JPH03181184A - Photoelectromotive element - Google Patents

Abstract

PURPOSE:To acquire a photoelectromotive element of uniform and high efficiency over a large area at a low cost by using polysilane compound which is expressed by a specified formula having weight average molecular weight of 6000 to 200000 as an organic semiconductor layer. CONSTITUTION:A Schottky junction type photoelectromotive element uses a straight chain polysilane compound which is expressed by a formula I and has a weight average molecular weight of 6000 to 200000 as an organic semiconductor layer. In the formula R1 expresses an alkyl group of carbon number of 1 or 2; R2 expresses an alkyl group of carbon number of 3 to 8, a cycloalkyl group, an aryl group or an aralkyl group; R3 expresses an alkyl group of carbon number of 1 to 4; and R4 expresses an alkyl group of carbon number of 1 to 4. Furthermore, (n), (m) are a mole ratio expressing a rate of the number of each monomer to gross monomer in polymer; and n+m=1, where 0<n<=1, 0<m<=1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a novel Schottky junction photovoltaic device using a polysilane compound as an organic semiconductor layer.

[Description of prior art]

Conventionally, photovoltaic devices using organic semiconductors have very low collection efficiency and low photoelectric conversion efficiency, so compared to research on pn junction type and pin junction type photovoltaic devices using crystalline silicon or amorphous silicon. Currently, research for practical application is lagging behind.

However, since thin films can be easily formed, it is expected that production costs will be reduced, and various studies have been conducted on organic semiconductors with the aim of improving photoelectric conversion efficiency.

Organic semiconductor materials suitable for photovoltaic devices include anthracene, tetracene, merocyanine, phthalocyanine, hydroxyne squaryllium, chlorophyll, pyrrole, etc. Among them, merocyanine, phthalocyanine, hydroxyne squaryllium, etc. are suitable for photovoltaic devices. Using a dye designed and developed as a material, the photoelectric conversion efficiency of the Schottky barrier cell is approximately 0.000% under AMO spectrum light.
It is about 2 to 1%. (Jpn J, Appl, Ph
ys.

20, 5upp1.20-2.135 (1980)
, Appl, Phys.

Lett, 32. 495 (1978),
J. Chew, Phys.

71, 1211 (1979)) The reason for this low photoelectric conversion efficiency is mainly due to the high carrier trap density in the organic semiconductor, and the carrier lifetime and mobility are both small and the diffusion length is short. It is thought that this is because

Furthermore, since organic semiconductors generally have a high resistivity, problems have been pointed out, such as difficulty in making ohmic contacts, and furthermore, a decrease in photoelectric conversion efficiency as the intensity of incident light increases.

On the other hand, polysilane compounds having silicon as a main skeleton are attracting attention as materials to replace the above-mentioned conventional organic semiconductor materials having carbon as main skeleton.

In the past, polysilane was reported to be insoluble in solvents [The Journal of American Chemical].
Society, 125.2291pp (1924))-
In recent years, it has been reported that polysilane is solvent soluble and can be easily formed into a film [The Journal of the American Ceramic Society; 61,504 p.
p (1978)) began to attract attention. Furthermore, since polysilane photodecomposes when irradiated with ultraviolet rays, research has been reported to apply it to resists [JP-A-60-9843]
No. 1, JP-A-60-119550].

In addition, polysilane has the property of a photosemiconductor in which charge can be transferred through the σ-bonds in its main chain, and it is expected to be applied to electrophotographic photoreceptors (Physical Review; B 35, 2818 pρ (1987)). became. However, for applications in such electronic materials, polysilane compounds must not only be solvent-soluble and film-forming;
It is necessary to be able to form a film without minute defects and with high homogeneity.

In addition, the method for synthesizing polysilane compounds is described in C The Journal of Organometallic Chemistry; 198p.
p, C27 (1980) or The Journal of Polymer Science, Polymer Chemistry Edition; Vol.

22.159-170pp (1984)).

Examples of using the above polysilane compounds as photoconductors have also been reported (U, S, P, 1m4618551
, u, s, p, Hiroshi 4772525, JP-A-62-269
No. 964), in particular, no study has been made regarding the application to photovoltaic elements that require good semiconductor properties.

[Purpose of the invention]

An object of the present invention is to solve the problems of the prior art described above, and to provide a photovoltaic device using an organic semiconductor that is inexpensive, uniform over a large area, and highly efficient.

Another object of the present invention is to provide a photovoltaic device using, as a semiconductor layer, a novel polysilane compound whose properties are significantly improved over conventional organic semiconductors.

Furthermore, another object of the present invention is to provide a photovoltaic device that is stable against changes in incident light intensity.

[Structure and effects of the invention]

In order to achieve the above-mentioned object, the present inventors have conducted intensive research and found that a linear polysilane compound represented by the following -format N) has dramatically improved characteristics compared to conventional organic semiconductors. After discovering that the photovoltaic device can be used as a photovoltaic device, he conducted research to make it fully operational and functional as a photovoltaic device. Weight average molecular weight is 6000 to 200
000 is used as an organic semiconductor layer.

R R1 1 1 ← T - 6 + 1 - ... (1) Rz
Ra (wherein, R1 is an alkyl group having 1 or 2 carbon atoms, R
2 is an alkyl group having 3 to 8 carbon atoms, a cycloalkyl group,
An aryl group or an aralkyl group, R1 represents an alkyl group having 1 to 4 carbon atoms, and R4 represents an alkyl group having 1 to 4 carbon atoms. n and m are molar ratios indicating the ratio of the number of each monomer to the total monomers in the polymer, and n+
m=1, and both may be the same or different. n and m are molar ratios indicating the ratio of the number of each monomer to the total monomers in the polymer, and n0m
=l, and Q<n≦1.0≦m<l. ) The polysilane compound preferably used in the present invention and having a weight average molecular weight of 6,000 to 200,000 and represented by form (1) is non-toxic and compatible with aromatic solvents such as toluene, Hensen, xylene, dichloromethane, dichloroethane, etc. It is easily soluble in halogenated solvents such as , chloroform and carbon tetrachloride, and other solvents such as tetrahydrofuran (THF) and dioxane, and has an excellent film forming part. The film formed using the polysilane compound of the present invention is homogeneous and has a uniform thickness, has excellent heat resistance, is rich in hardness, and has toughness.
ess).

For these reasons, the polysilane compound used in the present invention is a polymeric substance that can be used in the production of electronic devices, especially photovoltaic elements, and has high industrial utility value.

As mentioned above, the polysilane compound represented by the general formula (1) used in the present invention has a weight average molecular weight of 6,000 to 200,000. More preferable ones have a weight average molecular weight of 8,000 to 120,000.
The optimal one has a weight average molecular weight of 1000.
0 to 80,000.

Regarding the weight average molecular weight, those with a weight average molecular weight of 6,000 or less do not exhibit the characteristics of a polymer and do not have a film forming part, and those with a weight average molecular weight of 200,000 or more have poor solubility in solvents and cannot be used to form the desired film. Difficult to form.

The above-mentioned polysilane compound used in the present invention can be synthesized as follows.

That is, in a high-purity inert atmosphere free of oxygen and moisture, dichlorosilane monomer is brought into contact with a condensation catalyst made of an alkali metal to perform halogen elimination and condensation polymerization.

In the above synthesis operation, dichlorosilane, which is the starting material, and the alkali metal condensation catalyst are both highly reactive with oxygen and moisture. The above-mentioned polysilane compounds cannot be obtained.

Therefore, the above-mentioned operation for obtaining the polysilane compound of the present invention needs to be carried out in an atmosphere in which neither oxygen nor moisture is present. Therefore, care must be taken regarding the reaction container and all reagents used so that neither oxygen nor moisture is present in the reaction system. For example, regarding the reaction vessel, vacuum suction and argon gas replacement are performed in a glove box to prevent adsorption of moisture and oxygen into the system. In any case, the argon gas used is previously passed through a silica gel column to dehydrate it, and then the copper powder is passed through a column heated to 100° C. for deoxidation treatment.

The dichlorosilane monomer as a starting material is introduced into the reaction system after being distilled under reduced pressure using the above-mentioned argon gas which has been deoxygenated immediately before introduction into the reaction system.

Note that the solvent is dehydrated by distilling under reduced pressure using the deoxidized argon gas described above, and then further dehydrating with metallic sodium.

The above condensation catalyst is used in the form of wires or chips, and this operation is carried out in an anhydrous paraffinic solvent or in an atmosphere of an inert gas such as Ar or N to prevent oxidation.

The dichlorosilane monomer as a starting material used in producing the polysilane compound represented by the general formula (1) of the present invention is a silane compound represented by the general formula:
Silane compounds of the designation S + Cl 2 are selectively used.

As the above-mentioned condensation catalyst, an alkali metal capable of causing a condensation reaction by eliminating halogen is preferably used, and specific examples of the alkali metal include lithium, sodium, and potassium, with lithium and sodium being preferred.

General formula used when synthesizing the polysilane compound used in the present invention: R, R2S i Cl z
Alternatively, the dichlorosilane monomer represented by R*RaSiC1z is dissolved in a predetermined solvent and introduced into the reaction system. As the solvent, a paraffinic non-polar hydrocarbon solvent is preferably used. Preferred examples of the solvent include n-hexane, n-octane,
Mention may be made of n-nonane, n-dodecane, cyclohexane and cyclooctane.

Since the polysilane compound produced is insoluble in these solvents, it is convenient to separate the intermediate polymer from unreacted dichlorosilane monomer.

When condensing the above-mentioned dichlorosilane monomer using the above-mentioned alkali metal catalyst to obtain a desired polysilane compound, the degree of polymerization of the obtained polysilane compound can be appropriately controlled by adjusting the reaction temperature and reaction time. However, the reaction temperature at that time is preferably set between 60°C and 130°C.

The general formula (+
) A preferred embodiment of the method for producing the polysilane compound described above will be described in detail below.

The inside of the reaction system in the reaction vessel is completely free of oxygen and water and controlled by argon to maintain a predetermined internal pressure, then an anhydrous paraffinic solvent and an anhydrous condensation catalyst are added, then an anhydrous dichlorosilane monomer is added, The monomer is condensed by heating the whole to a predetermined temperature while stirring. At this time, the degree of condensation of the dichlorosilane monomer is adjusted by adjusting the reaction temperature and reaction time so that a polysilane compound with a desired degree of polymerization is produced. Make it.

In this reaction, as shown in reaction formula N) below, the chloro group of the dichlorosilane monomer and the catalyst cause a desalting reaction, and the Si groups repeatedly condense with each other to polymerize and produce a polysilane compound.

Catalyst nR+R, 5iC1, +mRyRa 5iC1, →R1
R3 ← 5 i-tr--child 6i -t1-Rz
Ra... (i) Note that the specific reaction procedure is to add the dichlorosilane monomer dropwise while stirring under suspension of paraffinic solution. The degree of polymerization is confirmed by sampling the reaction solution.

Polymerization can be easily confirmed by evaporating the sampling liquid and determining whether a film can be formed. As the condensation progresses and a polymer is formed, it becomes a white solid that precipitates out of the reaction system. Here, the reaction system is cooled, and the solvent containing the 7-mer is separated from the reaction system by decantation to obtain the desired polysilane compound.

Furthermore, the obtained polysilane compound was washed with n-hexane, ethanol, and water.

(Margins below) RJz SiC1z and 17. R, positioning property of SiC12): Among the following compounds, a-2 to 16.18.20
．． 2123.24 is used for R, R, SiC1z, a
-1゜2.11.17, 19, 22, 23.25 is R3
Used for R4SiC12z.

(013) zsic I! z -1 ((C113)zODtSiC4t A-na ((013) :lOtsic 12 tar-ru wood in Polysilanization A of al.

÷Si→Co -1 C, I+.

H2 ÷5i-)y- -7 ÷SiS meat Mar9 C1l□ Cll.

÷Si→Co- -11 C et al. )3 1lz C.I.

14Si)y→Sito' -13 113 C) +3 I3 CH3 C1l.

113 01゜ Oh (CII2) 3 CII) CH3 ub CI(3 (CI(i)zol C1l, CI et al. →S1 ト「→Sisu1− (CH3) 2CHCH3 Cl, CH.

→Si )-SSi 'j-r- (CH:l) zcHCzHs Clh Cl11aIt A Si hr(sif (CIlff) Jl (Cll,)2CHCIIff
CHg co.

A Si +−Y−(−si)v− (CHz) zol (CIIZ) sll3 CHJUt (Qh)3C →Si )T(Sisu1− (cox) tOI(CII:+) ffCC1h
(Oh) zOI 1J5 z -21 b-Shiosu-Otsu-Mustb-ru CH3 CI(ff CII3CI(z CII3 13 Carp, C11□ CH3 Q(s (CI(2) s C)+3 C8, CII.

Note: Both X and Y in the above structural formula represent monomer polymer units. Then, n is X/(X + Y), and m is
Each is calculated using the formula Y/(X+Y).

[Synthesis Example] Synthesis examples are given below to explain in more detail the method for synthesizing the polysilane compound preferably used in the present invention, but the method for synthesizing the polysilane compound used in the present invention is limited to these methods. Never.

Okashiro Oto Globebo performed vacuum suction and argon replacement.

A three-way flask was prepared in a vacuum box, a reflux condenser, a thermometer, and a dropping funnel were attached to it, and argon gas was passed through the dropping funnel's bypass pipe.

150 g of dehydrated dodecane and 0.3 mol of wire-shaped sodium metal were placed in this Mitsuroh flask and heated to 100° C. with stirring. Next, 0.1 mol of dichlorosilane monomer (manufactured by Chisso ■) (a-3) was dissolved in 40 grams of dehydrated dodecane, and the prepared solution was slowly dropped into the reaction system.

After the dropwise addition, a white solid was precipitated by condensation polymerization at 110° C. for 1 hour. Thereafter, the white solid was cooled, the dodecane was decanted, and the white solid was washed with n-hexane, ethanol, and water, and the polysilane compound 11hl (
b-3) was obtained. The yield was 63%.

The weight average molecular weight of this porinlan compound was determined to be 72,000 by GPC method with THF development (
Polystyrene was used as the mark r7).

For identification, a KBr pellet was prepared and IR was measured using PerkinElmer FT-IR1720X (manufactured by PerkinElmer Japan). In addition, NMRI; tsu7 pull was dissolved in CD (1!,
(JEOL Ltd.). The results are shown in Table 2.

In addition, in the porinlan compound obtained in the present invention,
No IR absorption attributed to 5i-0-3i in the main chain was observed.

A Mitsuru flask was prepared in a glove box that had been vacuum-suctioned and replaced with argon, and a reflux condenser, thermometer, and dropping funnel were attached to it, and argon gas was passed through the bypass pipe of the dropping funnel.

In this Mitsuro flask, 150 grams of dehydrated dodecane and 1
Prepared by dissolving 0.1 mole of zero-order dichlorosolane monomer (manufactured by Chisso ■) (a-13) in 30 g of dehydrated dodecane, which was prepared by charging 0.3 mole of m-square metallic lithium and heating it to 90°C while stirring. The solution was slowly added dropwise to the reaction system. After the dropwise addition, a white solid was precipitated by condensation polymerization at 100° C. for 2 hours. Thereafter, the white solid was cooled, the dodecane was decanted, and the white solid was washed with n-hexane, ethanol, and water to form a polysilane compound m2.
(b-7) was obtained. The yield was 70% and the weight average molecular weight was 65,000.

The identification results are shown in Table 2.

Polysilane compound m3 (b-8) was prepared using the same procedure except that dichlorosilane monomer (a-14) was used in place of the dichlorosilane monomer (manufactured by Chisso ■) (a-3) used in Main Synthesis Example 1. ) was synthesized. The yield was 65% and the weight average molecular weight was 48,000. The identification results are shown in Table 2.

In addition, in this polysilane compound, 5i in the main chain
An IR absorption spectrum assigned to -0-3i was not observed.

Polysilane compound 11h4 (b- 9) was synthesized. Yield is 70%
The weight average molecular weight was 55,000. The identification results are shown in Table 2.

In addition, in this polysilane compound, 5i in the main chain
-0-3i [R absorption spectrum was not observed.

A Mitsuro flask was prepared in a glove box that had been vacuum-suctioned over the coal pig and replaced with argon, and a reflux condenser, thermometer, and dropping funnel were attached to it, and argon gas was passed through the bypass pipe of the dropping funnel.

150 grams of dehydrated n-hexane and 0.3 mol of 111 square metal sodium were charged into this Mitsuro flask and heated to 90° C. with stirring. Next, a solution prepared by dissolving 0.1 mole of dichlorosilane monomer (manufactured by Chisso ■) (a-20) in dehydrated n-hexane was slowly added dropwise to the reaction system. After the 0 drop, condensation polymerization was carried out at 80°C for 3 hours. As a result, a white solid was precipitated. Thereafter, the mixture was cooled, n-hexane was decanted, and further washed with ethanol and water to obtain polysilane compound m5 (b-10).

The yield was 65% and the weight average molecular weight was 52,000. The identification results are shown in Table 2.

In addition, in this polysilane compound, Si-
There was no IR absorption assigned to 0-5i.

Plan I Two Soil 1 A polysilane compound was synthesized in the same manner as in Synthesis Example 1 using the two types of dichlorosilane monomers shown in Table 1.

Yield, weight average molecular weight, I of the synthesized polysilane compound
R and NMR data are shown in Table 2.

The copolymerization ratio of the silane monomers was determined from the number of protons in NMR. In addition, in this polysilane compound,
A JR absorption spectrum attributed to 5i-0-5i in the main chain was not observed.

Next, the configuration of the photovoltaic device of the present invention will be explained.

In the photovoltaic device of the present invention, a Schottky junction can be formed at a relatively low temperature, and high photoelectric conversion efficiency can be obtained despite the simple structure.

Furthermore, since the polysilane compound used in the photovoltaic device of the present invention is sensitive to relatively short wavelength light,
Compared to conventional photovoltaic elements using organic semiconductors, it is possible to obtain a higher open circuit voltage and significantly improve photoelectric conversion efficiency.

The polysilane compound used in the photovoltaic device of the present invention is easily soluble in many types of solvents and has excellent film-forming ability, so that it can be uniformly formed over a large area.
It has excellent adhesion to the support and excellent uniformity of properties.

Therefore, it can be suitably used as a photovoltaic element for a solar cell that requires a large area for electric power.

The polysilane compound used in the present invention has a significantly smaller change in photoelectric conversion efficiency over time than that of photovoltaic elements using conventional organic semiconductors, and the photoelectric conversion efficiency is also lower than that of conventional photovoltaic devices using organic semiconductors. This is a significant improvement compared to electromotive force elements.

Furthermore, the phenomenon of a decrease in photoelectric conversion efficiency due to an increase in the amount of incident light has been significantly improved. Furthermore, it has excellent stability, and stable output characteristics can be obtained even under conditions of severe temperature changes.

The light absorption characteristics of the polysilane compound used in the present invention can be arbitrarily changed by changing the molecular weight distribution or substituents on its side chains, making it possible to design a photovoltaic device tailored to the usage environment.

In the photovoltaic device of the present invention, since light is incident from the metal layer side, it is necessary to suppress absorption of light in the metal layer as much as possible. Furthermore, in the metal layer, since the height of the barrier caused by the work function of the metal largely controls the collection efficiency, it is necessary to appropriately select the constituent material and film thickness of each layer.

Examples of the layer structure of the photovoltaic device of the present invention are shown below, but the photovoltaic device of the present invention is not limited thereby.

FIGS. 1A and 1B are diagrams schematically showing typical examples of the layer fJI when the polysilane semiconductor film according to the present invention is used as the photovoltaic element of the present invention.

In the example shown in FIG. 1(A), the lower electrode 1 is placed on the support 101.
02, a photovoltaic device 100 in which a polysilane semiconductor layer 103, a metal layer 104, an antireflection film 105, and a current collecting electrode 106 are deposited in this order.

Note that in the photovoltaic element, light is incident from the metal layer 104 side.

The example shown in FIG. 1(B) is a photovoltaic device in which a current collector electrode 10G, an antireflection film 105, a metal layer 104, a polysilane semiconductor layer 103, and a lower electrode 102 are deposited in this order on a transparent support 101. The power element is +00. Note that in this photovoltaic element, light is incident from the transparent support 101 side.

The configurations of these photovoltaic elements will be explained in detail below.

Polysilane Semiconductor Examples of polysilane compounds suitably used for the polysilane semiconductor layer in the photovoltaic device of the present invention include the polysilane compounds b-1 to b-30 described above.

These polysolane compounds not only have good semiconductor properties but also excellent moldability.

Examples of the method for forming a film on the support include a coating method, a spin coating method, a dipping method, an electrodeposition method, a sublimation electrodeposition method, and the like, which are appropriately selected depending on the shape of the support used and the like.

In order to form a Schottky junction and obtain sufficient photoelectric conversion efficiency, the thickness of the polysilane semiconductor layer is preferably lnm to lxloSn, more preferably 5nm to IXIQ'nm, and optimally 10nm to lx10'n.
It is desirable to set it to m.

In the present invention, the material of the metal layer suitably used to form the Schottky junction is appropriately determined depending on the work function of the polysilane semiconductor used, and specifically, Au+Pt, Ag.

It is selected from metal thin films such as W, Cu, and Ni.

Furthermore, the thickness of the metal layer must ensure a sufficient i3 ratio of light, and is preferably 1 μm or less, more preferably 0.8 μm or less.

The above metal thin film can be produced by vacuum evaporation, electron beam electrodeposition,
It is formed by a sputtering method or the like.

The support 101 used in the present invention may be conductive or insulating, and furthermore may be translucent or non-transparent. Although it may be a photosensitive material, if light is to be incident from the support 101 side, it is of course necessary to be translucent. Specific examples include Fe, Ni, Cr, Mg, Aj!
9M.

Examples include metals such as Ta, V, Ti, Nb, Pb, Au, Ag, and PL, and alloys thereof, such as stainless steel, duralumin, nichrome, and brass.

In addition to these, examples include films or sheets of synthetic resins such as polyester, polyethylene, polycarbonate, cellulose, acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, and polyethylene terephthalate, as well as glass and ceramics. .

Also, S i = G e + Na CIt +
Examples include those sliced from a single crystal or polycrystal such as Ca F t + L' F -[3aFz and processed into a wafer shape, etc., and those on which a substance with a similar lattice constant is epitaxially grown.

The shape of the support may be a plate with a smooth or uneven surface, a long belt, a cylinder, etc. depending on the purpose and use, and the thickness may be determined as appropriate to form the desired photovoltaic element. However, if flexibility is required, or if light is incident from the side of the support, it can be made as thin as possible within the range that allows it to function as a support. .

However, from the viewpoint of manufacturing and handling of the support, mechanical strength, etc., the thickness is usually set to 10 μm or more.

1. In the photovoltaic device of the present invention, IJIr of the device
Appropriate electrodes are selected and used depending on the fi configuration. Specifically, a lower electrode and a current collecting electrode can be mentioned.

``UNI''] 艷药电子Since the lower electrode used in the present invention is provided for the purpose of extracting current from the polysilane semiconductor layer,
It is necessary that good ohmic contact be made with the polysilane semiconductor layer.

The position of the lower electrode 102 used in the present invention differs depending on the material of the support 101 described above or the direction of light incidence.

For example, in the case of the layer structure shown in FIG. 1(A), the support 101
However, if the support 101 is made of a material with sufficient conductivity, the lower electrode 102 is not provided and the support 101 can also serve as the lower electrode. On the other hand, if the support 101 is insulative, or if the support 101 is conductive but has a high sheet resistance, the lower electrode 102 must be provided for current extraction.

In the case of FIG. 1(B), a transparent support 101 is used, and since light is incident from the support 101 side, for the purpose of current extraction and light reflection at the electrode,
It is provided facing the support 101 with the polysilane semiconductor N103 sandwiched therebetween.

As an electrode material, Aj! , Mg, Cr, Cu.

Examples include metals such as Ag, Au, Pt, Ti, Mo, and W, and alloys thereof, and are appropriately selected and used depending on the characteristics of the polysilane semiconductor layer. Further, the Ei film of these metals is formed by a vacuum evaporation method, an electron beam evaporation method, a sputtering method, or the like. Furthermore, the formed metal thin film preferably has a sheet resistance value of 50Ω or less, more preferably 10Ω.
The following is desirable.

The current collecting electrode 106 used in the present invention has a metal layer 1
04 and on the antireflection film 105 for the purpose of reducing the surface resistance value of the antireflection film 105.

As electrode materials, Ag, Cr, Ni, Aj! , Aupt.
, Ti, W, MO, Cu, or alloys thereof. These metal Fjl films can be used in a stacked manner. Further, the shape and area of the semiconductor layer are appropriately designed to ensure sufficient light incidence on the semiconductor layer.

For example, it is desirable that the shape spreads uniformly over the light-receiving surface of the photovoltaic element, and that its area is preferably 15% or less, more preferably 10% or less of the light-receiving area.

Further, the sheet resistance value is preferably 50Ω or less, more preferably 10Ω or less.

In the photovoltaic device of the present invention, metal II! It is effective to provide an antireflection film 105 on 104.

The film is required to have an optical antireflection effect and also has the function of an electrode for extracting current from the metal layer.

Therefore, it is desirable that the transmittance in the visible light range is 85% or more, and the film thickness is set to be approximately 0.8 μm, which is an appropriate film thickness that satisfies the antireflection condition. Of course, it is also possible to use a stack of thin films made of materials with different refractive indexes.

Regarding electrical conductivity, it is desirable that the sheet resistance value be 100Ω or less so as not to become a resistance component with respect to the output of the photovoltaic element.

Specifically, materials with such characteristics include S
nO2, TnzOi, ZnO, CdO.

Examples include metal oxide thin films such as ITO (In, O, +5nOz).

Methods for forming these metal oxide thin films include reactive resistance heating evaporation, electron beam evaporation, reactive sputtering, spraying, and the like, and are appropriately selected depending on needs.

In the present invention, as a means for forming a good Schottky junction, it is desirable that the interface between the polysilane semiconductor layer and the metal layer be continuously formed in a vacuum or in an inert gas atmosphere.

In particular, when the polysilane semiconductor layer is produced by a method using a solvent, it is necessary to thoroughly dry the solvent. Furthermore, it is preferable to dry the solvent at a temperature that does not exceed the glass transition point of the polysilane compound.

〔Example〕

The photovoltaic device of the present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples in any way.

Schottky junction photovoltaic device 1 shown in Figure 1 (A) above
00 was produced by the following operation.

First, 10 Qnx 100mmx which was precision cleaned
A stainless steel substrate 101 with a size of O52 is placed in a sputtering device and evacuated to below 10 Torr, and then the internal pressure is 4 using Ag (purity 99.9999%) as a target metal and Ar gas as a sputtering gas.
About 1,500 Ag thin films, which will become the lower electrode 102, were deposited on the substrate 101 at room temperature under mTorr and RF discharge power of 200 W.

Next, 1 kl (b-3) of the polysilane compound synthesized in the above-mentioned Synthesis Example 1 was added to toluene 11 which had been sufficiently dehydrated in advance.
A coating liquid in which 250 parts by weight of 250 parts by weight of 100% of the sample was dissolved was placed in a spin coke installed in a globe bomber with an atmosphere of 1.5 mm.

Subsequently, the substrate 10 is formed up to the lower electrode 102.
1 was taken out from the sputtering apparatus under an inert gas A atmosphere and immediately set on a spin coater installed in the Grof Bonox. When transferring the substrate, an Ar-filled carrier box was used.

The lower electrode 10 is coated with a spin coater in an Ar air flow.
A polysilane semiconductor layer 103 with a thickness of 2800 nm is formed on the substrate 101 at room temperature, and the substrate 101 is heated at 80° C. in an Ar air flow.
The solvent was dried while heating.

Next, the substrate 101, which has been formed up to the polysilane semiconductor layer 103 by the above operation, is taken out into an Ar-filled carrier box, and immediately placed in a DC magnetron buffeting device to set the substrate temperature to 70° C., and A1 ( Purity 99.9999%) was used as the target metal, Ar gas was used as the sputtering gas, and the internal pressure was 3.5 m To
rr, an AI thin film as a metal layer 104 was deposited on the polysilane semiconductor N103 at a sputtering voltage of 370V.
People piled up.

Subsequently, in the sputtering apparatus, the A1 target and the previously set In*OsS n O were replaced with the sintered body target, and Ar10x/H! (100/
Using a mixed gas of 40/1) as a buffeting gas, an IT layer was formed as an antireflection layer 105 on the metal layer 104 at an internal pressure of 6 mTorr and a sputtering voltage of 420 V.
680 O membranes were deposited.

After cooling, the substrate +01 on which the anti-reflection layer 105 has been formed is taken out, and a comb-shaped permalloy mask for forming a collector electrode pattern is brought into close contact with the upper surface of the anti-reflection layer 105, and set in a vacuum plating device. After evacuation to 10-'Torr or less, 1 μmg of an Ag thin film as a comb-shaped current collecting electrode 106 is deposited on the antireflection layer 105 by a resistance heating method.
I arrived.

The photovoltaic element formed by the above operation was designated as element tml, and its characteristics were evaluated as follows.

First, from the antireflection layer 106 side of element M1, a wavelength of 470n is applied.
The photoelectric conversion efficiency was measured when irradiating light with a light intensity of 0.1 mW/-. Furthermore, without changing the wavelength, the light intensity is Q,
The photoelectric conversion efficiency was measured when the power was changed to 2 mW/aj and 0.3 mW/cd.

Furthermore, after continuously irradiating this element Hiro 1 with AMI light (roomW/CI) for 10 hours, the photoelectric conversion efficiency (wavelength 470 nm, light intensity 0.1 mW/-) was measured by the above measurement method,
The rate of change with respect to the initial photoelectric conversion efficiency was determined.

Further, the element 1 was set in a bending tester, and a bending test was repeated 103 times to evaluate changes in film adhesion and photoelectric conversion efficiency.

The above evaluation results are shown in Table 3.

From these results, the photovoltaic device fabricated in this example showed high photoelectric conversion efficiency regardless of changes in light intensity, had little photodeterioration, had strong mechanical strength, had excellent adhesion, and was stable. The characteristics were shown.

In Example 1, polysilane compounds ml (b-3) used in forming the polysilane semiconductor layer 103 were replaced with polysilane compounds 2 to 5 synthesized in Synthesis Examples 2 to 5 above. Photovoltaic devices were produced in the same manner and designated as devices M2 to M5.

The same measurements and evaluations as in Example 1 were performed on these elements. The evaluation results are shown in Table 3.

From these results, all of the photovoltaic devices produced in this example showed high photoelectric conversion efficiency regardless of changes in light intensity, little photodeterioration, strong mechanical strength, and good adhesion. It showed excellent and stable characteristics.

Inuzuki 10 Hi-10 In Example 1, instead of 1 ml of the polysilane compound (b-3) used when forming the polysilane semiconductor layer 103, the polysilane compound Asahi 6-IO synthesized in the aforementioned Synthesis Examples 6 to 10 was used. Polysilane semiconductor Fil 0
3, and as the lower electrode 102, AgF! Photovoltaic devices were fabricated in the same manner as device groups 6 to 10, except that a Cr thin film was deposited in place of the film, and a Au thin film was deposited as the metal layer 104 in place of the Ae thin film.

The same measurements and evaluations as in Example I were performed on these elements. The evaluation results are shown in Table 3.

From these results, all of the photovoltaic devices produced in this example showed high photoelectric conversion efficiency regardless of changes in light intensity, little photodeterioration, strong mechanical strength, and good adhesion. It showed excellent and stable characteristics.

In Example 1, polysilane compounds m11 to 14 synthesized in Synthesis Examples 11 to 14 described above were used instead of the polysilane compound 11hl (b-3) used in the preparation of the borinlane semiconductor 11103 type. Photovoltaic devices were fabricated in the same manner except that the polysilane semiconductor layer 103 was formed, and devices 1m11 to 14 were prepared.

The same measurements and evaluations as in Example 1 were performed on these elements. The evaluation results are shown in Table 3.

From these results, all of the photovoltaic devices produced in this example showed high photoelectric conversion efficiency regardless of changes in light intensity, little photodeterioration, strong mechanical strength, and good adhesion. It showed excellent and stable characteristics.

In Example 1, polysilane compounds 11kL15 to 17 synthesized in Synthesis Examples 15 to 17 described above were used instead of the polysilane compound ml (b-3) used in the polysilane semiconductor layer 103 form. The polysilane semiconductor layer 103 is formed, and the metal layer 104 is made of AI'i.
Photovoltaic devices were fabricated in the same manner as device groups 15 to 17, except that 40 Au thin films were deposited instead of the II film.

The same measurements and evaluations as in Example 1 were performed on these elements. The evaluation results are shown in Table 4.

From these results, all of the photovoltaic devices produced in this example showed high photoelectric conversion efficiency regardless of changes in light intensity, little photodeterioration, strong mechanical strength, and good adhesion. It showed excellent and stable characteristics.

PET (
Thickness 100I! Photovoltaic devices were fabricated using the same procedure except that the m) type substrate 101 was used, and the photovoltaic devices were designated as Device Hiro 18 to 21.

The same measurements and evaluations as in Example 1 were performed on these elements. The evaluation results are shown in Table 4.

From these results, all of the photovoltaic devices produced in this example showed high photoelectric conversion efficiency regardless of changes in light intensity, little photodeterioration, strong mechanical strength, and good adhesion. It showed excellent and stable characteristics.

A photovoltaic device was produced in the same manner as in Example 1 except that a 5-inch n'si single crystal wafer was used instead of the stainless steel substrate 101, and the device was designated as device m22.

When the collection efficiency was measured by irradiating light separated by a monochromator from the anti-aging layer 105 side of this element, it was 63% in the visible light region showing maximum absorption.

Also, 80mW/c+! The FF when exposed to sunlight was 0.50.

Table 3 [Summary of effects of the invention] As described in detail above, the photovoltaic device of the present invention has high sensitivity to short wavelength light, compared to conventional photovoltaic devices using organic semiconductors. This makes it possible to significantly improve photoelectric conversion efficiency.

The polysolane compound used in the photovoltaic device of the present invention is easily soluble in many types of solvents and has excellent film-forming ability, so that it can be uniformly formed over a large area.
It has excellent adhesion to the support and excellent uniformity of properties.

The polysilane compound used in the present invention has a significantly smaller change in photoelectric conversion efficiency over time than that of conventional photovoltaic elements using organic semiconductors.

Furthermore, the phenomenon of a decrease in photoelectric conversion efficiency due to an increase in the amount of incident light is also significantly improved. Furthermore, it has excellent heat resistance, and stable output characteristics can be obtained even under conditions of severe temperature changes.

[Brief explanation of drawings]

FIGS. 1(A) and (B) are schematic cross-sectional views of typical examples of the layer structure of the photovoltaic device of the present invention. With respect to FIG. ...Support, 10
2... Lower electrode, 103... Polysilane semiconductor layer, 104... Metal layer, 105... Antireflection layer, 106
...Collecting electrode.

Claims (1)

[Claims] (1) Represented by general formula (I) and has a weight average molecular weight of 600
1. A Schottky junction photovoltaic device characterized in that a polysilane compound having a molecular weight of 0 to 200,000 is used as an organic semiconductor layer. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (However, in the formula, R_1 is an alkyl group with 1 or 2 carbon atoms,
R_2 represents an alkyl group having 3 to 8 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group, R_3 represents an alkyl group having 1 to 4 carbon atoms, and R_4 represents an alkyl group having 1 to 4 carbon atoms. n and m are molar ratios indicating the ratio of the number of each monomer to the total monomers in the polymer, n+m=1, 0<n≦1, 0≦m<1. )