JPS63236372A - Photoelectric conversion device - Google Patents

Abstract

PURPOSE:To improve on the photoelectric conversion efficiency by a method wherein a substrate is constituted of a colorless, transparent polyimide film of a specified cycling order and light is projected from the substrate side. CONSTITUTION:In a photoelectric conversion device constituted of a substrate and a photoelectric conversion element capable of changing optical energy into electrical energy, the substrate is constructed of a colorless, transparent polyimide film mainly composed of a polyimide equipped with a cycling order represented by a general formula (I) and/or (II). In an amorphous silicon solar battery incorporating a colorless, transparent polyimide film of this composition, with the light coming from the side of the substrate of a good quality, the loss, attributable to the recombination of electrons and holes mainly generated in the intrinsic silicon thin film taking place at a spot containing a number of structural defects, is greatly controlled.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention uses a colorless and transparent polyimide film as a substrate,
The present invention relates to a photoelectric conversion device that improves photoelectric conversion efficiency by irradiating light from the substrate side.

(b) Prior art A photoelectric conversion device that converts light energy into electrical energy using an amorphous silicon thin film or the like is a low-cost solar cell (solar cells are also included in the photoelectric conversion device in the present invention), optical sensors, etc. It is applied to.

Photoelectric conversion devices, such as solar cells, conventionally have a structure in which p-type, i-type, and n-type amorphous silicon thin films are sequentially deposited on a metal plate such as stainless steel foil, and a light-transmitting conductive thin film is further laminated. and a light-transmitting conductive thin film on a glass plate.
A structure in which amorphous silicon thin films of type, i-type, and n-type are sequentially deposited and a conductive thin film of aluminum or the like is further laminated has been put into practical use.

In the case of a metal substrate such as stainless steel, the sheet resistance of the substrate is low enough that a single solar cell can be formed on the substrate.
A large output current can be obtained from a board with a fixed area.

On the other hand, when using an insulating substrate such as glass, it is convenient to arrange two or more photoelectric conversion elements adjacent to each other and easily connect them in series with a conductor to obtain more than twice the voltage. .

Currently, efforts are being made to reduce the cost of amorphous silicon solar cells by improving their photoelectric conversion efficiency as well as improving materials and production processes. As this ring, a thin film of stainless steel or the like is provided on a heat-resistant plastic film such as a polyimide film, an amorphous silicon thin film is deposited on it, and an indium oxide-tin oxide (hereinafter abbreviated as IT04 thin film) is deposited on top of it. ) or with a transparent conductive thin film of tin oxide etc. have been proposed (for example, JP-A No. 54-149489, JP-A No. 55-4994, JP-A No. 55-29154, and JP-A No. 57-103839).
Publications, etc.). These materials have low material costs, and the substrate is flexible and can be rolled into a roll for continuous processing, which has great advantages in terms of production costs.Furthermore, since the shape can be selected arbitrarily, a wide range of applications and applications are expected. has been done.

However, although amorphous silicon solar cells using a polyimide film as a substrate are currently expected to have many possibilities, they have not yet been put into practical use. This is because the photoelectric conversion efficiency is generally much lower than that of a substrate made of a stainless steel foil glass plate, and it lacks stability over time and stability against bending stress.

One of the reasons for these drawbacks is that the temperature between 250'C and 35
When depositing an amorphous silicon thin film on a substrate under conditions of 0°C, moisture adsorbed on the substrate, residual solvent in the polyimide film, and moisture generated by condensation of residual unreacted parts, etc. Incorporated into the film as an impurity,
Another reason is that distortion occurs at the interface between the substrate film and the stainless steel foil film for electrodes due to irreversible heat shrinkage (when the thin film is returned to room temperature after deposition, it shrinks more than its initial size). The point is that it remains. As a method to improve these, a method has been proposed in which the substrate is preheated before depositing an amorphous silicon thin film (Japanese Patent Publication No. 59-53178) Q (C) Problems to be Solved by the Invention Although the above-mentioned method of preheating a substrate is extremely superior in that it alleviates the essential problems of the substrate, it is not a method for improving the photoelectric conversion efficiency of solar cells and is not an essential improvement measure. is not.

That is, solar cells using a polyimide film as a substrate have conventionally been produced by sputtering a stainless steel thin film on a non-light-transmitting polyimide film, sequentially depositing an amorphous silicon thin film on this, and then laminating an ITO conductive thin film. Has a structure. Then, light is irradiated from the side opposite to the substrate, that is, from the ITO film side, and the light energy is converted into air energy.

Incidentally, the deposition state of the amorphous silicon thin film depends on the smoothness of the base substrate, in other words, the fine unevenness V on the surface.
CG grows while forming domains, and as a result, as the thickness of the amorphous silicon thin film increases to about 1 to 2 μm, a film with more structural defects is generally formed.

Furthermore, electrons and holes generated in the intrinsic layer are more likely to recombine at locations where there are many structural defects in the thin film, and it is thought that the loss of photocurrent is large at such locations. Therefore, it is assumed that the photoelectric conversion efficiency becomes worse the farther from the substrate, that is, closer to the surface opposite to the surface on the substrate side. When irradiated from the substrate, the surface roughness of the polyimide film is the same between those using a polyimide film as the substrate and those using mirror-finished stainless steel foil, so it is thought that the photoelectric conversion efficiency will be worse with the polyimide film. (There is a limit to the surface smoothness of polyimide film.)

(d) Means to solve the problem Therefore, the present inventors developed a colorless and transparent polyimide film that has excellent heat resistance, and created a photoelectric conversion device # using this as a substrate. However, as a result of investigating the photoelectric conversion efficiency by irradiating light from the substrate side, it was found that in this type of photoelectric conversion device, absorption of light by the substrate is unavoidable, but surprisingly, despite this, conventional polyimide The present invention was completed based on the discovery that photoelectric conversion efficiency is significantly improved compared to substrate-type solar cells.

That is, the present invention provides a photoelectric conversion device in which a photoelectric conversion element for converting light energy into electrical energy is provided on a substrate, in which the substrate is a polyimide film mainly composed of polyimide having repeating units represented by the general formula %. It is characterized by being formed of.

The present invention will be explained in detail below.

In the present invention, the photoelectric conversion device refers to a device that converts light energy into electrical energy, and can be applied to any device provided with a photoelectric conversion element on a substrate. Examples include batteries and optical sensors.

The most significant feature of the present invention is that a colorless and transparent light-transmitting polyimide film is used as the substrate.

Colorless and transparent means that the visible light (500 nm) transmittance for a polyimide film having a thickness of 50±5 μm is 70% or more and the yellowness index is 40 or less.

Although polyimide film is heat resistant, there has never been a colorless and transparent polyimide film, and this film was completed as a result of research by the present inventors.

The colorless and transparent polyimide film used in the present invention has as its main component a polyimide having a repeating unit represented by the general formula %.

The colorless and transparent polyimide used in the present invention has the general formula (
1) Obtained by reacting biphenyltetracarboxylic dianhydride represented by formula % with aromatic diamino compounds represented by general formulas (IY) and (V).

The above-mentioned biphenyltetracarboxylic dianhydride includes the following 3.3', 4.4'-biphenyltetracarboxylic dianhydride and 2, 3.3', 4'-biphenyltetracarboxylic dianhydride. can be mentioned.

Also, is there an amino group at the above meta position? Among the aromatic diamino compounds, the following are representative examples of the aromatic mononuclear diamine represented by the general formula (1'V).

H2N-o-NF2 m-phenylenediamine 2.4-toluenediamine 4.6-:/methyl-m-phenylenediamine 2.4-
Diaminomesitylene 4-chloro-m-phenylenediamine 3.5-diaminobenzoic acid 5-nitro-m-phenylenediamine also. Representative examples of the aromatic trinuclear diamine represented by the general formula (V) include the following.

1.4-bis(3-aminophenoxy)ben/cene 1.3
-Bis(3-aminophenoxy)be/cene Aromatic 1 above
The nuclear diamine and the aromatic trinuclear diamine may be used alone or in appropriate combinations.

A biphenyltetracarboxylic dianhydride as described above and an aromatic mononuclear diamine having an amino group at the meta position and/or
Alternatively, only by combining an aromatic trinuclear diamine with gold can a colorless and transparent polyimide whose main component is a repeating unit represented by the above general formula (1) and/or (n) be obtained.

Here, the term "main component" is intended to include cases where the entire component consists only of the above general formula (1) and/or (l[).

In this case, in the polyimide thus obtained, the higher the content of the polyimide represented by the repeating unit represented by the above general formula (1) and/or the repeating unit represented by the above general formula (11), the more The colorless transparency of the resulting polyimide film increases. However, the above general formula (
If the polyimide of the repeating unit represented by 1) and/or the repeating unit represented by general formula (■) contains 70 mol or more, at least the colorless transparency required by this invention is ensured, so it is within that range. In this method, use of an aromatic tetracarboxylic dianhydride other than the biphenyltetracarboxylic dianhydride and a diamino compound other than the aromatic mononuclear/trinuclear diamine having an amino group at the meta position. Can be done.

That is, the preferred range of the polyimide represented by the repeating unit represented by the above general formula (1) and/or the repeating unit represented by the general formula (■) is 70 mol% or more, and the most preferred range is 95 mol%. That's all.

Examples of the other aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 3.3', 4.4'-benzophenonetetracarboxylic dianhydride, 4°4'-oxycyphthalic dianhydride, 3.3', 4.4'-diphenylsulfone tetracarboxylic dianhydride, 4.4'-
Bis(3,4-dicarboxyphenoxy)diphenylsulfone dianhydride, 2,2-bis(3°4-dicarboxyphenyl)hexafluoropropani dianhydride, 2. 3
．． 6. 7-naphthalenetetracarboxylic dianhydride,
1,2,5.6-naphthalenetetracarboxylic dianhydride, 1. 4. 5. Examples include derivatives such as 8-naphthalenetetracarboxylic dianhydride or its ester,
These can be used alone or in combination.

In addition, other diamino compounds include 4゜4'-diaminodiphenyl ether, 3,47-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylmethane, 4,4'-diaminobenzophenone, .4'-Diaminodiphenylpropane, P-phenylenediamine, 2.5-)lylenediamine, 2.5-diaminochlorobenzene, benzidine, 3.3'-dimethylbenzidine, 4.4'-diaminodiphenylthioether, 3,3' -dimethoxy-4
, 4'-diaminodiphenylmethane, 3,3'-dimethyl-4,47-diaminodiphenylmethane, bis[4-
(4-aminophenoxy)phenyldisulfone, 2.2
~BisC4-C4-aminophenoxy)phenyldipropane, 2.2-bis(:4-(4-aminophenoxy)
phenyl]hexafluoropropane, 1,3-bis(4
-aminophenoxy)benzene and 1,4-bis(4-aminophenoxy)benzene, which can be used alone or in combination.

The colorless and transparent polyimide film used in the present invention is prepared by polymerizing the above-mentioned aromatic tetracarboxylic dianhydride and diamino compound in an organic polar solvent at a temperature of 80°C or less to prepare a polyimide precursor solution. A molded body of a desired shape is formed using a polyimide precursor solution by a method such as casting or roll coating, and the molded body is placed in air or an inert gas at a temperature of 50 to 35.
0”C.

It is obtained by evaporating and removing the organic polar solvent under normal or reduced pressure conditions and simultaneously dehydrating and ring-closing the polyimide precursor.

Alternatively, instead of the above method, the polyimide precursor can be obtained by a method such as using a benzene solution of pyridine and acetic anhydride, and imidizing it with a debathing medium to form a polyimide.

Examples of the above organic polar solvent include N,N-dimethylformamide, N,N-dimethylacetamide, diglyme,
Cresol, halogenated phenol, etc. are preferred, but
In particular, N,N-dimethylacetamide is preferred because it is a good solvent and has an extremely low boiling point. These organic polar solvents may be used alone, or alternatively, two or more of them may be used in combination without any problem.

As organic polar solvents, the above-mentioned solvents have low boiling points, so they do not cause problems such as decomposition during dehydration and ring closure by heating, and the decomposed products remain in the polyimide and color the polyimide. .

However, if a high boiling point polymerization solvent such as N-methyl-2-pyrrolidone is used to synthesize the polyimide precursor and the resulting polyimide precursor is dissolved in the above-mentioned suitable solvent by solvent substitution, the above-mentioned disadvantages can be avoided. Eliminate the vines.

In this case, the preferred self-solvent exemplified above would be a diluting solvent. When manufacturing the above polyimide film, in this way,
It is also possible to use different types of polymerization solvent and dilution solvent, and to dissolve the produced polyimide precursor in the dilution solvent by solvent substitution.

When using the suitable organic polar solvents listed above, add solvents such as ethanol, toluene, benzene, xylene, dioxane, tetrahydrofuran, nitrobenzene, etc. to this solvent within a range that does not impair the colorless transparency of the polyimide film. One type or two or more types may be appropriately mixed and used in the above manner.
0.59/100tttl in dimethylacetamide solvent
V:) concentration measured at 30 °C) is 0.3 to 5.0
It is preferable to adjust the number of questions so that the number of questions is i1. More preferred is 0.4 to 2.0. If the logarithmic viscosity is too low, the resulting polyimide film will have low mechanical strength, which is not preferable. On the other hand, if the logarithmic viscosity is too high, it is not preferable because it becomes difficult to cast the polyimide precursor solution into an appropriate shape, making the work difficult. In addition, from the viewpoint of workability, the concentration of the polyimide precursor solution is 5 to 3.
It is desirable that the content be 0% by weight, preferably 15-255-25% by weight.

Note that the above-mentioned logarithmic viscosity is calculated by the following formula, and the viscosity in the formula is measured by a capillary viscometer.

To obtain a polyimide film with excellent colorless transparency using a polyimide precursor solution, the polyimide precursor solution is cast onto a mirror surface such as a glass plate or a stainless steel plate to a certain thickness, and the thickness is 100 to 350°. This is carried out by gradually heating the polyimide precursor at a temperature of Heating may be carried out continuously, or these steps may be carried out under reduced pressure or in an inert gas atmosphere.Furthermore, for a short period of time, by final heating to around 400 °C, The properties of the resulting polyimide film can be improved.

Another method for forming a polyimide film is to cast the above polyimide precursor solution onto a glass plate or the like.
A method of forming a gold film by heating and drying at 150°C for 30 to 120 minutes, and immersing this film in a benzene solution of pyridine and acetic anhydride to remove the solvent and perform an imidization reaction, thereby converting the film into a polyimide film. A colorless and transparent polyimide film can also be obtained by this method.

The thickness of the polyimide film thus obtained is preferably set to about 7 to 550 μm. If the thickness exceeds 550 μm, the light transmittance will deteriorate and the flexibility will be lacking, making it difficult to continuously wind the film into a roll, which will cause problems in productivity. If it is less than 7 μm, sufficient mechanical strength will not be obtained, and the temperature (250
C to 350 C), and the substrate may be deformed by this thermal stress, which is not preferable.

This polyimide film is colorless and transparent and is not colored yellow or yellowish brown as in conventional films, so it has extremely good colorless transparency even if it is a relatively thick film.

In the case where the polyimide precursor solution is imidized to form polyimide as described above, the generated polyimide is
From the point of view of properties, logarithmic viscosity (0.597 d in 97 wt% sulfuric acid)
tl-0,3~5.
It is preferable to set it within the range of 0.

The most preferred range is 0.4 to 4.0.

The polyimide film obtained in this manner is completely different from conventional films, and is colorless and transparent, and has extremely high transparency.

A photoelectric conversion device a is formed by depositing photoelectric conversion elements on the polyimide film substrate thus obtained.

In the present invention, step A is first carried out in which an ITO film, a tin oxide film, and a light-transmitting conductive thin film are laminated on a substrate by a vapor deposition method or a sputtering method.

The thickness of the conductive thin film is 0.01. ~1.0μ7n
If it is less than 0.01 μm, the desired conductivity (surface resistance of 1000 Ω/mouth or less) cannot be obtained, and if it exceeds 1.0 μm, the transparency of the conductive thin film of the polyimide film will be impaired. Undesirable.

In the present invention, next step B is performed in which a photoelectric conversion element is deposited on the conductive thin film.

The photoelectric conversion element may include an amorphous silicon thin film deposited on the conductive thin film, for example, in the p-1-n or n-1-p order, or a p-type silicon thin film deposited on the conductive thin film. Examples include a variety of photoelectric conversion elements formed by depositing a valvus crystalline silicon carbide thin film, an i-type valvate silicon thin film, and an n-type valvate silicon thin film in this order.

The p-type valvus silicon thin film, i-type valvate silicon thin film, and n-type valvate silicon thin film can be deposited using various methods such as sputtering method, glow discharge method, photo-CVD method, and ion blating method. method can be adopted.

For example, in the case of glow discharge method, the temperature is 200-350'
A substrate with a transparent conductive thin film formed on one side is held in a substrate holder heated to C, and the nuclear substrate holder is used as one electrode, and the opposite electrode is connected to the substrate at 13.56 MHz.
of high-frequency power.

For example, to form a p-type crystalline silicon thin film, phosphine (PH3)f: is mixed into silane, while to form a p-type amorphous silicon thin film, diborane (82H6) is introduced into silane. It's okay.

Further, the above-mentioned amorphous silicon thin film refers to hydrogenated amorphous silicon and fluorinated amorphous silicon.

In the present invention, a thin film of a metal such as aluminum, nickel, titanium, chromium, iron, stainless steel, or nickel-chromium alloy is formed on the thus obtained photoelectric conversion element by an appropriate method such as vapor deposition or sputtering. For example, in the vapor deposition method, the vacuum level is 10 -4 to 1 torr, and the temperature of the vapor deposition source is around the melting point of the material used.

(e) When depositing an amorphous silicon thin film on a working substrate, the film thickness is 1
Up to 2 μm, the thicker the film, the worse the film quality (the more structural defects there are) due to the effect of the smoothness of the substrate surface. This tendency is independent of the presence or absence of a metal thin film for electrodes at the boundary between the substrate and the amorphous silicon thin film. In conventional amorphous silicon solar cells, which have a structure in which a transparent conductive thin film is deposited, light is irradiated from the surface opposite to the substrate with good film quality, but in other words, light is irradiated from the side with poor film quality. On the other hand, in the case of an amorphous silicon solar cell using a colorless and transparent polyimide film as a substrate according to the present invention, light is irradiated from the substrate side with good film quality, and as a result, the electrons mainly generated in the intrinsic silicon thin film are It is presumed that the rate at which holes and holes are recombined and lost at locations with many structural defects is suppressed as much as possible.

In other words, in the photoelectric conversion device of the present invention, since light is irradiated from the side with better film quality (the side with fewer structural defects), in other words, from the substrate side, there is a high rate of recombination of electrons and holes generated upon receiving light. This is thought to have the effect of lowering the photoelectric conversion efficiency and significantly increasing the photoelectric conversion efficiency.

(f) Examples Example 1 Using N,N-dimethylacetamide as a solvent, m
-t for 1 mol of phenylenediamine, 3°3', 4
．． 1 mo of 4'-biphenyltetracarboxylic dianhydride
1 reaction to obtain a solution of a polyimide precursor. This solution is cast onto a glass plate to form a film, which is dried with hot air, and finally heated at 300°C for 5 hours to complete the imidization reaction, forming a polyimide film with a thickness of 50 μm. Obtained.

The light transmittance (wavelength: 500 nm) of this film is 82 inches, and the surface roughness on both sides is 85A1 temperature: 350°C.
The heat shrinkage rate was 2% or less.

Using the thus obtained colorless and transparent polyimide film as a substrate, an amorphous silicon solar cell was produced according to the following procedure.

One side of the substrate is coated with a thickness of 600 mm by sputtering.
The ITO conductive thin film of A was provided, and the substrate with this ITO conductive thin film was held in a holder equipped with a heater in an internal electrode type high frequency (13,56 MHz) glow discharge device.
After keeping the temperature around 0°C, silane diluted with hydrogen to 10 molar and diborane diluted with hydrogen to 5,000 pPm were mixed (82H6/ (5iHa + B2H6) =
A 200A p-type crystalline silicon substrate was prepared by applying LOW high-frequency power under a vacuum of 0.2 Torr to dope t-iodine onto the substrate. Layers were provided. Subsequently, only the above hydrogen-diluted silane was introduced and the same reaction was carried out to deposit a non-doped i-type crystalline silicon thin film with a thickness of 4500A, and further hydrogen-diluted silane and hydrogen were added. Phosphine (PHa)ta combination (PHa/(S iH4
+PHa ) = 0.5 mol %) and introduced into a glow discharge device to provide a 500A n-type valvus silicon thin film doped with phosphorus on the i-type valvus silicon thin film.

That is, IT is placed on a colorless and transparent polyimide film substrate.
Through a conductive thin film of O, p-type, 1-type, n-type amorphous
A photoelectric conversion element consisting of a 771J film was formed.

Next, this was held in a vacuum evaporation apparatus, and a conductive thin film made of aluminum having a thickness of 0.1 μm was laminated on the n-type crystalline silicon thin film by a conventional vapor deposition method.

The photoelectric conversion efficiency of the solar cell thus obtained is AM=1
, measured with a 100 mW/al solar simulator. In this case, light was irradiated from the substrate side.

The results are shown in Table 1.

Example 2 -c, 1.3bis(3-
A polyimide film with a thickness of 50 μm was obtained in the same manner as in Example 1 except that aminophenoxy)benzene was used.

The light transmittance (wavelength: 500 nm) of this film was 85 cm, the surface roughness was 70 cm on both sides, and the heat shrinkage rate at a temperature of 350°C was 2% or less.

An amorphous solar cell substrate was produced in the same manner as in Example 1 using the colorless and transparent polyimide film obtained as described above as a substrate.

The photoelectric conversion efficiency of the obtained solar cell was measured in the same manner as in Example 1, and is shown in Table 1.

Example 3 Same as Example 1 except that m-phenylenediamine was substituted with 1,4-bis(3-aminophenoxy)benzene & N,N-dimethylformamide was used instead of N,N-dimethylacetamide. A polyimide film with a thickness of 50 μm was obtained.

The light transmittance of this film (wavelength 500nm) is 83%
Also, the surface roughness was 80 on both sides, and the heat shrinkage rate at a temperature of 350°C was 2% or less.

Using the thus obtained colorless and transparent polyimide film as a substrate, an amorphous silicon solar cell substrate was produced in the same manner as in Example 1. The photoelectric conversion efficiency of the obtained solar cell was measured in the same manner as in Example 1, and is shown in Table 1.

Comparative Example 1 In order to compare the characteristics with Examples 1 to 3, the thickness was 50 μm.
A conventional amorphous silicon solar cell was prepared using a t-substrate made of a non-transparent polyimide film (Kapton H manufactured by DuPont) with a surface roughness of 80.

Note that the basic structure of this battery is the same as in Example 1.

The specific method for creating it is as follows.

That is, a layer with a thickness of 5 mm was formed on one side of the substrate by sputter deposition.
,0OOA stainless steel conductive thin film was provided. Next, using the same apparatus and under the same conditions as in Example 1, a phosphorous-doped n-type valvus crystalline silicon thin film with a thickness of 500 A and a non-doped i-type valvus crystalline silicon thin film with a thickness of 4SOO5- were deposited on the conductive thin film. and p of thickness 200A doped with boron.
A photoelectric conversion element was formed by sequentially depositing crystalline silicon thin films. Furthermore, an ITO conductive thin film having a thickness of 600λ was provided on the p-type crystalline silicon thin film by sputter deposition. Next, the photoelectric conversion efficiency of this battery was measured in the same manner as in Example 1. In this case, the light is directed to the opposite side of the substrate, that is, to the ITO
Irradiation was performed from the conductive thin film side.

Reference Example 1 An amorphous silicon solar cell having the same structure as in Example 1 was manufactured, except that Pyrex glass with a thickness of 1.00 mm was used as the substrate, and the photoelectric conversion efficiency was measured in the same manner as in Example 1.

Example 4 Using the colorless and transparent polyimide film obtained in Example 1 as a substrate, an amorphous silicon solar cell was produced according to the following procedure.

An ITO conductive thin film was formed on one side of the substrate in the same manner as in Example 1, and the temperature in the glow discharge device was lowered to 2 as in Example 1.
After maintaining the temperature around 50'C, 10 molti, 10 molti and 5,000 ppm of hydrogen were added into the glow discharge device, respectively.
A mixture of silane, ethylene and diborane diluted to 82
H6/(SiHa+C2H4)=0.5molti, C2H
4/(SiH4+C2H*)=0.8 mol%) gas was introduced and 10WO high frequency power was applied in an atmosphere with a degree of vacuum of 0.2 Torr to form a 200A thick p-type substrate doped with boron. A crystalline silicon carbide thin film was provided.

Next, by the same operation as in Example 1, a non-doped i-type valvus silicon thin film having a thickness of 4500 Å and a phosphorus-doped n-type valvulite silicon thin film having a thickness of 500 Å were provided.

That is, a photoelectric conversion element consisting of a p-type valvus silicon carbide thin film, an i-type valvus crystalline silicon thin film, and an n-type valvus crystalline silicon thin film was formed via an ITO conductive thin film. Next, an aluminum conductive thin film having a thickness of 0.1 μm was provided by the same method as in Example 1.

Photoelectric conversion efficiency of this solar cell t'AM=1.100mW
/d solar simulator.

In this case, light was irradiated from the substrate side.

The results are shown in Table 1.

Example 5 An amorphous silicon solar cell was produced in the same manner as in Example 4, except that the colorless and transparent polyimide film obtained in Example 2 was used instead of the colorless and transparent polyimide film obtained in Example 1. The photoelectric conversion efficiency of the obtained solar cell was measured in the same manner as in Example 4, and is shown in Table 1.

Example 6 An amorphous silicon solar cell was produced in the same manner as in Example 4, except that the colorless and transparent polyimide film obtained in Example 3 was used in place of the colorless and transparent polyimide film obtained in Example 1. The photoelectric conversion efficiency of the obtained thick battery was measured in the same manner as in Example 4, and is shown in Table 1.

Comparative Example 2 In order to compare the characteristics with Examples 4 to 6, the thickness was 50 μm.
A conventional amorphous silicon solar cell was fabricated using a non-transparent polyimide film with a surface roughness of 80 as a substrate.

Note that the basic structure of this battery is the same as in Example 1.

The specific method for making this battery is as follows.

Similarly to Comparative Example 1, a conductive thin film made of stainless steel with a thickness of 5,000A was placed on a substrate, and a conductive thin film made of stainless steel with a thickness of 500A (1
) Thickness 450 with n-type crystalline silicon thin film and non-doped
A 0^ i-type crystalline silicon thin film was deposited. Furthermore i
After depositing a 200^ thick p-type valvus silicon carbide thin film doped with boron in the same manner as in Example 4 on the p-type valvus silicon carbide thin film, ITO was deposited on the p-type valvus crystalline silicon carbide thin film. A conductive thin film was deposited.

The photoelectric conversion efficiency of this battery was measured in the same manner as in Example 4, and the results are shown in Table 1.

Reference Example 2 An amorphous silicon solar cell having the same structure as in Example 4 was manufactured, except that Pyrex glass with a thickness of 0.5×11 ml was used as the substrate, and the photoelectric conversion efficiency was measured in the same manner as in Example 4.

Table 1 From Table 1, solar cells that use a colorless and transparent polyimide film as a substrate and irradiate light from the substrate side use a non-transparent polyimide film substrate and irradiate light from the side opposite to the substrate. It is recognized that the photoelectric conversion efficiency is significantly higher than that of the one in which light is irradiated from the outside.

Although the above embodiment described a solar cell, the present invention
Alternatively, it can also be applied to optical sensors, etc.

(g) Effect The photoelectric conversion device of the present invention uses a colorless and transparent polyimide film as its substrate, and the substrate side is designed to irradiate light with excellent film quality, so it has higher photoelectric conversion efficiency than conventional devices. This can be significantly improved.

In addition, the substrate is made of a colorless and transparent polyimide film,
Since the substrate is flexible, photoelectric conversion devices can be manufactured continuously by continuously pulling out the substrate wound into a roll,
As a result, productivity can be improved and the manufacturing cost t- can be lowered.Moreover, the materials are inexpensive, and from this point of view as well, the manufacturing cost can be reduced.

Furthermore, since polyimide film is used for the substrate, it is heat resistant and has a low heat shrinkage rate, so distortion due to temperature changes is small.
As a result, there are fewer problems such as the photoelectric conversion elements deposited on the substrate cracking or chipping due to temperature changes.

In particular, since the substrate is made of a colorless and transparent polyimide film and is electrically insulating, when forming a solar cell using the substrate, it is difficult to directly connect multiple solar cell elements on the same substrate. Parallel connections are possible, and various types of solar cells can be manufactured easily.

Claims (1)

[Claims] (1) In a photoelectric conversion device that has a photoelectric conversion element that converts light energy into electrical energy on a substrate, the substrate has a general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (I) [However, X_1 ~X_4 is H, CH_3, C_2H
_5, NO_2; F, Cl or COOH, which may be the same or different. ] and/or ▲ Numerical formulas, chemical formulas, tables, etc. ▼... (II) A photoelectric conversion device characterized by being formed of a polyimide film containing polyimide as a main component having a repeating unit represented by the following.