JP2011046697A - New phosphine compound, electrode buffer material, and photoelectric conversion element using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compound having high heat resistance while keeping an interaction with an electrode and mobility as an electrode buffer material, and to provide an electrode buffer material and a photoelectric conversion element using the compound. <P>SOLUTION: There is provided a phosphine sulfide compound represented by general formula (I), wherein Ar<SP>1</SP>to Ar<SP>3</SP>each independently represents an aromatic group which may have a substituent, and at least one of Ar<SP>1</SP>to Ar<SP>3</SP>represents a condensed polycyclic aromatic group having seven or more double bonds. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a novel phosphine compound having a condensed polycyclic skeleton as a linking group, a photoelectric conversion element material obtained using the compound, and a photoelectric conversion element.

Organic thin-film solar cells have an element structure in which an organic p-type semiconductor such as benzoporphyrin, phthalocyanine, or a conjugated polymer and a thin film composed of an organic n-type semiconductor such as perylene diimide or fullerene derivatives are sandwiched between electrodes. However, at present, the photoelectric conversion efficiency is still 4-6%, and further improvement in efficiency is an issue.
As means for solving the improvement in the efficiency of organic thin-film solar cells, Patent Document 1 studies using a phosphine oxide compound as an electron transport material.

JP 2006-073583 A

However, according to the study by the inventors of the present application, it has been found that it is insufficient in terms of performance (photoelectric conversion characteristics) to adapt the phosphine oxide compound described in Patent Document 1 for solar cells. This point can be a big problem in practice for application to solar cell applications exposed to sunlight.
In view of the above-described conventional situation, the present invention provides a compound having high heat resistance while maintaining interaction and mobility with an electrode as an electrode buffer material, and an electrode buffer material and a photoelectric conversion element using the same. With the goal.

As a result of intensive studies to solve the above-described problems, the present inventors have succeeded in a high Tg phosphine sulfide compound, an electrode buffer material using these compounds, and a photoelectric conversion element, and have achieved the present invention.
That is, the gist of the present invention is as follows.
A phosphine sulfide compound represented by the following general formula (I).

In the formula, Ar ^{1 to} Ar ³ are each independently an aromatic group which may have a substituent, and at least one of Ar ^{1 to} Ar ³ is a condensed polycycle having 7 or more double bonds. It is an aromatic group.

  The phosphine sulfide compound of the present invention is useful as an electrode buffer material having high heat resistance while maintaining interaction and mobility with an electrode, and can be used for a photoelectric conversion element.

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

Hereinafter, embodiments of the present invention will be described in detail.
The description of the constituent requirements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not specified in these contents unless it exceeds the gist.
<Phosphine sulfide compound>
The phosphine sulfide compound of the present invention is represented by the following general formula (I).

In the formula, Ar ^{1 to} Ar ³ are each independently an aromatic group which may have a substituent, and at least one of Ar ^{1 to} Ar ³ is a condensed polycycle having 7 or more double bonds. It is an aromatic group.
In the present invention, “may have a substituent” means that one or more substituents may be present.
Ar ¹ to Ar ³ are each independently an aromatic group which may have a substituent. Specifically, phenyl group, naphthyl group, phenanthryl group, biphenylenyl group, triphenylene group, anthryl group, pyrenyl group, fluorenyl group, azulenyl group, acenaphthenyl group, fluoranthenyl group, naphthacenyl group, perylenyl group, pentacenyl group, triphenylenyl Aromatic hydrocarbon group such as a group, pyridyl group, thienyl group, furyl group, pyrrolyl group, oxazolyl group, thiazolyl group, oxadiazolyl group, thiadiazolyl group, pyrazinyl group, pyrimidinyl group, pyrazoyl group, imidazolyl group, benzothienyl group, dibenzo Furyl group, dibenzothienyl group, phenylcarbazoyl, phenoxathienyl group, xanthenyl group, benzofuranyl group, thianthenyl group, indolizinyl group, phenoxazinyl group, phenothiazinyl group, acridinyl , Phenanthridinyl group, quinolyl group, isoquinolyl group, indolyl group, an aromatic heterocyclic group such as a quinoxalinyl group. Preferably, an aromatic hydrocarbon group such as phenyl group, naphthyl group, phenanthryl group, triphenylene group, anthryl group, pyrenyl group, fluorenyl group, acenaphthenyl group, fluoranthenyl group, perylenyl group, triphenylenyl group; pyridyl group, pyrazinyl group , Pyrimidinyl group, pyrazoyl group, quinolyl group, isoquinolyl group, imidazoyl group, acridinyl group, phenanthridinyl group, quinoxalinyl group, dibenzofuryl group, dibenzothienyl group, phenylcarbazoyl, xanthenyl group, phenoxazinyl group, etc. It is a group.

At least one of Ar ^{1 to} Ar ³ is a condensed polycyclic aromatic group having 7 or more double bonds. The number of double bonds is more preferably 8 or more. Moreover, 30 or less is preferable, More preferably, it is 28 or less. If the number of double bonds is too small, there will be a problem that the overlap between substituents will be reduced and the movement of electrons will be low, and if it is too large, the solubility will be too poor and purification will not be possible.

The ring forming the condensed polycyclic aromatic group is preferably a cyclic alkyl group which may have a substituent, an aromatic hydrocarbon group which may have a substituent, or an aromatic which may have a substituent It is a heterocyclic group.
Specific examples of the cyclic alkyl group include a cyclopentyl group and a cyclohexyl group.

A specific example of the aromatic hydrocarbon group is a phenyl group.
Specific examples of the aromatic heterocyclic group include pyridyl group, thienyl group, furyl group, pyrrolyl group, oxazolyl group, thiazolyl group, oxadiazolyl group, thiadiazolyl group, pyrazinyl group, pyrimidinyl group, pyrazoyl group, imidazolyl group. , Etc. As the aromatic heterocyclic group, a pyridyl group and a thienyl group are preferable.

The condensed polycyclic aromatic group is a group in which the ring is condensed. Preferably, a condensed polycyclic hydrocarbon group such as phenanthryl group, anthryl group, pyrenyl group, fluoranthenyl group, naphthacenyl group, perylenyl group, pentacenyl group, triphenylenyl group, phenoxazinyl group, phenothiazinyl group, acridinyl group, phenantine And lysinyl group.
The substituent that Ar ^{1 to} Ar ³ may have is not particularly limited, but preferably a halogen atom, a hydroxyl group, a cyano group, an amino group, a carboxyl group, a carbonyl group, an acetyl group, a sulfonyl group, a silyl group, A boryl group, a nitrile group, an alkyl group, a perfluoroalkyl group, an alkenyl group, an alkynyl group, an alkoxyl group, an aromatic hydrocarbon group, and an aromatic heterocyclic group.

  The aromatic hydrocarbon group preferably has 6 to 16 carbon atoms, and is not limited to a monocyclic group, and may be a condensed polycyclic hydrocarbon group or a ring condensed hydrocarbon group. Specific examples include monocyclic groups such as phenyl groups, rings such as biphenyl groups, phenanthryl groups, naphthyl groups, anthryl groups, fluorenyl groups, pyrenyl groups, and perylenyl groups, biphenyl groups, and terphenyl groups. A condensed hydrocarbon group etc. are mentioned. The aromatic hydrocarbon group is preferably a phenyl group or a naphthyl group.

  As the aromatic heterocyclic group, those having 5 to 20 carbon atoms are preferable, and specific examples include pyridyl group, thienyl group, furyl group, oxazolyl group, thiazolyl group, oxadiazole group, benzothienyl group, dibenzofuryl group, Examples thereof include a dibenzothienyl group, a pyrazinyl group, a pyrimidinyl group, a pyrazoyl group, an imidazolyl group, and a phenylcarbazoyl group. The aromatic heterocyclic group is preferably a pyridyl group, a thienyl group, a benzothienyl group, a dibenzofuryl group, a dibenzothienyl group, or a phenanthryl group.

A halogen atom is preferably a fluorine atom. As an alkyl group, a C1-C20 thing is preferable and a methyl group, an ethyl group, i-propyl group, t-butyl group, a cyclohexyl group etc. are mentioned as a specific example.
The perfluoroalkyl group is preferably a trifluoromethyl group. The alkenyl group preferably has 2 to 20 carbon atoms, and specific examples include a styryl group and a diphenylvinyl group.

As the alkynyl group, those having 2 to 20 carbon atoms are preferable, and specific examples include a methylethynyl group, a phenylethynyl group, a trimethylsilylethynyl group, and the like.
As the silyl group, those having 2 to 20 carbon atoms are preferable, and specific examples thereof include a trimethylsilyl group and a triphenylsilyl group.
These substituents may further have a substituent. Further, the substituents that may be included are aryl group, arylamino group, alkyl group, perfluoroalkyl group, halide group, carboxyl group, cyano group, alkoxyl group, aryloxy group, carbonyl group, oxycarbonyl group, carboxyl group An acid group, a heterocyclic group, etc. are mentioned. Preferably, an aryl group having 6 to 16 carbon atoms, an arylamino group having 12 to 30 carbon atoms, an alkyl group having 1 to 12 carbon atoms, a perfluoroalkyl group having 1 to 12 carbon atoms, a fluoride group, and 1 to 10 carbon atoms. An oxycarbonyl group, a cyano group, an alkoxy group having 1 to 10 carbon atoms, an aryloxy group having 6 to 16 carbon atoms, a carbonyl group having 2 to 16 carbon atoms, an aromatic heterocyclic group having 5 to 20 carbon atoms, and the like. It is done.

  Further, among the substituents that may be included, examples of the aryl group having 6 to 16 carbon atoms include a phenyl group, a naphthyl group, a phenanthryl group, a pyrenyl group, a perylenyl group, and an anthryl group. Examples of the arylamino group having 12 to 30 carbon atoms include a diphenylamino group, a carbazoyl group, and a phenylcarbazoyl group. Examples of the alkyl group having 1 to 12 carbon atoms include a methyl group, an ethyl group, a butyl group, and a t-butyl group. A trifluoromethyl group etc. are mentioned as an example of a C1-C12 perfluoroalkyl group.

  Examples of the oxycarbonyl group having 1 to 10 carbon atoms include a methoxycarbonyl group and an ethoxycarbonyl group. Examples of the alkoxy group having 1 to 10 carbon atoms include a methoxy group and an ethoxy group. Examples of the aryloxy group having 6 to 16 carbon atoms include a phenyloxy group. Examples of the carbonyl group having 2 to 16 carbon atoms include an acetyl group and a phenylcarbonyl group. Examples of the aromatic heterocyclic group having 5 to 20 carbon atoms include pyridyl group, thienyl group, oxazolyl group, oxadiazolyl group, benzothienyl group, dibenzofuryl group, dibenzothienyl group, pyrazinyl group, pyrimidinyl group, pyrazoyl group, imidazolyl Groups and the like.

Specific examples of the condensed polycyclic aromatic group having 7 or more double bonds among Ar ^{1 to} Ar ³ include, but are not limited to, the following.

  Preferable specific examples of the phosphine material represented by the general formula (I) include, for example, those exemplified below. However, as long as the gist of the present invention is not exceeded, it is not limited to these.

The phosphine sulfide compound of the present invention is a high-performance compound that has an effect of improving photoelectric conversion characteristics, particularly improving open-circuit voltage Voc and improving durability when used as an electrode buffer material for the following reasons. .
1) The P = S skeleton of the phosphine sulfide compound has a longer interatomic distance than P = O of the phosphine compound, and can maintain the planarity of the whole molecule.
2) Since the P = S skeleton of the phosphine sulfide compound has a deeper IP (ionization potential) than the P = O skeleton of the phosphine compound, the hole blocking performance can be improved.
3) High coordination ability to the electrode.

<Method for producing phosphine sulfide compound>
There is no limitation in particular as a manufacturing method of the compound represented by general formula (I). For example, Synthesis
It can be obtained by the following scheme described in 2006, 2,354.

The compound obtained by general formula (I) can be obtained by reacting the obtained compound with S ₈ in an organic solvent.
The phosphine sulfide compound represented by Ar ² = Ar ³ is represented by the following scheme when Ar ¹ = phenyl group is described as an example.

That is, aryl dihalide is reacted with a metal reagent such as butyl lithium or magnesium to synthesize a metal compound: M-Ar, and then reacted with phosphine chloride (1-1) in an organic solvent ( 1-2) can be obtained.
As the organic solvent, diethyl ether, tetrahydrofuran (THF) and the like are preferable.

Although this reaction temperature changes with metal reagents to be used, it is preferably -78 ° C to 110 ° C.
Next, the compound represented by the formula (1-2) obtained by the above reaction and sulfur (S8) are reacted in an organic solvent to obtain the compound represented by the formula (1-3). .
In addition, as said organic solvent, acetone, tetrahydrofuran (THF), etc. are preferable.

The reaction temperature varies depending on the organic solvent used, but is preferably 0 ° C to 110 ° C.
<Application>
The phosphine sulfide compound of the present invention can be preferably used for photoelectric conversion elements, electrode buffer materials such as photoelectric conversion elements, and n-type semiconductors. Among these, it is useful as an electrode buffer material for photoelectric conversion elements.

  The electrode buffer material contains at least the phosphine sulfide compound described above. Among the phosphine sulfide compounds of the present invention, any one of them may be contained alone, or two or more thereof may be contained in any combination. Moreover, although it may consist only of the phosphine sulfide compound of the present invention, it may contain other components (for example, other polymers and monomers, various additives, inorganic salts, etc.).

The glass transition temperature of the electrode buffer material is not particularly limited, but is preferably 90 ° C. or higher. More preferably, it is 120 ° C. or higher. More preferably, it is 130 degreeC or more. If the glass transition temperature is too low, there is a problem of crystallization during the annealing process.
The electron mobility of the electrode buffer material is not particularly limited, but preferably 10 ⁻⁸ cm ² / V.
s or more. More preferably, it is 10 ^<-7 > cm ^{< 2} > / Vs or more, More preferably, it is 10 ^<-6 > cm ^{< 2} > / Vs or more. If the electron mobility is too low, it is difficult to extract current and there is a problem that the photoelectric conversion efficiency is lowered.

<Photoelectric conversion element>
The photoelectric conversion element according to the present invention has at least one pair of electrodes, an active layer, and a buffer layer. The active layer and the buffer layer are disposed between the electrodes. FIG. 1 shows a photoelectric conversion element used in a general organic thin film solar cell, but is not limited thereto.
(electrode)
In the photoelectric conversion element according to the present invention, any one of the pair of electrodes may be translucent, and both may be translucent. Translucency means that sunlight passes through 40% or more. In addition, it is preferable that the transparent electrode has a solar ray transmittance of 70% or more in order to allow light to reach the active layer through the transparent electrode. The light transmittance can be measured with a normal spectrophotometer.

  The material used for the transparent electrode is not particularly limited as long as it has conductivity. For example, nickel oxide, tin oxide, indium oxide, indium tin oxide (ITO), indium-zirconium oxide ( IZO), conductive metal oxides such as titanium oxide, indium oxide and zinc oxide, metals such as gold, platinum, silver and chromium and alloys thereof, PEDOT / PSS in which polythiophene derivatives are doped with polystyrene sulfonic acid, polypyrrole and Examples thereof include conductive polymers doped with iodine or the like in polyaniline. These electrode materials may be used alone, or a plurality of materials may be mixed and used. Especially, it is preferable to use transparent electrodes, such as oxides, such as ITO, a tin oxide, a zinc oxide, and an indium zinc oxide (IZO), in the electrode in the position which light permeate | transmits. Further, a material having a high work function such as ITO (indium tin oxide), tin oxide, zinc oxide, gold, cobalt, nickel, platinum, and aluminum, silver, lithium, indium, calcium, magnesium, etc. may be used in combination. Good.

  The film thickness of the transparent electrode is not limited and can be arbitrarily selected according to the resistance value. However, it is preferably 10 nm or more, particularly 50 nm or more, and usually 1000 nm or less, particularly 500 nm or less, more preferably 300 nm or less, and particularly preferably 100 nm or less. If the electrode is too thick, the transparency may decrease and the cost may be high. If the electrode is too thin, the series resistance may be large and the performance may be deteriorated.

The sheet resistance of the transparent electrode is 300Ω / □ or less, more preferably 200Ω / □ or less, from the viewpoint of increasing the short-circuit current.
The electrode has a function of collecting holes and electrons generated by light absorption. Therefore, it is preferable to use an electrode material suitable for collecting holes and electrons for the electrode.
Examples of the electrode material suitable for collecting holes include materials having a high work function such as Au and ITO. On the other hand, an electrode material suitable for collecting electrons includes a material having a low work function such as Al.

In addition, there is no restriction | limiting in the formation method of an electrode. For example, it can be formed by a dry process such as vacuum deposition or sputtering. Further, for example, it can be formed by a wet process using a conductive ink or the like. At this time, any conductive ink can be used. For example, a conductive polymer, a metal particle dispersion, or the like can be used.
Furthermore, two or more electrodes may be stacked, and characteristics (electric characteristics, wetting characteristics, etc.) due to surface treatment may be improved.

  The counter electrode is preferably a metal such as platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium, sodium, potassium, cesium, calcium and magnesium, and alloys thereof, lithium fluoride, fluorine. Examples thereof include inorganic salts such as cesium oxide, metal oxides such as nickel oxide, aluminum oxide, lithium oxide, and cesium oxide. From the viewpoint of electrode protection, metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium, or alloys using these metals are preferable.

The film thickness of the counter electrode is not limited and can be arbitrarily selected according to the resistance value. However, it is preferably 10 nm or more, particularly 50 nm or more, and usually 1000 nm or less, particularly 500 nm or less, more preferably 300 nm or less, and particularly preferably 100 nm or less.
There is no restriction | limiting also in the formation method of an electrode. For example, it can be formed by a dry process such as vacuum deposition, electron beam, sputtering, plating, or CVD. Further, for example, it can be formed by a wet process such as ion plating coating, sol-gel, spin coating, and ink jet. At this time, any conductive ink can be used. For example, a conductive polymer, a metal particle dispersion, or the like can be used. Further, two or more electrodes may be laminated, and characteristics (electric characteristics, wetting characteristics, etc.) may be improved by surface treatment.

(Active layer)
In the photoelectric conversion element according to the present invention, the active layer is not particularly limited. The active layer includes a p-type semiconductor and an n-type semiconductor. In the photoelectric conversion element, light is absorbed by the active layer, electricity is generated at the interface between the p-type semiconductor and the n-type semiconductor, and the generated electricity is extracted from the electrode.
Although there is no limitation in particular as a p-type semiconductor, a low molecular material and a high molecular material are mentioned. As low molecular weight materials, condensed aromatic hydrocarbons such as naphthacene, pentacene, pyrene, fullerene; oligothiophenes containing 4 or more thiophene rings such as α-sexithiophene; thiophene ring, benzene ring, fluorene ring, naphthalene ring , Anthracene ring, thiazole ring, thiadiazole ring, benzothiazole ring in total 4 or more linked; phthalocyanine compounds such as copper phthalocyanine, zinc phthalocyanine, perfluoro copper phthalocyanine, porphyrin compounds such as tetrabenzoporphyrin and metal complexes thereof, and the like Examples also include macrocyclic compounds such as metal salts. Low molecular weight materials include a method of forming a film by a vapor deposition method and a method of forming a film by converting a soluble precursor of a semiconductor into a semiconductor after coating.

  The polymer material is not particularly limited, and examples thereof include conjugated polymer semiconductors such as polythiophene, polyfluorene, polythienylene vinylene, polyacetylene, and polyaniline; and polymer semiconductors such as alkyl-substituted oligothiophenes. Moreover, the polymer semiconductor which copolymerized 2 or more types of monomer units is also mentioned. These are semiconductors that are soluble in an organic solvent, and are preferable because a coating method can be used in the manufacturing process of an organic solar cell element.

  Conjugated polymer semiconductors are described in, for example, Handbook of Conducting Polymers, 3rd Ed. (2 volumes), 2007, Materials Science and Engineering, 2001, 32, 1-40, Pure Appl. Chem. Use polymers that can be synthesized by polymers described in known literature such as 2002, 74, 2031-3044, Handbook of THIOPHENE-BASED MATERIALS (2 volumes in total), 2009, or derivatives thereof, or combinations of the monomers described. Can do. Polymer or monomer substituents can be selected to control solubility, crystallinity, film formability, HOMO level or LUMO level.

A polymer material soluble in an organic solvent is preferable because a coating method can be used in the manufacturing process of the organic solar cell element. Note that the above-mentioned one kind of compound or a mixture of plural kinds of compounds may be used. The polymer material may have any self-organized structure in the film-formed state, or may be in an amorphous state.
Specific examples of the polymer material include the following, but are not limited thereto.

As the p-type semiconductor, it is preferable to use at least one of a porphyrin compound and a polymer semiconductor.
The n-type semiconductor is not particularly limited, but fullerene derivatives, quinolinol derivative metal complexes typified by 8-hydroxyquinoline aluminum, condensed ring tetracarboxylic acid diimides such as naphthalenetetracarboxylic acid diimide, perylenetetracarboxylic acid diimide, and terpyridine Metal complexes, tropolone metal complexes, flavonol metal complexes, perinone derivatives, benzimidazole derivatives, benzoxazole derivatives, benzthiazole derivatives, oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, aldazine derivatives, bisstyryl derivatives, pyrazine derivatives, phenanthroline derivatives, quinoxaline Derivatives, benzoquinoline derivatives, bipyridine derivatives, borane derivatives, anthracene, pyrene, naphthacene, pentacene, etc. All fluorides of aromatic, such as a single-walled carbon nanotubes, and the like.

Moreover, the n-type polymer which uses these as a structural unit is mentioned. These compounds may be substituted with N-alkyl to improve the solubility.
Among them, borane derivatives, thiazole derivatives, benzthiazole derivatives, benzothiadiazole derivatives, fullerene compounds, N-alkyl-substituted naphthalenetetracarboxylic acid diimides and N-alkyl-substituted perylene diimide derivatives and polymers having these as structural units Preferably, fullerene compounds, N-alkyl-substituted perylene diimide derivatives and N-alkyl-substituted naphthalene tetracarboxylic acid diimides, and n-type polymers containing them as constituent units are more preferable. You may contain 1 type, or 2 or more types of these compounds.

<Fullerene derivative>
The fullerene derivative of the present invention is a fullerene derivative having a partial structure represented by the general formula (n1), (n2), (n3) or (n4).

Fullerenes (FLN) in the general formulas (n1), (n2), (n3) and (n4) are carbon clusters having a closed shell structure. The carbon number of fullerene is not particularly limited as long as it is usually an even number of 60 to 130. As the fullerene, for example, C _{6 0} , C _{7 0} , C _{7 6} , C _{7 8} , C _{8 2} , C _8
4, C _{9 0,} such as C _94, C _{9 6} and higher carbon cluster having a number of carbon than these. Among these, C ₆₀ or C ₇₀ is preferable, and C ₆₀ is more preferable.

As fullerenes, carbon-carbon bonds on some fullerene rings may be broken. Some carbon atoms may be replaced with other atoms. Furthermore, a metal atom, a non-metal atom, or an atomic group composed of these may be included in the fullerene cage.
d, e, f and g are integers, and the sum of d, e, f and g is usually 1 to 5, preferably 1 to 3. The additional groups in (n1), (n2), (n3), and (n4) are added to the same 5-membered ring or 6-membered ring in the fullerene skeleton. L is an integer of 1-8. L is preferably an integer of 1 to 4, more preferably an integer of 1 to 2.

R ¹ in the general formula (n1) has an optionally substituted alkyl group having 1 to 14 carbon atoms, an optionally substituted alkoxy group having 1 to 14 carbon atoms, and a substituent. An aromatic group that may be present.
As an alkyl group, a C1-C10 alkyl group is preferable, a methyl group, an ethyl group, n-propyl group, isopropyl group, n-butyl group or isobutyl group is more preferable, and a methyl group and an ethyl group are especially preferable.

As an alkoxy group, a C1-C10 alkoxy group is preferable, a C1-C6 alkoxy group is more preferable, and a methoxy group and an ethoxy group are especially preferable.
As the aromatic group, an aromatic hydrocarbon group having 6 to 20 carbon atoms and an aromatic heterocyclic group having 2 to 20 carbon atoms are preferable, and a phenyl group, a thienyl group, a furyl group, and a pyridyl group are more preferable. More preferred are groups and thienyl groups.

The substituent which may be substituted on the alkyl group is a halogen atom or a silyl group. The halogen atom that may be substituted is preferably a fluorine atom.
The silyl group is preferably a diarylalkylsilyl group, a dialkylarylsilyl group, a triarylsilyl group, or a trialkylsilyl group, more preferably a dialkylarylsilyl group, and even more preferably a dimethylarylsilyl group.

R ^{2 to} R ⁴ in the general formula (n1) each represent an independent substituent, and may have a hydrogen atom, a C 1-14 alkyl group which may have a substituent, or a substituent. It is a good fluorinated alkyl group having 1 to 14 carbon atoms and an aromatic group which may have a substituent.
As an alkyl group, a C1-C10 alkyl group is preferable and a methyl group, an ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, and n-hexyl group are preferable.

As the fluorinated alkyl group, a perfluorooctyl group, a perfluorohexyl group, and a perfluorobutyl group are preferable.
The aromatic group is preferably an aromatic hydrocarbon group having 6 to 20 carbon atoms and an aromatic heterocyclic group having 2 to 20 carbon atoms, more preferably a phenyl group, a thienyl group, a furyl group and a pyridyl group, and a phenyl group and a thienyl group. Further preferred.

The substituent that the aromatic group may have is a fluorine atom, an alkyl group having 1 to 14 carbon atoms, a fluorinated alkyl group having 1 to 14 carbon atoms, an alkoxy group having 1 to 14 carbon atoms, and 3 to 3 carbon atoms. 10 aromatic groups are preferred, fluorine atoms and alkoxy groups having 1 to 14 carbon atoms are more preferred, and methoxy, n-butoxy and 2-ethylhexyloxy groups are even more preferred.
When an aromatic group has a substituent, although there is no limitation in the number, 1-3 are preferable and 1 is more preferable. When the aromatic group has a plurality of substituents, the types of the substituents may be different, but are preferably the same.

R ^{5 to} R ⁹ in the general formula (n2) are each independently a hydrogen atom or an alkyl group having 1 to 14 carbon atoms which may have a substituent or an aromatic group which may have a substituent. is there.
As the alkyl group, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an n-hexyl group and an octyl group are preferable, and a methyl group is more preferable.

The aromatic group is preferably an aromatic hydrocarbon group having 6 to 20 carbon atoms and an aromatic heterocyclic group having 2 to 20 carbon atoms, more preferably a phenyl group and a pyridyl group, and further preferably a phenyl group.
Although there is no limitation in particular as a substituent which an aromatic group may have, a fluorine atom, a C1-C14 alkyl group, a C1-C14 fluorinated alkyl group, and a C1-C14 alkoxy group are preferable. And more preferably an alkoxy group having 1 to 14 carbon atoms, and even more preferably a methoxy group.

When it has a substituent, the number is not limited, but 1 to 3 is preferable, and 1 is more preferable. The types of substituents may be different, but are preferably the same.
Ar ⁴ in the general formula (n3) is an optionally substituted aromatic hydrocarbon group having 6 to 20 carbon atoms or an aromatic heterocyclic group having 2 to 20 carbon atoms, and includes a phenyl group and a naphthyl group. Group, biphenyl group, phenanthryl group, anthryl group, fluorenyl group, pyrenyl group, perylenyl group, terphenyl group, thienyl group, furyl group, pyridyl group, pyrimidinyl group, quinolyl group, quinoxalyl group, pyrazinyl group, imidazolyl group, pyrazoyl group , Oxazolyl group, thiazolyl group, oxadiazolyl group, pyrrolyl group, triazolyl group, thiadiazolyl group, benzothienyl group, benzofuryl group, furanofuryl group, dibenzothienyl group, thienothienyl group, dibenzofuryl group, phenanthryl group, carbazoyl group, quinoxalyl group, benzo Quinoxalyl group, carbazoyl group Preferably finely phenyl carbazoyl group, a phenyl group, a thienyl group, a furyl group, a thiazolyl group, a pyrrolyl group, a triazolyl group and a thiadiazolyl group are more preferred.

  Although there is no limitation as a substituent which may have, a fluorine atom, a chlorine atom, a hydroxyl group, a cyano group, a silyl group, a boryl group, an amino group which may be substituted with an alkyl group, an alkyl group having 1 to 14 carbon atoms A fluorinated alkyl group having 1 to 14 carbon atoms, an alkoxy group having 1 to 14 carbon atoms, an alkylcarbonyl group having 1 to 14 carbon atoms, an alkylthio group having 1 to 14 carbon atoms, an alkenyl group having 1 to 14 carbon atoms, carbon Preferred are an alkynyl group having 1 to 14 carbon atoms, an ester group, an arylcarbonyl group, an arylthio group, an aryloxy group, an aromatic hydrocarbon group having 6 to 20 carbon atoms, and a heterocyclic group having 2 to 20 carbon atoms. An alkyl group having 1 to 14 carbon atoms, an alkoxy group having 1 to 14 carbon atoms, an ester group, an alkylcarbonyl group having 1 to 14 carbon atoms, and an arylcarbonyl group are more preferable.

The alkyl group having 1 to 14 carbon atoms is more preferably a methyl group, an ethyl group, or a propyl group.
More preferably, it is a methoxy group, an ethoxy group, and a propoxyl group as a C1-C14 alkoxy group.
The alkylcarbonyl group having 1 to 14 carbon atoms is more preferably an acetyl group.

More preferably, the ester group is a methyl ester group or an n-butyl ester group.
As the arylcarbonyl group, a benzoyl group is more preferable.
When it has a substituent, although there is no limitation in the number, 1-4 are preferable and 1-3 are more preferable. When there are a plurality of substituents, the types may be different, but are preferably the same.
R ^{10 to} R ¹³ in the general formula (n3) may each independently have a hydrogen atom, an alkyl group that may have a substituent, an amino group that may have a substituent, or a substituent. It is a good alkoxy group or an alkylthio group which may have a substituent. R ²² or R ²³ may form a ring with either one of R ²⁴ or R ²⁵ .

The structure in the case of forming a ring can be represented by, for example, the general formula (n5) which is a bicyclo structure in which an aromatic group is condensed.
H in the general formula (n5) is the same as the above f, and U is an amino group which may be substituted with an alkyl group having 1 to 6 carbon atoms such as an oxygen atom, a sulfur atom, a methyl group and an ethyl group, C1-C6 alkoxyl group such as methoxy group, C1-C5 hydrocarbon group, C6-C2
An arylene group such as a phenylene group or an alkylene group having 1 or 2 carbon atoms which may be substituted with a 0 aromatic hydrocarbon group or an aromatic heterocyclic group having 2 to 20 carbon atoms.

R ^{14 to} R ¹⁵ in the general formula (n4) each independently have a hydrogen atom, an alkoxycarbonyl group, an alkyl group having 1 to 14 carbon atoms which may have a substituent, or a substituent. Is also a good aromatic group.
The alkoxy group in the alkoxycarbonyl group is preferably a hydrocarbon group having 1 to 12 carbon atoms and a fluorinated alkyl group, more preferably a hydrocarbon group having 1 to 12 carbon atoms, methyl group, ethyl group, n-propyl group, isopropyl group. Group, n-butyl group, isobutyl group, n-hexyl group, octyl group, 2-propylpentyl group, 2-ethylhexyl group, 2-ethylhexyl group, cyclohexylmethyl group and benzyl group are more preferable, methyl group, ethyl group, Isopropyl, n-butyl, isobutyl and n-hexyl groups are particularly preferred.

  As the alkyl group, a linear alkyl group having 1 to 8 carbon atoms is preferable, and an n-propyl group is more preferable. There is no particular limitation on the substituent that the alkyl group may have, but an alkoxycarbonyl group is preferred. The alkoxy group of the alkoxycarbonyl group is preferably a hydrocarbon group having 1 to 14 carbon atoms and a fluorinated alkyl group, more preferably a hydrocarbon group having 1 to 14 carbon atoms, a methyl group, an ethyl group, an n-propyl group, an isopropyl group. Group, n-butyl group, isobutyl group, n-hexyl group, octyl group, 2-propylpentyl group, 2-ethylhexyl group, 2-ethylhexyl group, cyclohexylmethyl group and benzyl group are more preferable, methyl group and n-butyl group The group is particularly preferred.

The aromatic group is preferably an aromatic hydrocarbon group having 6 to 20 carbon atoms and an aromatic heterocyclic group having 2 to 20 carbon atoms, preferably a phenyl group, a biphenyl group, a thienyl group, a furyl group or a pyridyl group, And more preferred are thienyl groups. . As the substituent that the aromatic group may have, an alkyl group having 1 to 14 carbon atoms, a fluorinated alkyl group having 1 to 14 carbon atoms, and an alkoxy group having 1 to 14 carbon atoms are preferable, and 1 to 14 carbon atoms are preferable. Are more preferable, and a methoxy group and a 2-ethylhexyloxy group are particularly preferable. When it has a substituent, there is no limitation in the number, However, Preferably it is 1-3, More preferably, it is 1. The types of substituents may be different or the same, preferably the same.
When it has a substituent, there is no limitation in the number, However, Preferably it is 1-3, More preferably, it is 1. The types of substituents may be different or the same, preferably the same.

As the structure of the general formula (n4), preferably R ¹⁴ and R ¹⁵ are both alkoxycarbonyl groups, R ¹⁴ and R ¹⁵ are both aromatic groups, R ¹⁴ is an aromatic group, and R ¹⁵ Is a 3- (alkoxycarbonyl) propyl group.
In addition, as a fullerene compound, the said 1 type compound or the mixture of multiple types of compound may be sufficient.

The fullerene derivative can be formed by vapor deposition or coating. In particular, in order to be able to apply the coating method, it is preferable that the fullerene derivative itself can be applied in a liquid state or that the fullerene derivative is highly soluble in some solvent and can be applied as a solution.
The solvent for the fullerene derivative of the present invention is not particularly limited as long as it is a nonpolar organic solvent, but a non-halogen solvent is preferable. Although halogen-based solvents such as dichlorobenzene are also possible, alternatives are required in terms of environmental impact.

Examples of non-halogen solvents include non-halogen aromatic hydrocarbons. Of these, toluene, xylene, cyclohexylbenzene and the like are preferable.
[Method for producing fullerene derivative]
Although there is no restriction | limiting in particular as a manufacturing method of the fullerene derivative of this invention, For example, as a synthesis method of fullerene which has a partial structure (n1), international publication WO2008 / 059771 pamphlet, J. Org. Am. Chem. Soc. , 2008, 130 (46), 15429-15436, and can be carried out according to a method for synthesizing fullerene having a partial structure (n2). Am. Chem. Soc. 1993, 115, 9798-9799, Chem. Mater. 2007, 19, 5363-5372 and Chem. Mater. The synthesis method of fullerene having a partial structure (n3) can be carried out by publicly known literature described in 2007, 19, 5194-5199, and Angew. Chem. Int. Ed. Engl. 1993, 32, 78-80, Tetrahedron Lett. 1997, 38, 285-288, International Publication WO2008 / 018931 Pamphlet, International Publication WO2009 / 086212 Pamphlet can be carried out according to known methods, and as a synthesis method of fullerene having a partial structure (n4), J . Chem. Soc. Perkin Trans. 1, 1997 1595, Thin Solid Films 489 (2005) 251-256, Adv. Funct. Mater. 2005, 15, 1979-1987 and J. Org. Org. Chem. It can be carried out according to known documents described in 1995, 60, 532-538.

<N-alkyl-substituted perylene diimide derivatives>
The N-alkyl-substituted perylene diimide derivative according to the present invention is not particularly limited, and specifically, International Publication No. 2008/063609, International Publication No. 2009/115513, International Publication No. 2009/098250, Examples thereof include compounds described in International Publication No. 2009/000756 and International Publication No. 2009/091670. High electron mobility and absorption in the visible range are preferable because they contribute to both charge transport and power generation.

<Naphthalene tetracarboxylic acid diimide>
The naphthalene tetracarboxylic acid diimide according to the present invention is not particularly limited, but specifically described in International Publication No. 2008/063609, International Publication No. 2007/146250 and International Publication No. 2009/000756. Compounds. It is preferable from the viewpoint of high electron mobility, high solubility, and excellent coating properties.

<N-type polymer>
The n-type polymer according to the present invention is not particularly limited, but specifically, International Publication No. 2009 /
Examples include compounds described in 098253, WO2009 / 098250, WO2010 / 012710, and WO2009 / 098250. Since it has absorption in the visible region, it is preferable from the viewpoint of contributing to power generation, high viscosity, and excellent coating properties.

The active layer is composed of a thin film stack type in which a p-type semiconductor and an n-type semiconductor are stacked, a bulk heterojunction type in which a p-type semiconductor and an n-type semiconductor are mixed, and a p-type semiconductor and an n-type semiconductor in an intermediate layer of the thin film stack type. A structure having a layer (i layer) in which is mixed.
The thickness of the active layer is not particularly limited, but if it is less than 10 nm, there is a problem that uniformity is not sufficient and a short circuit is likely to occur. On the other hand, if the thickness of the layer containing the compound A and the compound B exceeds 1000 nm, the internal resistance increases, and the distance between the electrodes is increased, resulting in a problem that charge diffusion is deteriorated. Therefore, the thickness of the active layer is preferably 10 to 1000 nm, and more preferably 50 to 200 nm.

(Buffer layer)
As the material for the buffer layer, the phosphine sulfide compound of the present invention is preferably used. Examples of the buffer layer include a hole extraction layer and an electron extraction layer, and the phosphine sulfide compound of the present invention can be used in either layer. Preferably, it is an electron extraction layer.

(Electronic extraction layer)
The electron extraction layer may be doped with an alkali metal or an alkaline earth metal in addition to the material of the present invention.
The thickness of the electron extraction layer is not particularly limited, but is preferably 0.01 nm or more and 40 nm or less. More preferably, it is 20 nm or less. There is a problem that it is difficult to take out too large electrons and the photoelectric conversion efficiency is lowered, and when it is too small, there is a problem that the function as a buffer material cannot be performed.

(substrate)
The photoelectric conversion element according to the present invention usually has a substrate serving as a support. That is, an electrode, an active layer, and a buffer layer are formed on the substrate. The material of the substrate (substrate material) is arbitrary as long as the effects of the present invention are not significantly impaired. Preferable examples of substrate materials include inorganic materials such as quartz, glass, sapphire, and titania; polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene vinyl alcohol copolymer, fluorine Resin film, polyolefin such as vinyl chloride and polyethylene, cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene, epoxy resin and other organic materials; paper, synthetic paper and other paper materials; stainless steel, Examples thereof include composite materials such as those obtained by coating or laminating a surface of a metal such as titanium or aluminum to provide insulation.

Examples of the glass include soda glass, blue plate glass, and alkali-free glass. As for the glass material, alkali-free glass is preferred because it is better that there are fewer ions eluted from the glass.
There is no restriction | limiting in the shape of a board | substrate, For example, shapes, such as a board, a film, a sheet | seat, can be used. There is no limitation on the thickness of the substrate. However, it is preferably 5 μm or more, especially 20 μm or more, and usually 20 mm or less, especially 10 mm or less. If the substrate is too thin, the strength of the semiconductor device may be insufficient, and if the substrate is too thick, the cost may be increased or the weight may be increased. Further, when the substrate is glass, if it is too thin, the mechanical strength is lowered and it is easy to break. More preferably 0.1
mm or more is preferable. Moreover, since weight will become heavy when too thick, Preferably it is 1 cm or less and 0.5 cm or less.

(Hole extraction layer)
The material of the hole extraction layer is not particularly limited as long as it is a material capable of improving the efficiency of extracting holes from the active layer to the electrode. Specifically, PEDOT / PSS, polythiophene derivatives doped with polystyrene sulfonic acid, polythiophene, polypyrrole, polyacetylene, triphenylenediamine polypyrrole, and polyaniline doped with conductive polymers such as iodine, copper phthalocyanine (CuPC), arylamine, etc. Examples thereof include conductive organic compounds and the aforementioned p-type semiconductors. A thin film of metal such as gold, indium, silver or palladium can also be used. Furthermore, a thin film of metal or the like may be formed alone or in combination with the above organic material.

  The hole extraction layer and the electron extraction layer are disposed so as to sandwich the active layer between a pair of electrodes. That is, when the photoelectric conversion element according to the present invention includes both the hole extraction layer and the electron extraction layer, the electrode, the hole extraction layer, the active layer, the electron extraction layer, and the electrode are arranged in this order. When the photoelectric conversion element according to the present invention includes an electron extraction layer and does not include a hole extraction layer, the electrode, the active layer, the electron extraction layer, and the electrode are arranged in this order. The stacking order of the hole extraction layer and the electron extraction layer may be reversed, or at least one of the hole extraction layer and the electron extraction layer may be composed of a plurality of different films.

  There is no restriction | limiting in the formation method of a hole taking-out layer and an electron taking-out layer. For example, when a material having sublimation property is used, it can be formed by a vacuum deposition method or the like. Further, for example, when a material soluble in a solvent is used, it can be formed by a wet coating method such as spin coating or inkjet. When a semiconductor material is used for the hole extraction layer, the precursor may be converted into a semiconductor material after forming the layer using the precursor, similarly to the low-molecular compound of the active layer.

In the photoelectric conversion element of the present invention, photoelectric conversion elements may be stacked in order to improve conversion efficiency.
(Solar cell)
It is preferable that the photoelectric conversion element of this invention is used as a thin film solar cell as a solar cell element.

FIG. 2 is a cross-sectional view schematically showing the configuration of a thin film solar cell as one embodiment of the present invention. As shown in FIG. 2, the thin film solar cell 14 of this embodiment includes a weather-resistant protective film 1, an ultraviolet cut film 2, a gas barrier film 3, a getter material film 4, a sealing material 5, and a solar cell element. 6, a sealing material 7, a getter material film 8, a gas barrier film 9, and a back sheet 10 in this order, and further a sealing material 11 that seals the edges of the weatherproof protective film 1 and the back sheet 10. I have. 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, when using a highly waterproof sheet such as a sheet in which a fluororesin film is bonded to both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. .

[Weather-resistant protective film 1]
The weather-resistant protective film 1 is a film that protects the solar cell element 6 from weather changes.
Some components of the solar cell element 6 are deteriorated by temperature change, humidity change, natural light, erosion caused by wind and rain, and the like. Therefore, 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, it is suitable as a surface covering material for the thin-film solar cell 14 such as weather resistance, heat resistance, transparency, water repellency, stain resistance, and mechanical strength. It is preferable that it has a good performance and has the property of maintaining it for a long period of time in outdoor exposure.
Moreover, the weather-resistant protective film 1 is preferably one that 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, more preferably 90% or more, and particularly preferably 95%.

  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, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower. Preferably it is 300 degrees C or less. By increasing the melting point, it is possible to reduce the possibility that the weather resistant protective film 1 is melted and deteriorated when the thin film solar cell 14 is used.

  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, silicone resins, and polycarbonate resins.

  Among them, fluorine resin is preferable, and specific examples thereof include polytetrafluoroethylene (PTFE), 4-fluoroethylene-perchloroalkoxy copolymer (PFA), 4-fluoroethylene-6-fluoride. Propylene copolymer (FEP), 2-ethylene-4-fluoroethylene copolymer (ETFE), poly-3-fluoroethylene chloride (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), etc. Can be mentioned.

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 2 or more layers may be sufficient as it.
The thickness of the weather-resistant protective film 1 is not particularly specified, but is usually 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less. Increasing the thickness tends to increase mechanical strength, and decreasing the thickness tends to increase flexibility.

Moreover, you may perform surface treatment, such as a corona treatment and a plasma treatment, for the weather-resistant protective film 1 in order to improve 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.

[UV cut film 2]
The ultraviolet cut film 2 is a film that prevents the transmission of ultraviolet rays.
Some components of the thin film solar cell 14 are deteriorated by ultraviolet rays. Some of the gas barrier films 3 and 9 are deteriorated by ultraviolet rays depending on the type. Therefore, 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, 9 etc. Can be protected from ultraviolet rays and the power generation capacity can be kept high.

The degree of the ability to suppress the transmission of ultraviolet rays required for the ultraviolet cut film 2 is such that the transmittance of ultraviolet rays (for example, wavelength 300 nm) is preferably 50% or less, more preferably 30% or less, and particularly preferably. 10% or less.
Further, the ultraviolet cut film 2 is preferably one that 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, more preferably 90% or more, and particularly preferably 95% or more.

  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, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower, more preferably. Is 300 ° C. or lower. If the melting point is too low, the ultraviolet cut film 2 may melt when the thin film solar cell 14 is used.

Moreover, the ultraviolet cut film 2 has a high softness | flexibility, its adhesiveness with an adjacent film is favorable, and what can cut water vapor | steam and oxygen is preferable.
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 a film 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.

  As the ultraviolet absorber, for example, salicylic acid-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based ones can be used. Of these, benzophenone and benzotriazole are preferable. Examples of this include various aromatic organic compounds such as benzophenone and benzotriazole. 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 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.

  Application | coating can be performed by arbitrary methods. Examples include reverse roll coating, gravure coating, kiss coating, roll brushing, spray coating, air knife coating, wire barber coating, pipe doctor method, impregnation / coating method, curtain coating method and the like. In addition, these methods may be performed alone or in any combination of two or more.

  The solvent used for the coating solution is not particularly limited as long as it can uniformly dissolve or disperse the UV absorber. For example, liquid resin can be used as a solvent, and examples thereof include various synthetic resins such as polyester, acrylic, polyamide, polyurethane, polyolefin, polycarbonate, and polystyrene. It is done. Further, for example, natural polymers such as gelatin and cellulose derivatives; water, alcohol mixed solutions such as water and ethanol, and the like can also be used as the solvent. Further, an organic solvent may be used as the solvent. If an organic solvent is used, it becomes possible to dissolve or disperse the pigment and the resin, and to improve the coatability. In addition, 1 type may be used for a solvent and it may use 2 or more types together by arbitrary combinations and a ratio.

The coating solution may further contain a surfactant. Use of the surfactant improves the dispersibility of the ultraviolet absorbing dye in the resin. Thereby, in an ultraviolet absorption layer, generation | occurrence | production of the dent by adhesion of foreign matters etc. by a micro bubble, the repelling in a drying process, etc. are suppressed.
Known surfactants (cationic surfactants, anionic surfactants, nonionic surfactants) can be used as the surfactant. Among these, silicone surfactants or fluorine surfactants are preferable. In addition, 1 type may be used for surfactant and it may use 2 or more types together by arbitrary combinations and a ratio.

In addition, the drying after apply | coating a coating liquid to a base film can employ | adopt well-known drying methods, such as a hot-air drying and the drying by an infrared heater, for example. Among these, hot air drying with a high drying speed is preferable.
Examples of specific products of the ultraviolet cut film 2 include Cut Ace (MKV Plastic Co., Ltd.).

The ultraviolet cut film 2 may be formed of one kind of material or may be formed of two or more kinds 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 defined, but is usually 5 μm or more, preferably 10 μm or more, more preferably 15 μm or more, and usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less. Increasing the thickness tends to increase the absorption of ultraviolet rays, and decreasing the thickness tends to increase the transmittance of visible light.

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.
[Gas barrier film 3]
The gas barrier film 3 is a film that prevents permeation of water and oxygen.

The solar cell element 6 tends to be vulnerable to moisture and oxygen. In particular, transparent electrodes such as ZnO: Al, compound semiconductor solar cell elements, and organic solar cell elements may be deteriorated by moisture and oxygen. Therefore, 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.
The degree of moisture resistance required for the gas barrier film 3 varies depending on the type of the solar cell element 6 and the like. For example, when the solar cell element 6 is a compound semiconductor solar cell element, the water vapor transmission rate per unit area (1 m ² ) per day is 1 × 10 ⁻¹ g / m ² / day or less. Is preferably 1 × 10 ⁻² g / m ² / day or less, more preferably 1 × 10 ⁻³ g / m ² / day or less, and further preferably 1 × 10 ⁻⁴ g / m ^2. / Day or less is preferable, 1 × 10 ⁻⁵ g / m ² / day or less is particularly preferable, and 1 × 10 ⁻⁶ g / m ² / day or less is particularly preferable. Moreover, when the solar cell element 6 is an organic solar cell element, the water vapor permeability per unit area (1 m ² ) per day is preferably 1 × 10 ⁻¹ g / m ² / day or less. It is more preferably 1 × 10 ⁻² g / m ² / day or less, further preferably 1 × 10 ⁻³ g / m ² / day or less, and further preferably 1 × 10 ⁻⁴ g / m ² / day. Among them, the following is particularly preferable, and 1 × 10 ⁻⁵ g / m ² / day or less is particularly preferable, and 1 × 10 ⁻⁶ g / m ² / day or less is particularly preferable. The more water vapor has to pass through, the lower the degradation caused by the reaction of the solar cell element 6 and the transparent electrode such as ZnO: Al of the element 6 with moisture, thus increasing the power generation efficiency and extending the life.

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. For example, when the solar cell element 6 is a compound semiconductor solar cell element, the oxygen permeability per unit area (1 m ² ) per day is 1 × 10 ⁻¹ cc / m ² / day / atm or less. Preferably, it is 1 × 10 ⁻² cc / m ² / day / atm or less, more preferably 1 × 10 ⁻³ cc / m ² / day / atm or less, and further preferably 1 × 10 2. ⁻⁴ cc / m ² / day / atm or less is particularly preferable, and 1 × 10 ⁻⁵ cc / m ² / day / atm or less is particularly preferable, and 1 × 10 ⁻⁶ cc / m ² / day. / Atm or less is particularly preferable. For example, when the solar cell element 6 is an organic solar cell element, the oxygen permeability per unit area (1 m ² ) per day is 1 × 10 ⁻¹ cc / m ² / day / atm or less. Preferably, it is 1 × 10 ⁻² cc / m ² / day / atm or less, more preferably 1 × 10 ⁻³ cc / m ² / day / atm or less, and further preferably 1 × 10 2. ⁻⁴ cc / m ² / day / atm or less is particularly preferable, and 1 × 10 ⁻⁵ cc / m ² / day / atm or less is particularly preferable, and 1 × 10 ⁻⁶ cc / m ² / day. / Atm or less is particularly preferable. The deterioration due to oxidation of the solar cell element 6 and the transparent electrode such as ZnO: Al of the element 6 is suppressed as the oxygen does not permeate.

  Conventionally, it has been difficult to mount the gas barrier film 3 having such a high moisture-proof and oxygen-blocking capability, so that a solar cell including an excellent solar cell element such as a compound semiconductor solar cell element and an organic solar cell element is realized. Although it was difficult to carry out, implementation of the thin film solar cell 14 which utilized the outstanding properties, such as a compound semiconductor type solar cell element and an organic solar cell element, becomes easy by applying such a gas barrier film 3.

  Further, the gas barrier film 3 is preferably one that transmits visible light from the viewpoint of not preventing the light absorption of the solar cell element 6. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 60% or more, preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, and particularly preferably 85% or more. Preferably it is 90% or more, Especially preferably, it is 95% or more, Especially preferably, it is 97% or more. This is to convert more sunlight into electrical energy.

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, 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 gas barrier film 3 is melted and deteriorated when the thin film solar cell 14 is used.

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.
Hereinafter, the configuration of the gas barrier film 3 will be described with examples.

Two examples of the configuration of the gas barrier film 3 are preferable.
The first example is a film in which an inorganic barrier layer is disposed on a plastic film substrate. In this case, the inorganic barrier layer may be formed only on one side of the plastic film substrate, or may be formed on both sides of the plastic film substrate. When forming on both surfaces, the number of inorganic barrier layers formed on both surfaces may be the same or different.

  The second example is a film in which a unit layer composed of two layers in which an inorganic barrier layer and a polymer layer are arranged adjacent to each other is formed on a plastic film substrate. At this time, a unit layer composed of two layers in which an inorganic barrier layer and a polymer layer are arranged adjacent to each other is regarded as one unit, and this unit layer is composed of one unit (one inorganic barrier layer and one polymer layer are combined into one unit). (Meaning of unit) may be formed, but two or more units may be formed. For example, 2 to 5 units may be laminated.

  The unit layer may be formed only on one side of the plastic film substrate, or may be formed on both sides of the plastic film substrate. When forming on both surfaces, the numbers of inorganic barrier layers and polymer layers formed on both surfaces may be the same or different. In addition, when forming a unit layer on a plastic film substrate, an inorganic barrier layer may be formed and then a polymer layer may be formed thereon, or after forming a polymer layer and forming an inorganic barrier layer. Also good.

(Plastic film substrate)
The plastic film substrate used for the gas barrier film 3 is not particularly limited as long as it is a film capable of holding the above-described inorganic barrier layer and polymer layer, and can be appropriately selected from the purpose of use of the gas barrier film 3 and the like.
Examples of plastic film base materials include polyester resins, polyarylate resins, polyethersulfone resins, fluorene ring-modified polycarbonate resins, alicyclic modified polycarbonate resins, and acryloyl compounds. It is also preferable to use a condensation polymer containing spirobiindane or spirobichroman. Among the polyester resins, biaxially stretched polyethylene terephthalate (PET) and biaxially stretched polyethylene naphthalate (PEN) are preferably used as a plastic film substrate because they are excellent in thermal dimensional stability.

In addition, 1 type may be used for the material of a plastic film base material, and 2 or more types may be used together by arbitrary combinations and a ratio.
The thickness of the plastic film substrate is not particularly defined, but is usually 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less. Increasing the thickness tends to increase mechanical strength, and decreasing the thickness tends to increase flexibility.

  The plastic film substrate is preferably one that 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, preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, and particularly preferably 85% or more. Preferably it is 90% or more, Especially preferably, it is 95% or more, Especially preferably, it is 97% or more. This is to convert more sunlight into electrical energy.

  An anchor coat agent layer (anchor coat layer) may be formed on the plastic film substrate in order to improve adhesion to the inorganic barrier layer. Usually, the anchor coat layer is formed by applying an anchor coat agent. Examples of the anchor coating agent include polyester resins, urethane resins, acrylic resins, oxazoline group-containing resins, carbodiimide group-containing resins, epoxy group-containing resins, isocyanate-containing resins, and copolymers thereof. Among these, a combination of at least one of a polyester resin, a urethane resin, and an acrylic resin and at least one of an oxazoline group-containing resin, a carbodiimide group-containing resin, an epoxy group-containing resin, and an isocyanate group-containing resin is preferable. In addition, an anchor coat agent may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  The thickness of the anchor coat layer is usually 0.005 μm or more, preferably 0.01 μm or more, and usually 5 μm or less, preferably 1 μm or less. If the thickness is less than or equal to the upper limit of this range, the slipperiness is good and there is almost no peeling from the plastic film substrate due to the internal stress of the anchor coat layer itself. Moreover, if it is the thickness more than the lower limit of this range, a uniform thickness can be maintained and it is preferable.

In addition, in order to improve the applicability and adhesion of the anchor coating agent to the plastic film substrate, the plastic film substrate may be subjected to a surface treatment such as normal chemical treatment or electric discharge treatment before application of the anchor coating agent. Good.
(Inorganic barrier layer)
The inorganic barrier layer is usually a layer formed of a metal oxide, nitride or oxynitride. In addition, the metal oxide, nitride, and oxynitride which form an inorganic barrier layer may be 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Examples of the metal oxide include oxides such as Si, Al, Mg, In, Ni, Sn, Zn, Ti, Cu, Ce, and Ta, nitrides, and oxynitrides. Among these, in order to achieve both high barrier properties and high transparency, it is preferable to include aluminum oxide or silicon oxide, and it is particularly preferable to include silicon oxide from the viewpoint of moisture permeability and light transmittance.

The ratio of each metal atom to oxygen atom is also arbitrary, but in order to improve the transparency of the inorganic barrier layer and prevent coloring, the oxygen atom ratio should be extremely small from the stoichiometric ratio of the oxide. Is desirable. On the other hand, in order to improve the denseness of the inorganic barrier layer and increase the barrier property, it is desirable to reduce oxygen atoms. From this viewpoint, for example, when SiO _x is used as the metal oxide, the value of x is particularly preferably 1.5 to 1.8. For example, when AlO _x is used as the metal oxide, the value of x is particularly preferably 1.0 to 1.4.

  Moreover, when an inorganic barrier layer is comprised from 2 or more types of metal oxides, it is desirable to contain aluminum oxide and silicon oxide as a metal oxide. Among them, when the inorganic barrier layer is made of aluminum oxide and silicon oxide, the ratio of aluminum to silicon in the inorganic barrier layer can be arbitrarily set, but the ratio of Si / Al is usually 1/9 or more, preferably 2/8 or more, and usually 9/1 or less, preferably 2/8 or less.

When the thickness of the inorganic barrier layer is increased, the barrier property tends to be increased. However, it is desirable to reduce the thickness in order to prevent cracking and prevent cracking when bent. Therefore, the appropriate thickness of the inorganic barrier layer is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably 200 nm or less.
Although there is no restriction | limiting in the film-forming method of an inorganic barrier layer, Generally, it can carry out by sputtering method, a vacuum evaporation method, an ion plating method, plasma CVD method etc. For example, the sputtering method can be formed by a reactive sputtering method using plasma using one or more metal targets and oxygen gas as raw materials.

(Polymer layer)
Any polymer can be used for the polymer layer, and for example, a film that can be formed in a vacuum chamber can be used. In addition, the polymer which comprises a polymer layer may use 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
A wide variety of compounds can be used as the compound that gives the polymer, and examples include the following (i) to (vii). In addition, 1 type may be used for a monomer and it may use 2 or more types together by arbitrary combinations and a ratio.

  (I) Examples include siloxanes such as hexamethyldisiloxane. An example of a method for forming a polymer layer in the case of using hexamethyldisiloxane is to introduce hexamethyldisiloxane as a vapor into a parallel plate type plasma apparatus using an RF electrode, to cause a polymerization reaction in the plasma, The polymer layer can be formed as a polysiloxane thin film by being deposited on a plastic film substrate.

  (Ii) Examples include paraxylylene such as diparaxylylene. As an example of a method for forming a polymer layer in the case of using diparaxylylene, first, the vapor of diparaxylylene is heated at 650 ° C. to 700 ° C. in a high vacuum to generate thermal radicals. Then, when the radical monomer vapor is introduced into the chamber and adsorbed onto the plastic film substrate, a polymer layer can be formed by simultaneously depositing polyparaxylylene by advancing the radical polymerization reaction.

(Iii) For example, a monomer capable of alternately repeating addition polymerization of two kinds of monomers can be mentioned. The polymer thus obtained is a polyaddition polymer. Examples of the polyaddition polymer include polyurethane (diisocyanate / glycol), polyurea (diisocyanate / diamine), polythiourea (dithioisocyanate / diamine), polythioether urethane (bisethyleneurethane / dithiol), polyimine ( Bisepoxy / primary amine), polypeptide amide (bisazolactone / diamine), polyamide (diolefin / diamide) and the like.

(Iv) For example, an acrylate monomer can be mentioned. The acrylate monomer includes monofunctional, bifunctional, and polyfunctional acrylate monomers, and any of them may be used. However, in order to obtain an appropriate evaporation rate, degree of cure, cure rate, etc., it is preferable to use a combination of two or more of the above acrylate monomers.
Examples of monofunctional acrylate monomers include aliphatic acrylate monomers, alicyclic acrylate monomers, ether acrylate monomers, cyclic ether acrylate monomers, aromatic acrylate monomers, hydroxyl group-containing acrylate monomers, carboxy group-containing acrylate monomers, and the like. There are, but any can be used.

(V) Monomers capable of obtaining a photocationically cured polymer, such as epoxy and oxetane, are exemplified. As the epoxy monomer, for example, an alicyclic epoxy monomer,
A bifunctional monomer, a polyfunctional oligomer, etc. are mentioned. Examples of the oxetane monomer include monofunctional oxetane, bifunctional oxetane, and oxetane having a silsesquioxane structure.

(Vi) An example is vinyl acetate. When vinyl acetate is used as a monomer, polyvinyl alcohol is obtained by saponifying the polymer, and this polyvinyl alcohol can be used as a polymer.
(Vii) For example, acrylic acid, methacrylic acid, ethacrylic acid, fumaric acid, maleic acid,
Examples thereof include unsaturated carboxylic acids such as itaconic acid, monomethyl maleate, monoethyl maleate, maleic anhydride and itaconic anhydride. These constitute a copolymer with ethylene, and the copolymer can be used as a polymer. Furthermore, a mixture thereof, a mixture obtained by mixing glycidyl ether compounds, and a mixture with an epoxy compound can also be used as the polymer.

  There is no restriction | limiting in the polymerization method of a monomer when superposing | polymerizing the said monomer and producing | generating a polymer. However, the polymerization is usually carried out after a composition containing a monomer is applied or deposited to form a film. As an example of the polymerization method, when a thermal polymerization initiator is used, the polymerization is started by contact heating with a heater or the like; radiation heating with infrared rays, microwaves or the like; Moreover, when a photoinitiator is used, an active energy ray is irradiated and polymerization is started. Various light sources can be used when irradiating active energy rays, such as mercury arc lamps, xenon arc lamps, fluorescent lamps, carbon arc lamps, tungsten-halogen radiation lamps, and sunlight irradiation light. Can do. Further, electron beam irradiation or atmospheric pressure plasma treatment can also be performed.

Examples of the method for forming the polymer layer include a coating method and a vacuum film forming method.
When the polymer layer is formed by a coating method, for example, methods such as roll coating, gravure coating, knife coating, dip coating, curtain flow coating, spray coating, and bar coating can be used. Moreover, you may make it apply | coat the coating liquid for polymer layer formation in mist form. In this case, the average particle size of the droplets may be adjusted to an appropriate range. For example, when forming a coating liquid containing a polymerizable monomer in the form of a mist on a plastic film substrate, the droplets The average particle size is 5 μm or less, preferably 1 μm or less.

On the other hand, when forming a polymer layer by a vacuum film-forming method, film-forming methods, such as vapor deposition and plasma CVD, are mentioned, for example.
The thickness of the polymer layer is not particularly limited, but is usually 10 nm or more, and is usually 5000 nm or less, preferably 2000 nm or less, more preferably 1000 nm or less. By increasing the thickness of the polymer layer, the uniformity of the thickness can be easily obtained, and structural defects of the inorganic barrier layer can be efficiently filled with the polymer layer, and the barrier property tends to be improved. In addition, by reducing the thickness of the polymer layer, the barrier property can be improved because the polymer layer itself is less likely to crack due to an external force such as bending.

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, preferably 10 μm or more, more preferably 15 μm or more, and is usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less. Increasing the thickness tends to increase gas barrier properties, and decreasing the thickness tends to increase flexibility and improve visible light transmittance.

  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. Then, the edges of the gas barrier films 3 and 9 are sealed with the sealing material 11, and the solar cell element 6 is placed in the space surrounded by the gas barrier films 3 and 9 and the sealing material 11. It can be protected from oxygen. In addition, when using a highly waterproof sheet such as a sheet in which a fluororesin film is bonded to both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. .

[Getter material film 4]
The getter material film 4 is a film that absorbs moisture and / or oxygen. Some components of the solar cell element 6 are deteriorated by moisture as described above, and some are deteriorated by oxygen. Therefore, 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, when the solar cell element 6 is covered with the gas barrier film 3 or the like, the getter material film 4 absorbs moisture that slightly enters the space formed by the gas barrier films 3 and 9 and the sealing material 11. Can be captured and the influence of moisture on the solar cell element 6 can be eliminated.

The degree of water absorption capacity of the getter material film 4 is usually 0.1 mg / cm ² or more, preferably 0.5 mg / cm ² or more, more preferably 1 mg / cm ² or more. The higher this value, the higher the water absorption capacity, and the deterioration of the solar cell element 6 can be suppressed. Moreover, although there is no restriction | limiting in an 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, 9, etc., because the getter material film 4 absorbs oxygen, it slightly enters the space formed by the gas barrier films 3, 9 and the sealing material 11. Oxygen is captured by the getter material film 4 and the influence of the oxygen on the solar cell element 6 can be eliminated.

  Furthermore, the getter material film 4 is preferably one that 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, preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, and particularly preferably 85% or more. Preferably it is 90% or more, Especially preferably, it is 95% or more, Especially preferably, it is 97% or more. This is to convert more sunlight into electrical energy.

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, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower, more preferably. 30
0 ° C. or lower. By increasing the melting point, it is possible to reduce the possibility that the getter material film 4 melts and deteriorates when the thin-film solar cell 14 is used.

  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, alkaline earth metal oxide, alkali metal or alkaline earth metal hydroxide, silica gel, zeolite compound, magnesium sulfate as a substance that absorbs moisture. 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, an aluminum metal complex, etc. are also mentioned. Specific product names include, for example, OleDry (manufactured by 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, preferably 10 μm or more, more preferably 15 μm or more, and usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less. Increasing the thickness tends to increase mechanical strength, and decreasing the thickness tends to increase flexibility.
The getter material film 4 is not limited in its formation position as long as it is in the space formed by the gas barrier films 3 and 9 and the sealing material 11, but the front surface of the solar cell element 6 (the surface on the light receiving surface side; lower in FIG. 2). Side surface) and the back surface (surface opposite to the light receiving surface; upper surface in FIG. 2) are preferably covered. 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 such as a sheet in which a fluororesin film is bonded to both surfaces of an aluminum foil as the back sheet 10 described later, the getter material film 8 and / or the gas barrier film 9 may not be used depending on the application. .

  The getter material film 4 can be formed by any method depending on the type of the water-absorbing agent or desiccant. For example, a method in which a film in which the water-absorbing agent or desiccant is dispersed is attached with a pressure-sensitive adhesive, A method of applying the solution by a spin coating method, an inkjet method, a dispenser method, or the like can be used. A film forming method such as a vacuum evaporation method or a sputtering method may be used.

  As a film for a water absorbing agent or a desiccant, for example, polyethylene resin, polypropylene resin, cyclic polyolefin resin, polystyrene resin, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl chloride resin, fluorine resin, poly (meth) acrylic resin, polycarbonate resin, and the like can be used. Among these, films of polyethylene resin, fluorine resin, cyclic polyolefin resin, and polycarbonate resin are preferable. In addition, the said resin may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

[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.
In addition, the sealing material 5 is preferably one that 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, preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, and particularly preferably 85% or more, especially Preferably it is 90% or more, Especially preferably, it is 95% or more, Especially preferably, it is 97% or more. This is to convert more sunlight into electrical energy.

  Furthermore, 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, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower, more preferably. Is 300 ° C. or lower. By increasing the melting point, it is possible to reduce the possibility that the sealing material 5 melts and deteriorates when the thin film solar cell 14 is used.

  The thickness of the sealing material 5 is not particularly defined, but is usually 100 μm or more, preferably 150 μm or more, more preferably 200 μm or more, and usually 700 μm or less, preferably 600 μm or less, more preferably 500 μm or less. Increasing the thickness tends to increase the strength of the thin-film solar cell 14 as a whole, and decreasing the thickness tends to increase flexibility and improve visible light transmittance.

  As a material which comprises the sealing material 5, what used the ethylene-vinyl acetate copolymer (EVA) resin composition for the film (EVA film) etc. can be used, for example. In order to improve weather resistance, the EVA film is usually blended with a crosslinking agent to form a crosslinked structure. As the crosslinking agent, an organic peroxide that generates radicals at 100 ° C. or higher is generally used. Examples of such an organic peroxide include 2,5-dimethylhexane; 2,5-dihydroperoxide; 2,5-dimethyl-2,5-di (t-butylperoxy) hexane; Di-t-butyl peroxide or the like can be used. The compounding amount of these organic peroxides is usually 5 parts by weight or less, preferably 3 parts by weight or less, and usually 1 part by weight or more with respect to 100 parts by weight of the EVA resin. In addition, 1 type may be used for a crosslinking agent and it may use 2 or more types together by arbitrary combinations and a ratio.

This EVA resin composition may contain a silane coupling agent for the purpose of improving the adhesive strength. Examples of silane coupling agents provided for this purpose include γ-chloropropyltrimethoxysilane; vinyltrichlorosilane; vinyltriethoxysilane; vinyl-tris- (β-methoxyethoxy) silane; γ-methacryloxypropyltri Methoxysilane; β- (3,4-ethoxycyclohexyl) ethyltrimethoxysilane and the like can be mentioned. The compounding amount of these silane coupling agents is usually 5 parts by weight or less, preferably 2 parts by weight or less, and usually 0.1 parts by weight or more with respect to 100 parts by weight of EVA resin. In addition, 1 type may be used for a silane coupling agent and it may use 2 or more types together by arbitrary combinations and a ratio.

  Furthermore, in order to improve the gel fraction of the EVA resin and improve the durability, a crosslinking aid may be included in the EVA resin composition. Examples of the crosslinking aid provided for this purpose include monofunctional crosslinking aids such as trifunctional crosslinking aids such as triallyl isocyanurate and triallyl isocyanate. The amount of these crosslinking aids is usually 10 parts by weight or less, preferably 5 parts by weight or less, and usually 1 part by weight or more with respect to 100 parts by weight of the EVA resin. In addition, 1 type may be used for a crosslinking adjuvant, and 2 or more types may be used together by arbitrary combinations and a ratio.

Furthermore, for the purpose of improving the stability of the EVA resin, the EVA resin composition may contain, for example, hydroquinone; hydroquinone monomethyl ether; p-benzoquinone; methyl hydroquinone. These compounding quantities are normally 5 weight part or less with respect to 100 weight part of EVA resin.
However, since the EVA resin cross-linking process requires a relatively long time of about 1 to 2 hours, it may cause a reduction in the production rate and production efficiency of the thin-film solar cell 14. Further, when used for a long period of time, the decomposition gas (acetic acid gas) of the EVA resin composition or the vinyl acetate group of the EVA resin itself may adversely affect the solar cell element 6 and reduce the power generation efficiency. Therefore, as the sealing material 5, in addition to the EVA film, a copolymer film made of a propylene / ethylene / α-olefin copolymer can also be used. As this copolymer, the thermoplastic resin composition with which the following component 1 and the component 2 were mix | blended is mentioned, for example.

Component 1: The propylene-based polymer is usually 0 part by weight or more, preferably 10 parts by weight or more, and usually 70 parts by weight or less, preferably 50 parts by weight or less.
-Component 2: A soft propylene-type copolymer is 30 weight part or more, Preferably it is 50 weight part or more, and is 100 weight part or less normally, Preferably it is 90 weight part or less.
The total amount of component 1 and component 2 is 100 parts by weight. As described above, when component 1 and component 2 are in a preferred range, the moldability of the encapsulant 5 into a sheet is good, and the resulting encapsulant 5 has good heat resistance, transparency, and flexibility. Therefore, it is suitable for the thin film solar cell 14.

The thermoplastic resin composition in which the above component 1 and component 2 are blended has a melt flow rate (ASTM D 1238, 230 degrees, load 2.16 kg) of usually 0.0001 g / 10 min or more. It is 1000 g / 10 min or less, preferably 900 g / 10 min or less, more preferably 800 g / 10 min or less.
The melting point of the thermoplastic resin composition containing component 1 and component 2 is usually 100 ° C. or higher, preferably 110 ° C. or higher. Moreover, it is 140 degrees C or less normally, Preferably it is 135 degrees C or less.

Density of The thermoplastic resin composition Components 1 and 2 were compounded is preferably from 0.98 g / cm ³ or less, more preferably 0.95 g / cm ³ or less, more preferably 0.94 g / cm ³ or less .
In this sealing material 5, it is possible to mix | blend a coupling agent with the said component 1 and component 2 as an adhesion promoter with respect to a plastics. As the coupling agent, silane, titanate, and chromium coupling agents are preferably used, and a silane coupling agent (silane coupling agent) is particularly preferably used.

Known silane coupling agents can be used and are not particularly limited. For example, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (β-methoxy-ethoxysilane), γ-glycidoxypropyl-tri Examples include piltrimethoxysilane and γ-aminopropyltriethoxysilane. In addition, 1 type may be used for a coupling agent and it may use 2 or more types together by arbitrary combinations and a ratio.

These are usually 0.1 parts by weight or more, usually 5 parts by weight or less, preferably 100 parts by weight of the silane coupling agent, based on 100 parts by weight of the thermoplastic resin composition (total amount of Component 1 and Component 2). It is desirable to contain 3 parts by weight or less.
The coupling agent may be grafted to the thermoplastic resin composition using an organic peroxide. In this case, it is desirable that 0.1 to 5 parts by weight of the coupling agent is included with respect to 100 parts by weight of the thermoplastic resin composition (total amount of component 1 and component 2). Even if a silane-grafted thermoplastic resin composition is used, the same or better adhesiveness as that of the silane coupling agent blend can be obtained for glass and plastic.

When the organic peroxide is used, the organic peroxide is usually 0.001 part by weight or more, preferably 0.01 part by weight with respect to 100 parts by weight of the thermoplastic resin composition (total amount of Component 1 and Component 2). Part or more, and usually 5 parts by weight or less, preferably 3 parts by weight or less.
Further, a copolymer made of an ethylene / α-olefin copolymer can be used as the sealing material 5. Examples of the copolymer include a laminate film having a hot tack property of 5 to 25 ° C., which is formed by laminating a resin composition for a sealing material comprising the following components A and B and a substrate.

Component A: ethylene resin.
Component B: a copolymer of ethylene and an α-olefin having the following properties (a) to (d).
(A) Density is 0.86-0.935 g / cm ³ .
(B) Melt flow rate (MFR) is 1 to 50 g / 10 min.

(C) There is one peak in the elution curve obtained by temperature rising elution fractionation (TREF); the peak temperature is 100 ° C. or lower.
(D) The integrated elution amount by temperature rising elution fractionation (TREF) is 90% or more at 90 ° C.
The blending ratio (component A / component B) of component A and component B is usually 50/50 or more, preferably 55/45 or more, more preferably 60/40 or more, and usually 99 / 1 or less, preferably 90/10 or less, more preferably 85/15 or less. Increasing the amount of component B tends to increase transparency and heat sealability, and decreasing the amount of component B tends to increase the workability of the film.

  The melt flow rate (MFR) of the resin composition for a sealing material produced by blending component A and component B is usually 2 g / 10 minutes or more, preferably 3 g / 10 minutes or more, and usually 50 g / 10 minutes. Hereinafter, it is preferably 40 g / 10 min or less. In addition, the measurement and evaluation of MFR can be implemented by the method based on JISK7210 (190 degreeC, 2.16kg load).

The melting point of the encapsulant resin composition is preferably 50 ° C. or higher, more preferably 55 ° C. or higher, and is usually 300 ° C. or lower, preferably 250 ° C. or lower, more preferably 200 ° C. or lower. By increasing the melting point, the possibility of melting and deterioration during use of the thin-film solar cell 14 can be reduced.
The density of the resin composition for a sealing material is preferably 0.80 g / cm ³ or more, more preferably 0.85 g / cm ³ or more, and preferably 0.98 g / cm ³ or less, 0.95 g / cm ^3. The following is more preferable, and 0.94 g / cm ³ or less is more preferable. The measurement and evaluation of density can be performed by a method based on JIS K7112.

Further, in the encapsulant 5 using the ethylene / α-olefin copolymer, a coupling agent can be used as in the case of using the propylene / ethylene / α-olefin copolymer.
Since the sealing material 5 described above does not generate a decomposition gas derived from the material, the solar cell element 6 is not adversely affected, and has good heat resistance, mechanical strength, flexibility (solar cell sealing property), and transparency. Have sex. Further, since no material cross-linking step is required, the manufacturing time of the thin film solar cell 100 during sheet molding can be greatly reduced, and the thin film solar cell 14 after use can be easily recycled.

In addition, the sealing material 5 may be formed with 1 type of material, and may be formed with 2 or more types of materials. Moreover, although the sealing material 5 may be formed with the single layer film, the laminated | multilayer film provided with the film of 2 or more layers may be sufficient as it.
The thickness of the sealing material 5 is usually 2 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and usually 500 μm or less, preferably 300 μm or less, more preferably 100 μm or less. Increasing the thickness tends to increase mechanical strength, and decreasing the thickness tends to increase flexibility and light transmittance.

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.
[Solar cell element 6]
The solar cell element 6 is the same as the photoelectric conversion element of the other day.

・ Connection between solar cell elements
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.

[Encapsulant 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.
Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used.

[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.
Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used. It is also possible to use a film containing more water or oxygen absorbent than the getter material film 4. Examples of such absorbents include CaO, BaO, Zr-Al-BaO as moisture absorbents, and activated carbon, molecular sieves, etc. as oxygen absorbents.

[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.
Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used.

[Backsheet 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.

Moreover, since the constituent member on the back side of the solar cell element 6 does not necessarily need to transmit visible light, a member that does not transmit visible light can be used. For this reason, it is particularly preferable to use the following (i) to (iv) as the backsheet 10.
(I) As the back sheet 10, various resin films or sheets excellent in strength and excellent in weather resistance, heat resistance, water resistance, and light resistance can be used. For example, polyethylene resin, polypropylene resin, cyclic polyolefin resin, polystyrene resin, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl chloride resin, fluorine Resins, poly (meth) acrylic resins, polycarbonate resins, polyester resins such as polyethylene terephthalate or polyethylene naphthalate, polyamide resins such as various nylons, polyimide resins, polyamideimide resins, polyarylphthalate resins Sheet of various resins such as silicone resin, polysulfone resin, polyphenylene sulfide resin, polyethersulfone resin, polyurethane resin, acetal resin, cellulose resin, etc. It is possible to use. Among these resin sheets, it is preferable to use a fluorine resin, a cyclic polyolefin resin, a polycarbonate resin, a poly (meth) acrylic resin, a polyamide resin, or a polyester resin sheet. In addition, these may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

(Ii) As the back sheet 10, a metal thin film can also be used. For example, corrosion-resistant aluminum metal foil, stainless steel thin film, and the like can be mentioned. In addition, the said metal may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
(Iii) As the back sheet 10, for example, a highly waterproof sheet in which a fluorine resin film is bonded to both surfaces of an aluminum foil may be used. Examples of the fluorine resin include ethylene monofluoride (trade name: Tedlar, manufactured by DuPont), polytetrafluoroethylene (PTFE), a copolymer of tetrafluoroethylene and ethylene or propylene (ETFE), and vinylidene fluoride resin. (PVDF), vinyl fluoride resin (PVF) and the like. In addition, 1 type may be used for fluororesin and it may use 2 or more types together by arbitrary combinations and a ratio.

(Iv) As the back sheet 10, for example, an inorganic oxide vapor-deposited film is provided on one side or both sides of the base film, and further, on both sides of the base film provided with the inorganic oxide vapor-deposited film, You may use what laminated | stacked the heat resistant polypropylene resin film. Usually, when a polypropylene resin film is laminated on the base film, the lamination is performed by laminating with a laminating adhesive. By providing an inorganic oxide vapor-deposited film, it can be used as a back sheet 10 having excellent moisture resistance that prevents intrusion of moisture, oxygen and the like.

・ Base film
Basically, as the base film, various resin films having excellent close adhesion with an inorganic oxide vapor deposition film, etc., excellent strength, weather resistance, heat resistance, water resistance, and light resistance are used. Can be used. For example, polyethylene resin, polypropylene resin, cyclic polyolefin resin, polystyrene resin, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl chloride resin, fluorine Resins, poly (meth) acrylic resins, polycarbonate resins, polyester resins such as polyethylene terephthalate or polyethylene naphthalate, polyamide resins such as various nylons, polyimide resins, polyamideimide resins, polyaryl phthalate resins Silicone resin, polysulfone resin, polyphenylene sulfide resin, polyethersulfone resin, polyurethane resin, acetal resin, cellulosic resin, etc. It is possible to use. Among these, it is preferable to use a film of a fluorine resin, a cyclic polyolefin resin, a polycarbonate resin, a poly (meth) acrylic resin, a polyamide resin, or a polyester resin.

  Among the various resin films described above, for example, a film of a fluorine resin such as polytetrafluoroethylene (PTFE), vinylidene fluoride resin (PVDF), or vinyl fluoride resin (PVF) is used. More preferably it is used. Further, among the fluororesin films, in particular, a fluororesin film (PVF); a fluororesin film made of a copolymer of tetrafluoroethylene and ethylene or propylene (ETFE) is particularly preferable from the viewpoint of strength and the like. preferable. In addition, the said resin may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

Of the various resin films as described above, it is more preferable to use a film of a cyclic polyolefin resin such as cyclopentadiene and a derivative thereof, cyclohexadiene and a derivative thereof.
The film thickness of the base film is usually 12 μm or more, preferably 20 μm or more, and is usually 300 μm or less, preferably 200 μm or less.

・ Deposited film of inorganic oxide
As the inorganic oxide vapor-deposited film, basically any thin film on which a metal oxide is vapor-deposited can be used. For example, a deposited film of an oxide of silicon (Si) or aluminum (Al) can be used. At this time, for example, SiO _x (x = 1.0 to 2.0) can be used as silicon oxide, and for example, AlO _x (x = 0.5 to 1.5) can be used as aluminum oxide. .

In addition, the kind of metal and inorganic oxide to be used may be 1 type, and may use 2 or more types together by arbitrary combinations and ratios.
The film thickness of the inorganic oxide vapor deposition film is usually 50 mm or more, preferably 100 mm or more, and is usually 4000 mm or less, preferably 1000 mm or less.
As a method for forming the deposited film, a chemical vapor deposition method (chemical vapor deposition method, CVD method) such as a plasma chemical vapor deposition method, a thermal chemical vapor deposition method, or a photochemical vapor deposition method can be used. As a specific example, on one surface of the base film, a monomer gas for vapor deposition such as an organosilicon compound is used as a raw material, an inert gas such as argon gas or helium gas is used as a carrier gas, and oxygen is supplied. An oxygen oxide vapor or the like can be used as a gas, and a vapor deposition film of an inorganic oxide such as silicon oxide can be formed using a low temperature plasma chemical vapor deposition method using a low temperature plasma generator or the like.

-Polypropylene resin film As a polypropylene resin, the homopolymer of propylene; the copolymer of a propylene and another monomer (for example, alpha olefin etc.) can be used, for example. Moreover, an isotactic polymer can also be used as a polypropylene resin.
The melting point of the polypropylene resin is usually 164 ° C. to 170 ° C., the specific gravity is usually 0.90 to 0.91, and the molecular weight is usually 100,000 to 200,000.

Polypropylene resins are largely controlled by their crystallinity, but high isotactic polymers have excellent tensile strength and impact strength, good heat resistance and bending fatigue strength, and workability. Is very good.
·adhesive
When a polypropylene resin film is laminated on the base film, a laminating adhesive is usually used. Thereby, a base film and a polypropylene resin film are laminated | stacked via the adhesive bond layer for lamination.

  Examples of the adhesive constituting the adhesive layer for laminating include, for example, a polyvinyl acetate adhesive, a polyacrylate adhesive, a cyanoacrylate adhesive, an ethylene copolymer adhesive, a cellulose adhesive, and a polyester adhesive. Adhesives, polyamide adhesives, polyimide adhesives, amino resin adhesives, phenol resin adhesives, epoxy adhesives, polyurethane adhesives, reactive (meth) acrylic adhesives, silicone adhesives, etc. Is mentioned. In addition, 1 type may be used for an adhesive agent and it may use 2 or more types together by arbitrary combinations and a ratio.

The composition system of the adhesive may be any composition form such as an aqueous type, a solution type, an emulsion type, and a dispersion type. Further, the property may be any of film / sheet, powder, solid and the like. Furthermore, the bonding mechanism may be any form such as a chemical reaction type, a solvent volatilization type, a heat melting type, and a hot pressure type.
The adhesive can be applied by a coating method such as a roll coating method, a gravure roll coating method, a kiss coating method, or the like, or a printing method. As the amount of ^{coating, 0.1g / m 2 ~10g / m} 2 is desirable in the dry state.

[Sealant 11]
The sealing material 11 includes the weatherproof protective film 1, the ultraviolet cut film 2, the gas barrier film 3, the getter material film 4, the sealing material 5, the sealing material 7, the getter material film 8, the gas barrier film 9, and the back sheet 10. It is a member that seals the edge so that moisture and oxygen do not enter the space covered with these films.

The degree of moisture capacity required for the sealing member 11 is preferably water vapor transmission rate per day unit area (1 m ²⁾ is not more than ^{0.1g / m 2 / day, 0.05g} / m 2 / More preferably, it is not more than day. Conventionally, since it has been difficult to mount the sealing material 11 having such a high moisture-proof capability, it is possible to realize a solar cell including an excellent solar cell element such as a compound semiconductor solar cell element and an organic solar cell element. Although it was difficult, the implementation of the thin-film solar cell 14 utilizing the excellent properties of the compound semiconductor solar cell element and the organic solar cell element is facilitated by applying such a sealing material 11.

  Furthermore, since the thin film solar cell 14 is often heated by receiving light, it is preferable that the sealing material 11 also has heat resistance. From this viewpoint, the melting point of the constituent material of the sealing material 11 is usually 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 250 ° C. or lower, preferably 200 ° C. or lower, more preferably 180 ° C. or lower. If the melting point is too low, the sealing material 11 may melt when the thin film solar cell 14 is used.

Examples of the material constituting the sealing material 11 include polymers such as a fluorine resin, a silicone resin, and an acrylic resin.
In addition, the sealing material 11 may be formed with 1 type of material, and may be formed with 2 or more types of materials.
The sealing material 11 is provided at a position where at least the edges of the gas barrier films 3 and 9 can be sealed. Thereby, the space surrounded by at least the gas barrier films 3 and 9 and the sealing material 11 can be sealed, and moisture and oxygen can be prevented from entering the space.

Although there is no restriction | limiting in the method of forming this sealing material 11, For example, it can form by inject | pouring material between the weather-resistant protective film 1 and the back sheet | seat 10. FIG. Specific examples of the forming method include the following methods.
That is, for example, while the curing of the sealing material 5 proceeds, the semi-cured thin-film solar cell 14 is taken out from the laminating apparatus, and is the outer peripheral portion of the solar cell element 6, which is the weatherproof protective sheet 1 and the back sheet 10. A liquid polymer may be injected into a portion between the two and the polymer may be cured together with the sealing material 5. Further, after the sealing material 5 has been cured, it may be taken out from the laminating apparatus and cured alone. The temperature range for crosslinking and curing the polymer is usually 130 ° C. or higher, preferably 140 ° C. or higher, and is usually 180 ° C. or lower, preferably 170 ° C. or lower.

[Dimensions]
The thin film solar cell 14 of the present embodiment is usually a thin film member. By forming the thin film solar cell 14 as a film-like member in this way, the thin film solar cell 14 can be easily installed in building materials, automobiles, interiors, and 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 the cost can be greatly reduced.

Although there is no restriction | limiting in the specific dimension of the thin film solar cell 14, The thickness is 300 micrometers or more normally, Preferably it is 500 micrometers or more, More preferably, it is 700 micrometers or more, Moreover, it is 3000 micrometers or less normally, Preferably it is 2000 micrometers or less, More preferably. It is 1500 micrometers or less.
[Production method]
Although there is no restriction | limiting in the manufacturing method of the thin film solar cell 14 of this embodiment, For example, between the weather-resistant protective film 1 and the back sheet | seat 10, the 1 or 2 or more solar cell element 6 was connected in series or in parallel. The product can be manufactured by laminating with a general vacuum laminating apparatus together with the ultraviolet cut film 2, the gas barrier films 3, 9, the getter material films 4, 8, and the sealing materials 5, 7. At this time, the heating temperature 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 is usually 10 minutes or longer, preferably 20 minutes or longer, usually 100 minutes or shorter, preferably 90 minutes or shorter. The pressure 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 sealing materials 5 and 7 from the end can be prevented from protruding and film thickness reduction due to overpressure can be suppressed, and dimensional stability can be ensured.

[Usage]
There is no restriction | limiting in the use of the thin film solar cell 14 mentioned above, It is arbitrary. For example, as schematically shown in FIG. 3, a solar cell unit 13 in which a thin film solar cell 14 is provided on some base material 12 may be prepared and used by being installed at a place of use. As a specific example, when a building material plate is used as the base material 12, a thin-film solar cell 14 is provided on the surface of the plate material to produce a solar cell panel as the solar cell unit 13, and this solar cell panel is attached to the outer wall of the building. It can be installed and used.

  The substrate 12 is a support member that supports the solar cell element 6. 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. Organic materials such as resin films, vinyl chloride, polyethylene, cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene; paper materials such as paper and synthetic paper; metals such as stainless steel, titanium, and aluminum In addition, a composite material such as a material whose surface is coated or laminated in order to impart insulating properties may be used. 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.

Examples of fields to which the thin film solar cell of the present invention is applied include solar cells for building materials, solar cells for automobiles, solar cells for interiors, solar cells for railways, solar cells for ships, solar cells for airplanes, solar cells for spacecraft. It is suitable for use in batteries, solar cells for home appliances, solar cells for mobile phones, solar cells for toys, and the like. Specific examples include the following.
1. Architectural use
1.1 Solar cell as house roofing material
When a roof plate or the like is used as the base material, a thin film solar cell is provided on the surface of the plate material to produce a solar cell panel as a solar cell unit, and this solar cell panel is installed on the roof of the house. That's fine. Moreover, a roof tile can also be used directly as a base material. The solar cell of the present invention is suitable because it can be brought into close contact with the roof tiles by taking advantage of its flexibility.

1.2 Rooftop
It can also be installed on the roof of a building. A solar cell unit in which a thin film solar cell is provided on a base material can be prepared and installed on the roof of a building. At this time, it is desirable to use a waterproof sheet together with the base material to have a waterproof action. Furthermore, taking advantage of the property that the thin film solar cell of the present invention has flexibility, it can be brought into close contact with a non-planar roof, for example, a folded half roof. In this case, it is desirable to use a waterproof sheet in combination.

1.3 Top light
The thin-film solar cell of the present invention can also be used as an exterior at the entrance or a blow-off portion. Curves are often used for entrances and the like that have undergone some design processing, and in such a case, the flexibility of the thin film solar cell of the present invention is utilized. In addition, there is a case of see-through in an entrance or the like. In such a case, the green color of the organic solar cell is suitable because a design aesthetic can be obtained in an era when environmental measures are regarded as important.

1.4 Wall
When a building material plate is used as the base material, a thin film solar cell is provided on the surface of the plate material to produce a solar cell panel as a solar cell unit, and this solar cell panel may be installed on the outer wall of a building and used. . It can also be installed on curtain walls. In addition, it can be attached to a spandrel or a vertical.

In this case, the shape of the substrate is not limited, but a plate material is usually used. Moreover, what is necessary is just to set the material of a base material, a dimension, etc. arbitrarily according to the use environment. As an example of such a substrate, Alpolic (registered trademark; manufactured by Mitsubishi Plastics) and the like can be mentioned.
1.5 windows
It can also be used for see-through windows. The green color of the organic solar cell is preferable because a design aesthetic can be obtained in an era when environmental measures are important.

1.6 Other
It can also be used for eaves, louvers, handrails, etc. Even in such a case, the flexibility of the thin film solar cell of the present invention is suitable for these applications.
2. Interior
The thin film solar cell of the present invention can also be attached to a blind slat. Since the thin-film solar cell of the present invention is lightweight and rich in flexibility, such a use is possible. Further, the contents window can be used by utilizing the characteristic that the organic solar cell element is see-through.

3. Vegetable factory
Although the number of plant factories that use illumination light such as fluorescent lamps has increased, the current situation is that it is difficult to reduce cultivation costs due to the cost of electricity for lighting and replacement costs for light sources. Then, the thin film solar cell of this invention can be installed in a vegetable factory, and the illumination system combined with LED or the fluorescent lamp can be produced.

At this time, it is preferable to use an illumination system that combines an LED having a longer life than a fluorescent lamp and the solar cell of the present invention, because the cost required for illumination can be reduced by about 30% compared to the current situation.
Moreover, the solar cell of this invention can also be used for the roof and side wall of the reefer container (reefer container) which conveys vegetables etc. at fixed temperature.

4). Road materials and civil engineering
The thin film solar cell of the present invention can be used for an outer wall of a parking lot, a sound insulation wall of an expressway, an outer wall of a water purification plant, and the like.
5). Car
The thin film solar cell of the present invention can be used on the surfaces of automobile bonnets, roofs, trunk lids, doors, front fenders, rear fenders, pillars, bumpers, rearview mirrors and the like. The obtained electric power can be supplied to any of a traveling motor, a motor driving battery, an electrical component, and an electrical component battery. By providing the power generation status in the solar cell panel and the control means for selecting according to the power usage status in the motor for driving, the battery for driving the motor, the electrical equipment, and the battery for electrical equipment, the obtained power is Can be used properly and efficiently
In the above case, the shape of the substrate 12 is not limited, but a plate material is usually 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.

  Examples of such a substrate 12 include Alpolic (registered trademark; manufactured by Mitsubishi Plastics).

Examples The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
In the following, details of various analytical measurement methods are as follows.
<Glass transition temperature>
Put the sample in a sample container made of about 4 mg aluminum, and measure it under the conditions of N ₂ gas 50 ml / min and temperature rising rate 10 ° C./min using a differential thermal scanning calorimeter manufactured by SII Nano Technology Co., Ltd. Determined by

<Ionization potential>
Prepare a chloroform solution of the sample and apply it to the ITO substrate by spin coating (1000 rpm, 60 s) or vacuum deposit on the ITO substrate to form a 20-60 nm thin film, and measure an OPTEL PYS (PYS = photoelectron yield spectroscopy) measuring instrument. It was measured by.

<Synthesis Example 1> Synthesis of PSPy ₂

  Under a N2 atmosphere, a THF solution of 1-bromopyrene (1.4 g, 5 mmol) was cooled to -78 degrees, and then a hexane solution of n-butyllithium (3 mL, 1.6 M) was added dropwise. After stirring for 30 minutes, dichlorophenylphosphine (440 mg, 2.5 mmol) was slowly added dropwise, and the mixture was warmed to room temperature and stirred for 2 hours. The obtained precipitate was filtered, washed with hexane, dissolved in dichloromethane, insolubles were removed by filtration, and concentrated. By recrystallizing the obtained crude product with toluene, Compound 1 could be obtained in a yield of 50%. The resulting product was identified by mass spectrometry.

To a THF solution of compound 1 (1.53 g, 3 mmol), S ₈ (480 mg, 15 mmol) was added and heated to reflux. By subjecting the obtained product to column purification, the target product, PSPy ₂ : di (1-pyrenyl) phenylphosphine sulfide, was obtained. The resulting product was identified by NMR and mass spectrometry.
<Synthesis Example 2> Synthesis of POPy ₂

To a THF solution (70 mL) of compound 1 (1.48 g, 2.9 mmol) obtained in Synthesis Example 1, 30% aqueous hydrogen peroxide (manufactured by Wako Pure Chemical: 3 mL) is slowly added dropwise and stirred at room temperature for 30 minutes. did. After adding water to the reaction solution, THF was removed under reduced pressure, and the resulting crude product was washed with methanol. Further, POPy ₂ (1.28 g, 2.4 mmol) was obtained by sublimation purification of the crude product.

<Synthesis Example 3> C ₆₀ (QM) ₂ Synthesis

Under a nitrogen atmosphere, in a 500 mL three-necked eggplant flask, fullerene C60 (500 mg, 0
. 694 mmol), tetra n-butylammonium iodide (TBAI; 1.28 g, 3.47 mmol, 5 equivalents), and toluene (230 mL). After degassing under reduced pressure, α, α'-
Dibromo-o-xylene (916 mg, 3.47 mmol, 5 equivalents) was added and heated to reflux. After 10 hours, the temperature was returned to room temperature, applied to a silica gel filtration column (toluene), and concentrated. After subjecting to silica gel column chromatography (carbon disulfide: hexane = 1: 2), GPC purification (chloroform) was performed to obtain the desired product in a yield of 47% (304 mg, 0.328 mmol). By mass spectrometry (APCI method, negative), m / z: 928 [M ⁻ ] corresponding to the mass of the target product was detected.

  <Synthesis Example 4> Synthesis of SIMEF

The synthesis of SIMEF was performed by the method described in International Publication WO 2009/008323 Pamphlet.
<Synthesis Example 5> Synthesis of SIMEF2

The synthesis of SIMEF2 was performed as follows.
[Intermediate 1] Chloromethyl (2-methoxyphenyl) dimethylsilane, (o-An) Me ₂ SiCH ₂ Cl

In a 500-mL three-necked eggplant flask, a 1.0 M THF solution (100 mL, 0.1 mol) of 2-methoxyphenylmagnesium bromide was placed under a nitrogen atmosphere and stirred at room temperature. Chloromethyldimethylchlorosilane (11.25 mL, 0.085 mol) was slowly added dropwise thereto. After stirring at room temperature for 1 hour, the mixture was stirred at 40 ° C. for 3 hours. It returned to room temperature and water was added slowly. The mixture was extracted with ethyl acetate, washed with brine, dried over sodium sulfate, filtered, and concentrated under reduced pressure. The obtained liquid was distilled under reduced pressure to give the target product (chloromethyl (2-methoxyphenyl) dimethylsilane, (o-An) Me ₂ SiCH ₂ Cl) as a colorless liquid in a yield of 52% (11.2 g, 0 0522 mol).

[Intermediate 2] 1- (Dimethylphenylsilylmethyl) -1,9-dihydro (C ₆₀ -I _h ) [5,6] fullerene, C ₆₀ (CH ₂ SiMe ₂ Ph) H

Under a nitrogen atmosphere, N, N-dimethylformamide (6.45 mL, 83.3 mmol),
Fullerene C ₆₀ (2.00 g, 2.78 mmol) and 1,2-dichlorobenzene solution (500 mL) were mixed, degassed, and then re-pressured with nitrogen. To this was added a THF solution of Grignard reagent (PhMe ₂ SiCH ₂ MgCl, 9.80 mL, 0.850 M, 8.33 mmol) prepared from (chloromethyl) dimethylphenylsilane at 25 ° C. After stirring for 10 minutes, deaerated saturated ammonium chloride aqueous solution (1.0 mL) was added and stirred. The obtained solution was concentrated, dissolved in toluene (200 mL), passed through a silica gel filtration column, and concentrated. Methanol (about 100 to 200 mL) was added and reprecipitated to obtain a brown solid. The obtained solid was subjected to HPLC (Buckyprep column,
eluent: toluene / 2-propanol = 7/3) 1- (dimethylphenylsilylmethyl) -1,9-dihydro (C ₆₀ -I _h ) which is the target product by fractionation
[5,6] Fullerene (C ₆₀ (CH ₂ SiMe ₂ Ph) H, 1.99 g, 2.28 mmol
, 82% isolated yield, analytically pure).

[Synthesis of SIMEF2 (C ₆₀ (CH ₂ SiMe ₂ Ph) [CH ₂ SiMe ₂ (o-An))])]

1- (Dimethylphenylsilylmethyl) -1,9-dihydro (C ₆₀ -I _h ) [5,6] fullerene (C ₆₀ (CH ₂ SiMe ₂ Ph) obtained in the production of intermediate 2 under a nitrogen atmosphere H, 1.
02 g, 1.17 mmol) of benzonitrile solution, and then tert-butoxypotassium
(1.41 mL, 1.0 M, 1.41 mmol) in THF was added at 25 ° C. 10
After stirring for a minute, chloromethyl (2-methoxyphenyl) dimethylsilane ((o-An) Me ₂ SiCH ₂ Cl, 5.03 g, 23.4 mmol) obtained in the preparation of Intermediate 1 and potassium iodide were combined. The mixture was further stirred at 110 ° C. for 17 hours. To the obtained solution, 1.0 mL of a saturated aqueous ammonium chloride solution was added and concentrated. Toluene (100 mL) was added to the obtained crude product, filtered and concentrated,
Methanol (ca. 50 to 100 mL) was added to perform reprecipitation. The obtained crude product was subjected to silica gel column chromatography (eluent: CS ₂ / hexane = 1/1) purification, followed by HPLC fractionation (Buckyprep column, eluents: toluene / 2-propanol = 7/3) purification. By performing, the target product (SIMEF2) (0.810 g, 0.772 mmol, 66% isolated yield) was obtained.

<Example A1>
The glass transition temperature and ionization potential of PSPy ₂ obtained in Synthesis Example 1 were measured. The results are shown in Table 1.
<Comparative Example A1>
Table 1 shows the results of measuring the glass transition temperature and ionization potential of BCP manufactured by Tokyo Chemical Industry Co., Ltd.

<Comparative Example A2>
The glass transition temperature and ionization potential of POPy2 obtained in Synthesis Example 2 were measured. The results are shown in Table 1.

According to this example, the glass transition temperature was kept high and the ionization potential was also increased by 0.3 eV deeper than that of the phosphine compound.
<Example B1>
Regioregular poly-3-hexylthiophene (P3HT, manufactured by Aldrich) having an electron-donating molecular structure and 1- (3-methoxycarbonyl) propyl-1-phenyl (6,6) -C having an electron-accepting molecular structure ₆₀ ) (PCBM, manufactured by Frontier Carbon Co., Ltd.) was dissolved in o-dichlorobenzene at a weight ratio of 1: 0.8 and a concentration of 1.1% by weight. The obtained solution was stirred and mixed with a stirrer at 40 ° C. in a nitrogen atmosphere for 4 hours. The mixture was filtered through a 0.2 μm polytetrafluoroethylene (PTFE) filter to prepare a photoelectric conversion layer coating solution.

A glass substrate on which an indium tin oxide (ITO) transparent conductive film with a thickness of 155 nm is deposited is cleaned in the order of ultrasonic cleaning with a surfactant, water with ultrapure water, and ultrasonic cleaning with ultrapure water, followed by nitrogen blowing. And dried by heating at 120 ° C. in the air for 5 minutes. Finally, ultraviolet ozone cleaning was performed.
On this transparent substrate, poly (ethylenedioxythiophene) filtered through a 0.45 μm polyvinylidene fluoride (PVDF) filter: poly (styrenesulfonic acid) (PEDOT: PSS, manufactured by Starck Vitech, product name Baytron AI4083) After spin coating with a film thickness of 55 nm, it was dried by heating at 120 ° C. in the air for 10 minutes. Further, the substrate was heat-treated at 180 ° C. for 3 minutes in a nitrogen atmosphere.

  The photoelectric conversion layer coating solution was applied by spin coating on a glass substrate in a nitrogen atmosphere to form an active layer having a thickness of 70 nm. Thereafter, di (1-pyrenyl) phenylphosphine sulfide (PSPy2) obtained in Example 1 was formed into a film having a thickness of 8 nm, and aluminum having a thickness of 80 nm was sequentially formed by a resistance heating vacuum deposition method to form a film having a thickness of 5 mm. Square bulk heterojunction organic thin film solar cells were fabricated. The produced organic thin film solar cell was annealed at 150 ° C. for 10 minutes in a nitrogen atmosphere.

Evaluation of current-voltage characteristics of the produced solar cell was performed using a solar simulator (WXS-100SU-10, AM1.5G, manufactured by Wacom Denso Co., Ltd.) having an air mass (AM) of 1.5 and an irradiance of 100 mW / cm ² as an irradiation light source. It was. A current-voltage characteristic was evaluated with a 4 mm square metal mask, and the results are shown in Table 2.
<Example B2>
In Example B1, the fullerene derivative C ₆₀ (QM) ₂ obtained in Synthesis Example 3 was used instead of PCBM, the thickness of the active layer was changed to 200 nm, and the thickness of PSPy2 was changed to 6 nm. Table 2 shows the results of producing solar cells and measuring current-voltage characteristics.

<Comparative Example B1>
In Example B1, solar cells were prepared in the same manner except that BCP was used instead of PSPy ₂ and the thickness of the active layer was changed to 200 nm. The results of measuring current-voltage characteristics are shown in Table 2. It was.

<Example C1>
Poly (3,4) -ethylenedioxythiophene / polystyrenesulfonate aqueous dispersion as a hole extraction layer on a glass substrate on which an ITO electrode is patterned (trade name “CLEVIOS ^™ PVP” manufactured by H.C. Starck) AI4083 ") was applied by spin coating, and then the substrate was subjected to heat treatment on the hot plate at 120 ° C for 10 minutes in the air. The film thickness was about 30 nm.

  A compound represented by the following formula (A) (compound A) is placed in a metal boat arranged in a vacuum vapor deposition apparatus, heated, and tetrabenzoporphyrin is vapor-deposited on the substrate. The substrate was heat-treated at 180 ° C. for 20 minutes to form a p-type semiconductor layer having a thickness of about 25 nm on the hole extraction layer.

  A solution prepared by dissolving 0.6% by weight of Compound B and 1.4% by weight of the fullerene derivative SIMEF obtained in Synthesis Example 4 in a 1: 1 mixed solvent (weight) of chloroform / monochlorobenzene was prepared, filtered, The filtrate obtained under a nitrogen atmosphere was spin-coated at 1500 rpm and heated at 180 ° C. for 20 minutes. Thus, a mixture layer containing tetrabenzoporphyrin (compound A) and the fullerene derivative SIMEF was formed on the p-type semiconductor layer.

  Next, a solution in which 1.2% by weight of the fullerene derivative SIMEF was dissolved in toluene was prepared and filtered, and the filtrate obtained in a nitrogen atmosphere was spin-coated at 3000 rpm and subjected to heat treatment at 120 ° C. for 5 minutes. Thereby, a layer of the fullerene derivative SIMEF was formed on the mixture layer.

Then, PSPy2: di (1-pyrenyl) phenylphosphine sulfide obtained in Example 1 was placed in a metal boat placed in a vacuum vapor deposition apparatus, heated and vapor-deposited until the film thickness became 10 nm. An electron extraction layer was formed on the layer.
Furthermore, an aluminum electrode having a thickness of 80 nm was provided on the electron extraction layer by vacuum deposition, and then this solar cell was heated on a hot plate at 120 ° C. for 15 minutes to produce a solar cell.

The solar cell created was irradiated with light of 100 mW / cm ² with a solar simulator (AM1.5G) from the ITO electrode side, and between the ITO electrode and the aluminum electrode with a source meter (Keisley, Model 2400) The results of measuring the current-voltage characteristics are shown in Table 3.
<Example C2>
A poly (3,4-ethylenedioxythiophene) poly (styrenesulfonic acid) aqueous dispersion (manufactured by HC Starck Co., Ltd., trade name “CLEVIOUS ^TM PVP” as a hole extraction layer on a glass substrate on which an ITO electrode is patterned. AI4083 ") was applied by spin coating, and then the substrate was subjected to heat treatment on the hot plate at 120 ° C for 10 minutes in the air. The film thickness was about 30 nm.

  The substrate is first heat-treated at 180 ° C. for 3 minutes under a nitrogen atmosphere, and then a toluene solution containing 0.4 wt% of the coating conversion type bicycloporphyrin compound (C) is filtered and spin-coated on the substrate at 1500 rpm. It applied by doing. By heating the substrate at 180 ° C. in a nitrogen atmosphere, a layer of p-type semiconductor tetran benzoporphyrin (A) having a thickness of about 25 nm was formed on the hole extraction layer.

A solution prepared by dissolving 0.75% by weight of Compound B and 1.75% by weight of the fullerene derivative SIMEF2 obtained in Synthesis Example 5 in a 1: 1 mixed solvent (weight) of chloroform / monochlorobenzene was prepared, filtered, The filtrate obtained under a nitrogen atmosphere was spin-coated at 1500 rpm and heated at 180 ° C. for 20 minutes. As a result, a mixture layer containing tetrabenzoporphyrin (A) of about 100 nm and the fullerene derivative SIMEF2 was formed on the p-type semiconductor layer.
Next, a solution in which 0.65% by weight of the fullerene derivative C60 (QM) ₂ obtained in Synthesis Example 3 was dissolved in toluene was prepared, filtered, and the filtrate obtained in a nitrogen atmosphere was spin-coated at 3000 rpm. Heat treatment was performed at 120 ° C. for 5 minutes.

Thus, the fullerene derivative SIMEF2 mixture layer is replaced by a fullerene derivative C60 _{(QM) 2,} to form a layer of the fullerene derivative C60 _{(QM) 2} to tetrabenzoporphyrin layer.
Next, PSPy2 obtained in Synthesis Example 1 is placed in a metal boat placed in a vacuum vapor deposition apparatus, heated and evaporated to a film thickness of 6 nm, and buffered on the fullerene derivative C60 (QM) ₂ layer. A layer was formed.

  Furthermore, after an aluminum electrode having a thickness of 80 nm is provided on the buffer layer by vacuum deposition, the solar cell is placed on a 120 ° C. hot plate for 10 minutes, on a 150 ° C. hot plate for 10 minutes, and on a 180 ° C. hot plate. The solar cell was fabricated by heating for 10 minutes on a 200 ° C. hot plate for 10 minutes, 210 ° C. hot plate for 10 minutes, and 220 ° C. hot plate for 10 minutes.

The solar cell produced was irradiated with light of 100 mW / cm ² from the ITO electrode side with a solar simulator (AM1.5G), and between the ITO electrode and the aluminum electrode with a source meter (Keisley, Model 2400). The results of measuring the current-voltage characteristics are shown in Table 3.
<Comparative Example C1>
In Example C1, a solar cell was prepared in the same manner except that BCP was used instead of PSPy _{2 and} an aluminum electrode was provided and not heated. Table 3 shows the results of measuring the current-voltage characteristics. It was.

<Comparative Example C2>
In Example C1, instead of Pspy _2, except for using Popy _2, Similarly, to prepare a solar cell, the current - the result of the voltage characteristics were measured are shown in Table 3.
<Comparative Example C3>
In Example C1, except that PSPy ₂ was not used and heating was not performed after the aluminum electrode was provided, a solar cell was prepared in the same manner, and the results of measuring the current-voltage characteristics are shown in Table 3.

  From Tables 2 and 3, it can be seen that the use of the buffer layer material of the present invention for a photoelectric conversion element improves the open-circuit voltage and the photoelectric conversion efficiency (PCE) of the photoelectric conversion element.

  The present invention can be widely used for photoelectric conversion elements, and is particularly useful as a solar cell excellent in weather resistance.

100 substrate 101 transparent electrode 102 conductive material 103 p-type semiconductor 104 p-type semiconductor, n-type semiconductor mixed layer 105 n-type semiconductor 106 buffer layer 107 counter electrode 1 weathering protective film
2 UV cut film
3,9 Gas barrier film
4,8 Getter material film
5,7 Sealing material
6 Solar cell elements
10 Back sheet
11 Sealing material
12 Base material
13 Solar cell unit
14 Thin film solar cells

Claims (6)

A phosphine sulfide compound represented by the following general formula (I).
In the formula, Ar ^{1 to} Ar ³ are each independently an aromatic group which may have a substituent, and at least one of Ar ^{1 to} Ar ³ is a condensed polycycle having 7 or more double bonds. It is an aromatic group.   An electrode buffer material containing the phosphine sulfide compound according to claim 1.   The electrode buffer material according to claim 2, which has a glass transition temperature of 90 ° C. or higher. The electrode buffer material according to claim ^{2, wherein the} electron mobility is 10 ⁻⁷ cm ² / Vs.   A photoelectric conversion element comprising at least an active layer and a buffer layer between a pair of electrodes, wherein the buffer layer includes the electrode buffer material according to any one of claims 2 to 4.   The solar cell using the photoelectric conversion element represented by Claim 5.