JP2000243988A - Photoelectric conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photoelectric conversion element in which the size of a substrate can be made large and which prevents a drop in conversion efficiency due to a heat cycle and a wet heat cycle by a method wherein a polyarylate comprises a structure unit expressed by a specific formula and a specific residual monomer amount are provided on a polyarylate film. SOLUTION: In this photoelectric conversion element, a photoelectric conversion layer having one p-n junction or one pin junction is provided on a polyarylate film via a conductive layer. Polyarylate comprises a structure unit expressed by a formula (in the formula, R1 to R8 represent independently hydrogen atoms, halogen atoms, a 1 to 5C alkyl group, an aryl group, a phenyl group and a nitro group, and X is selected from a single bond, oxygen atoms, sulfur atoms, an alkylene group, an alkyliden group, a soxoalkylden group, a halo- substitution alkylene group, a halo-substitution alkylene group, a phenyl alkyliden group and the like), a residual monomer amount in the polyarylate film is set at 2000 ppm or lower, and a light transmission amount is set at 50% or higher at 550 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion element using a polyarylate film.

[0002]

2. Description of the Related Art In recent years, the use of fossil fuels has been reduced in order to prevent global warming.
Coveted all over the world. In Japan, too, the demand for photoelectric conversion elements has increased due to the system for subsidizing the purchase of photovoltaic power generators for ordinary houses by the Ministry of International Trade and Industry, and the system for purchasing surplus power by electric power companies, and further improvements in performance and price reductions are desired. . In particular, an amorphous silicon photoelectric conversion element using a flexible substrate can be attached to a roof or outer wall having a curved surface. It has the feature of being able to.

A flexible plastic substrate used for such a photoelectric conversion element requires heat resistance to withstand temperature changes when an amorphous silicon layer or the like is formed and sufficient surface smoothness. A polyimide film manufactured by a film method is widely used. However, a photoelectric conversion element using a polyimide film as a substrate has a high moisture absorption rate,
There is a problem that the conversion efficiency is reduced due to a heat cycle, a wet heat cycle, or the like during manufacture or use.

In order to solve such a problem, for example, Japanese Patent Publication No. 61-58989 discloses a photoelectric conversion element using a polyarylate film having a specific structure as a substrate. The polyarylate film disclosed in this publication is a so-called liquid crystal polymer film because of its chemical structure. Since this film has much smaller moisture absorption and heat shrinkage than the polyimide film, it is possible to prevent a decrease in conversion efficiency due to a wet heat cycle.

However, even when this film is used, there is a problem that the conversion efficiency gradually decreases due to the wet heat cycle, and the liquid crystal polymer is insoluble in most general-purpose solvents. Production is impossible, and it is necessary to produce a film by a melt extrusion method.However, since the melt viscosity of the polymer itself is high and the moldability is poor, it is difficult to obtain a film having sufficient surface smoothness, Since only an opaque film can be obtained with a liquid crystal polymer, application to a light receiving portion was impossible.

[0006]

In view of such circumstances, an object of the present invention is to use a polyarylate film as a substrate, make it possible to enlarge the surface, attach it to a curved roof or outer wall, An object of the present invention is to provide a photoelectric conversion element in which conversion efficiency is less likely to decrease due to a heat cycle, a wet heat cycle, and the like during the manufacture and use of the conversion element.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve such problems, and as a result, a photoelectric conversion device manufactured using a polyimide substrate or a film substrate obtained from a liquid crystal polymer has been developed. The decrease in the conversion efficiency of the device, not only the difference in hygroscopicity and heat shrinkage, but also the low molecular weight compound components on these film surfaces, in particular, residual monomers, solvents, and moisture
As a result of further study, using a film produced by casting method using a polyarylate having a specific structure described below, and the residual monomer content in the polyarylate film, that is, the residual phenol content and the residual phthalic acid content to 2000 ppm or less. The inventors have found that the object of the present invention is to solve the above problems, and have reached the present invention.

That is, the gist of the present invention resides in a photoelectric conversion element having at least one pn junction or pin junction on a polyarylate film via a conductive layer, wherein the polyarylate is represented by the formula (1). Having the following structural unit, the amount of residual monomer in the polyarylate film is 2,000 ppm or less, and the light transmittance is 55%.
It is a photoelectric conversion element characterized by being 50% or more at 0 nm.

[0009]

Embedded image

Wherein R _{1 to} R ₈ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an allyl group, a phenyl group or a nitro group, and X represents a single bond, an oxygen atom A sulfur atom, an alkylene group, an alkylidene group, a cycloalkylidene group, a halo-substituted alkylene group, a halo-substituted alkylidene group, a phenylalkylidene group, a substituted phenylalkylidene group, a carbonyl group, a sulfonyl group, a carboxylalkylene group, a carboxylalkylidene group,
It is selected from the group consisting of an alkoxycarbonylalkylene group, a fluorene group, a substituted fluorene group, an isatin group, an alkylsilane group, and a dialkylsilane group. ]

In the above-mentioned photoelectric conversion element, the polyarylate film has a carboxyl value of 30 mol / ton or less, the polyallylate film has a residual catalyst amount of 1000 ppm or less, and a residual alkali metal amount of 30 ppm or less. A photoelectric conversion element in which the amount of a solvent and moisture remaining in a certain photoelectric conversion element and a polyarylate film is 2000 ppm or less at normal temperature and normal pressure, respectively, is mentioned as a more preferable embodiment.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The polyarylate used in the present invention is obtained from a dihydric phenol component and a dihydric carboxylic acid component, and has a structural unit represented by the general formula (1).

Examples of the dihydric phenol constituting the polyarylate used in the present invention include the following. That is, 2-methyl-4,4'-dihydroxybiphenyl, 3-methyl-4,4'-dihydroxybiphenyl, 2-chloro-4,4'-dihydroxybiphenyl, 3-chloro-4,4'-dihydroxybiphenyl, 3,3′-dimethyl-4,4′-dihydroxybiphenyl, 2,2′-dimethyl-4,4′-dihydroxybiphenyl, 2,3′-dimethyl-4,4′-dihydroxybiphenyl, 3,3′- Dichloro-4,4'-dihydroxybiphenyl, 3,3'-di-tert-butyl-4,4'-dihydroxybiphenyl, 3,3'-dimethoxy-4,4'-dihydroxybiphenyl, 2,2-
Bis (3,5-dimethyl-4-hydroxyphenyl) propane (tetramethylbisphenol A), 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-biscresolfluorene, 9,9-bis (3 5-dimethyl-4-hydroxyphenyl) fluorene, 3,
3 ′, 5,5′-tetramethyl-4,4′-dihydroxybiphenyl, 3,3 ′, 5,5′-tetra-tert
-Butyl-4,4'-dihydroxybiphenyl, 3,
3 ', 5,5'-tetrachloro-4,4'-dihydroxybiphenyl, 2,2'-dihydroxy-3,3'-dimethylbiphenyl, 3,3'-difluoro-4,4'-
Biphenol, 2,2'-dihydroxy-3,3 ',
5,5′-tetramethylbiphenyl,

3,3 ', 5,5'-tetrafluoro-
4,4′-biphenol, 2,2 ′, 3,3 ′, 5
5'-hexamethyl-4,4'-biphenol, bis (4-hydroxyphenyl) methane, 1,1-bis (4
-Hydroxyphenyl) ethane, bis (4-methyl-2)
-Hydroxyphenyl) methane, bis (3,5-dimethyl-4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-
Bis (4-hydroxyphenyl) -4-methylpentane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (3-methyl-4-hydroxyphenyl) propane, 2,2-bis (3 , 5-dimethyl-4-
Hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,1-bis (4-hydroxyphenyl) -2-ethylhexane,
2,2-bis (3-phenyl-4-hydroxyphenyl) propane, bis (3-methyl-4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) butane, 1,1-bis (4 -Hydroxyphenyl)
-2-methylpropane, bis (4-hydroxyphenyl) phenylmethane,

2,2-bis (4-hydroxyphenyl)
Octane, 1,1-bis (3-methyl-4-hydroxyphenyl) cyclohexane, 2,2-bis (3-allyl-4-hydroxyphenyl) propane, 2,2-bis (3-isopropyl-4-hydroxyphenyl) ) Propane, 2,2-bis (3-tert-butyl-4-hydroxyphenyl) propane, 2,2-bis (3-sec-
Butyl-4-hydroxyphenyl) propane, 1,1-
Bis (2-methyl-4-hydroxy-5-tert-butylphenyl) -2-methylpropane, 4,4'-
[1,4-phenylene-bis (1-methylethylidene)] bis (3-methyl-4-hydroxyphenyl),
1,1-bis (3-phenyl-4-hydroxyphenyl) cyclohexane, bis (2-hydroxyphenyl)
Methane, 2,4'-methylenebisphenol, bis (3
-Methyl-4-hydroxyphenyl) methane, 1,1-
Bis (4-hydroxyphenyl) propane, 1,1-bis (2-hydroxy-5-methylphenyl) ethane,
1,1-bis (4-hydroxyphenyl) -3-methyl-butane, bis (2-hydroxy-3,5-dimethylphenyl) methane, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1 -Bis (3-methyl-4-
(Hydroxyphenyl) cyclopentane, 3,3-bis (4-hydroxyphenyl) pentane, 3,3-bis (3-methyl-4-hydroxyphenyl) pentane,

3,3-bis (3,5-dimethyl-4-hydroxyphenyl) pentane, 2,2-bis (2-hydroxy-3,5-dimethylphenyl) propane, 2,2
-Bis (4-hydroxyphenyl) nonane, 1,1-bis (3-methyl-4-hydroxyphenyl) -1-phenylethane, 1,1-bis (3,5-dimethyl-4-hydroxyphenyl) cyclohexane, 2,2-bis (4
-Hydroxyphenyl) decane, 1,1-bis (4-hydroxyphenyl) decane, 1,1-bis (2-hydroxy-3-tert-butyl-5-methylphenyl) methane, bis (4-hydroxyphenyl) diphenylmethane , Terpene diphenol, 1,1-bis (3-ter
t-butyl-4-hydroxyphenyl) cyclohexane, 1,1-bis (2-methyl-4-hydroxy-5-
tert-butylphenyl) -2-methylpropane;
2,2-bis (3-cyclohexyl-4-hydroxyphenyl) propane, bis (3,5-di-tert-butyl-4-hydroxyphenyl) methane, bis (3,5-
Di-sec-butyl-4-hydroxyphenyl) methane, 1,1-bis (3-cyclohexyl-4-hydroxyphenyl) cyclohexane, 1,1-bis (2-hydroxy-3,5-di-tert-butylphenyl) ) Ethane, 1,1-bis (3-nonyl-4-hydroxyphenyl) methane,

2,2-bis (3,5-di-tert-butyl-4-hydroxyphenyl) propane, 1,1-bis (2-hydroxy-3,5-di-tert-butyl-
6-methylphenyl) methane, 1,1-bis (3-phenyl-4-hydroxyphenyl) -1-phenylethane, α, α′-bis (4-hydroxyphenyl) acetic acid butyl ester, 1,1-bis ( 3-fluoro-4-hydroxyphenyl) methane, bis (2-hydroxy-5-
Fluorophenyl) methane, 2,2-bis (3-fluoro-4-hydroxyphenyl) propane, 1,1-bis (3-fluoro-4-hydroxyphenyl) -1-phenylmethane, 1,1-bis (3 -Fluoro-4-hydroxyphenyl) -1- (p-fluorophenyl) methane, 1,1-bis (4-hydroxyphenyl) -1-p
-Fluorophenyl) methane, 2,2-bis (3-chloro-4-hydroxy-5-methylphenyl) propane,
2,2-bis (3,5-dichloro-4-hydroxyphenyl) propane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane, 1,1-bis (3,5-dibromo-4- (Hydroxyphenyl) methane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane, 2,2-bis (3-nitro-4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) dimethylsilane ,

Bis (2,3,5-trimethyl-4-hydroxyphenyl) -1-phenylmethane, 2,2-bis (4-hydroxyphenyl) dodecane, 2,2-bis (3-methyl-4-hydroxyphenyl) Phenyl) dodecane,
2,2-bis (3,5-dimethyl-4-hydroxyphenyl) dodecane, 1,1-bis (3-tert-butyl-4-hydroxyphenyl) -1-phenylethane,
1,1-bis (3,5-di-tert-butyl-4-hydroxyphenyl) -1-phenylethane, 1,1-bis (2-methyl-4-hydroxy-5-cyclohexylphenyl) -2-methyl Propane, 1,1-bis (2-
Hydroxy-3,5-di-tert-butylphenyl)
Ethane, 2,2-bis (4-hydroxyphenyl) propanoic acid methyl ester, 2,2-bis (4-hydroxyphenyl) propanoic acid ethyl ester, 2,2 ′, 3
3 ', 5,5'-hexamethyl-4,4'-biphenol, bis (2-hydroxyphenyl) methane, 2,4'
-Methylenebisphenol, 1,2-bis (4-hydroxyphenyl) ethane, 2- (4-hydroxyphenyl) -2- (2-hydroxyphenyl) propane, bis (2-hydroxy-3-allylphenyl) methane, ,
1-bis (2-hydroxy-3,5-dimethylphenyl) -2-methylpropane, 1,1-bis (2-hydroxy-5-tert-butylphenyl) ethane, bis (2-hydroxy-5-phenylphenyl) )methane,
1,1-bis (2-methyl-4-hydroxy-5-te
rt-butylphenyl) butane, bis (2-methyl-4)
-Hydroxy-5-cyclohexylphenyl) methane,
2,2-bis (4-hydroxyphenyl) pentadecane,

2,2-bis (3-methyl-4-hydroxyphenyl) pentadecane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) pentadecane,
2-bis (3,5-di-tert-butyl-4-hydroxyphenyl) ethane, bis (2-hydroxy-3,5
-Di-tert-butylphenyl) methane, 2,2-bis (3-styryl-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -1-
(P-nitrophenyl) ethane, bis (3,5-difluoro-4-hydroxyphenyl) methane, bis (3,5
-Difluoro-4-hydroxyphenyl) -1-phenylmethane, bis (3,5-difluoro-4-hydroxyphenyl) diphenylmethane, bis (3-fluoro-4
-Hydroxyphenyl) diphenylmethane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane,
1,1-bis (4-hydroxyphenyl) -3,3-dimethyl-5-methyl-cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3-dimethyl-5,
5-dimethyl-cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3-dimethyl-4-methyl-
Cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3-dimethyl-5-ethyl-cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3
-Dimethyl-5-methyl-cyclopentane, 1,1-bis (3,5-dimethyl-4-hydroxyphenyl)-
3,3-dimethyl-5-methyl-cyclohexane, 1,
1-bis (3,5-diphenyl-4-hydroxyphenyl) -3,3-dimethyl-5-methyl-cyclohexane, 1,1-bis (3-methyl-4-hydroxyphenyl) -3,3-dimethyl- 5-methyl-cyclohexane, 1,1-bis (3-phenyl-4-hydroxyphenyl) -3,3-dimethyl-5-methyl-cyclohexane, 1,1-bis (3,5-dichloro-4-hydroxyphenyl) ) Diphenols such as -3,3-dimethyl-5-methyl-cyclohexane and 1,1-bis (3,5-dibromo-4-hydroxyphenyl) -3,3-dimethyl-5-methyl-cyclohexane. And one or more of these can be selected.

Particularly preferred dihydric phenols include:
2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 2,2-bis (3-methyl-4-hydroxyphenyl) propane (bisphenol C),
1,1-bis (4-hydroxyphenyl) cyclohexane (bisphenol Z), 1,1-bis (4-hydroxyphenyl) -1-phenylethane (bisphenol A
P), 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane (tetramethylbisphenol A), 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-biscresolfluorene, 9 , 9-bis (3,5-dimethyl-4-hydroxyphenyl) fluorene.

As the divalent carboxylic acid constituting the polyarylate used in the present invention, terephthalic acid, isophthalic acid, phthalic acid and a mixture thereof are used, and 10 to 90 mol% of terephthalic acid and 90% of isophthalic acid are used. ~ 1
A mixture consisting of 0 mol% is preferred, and particularly preferred is
It is an equal mixture of terephthalic acid and isophthalic acid. In the actual production, these derivatives, for example, divalent carboxylic acid halides such as phthalic chloride and phthalic bromide are preferably used due to cost factors.

The terminal of the polyarylate may be blocked with a monovalent phenol or a monovalent carboxylic acid. Monovalent phenols include phenol, cresol, p-tert-butylphenol, o-phenylphenol and the like. Monovalent carboxylic acids include benzoic acid chloride, methanesulfonyl chloride, phenylchloroformate and the like. Trivalent acid chlorides, monohydric alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, dodecyl alcohol, stearyl alcohol, benzyl alcohol, phenethyl alcohol, acetic acid, Examples include propionic acid, octanoic acid, cyclohexanecarboxylic acid, benzoic acid, toluic acid, phenylacetic acid, p-tert-butylbenzoic acid, and p-methoxyphenylacetic acid.

The polyarylate used in the present invention can be produced according to a conventional method. The polyarylate can be prepared by mixing a divalent phthalic halide dissolved in an organic solvent incompatible with water with a divalent phenol dissolved in an aqueous alkali solution. Polymerization method (WMEareckson J. Poly. Sci. XL399 1959
(Japanese Patent Publication No. 40-1959). Interfacial polymerization is faster than solution polymerization,
Therefore, it is possible to minimize the hydrolysis of phthalic acid halide. However, phthalic acid by-products cannot be completely suppressed. In addition, a high molecular weight polymer can be obtained by selecting a polymerization catalyst, which will be described later, but it is well known that oligomers are liable to be generated such that the molecular weight distribution is sometimes divided into a high molecular weight region and a low molecular weight region. ing.

The production method by the interfacial polymerization method will be described in more detail. An alkaline aqueous solution of a dihydric phenol is prepared,
Subsequently, a polymerization catalyst is added. The polymerization catalyst is not particularly limited as long as a polymer having a high molecular weight can be obtained, but tributylbenzylammonium halide, tetrabutylammonium halide, tetrabutylphosphonium halide, and tributylbenzylphosphonium halide are polymers having a high molecular weight and a low carboxyl number. Is preferred. Trimethylbenzylammonium halide, triethylbenzylammonium halide or the like having a short alkyl chain of a quaternary ammonium salt is not preferable because a high molecular weight polymer cannot be obtained depending on the kind of dihydric phenol to be polymerized.

On the other hand, a solvent which is incompatible with water and dissolves polyarylate, for example, methylene chloride, 1,2-
Dichloroethane, chloroform, carbon tetrachloride, chlorobenzene, 1,1,2,2-tetrachloroethane, 1,
A solution obtained by dissolving a divalent carboxylic acid halide in a chlorinated solvent such as 1,1-trichloroethane, oo-, m-, or p-dichlorobenzene, or an aromatic hydrocarbon such as toluene, benzene, or xylene is used. A polyarylate can be obtained by adding to an alkali solution and performing a reaction while stirring at a temperature of 25 ° C. or lower for 1 to 5 hours.
Examples of the alkali that can be used here include sodium hydroxide and potassium hydroxide.

Methods for reducing the amount of monomers, oligomers, catalysts and alkali metals remaining in the polyarylate include reprecipitation, a combination of centrifugation and kneader,
A combination of a centrifugal separation method and a hot water granulation method is employed. In particular, a warm water granulation method as disclosed in Japanese Patent Application No. 9-219147 is useful for removing residual monomers and oligomers from a polyarylate resin obtained by interfacial polymerization. In general, it has been reported that, when a large amount of residual monomers and oligomers are present in a polymer molded product, these are concentrated on the interface between the molded product and air, that is, on the surface of the molded product (T. Kajiyama). , et. al.,
Macromolecule, 28, 3482-3484, 1995). Residual monomers and oligomers, particularly residual monomers, migrate to the film surface at the time of film formation and come into contact with the conductive layer to be formed when the photoelectric conversion element is manufactured. Therefore, on the polyarylate film, an n-type amorphous silicon layer (n-layer), a p-type amorphous silicon layer (p-layer), and if necessary, a non-doped amorphous silicon layer (i-layer) and other oxide layers This residual monomer has an adverse effect on the conductive layer formed on the film due to heat at the time of forming. That is,
Here, since the conductivity of the conductive layer decreases, the pn junction or p
Even if the photoelectric conversion efficiency of the photoelectric conversion layer itself having the in-junction does not decrease, a phenomenon that the photoelectric conversion efficiency decreases in the entire device is observed. This phenomenon can be seen
20 residual monomer content in polyarylate film
This is the case when it is more than 00 ppm. Therefore, in the present invention, the amount of the residual monomer is 2,000 ppm or less, preferably 500 ppm or less.

The catalyst used in the production of polyarylate in the present invention is one of surfactants. If these are present in a large amount in the polyarylate film, it adversely affects the change in film dimensions due to moisture absorption. Therefore, the amount of the residual catalyst is preferably 1000 ppm or less,
More preferably, it is not more than 00 ppm.

It is preferable that the residual alkali metal content of the polyarylate is 30 ppm or less. The interfacial polymerization method for producing a polyarylate is a reversible reaction, and when sufficient moisture and alkali, and further heat, a depolymerization reaction is caused to increase the amount of residual monomers in the resin. If the amount of the residual alkali metal in the polyarylate exceeds 30 ppm, the performance degradation of the film may not be ignored. Considering this point, the amount of the residual alkali metal in the polyarylate film is set to 30 ppm or less.

The molecular weight of the polyarylate used in the present invention can be controlled by the addition amount of the above-mentioned end-capping material, and tetrachloroethane is used as a solvent for viscosity measurement, and the inherent viscosity of a 1 g / dl solution at 25 ° C. The viscosity is preferably 0.7 or more, more preferably 0.8 to 2.5. When the inherent viscosity is less than 0.7, the heat stability may be insufficient, and when a film is produced by a casting method as described below,
Insufficient viscosity cannot be given to the polymer dope,
Poor in film formability. On the other hand, if it exceeds 2.5, the viscosity of the dope solution may be too high, and it may be difficult to discharge the dope solution. To this dope solution, various antioxidants such as hindered phenol-based, hindered amine-based, thioether-based, and phosphorus-based agents can be added as long as the properties are not impaired in order to further improve the heat resistance.

Further, the polyarylate film used in the present invention preferably has a carboxyl value of 30 mol / ton or less. If the carboxyl number exceeds 30 mol / ton, the film dimensions may significantly change during moist heat, leading to cracks and cracks in the photoconductive film. The carboxyl number can be adjusted by controlling the molar ratio of phthalic acid halide and dihydric phenol used in the production of polyarylate and the reaction time.

Since the polyarylate having the structural unit represented by the formula (1) used in the present invention is a resin having excellent transparency, the light transmittance of the polyarylate film obtained therefrom is at least 50% at 550 nm.

The polyarylate used in the present invention has high solubility in halogen-based solvents such as methylene chloride and chloroform, and general-purpose solvents such as tetrahydrofuran and toluene. Therefore, as a method for producing a polyarylate film, a casting method utilizing such properties is suitably used. With the casting method, polyarylate is dissolved in a solvent to make a dope solution, and this is spread on a steel belt, a polymer film that is not attacked by the solvent in which the polyarylate is dissolved, or glass, and the solvent is removed to remove the film. It is a method of obtaining.

It is important to control the amounts of the solvent and water remaining in the polyarylate film to be as small as possible, in order to prevent deposition loss due to outgas when constructing the conductive layer. is there. The amount is
It is preferably at most 2,000 ppm at room temperature and pressure, more preferably at most 1,000 ppm. If each of the residual solvent and the water content is more than 2000 ppm, this conductive layer does not show sufficient conductivity. The amount of solvent and water remaining in the polyarylate film is greatly affected by the drying conditions. Usually, under pressures below normal pressure,
It is preferable to dry at a temperature higher than the boiling point of the solvent used for 1 to 24 hours.

The thickness of the polyarylate film used in the present invention is preferably from 1 to 1000 μm,
More preferably, it is 500 μm. If the thickness is less than 1 μm, the strength of the obtained film is often insufficient.
If it exceeds 00 μm, it is difficult to uniformly remove the solvent when the film is dried, so that drying unevenness and surface irregularities of a size that cannot be ignored tend to occur.

As the conductive layer, a stainless thin film, iron thin film, chromium thin film, nickel thin film, zirconium thin film, niobium thin film, silver thin film, indium tin oxide thin film (IT
O), zinc oxide thin film (ZnO), tin oxide thin film (SnO)
₂ ) and alloys thereof are formed by a film forming method such as a sputtering method, a vacuum evaporation method, a CVD (chemical vapor deposition) method, a sol-gel method, a molecular beam epitaxy method, and a film formation by a plasma gun. In particular, a DC magnetron sputtering method, a dual magnetron sputtering method, or the like is preferably used because the obtained conductive film has a high density, has excellent adhesion to a polyarylate film as a substrate, and has a high film formation rate. Of these conductive layers, a transparent one is used as a transparent conductive layer.

The thickness of the conductive layer or the transparent conductive layer is usually from 5 to
It is 750 nm, preferably 10 to 500 nm. When the thickness of the conductive layer or the transparent conductive layer is less than 5 nm, the conductivity tends to deteriorate. Conversely, if the thickness exceeds 750 nm, the conductive layer or the transparent conductive layer is liable to cause cracks and cracks, and as a result, adversely affects the conductivity. The problem to be solved by the present invention is not a photoelectric conversion efficiency derived from a pn layer or a pin layer, but a method for eliminating a decrease in photoelectric conversion efficiency based on deterioration of a conductive thin film due to impurities such as residual low molecular weight compounds in a film. Is. For this reason, the present invention can be used for all combinations used for photoelectric conversion elements having a pn junction or a pin junction, and FIGS. 1 to 3 show cross-sectional views of structural examples of the photoelectric conversion element in the present invention. 1 to 3, reference numeral 1 denotes a polyarylate film, 2 denotes a conductive layer, 3 denotes an n layer, 4 denotes a p layer, 5 denotes a transparent conductive layer, 6 denotes a grid electrode, 7 denotes an extraction electrode, and 8 denotes an i layer. . Since the polyarylate film used in the present invention has high transparency, it is used not only as a substrate of a photoelectric conversion element as shown in FIG. 1 or FIG. 2 but also on a light receiving surface side on a transparent conductive layer 5 as shown in FIG. You can also.

Further, according to the present invention, a metal barrier is provided on the interface (intermediate layer) between the conductive layer and the plastic film, or on the film surface (outer surface) on which the conductive layer is not formed, in order to improve gas barrier properties, adhesiveness, and light reflectivity. The formation of at least one of an oxide film layer, a nitride layer, a carbide layer, a diamond thin film layer, a polymer thin film layer, an organic thin film layer, an inorganic fine particle layer, and an organic fine particle layer is an effect of the present invention by this step. This is a possible mode within a range that does not impair.

[0038]

EXAMPLES Next, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these, and various modifications and applications may be made without departing from the spirit of the present invention. It is possible. The production conditions for the cast film are as follows:
It varies depending on the type of polyarylate used and the thickness of the polyarylate film to be produced. The same applies to the sputtering conditions. Therefore, here are the general conditions

The characteristic values of the polyarylate resin and the polyarylate film obtained therefrom were measured by the following methods. (1) Solution viscosity Using 1,1,2,2-tetrachloroethane as a solvent, the viscosity was measured at a temperature of 25 ° C. and a concentration of 1 g / dL. (2) Carboxyl number 0.15 g of polyarylate film was precisely weighed in a test tube,
5 ml of benzyl alcohol was added and dissolved by heating, and this was mixed with 10 ml of chloroform to prepare a test sample. Using phenol red as an indicator, under stirring,
Neutralization titration was performed with a 0.1 N KOH benzyl alcohol solution, and the carboxyl value was determined.

(3) Amount of Residual Monomer 10 g of the polyarylate film was subjected to Soxhlet extraction with 100 mL of n-hexane for 12 hours, n-hexane was extracted, concentrated, and quantitatively analyzed by H-NMR. The amount of residual phenol and the amount of residual phthalic acid, which are residual monomer amounts, were determined. (4) Amount of residual catalyst 5 g of polyarylate film was added to 100 ml of chloroform.
After that, the solution was added dropwise to 5 L of methanol to precipitate the resin. Next, the resin was separated and methanol was concentrated, and the amount of the catalyst present therein was measured by gas chromatography (HP-5890 manufactured by Hewlett-Packard Company).
The amount was quantified in Series II) under the following conditions, and was determined as the remaining amount in the resin. Measurement conditions Column: methyl silicon capillary (5m × id.
0.53mm) Column temperature: 250 ° C Carrier gas: He Detector: FID

(5) Amount of residual alkali metal The polyarylate film was measured by an atomic absorption method. (6) Light transmittance The light transmittance was measured using a polyarylate film having a thickness of 100 μm and a U-4000 spectrophotometer manufactured by Hitachi, Ltd. In the polyarylate film used in the present invention, the light transmittance at 550 nm was 75 to 95% regardless of the type. (7) Photoelectric conversion efficiency The photoelectric conversion efficiency is determined by the short-circuit current JSC = 10 (mA / cm
² ), open circuit voltage VOC = 700 (mV), fill factor FF
= 0.55.

Examples 1 to 6 In a reaction vessel equipped with a stirrer, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A),
2,2-bis (3-methyl-4-hydroxyphenyl)
Water is 30 to 50 times the weight of 1.7 mole percent of dihydric phenol monomer such as propane (bisphenol C) or 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane (TMBPA). P
-Tert-butylphenol (abbreviated as PTBP), 210 to 400 mol% of sodium hydroxide, and 1 mol% of tri-n-butylbenzylammonium chloride as a polymerization catalyst (aqueous phase). Separately from this, an organic phase obtained by dissolving a dihydric phenol monomer and an equimolar terephthalic acid chloride / isophthalic acid chloride 1/1 mixture (abbreviated as MPC) in 15 to 30 times by weight of methylene chloride with respect to MPC. Was added to the previous aqueous phase under vigorous stirring to carry out a polymerization reaction at 20 ° C. for 3 hours. Thereafter, acetic acid was added so that the reaction solution became weakly acidic to stop the reaction, and the aqueous phase and the organic phase were separated. This is repeatedly washed with water until the organic phase becomes neutral, and then
A polyarylate resin was obtained by a reprecipitation method using methanol as a reprecipitation solvent. This resin was dissolved in methylene chloride or chloroform to produce a cast film of 50 to 200 μm.

Using the obtained polyarylate film,
As described below, a photoelectric conversion element as shown in the sectional view of FIG. 1 was prepared. That is, a conductive layer 2 made of a silver thin film of 200 nm is formed on a polyarylate film 1 by a sputtering method, and subsequently an n-type amorphous silicon layer 3, a non-doped amorphous silicon layer, that is, an i-type amorphous silicon layer 8, a p-type amorphous silicon layer 8 are formed by a plasma CVD method. An amorphous silicon layer 4 was formed. This p
A transparent conductive layer 5 made of an indium tin oxide layer (ITO layer) is formed on the amorphous silicon layer 4, and a silver thin film is formed by sputtering to form a grid electrode 6.
And an extraction electrode 7 were formed. The thus-obtained photoelectric conversion element was heat-treated at 100 or 150 ° C. for 24 hours in the air, and the change in photoelectric conversion efficiency was measured.

Examples 7 and 8 In a reaction vessel equipped with a stirrer, 30 parts of water were added to 9,9-bis (4-hydroxyphenyl) fluorene (BPF) and 9,9-biscresolfluorene (BCF). ~
PTBP, 50 mol times, 1.7 mol% of PTBP, 250 to 400 mol% of sodium hydroxide, and 1 mol% of tri-n-butylbenzylammonium chloride as a polymerization catalyst were charged (aqueous phase). Separately from this, MPC equivalent to a dihydric phenol monomer is added to MPC.
An organic phase dissolved in 15 to 30 times by weight of methylene chloride with respect to C was prepared, and added to the previous aqueous phase with vigorous stirring.
The polymerization reaction was performed at 20 ° C. for 3 hours. Thereafter, acetic acid was added so that the reaction solution became weakly acidic to stop the reaction, and the aqueous phase and the organic phase were separated. This was repeatedly washed with water until the organic phase became neutral, and thereafter, a polyarylate resin was obtained by using a warm water granulation method. Using this resin, a photoelectric conversion element was produced in the same manner as in Examples 1 to 6,
Alternatively, it was heated to 150 ° C. for 24 hours, and the change in photoelectric conversion efficiency was measured.

Examples 9 and 10 In a reaction vessel equipped with a stirrer, 2,2-bis (3,5-
Dimethyl-4-hydroxyphenyl) propane (tetramethylbisphenol A) 30 mole percent and 9.9
Using a mixture of 70 mole percent biscresol fluorene (BCF), with water
1.7 mol% of PTBP, 250 to 400 mol% of sodium hydroxide, and 1 mol% of tri-n-butylbenzylammonium chloride as a polymerization catalyst were charged (aqueous phase). Separately, an organic phase was prepared by dissolving MPC equivalent to the dihydric phenol monomer in an equimolar amount to methylene chloride at 15 to 30 times the weight of MPC, and added to the above aqueous phase with vigorous stirring. And 20 ° C
For 3 hours. Thereafter, acetic acid was added so that the reaction solution became weakly acidic to stop the reaction, and the aqueous phase and the organic phase were separated. This was repeatedly washed with water until the organic phase became neutral. Thereafter, a polyarylate resin was obtained by a reprecipitation method using methanol as a reprecipitation solvent. Using this resin, a photoelectric conversion element was produced in the same manner as in Examples 1 to 6, and under air. Heated to 100 or 150 ° C. for 24 hours,
The change in photoelectric conversion efficiency was measured.

Comparative Examples 1 to 10 A polymer obtained by polymerization in the same manner as in Examples 1 to 10 was washed until the organic phase became neutral, and the organic layer was separated and dried to obtain a resin. . Using these resins, photoelectric conversion elements were prepared in the same manner as in Examples 1 to 6, heated at 100 or 150 ° C. for 24 hours in the atmosphere, and the change in photoelectric conversion efficiency was measured.

Comparative Examples 11 to 15 Several kinds of monomers were selected from the monomers used in Examples 1 to 10, and these were used and 1.1 to 1.25 equivalents of MPC were used.
A photoelectric conversion element was produced in the same manner as in the example, heated at 100 or 150 ° C. for 24 hours in the atmosphere, and a change in photoelectric conversion efficiency was measured.

Comparative Examples 16 to 20 The same method as in the examples except that several kinds were selected from the monomers used in the examples 1 to 10 and the drying time of the cast film was changed to 1/10 to 1/2 of the examples. Was prepared and heated at 100 or 150 ° C. in the atmosphere for 24 hours, and the change in photoelectric conversion efficiency was measured. Example 1
Table 1 shows the results of No. 10 and Comparative Examples 1 to 20.

[0049]

[Table 1]

[0050]

As described above, the photoelectric conversion element of the present invention is manufactured by the casting method as a substrate and uses a polyarylate film having a small amount of residual impurities. It can be attached to a roof or an outer wall, and a reduction in conversion efficiency due to a heat cycle, a wet heat cycle, or the like during formation or use of the photoelectric conversion layer can be reduced. Further, since the polyarylate film is excellent in transparency, a film using this film for the light receiving portion of the photoelectric conversion element can be produced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of the structure of a photoelectric conversion element according to the present invention.

FIG. 2 is a sectional view showing an example of the structure of the photoelectric conversion element according to the present invention.

FIG. 3 is a sectional view showing an example of the structure of the photoelectric conversion element according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 polyarylate film 2 conductive layer 3 n-type amorphous silicon layer (n-layer) 4 p-type amorphous silicon layer (p-layer) 5 transparent conductive layer 6 grit electrode 7 extraction electrode 8 i-type amorphous silicon layer (i-layer)

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Akihiko Hasegawa 23 Uji Kozakura, Uji-city, Kyoto Prefecture Unitika Central Research Laboratory (72) Inventor Shinya Takagi 23 Uji Kozakura, Uji-city, Kyoto Unitika Central Research, Ltd. In-house (72) Inventor Takamasa Akizuki 23 Uji Kozakura, Uji City, Kyoto Prefecture Unitika Central Research Laboratories F-term (reference)

Claims (4)

[Claims] 1. A photoelectric conversion device having a photoelectric conversion layer having at least one pn junction or pin junction on a polyarylate film via a conductive layer, wherein the polyarylate has a structural unit represented by the formula (1). The amount of residual monomer in the polyarylate film is 2,000 ppm or less, and the light transmittance of the polyarylate film is 55
A photoelectric conversion element characterized by being 50% or more at 0 nm. Embedded image [Wherein R _{1 to} R ₈ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an allyl group, a phenyl group, or a nitro group, and X represents a single bond, an oxygen atom, a sulfur atom. , Alkylene group, alkylidene group, cycloalkylidene group, halo-substituted alkylene group, halo-substituted alkylidene group, phenylalkylidene group, substituted phenylalkylidene group, carbonyl group, sulfonyl group, carboxylalkylene group, carboxylalkylidene group, alkoxycarbonylalkylene group, fluorene Group, substituted fluorene group, isatin group, alkylsilane group, dialkylsilane group. ] 2. The photoelectric conversion device according to claim 1, wherein the carboxyl number of the polyarylate film is 30 mol / ton or less. 3. The amount of the residual catalyst in the polyarylate film is 1000 ppm or less, and the amount of the residual alkali metal is 30 pp.
The photoelectric conversion element according to claim 1 or 2, wherein m is equal to or less than m. 4. The amount of solvent and water remaining in the polyarylate film is 2000 p each at normal temperature and normal pressure.
The photoelectric conversion element according to any one of claims 1 to 3, which is not more than pm.