an organic photoelectric conversion layer, and an upper transparent electrode in this order on a transparent substrate, wherein the upper transparent electrode includes a metal layer and a transparent conductive oxide layer. An organic thin film solar cell element.   The organic thin-film solar cell element of Claim 1 which has an contact bonding layer and a gas barrier film in order on the said upper transparent electrode.   The organic thin-film solar cell element according to claim 1 or 2, wherein the metal of the metal layer is silver.   The organic thin-film solar cell element of any one of Claims 1-3 whose thickness of the said metal layer is 30 nm or less.   The organic thin-film solar cell element of any one of Claims 1-4 whose conductive oxide of the said transparent conductive oxide layer is a compound containing an indium oxide.   The organic thin-film solar cell element according to any one of claims 2 to 5, wherein the adhesive layer is a thermosetting resin layer.   The organic thin-film solar cell element according to any one of claims 1 to 6, wherein the transparent substrate is an organic resin film.

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