JPH01119072A - Manufacture of flexible photoelectric conversion element - Google Patents

Abstract

PURPOSE:To reduce or eliminate heat shrinkage and to prevent generation of curl of a flexible photoelectric conversion element when temperature is cooled down to a room temperature by allowing an electrical insulation layer with nearly the same thermal coefficient of expansion as a transparent plastic substrate to join a semiconductor layer at high temperature through a rear surface electrode layer. CONSTITUTION:A film is continuously formed by casting a solution of polyimide precursor to a support consisting of a roll-like copper box. A semiconductor layer with photoconductivity consisting of p-type-i-type-n-type amorphous silicon thin film is formed on an colorless and transparent polyimide film substrate through a conductive thin film of ITO. Then, it is retained within a high-vacuum metal deposition device and an aluminum rear surface electrode layer with a thickness of 0.1mum is built up on an n-type amorphous silicon thin film. Then, an electrical insulation layer is formed by changing into imide and the support is eliminated by performing etching to obtain a flexible photoelectric conversion element consisting of a substrate, a transparent electrode layer, a semiconductor layer, a rear surface electrode, and an electrical insulation layer. The flexible photoelectric conversion element thus obtained is flat in terms of appearance and does not produce curl.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Industrial Application Field The present invention relates to a method for manufacturing a flexible charge conversion element, and in particular to a method for manufacturing a flexible photoelectric conversion element using transparent plastic as a substrate.
Regarding JI dispatch method.

(b) Prior Art Photoconductive elements, photodiodes, solar cells, e) transistors, photothyristors, and the like are known as photoelectric conversion elements that input light and output electricity.

Semiconductors having photoconductivity are used in these photoelectric conversion elements, and among them, those using amorphous silicon are inexpensive and widely used as solar cells or optical sensors.

For example, in a solar cell, p-type, i-type, and p-type amorphous silicon are sequentially deposited in thin films on a substrate made of a metal plate that also serves as an electrode, and then a transparent electrode layer is formed on top of the Nfr4 amorphous silicon.
Alternatively, a transparent electrode layer, p-type crystalline silicon, i-type crystalline silicon, and n-type crystalline silicon are sequentially deposited on a substrate made of a glass plate, and further a metal electrode layer made of aluminum or the like. Those with an Mt layer have been put into practical use.

The substrate that also serves as the metal electrode layer is made of, for example, a foil or thin plate of stainless steel, aluminum, copper, etc., and the transparent electrode layer is made of, for example, tin oxide, indium oxide, or the like.

In the former case, which uses a metal substrate, the electric resistance of the substrate is sufficiently low, so a large output can be obtained from a substrate of a fixed area.

In addition, in the latter case where a glass plate is used as a substrate, since the substrate has insulating properties, it is possible to obtain more than twice the voltage by arranging multiple semiconductors adjacent to each other and connecting them in series with a conductor. It's extremely easy.

By the way, solar cells using such amorphous silicon (referred to as amorphous silicon solar cells) are currently undergoing efforts to reduce material costs, be lighter, thinner, etc., as well as improve production processes and The use of flexible substrates has been proposed in order to facilitate handling during transportation and reduce production costs, transportation costs, and the like.

For example, it has been proposed that a heat-resistant plastic film such as a polyimide film is used as a substrate, and a metal electrode layer such as a whistle or membrane made of stainless steel W4, an amorphous silicon layer, and a transparent electrode layer are laminated on this substrate. (For example, JP-A-54-149489, JP-A-55-4994, JP-A-55-29154, JP-A-57-10)
3839, etc.).

This type of amorphous silicon solar cell is lightweight, thin, and has low material cost, and is highly flexible, so it can be rolled into a roll and processed continuously to reduce production and transportation costs. It is very advantageous in reducing

Furthermore, since it can be formed into any shape, it is expected to have a wide range of applications and uses.

(c) Problems to be Solved by the Invention However, to date, amorphous silicon solar cells using heat-resistant plastic films such as polyimide films as substrates have not met with high expectations. However, it has not been put into practical use due to the following problems.

That is, during manufacturing, curling occurs on the substrate film when the substrate film is heated to an elevated temperature, and curling occurs on the product due to the difference in thermal expansion coefficient between the substrate film and the amorphous silicon layer. ing.

In addition, the occurrence of such curls not only poses a problem in terms of handling, but also causes a problem in that the photoelectric conversion efficiency is reduced due to the occurrence of curls.

Furthermore, if such curling becomes extreme, cracks will occur in the amorphous silicon layer, resulting in disconnection, reducing reliability.

By the way, at higher temperatures than polyimide film (250 ~
If an aromatic polyimide film with a high initial Young's modulus at 350°C is used for the substrate, the initial Young's modulus at high temperatures will be improved, but the thermal shrinkage at 300°C will be lower than that of conventional products. While it is 0.5%, that of aromatic polyimide film is less than 0.7%.
Since it is about one order of magnitude larger than that of the semiconductor layer, curling of the product cannot be prevented.

The method for manufacturing a flexible photoelectric conversion element according to the present invention was made in consideration of the above-mentioned circumstances associated with the method for manufacturing a flexible photoelectric conversion element using a transparent plastic having heat resistance and electrical insulation properties as a substrate. The object of the present invention is to provide a method for manufacturing a flexible photoelectric conversion element that can prevent curling of the product.

The method for manufacturing a flexible photoelectric conversion element according to the present invention includes a step (A) of forming a transparent plastic substrate having heat resistance, visibility, and electrical insulation on the surface of a support; and the step (A). ) A step (B) of laminating a transparent electrode layer on the surface of the substrate formed in step (B), and a step of forming a photovoltaic semiconductor layer on the surface of the transparent electrode layer formed in step (B) above. (C), a step <D> of forming a back electrode layer on the surface of the semiconductor layer formed in the above step (C), and a step <D> of forming a back electrode layer on the surface of the back electrode layer formed in the above step (D); Step (E) of forming an electrically insulating layer having heat shrinkage characteristics equivalent to that of , and having heat resistance and flexibility;
) to step (F) of removing it from the visible photoelectric conversion element obtained through steps (E) in this order.

In other words, the present invention relates to a method for using a flexible photoelectric conversion element, and in the present invention, a flexible photoelectric conversion element is a photoelectric conversion element that inputs light and outputs electricity, and is visible. It includes everything that has properties, and specific examples include photoconductive elements, photodiodes, solar cells, phototransistors, and photocyclists. Furthermore, the light referred to here includes not only visible light but also infrared and ultraviolet rays.

The present invention will be explained in detail below.

In the present invention, first, the step (A) of forming a transparent plastic substrate having heat resistance, flexibility, and electrical insulation properties on the surface of a support is carried out.

The transparent plastic constituting the substrate is not particularly limited as long as it has heat resistance, flexibility, and electrical insulation properties, and typical examples include polynythiol 7-one etherimide, 4-methyl Films such as pentene terephthalate may be mentioned.

Among these, in particular, the following general formula (1) or (II),
Alternatively, a polyimide film mainly composed of polyimide having repeating units represented by (I) and (II) is particularly recommended since it has good heat resistance and light transmittance.

That is, this polyimide film has a visible light (500nLL1
) If the transmittance is 70% or more and the yellow index is 40 or less, increase by +11.

It should be noted that the term "main component" as used herein means that the entire component corresponds to the above general formula (1
) and/or (II) only.

And/or such a transparent polyimide film substrate can be prepared by, for example, producing a colorless transparent polyimide film substrate having excellent heat resistance, visibility, and electrical insulation on the surface of the support by the following process. is formed as.

That is, such a polyimide film substrate is obtained by reacting biphenyltetracarboxylic dianhydride represented by the general formula (I[) with aromatic diamino compounds represented by the general formulas (IV) and (V). It will be done.

The support used in this step (A) includes zinc, tin,
Thin plates or foils made of metals such as copper and aluminum or alloys containing these as main components are used.

The thickness of this support is conveniently in the range of 5 to 500 .mu.m, preferably 10 to 300 .mu.m, considering the strength and the difficulty of removal by etching.

Among these, aluminum or copper metal foil is most suitable for performing each process continuously.

In this case, the thickness of the aluminum foil is 5 to 500 μm.
m, particularly preferably in the range of 10 to 300 μm,
In addition, the thickness of the copper foil is 5 to 500 μm, especially 10 to 3 μm.
It is desirable to set it in the range of 00 μm.

As described above, when copper foil or aluminum foil is used as a support, if the thickness is too thick, it becomes difficult to carry out each step continuously or to etch the support in the final step.

On the other hand, if it is too thin, it will lack the rigidity as a support.
Curling occurs after forming the substrate and during forming the semiconductor layer.

However, even if the substrate curls inward at room temperature, the substrate layer will thermally expand and curl at the semiconductor layer formation temperature (for example, around 250°C, which is convenient for depositing amorphous silicon in the glow discharge method). It is desirable to make adjustments so that the
A resin solution for forming a substrate coated on a support (for example,
It is very advantageous to keep the temperature for formation using a polyimide precursor solution and the semiconductor layer deposition (formation) temperature close to each other.

At room temperature, curling can be forcibly prevented by winding it into a roll or applying tension.

Note that after this step (A) and prior to step (B) described later, if the surface of the transparent plastic substrate is processed to have an uneven shape by honing, chemical treatment, etc., the incident light on this surface will be This is advantageous in inducing diffuse reflection of light, reducing the reflection, and expanding the optical path in the semiconductor layer, which is advantageous in improving photoelectric conversion efficiency.

Furthermore, if silica powder, calcium carbonate powder, or calcium silicate powder is added to the transparent polyimide precursor or its solution in advance, these particles will form irregularities on the surface after film formation, which will prevent incident light from entering. can induce diffuse reflection.

A step (B) of laminating a transparent electrode layer on the surface of the substrate formed in the above step (A) is performed.

In this step (B), a transparent electrode layer is formed on the substrate by a method such as sputtering, vapor deposition, or printing.

The thickness of the transparent electrode layer is not particularly limited, but
For example, if there are 500 to 5,000 people, there will be a lot of heat. If the thickness of the transparent electrode layer becomes too thin, the desired conductivity (surface resistance of 1000 Ω/mouth or less) cannot be obtained, which is undesirable.On the other hand, if it becomes too thick, the transparency of the transparent electrode layer may decrease. So I don't like it.

In addition, when forming multiple cells on one substrate,
For example, unnecessary portions of the transparent electrode are removed by a technique such as 7-etching.

The transparent electrode layer may be made of a known material, such as tin oxide, indium oxide, or a solid solution of both (
ITO), etc.

In the present invention, a step (C) of forming a photovoltaic semiconductor layer on the surface of the transparent electrode layer on the substrate formed in the step (B) is performed.

In this step (C), the semiconductor layer may be continuously formed while transporting the laminated sheet obtained in the above step (B), but the laminated sheet may be cut and the semiconductor layer formed one by one. It may be formed.

The semiconductor constituting the semiconductor layer is not particularly limited as long as it has photovoltaic properties, and examples include infrared ray derma (Ge), selenium (Se), indium antimony (InSb), Cadmium sulfide (CdS), cadmium selenide (CclSe) for radiation and visible light.
), silicon for visible light (S i ), etc. are listed as examples.

Furthermore, cadmium chloride (CdCN2), copper chloride (CuC12), and silver salts may be freely used as active impurities in these semiconductors.

For example, it is advantageous to deposit p-type valvate silicon, i-type valvate silicon, and n-type valvate silicon in sequence in order to reduce the thickness of the semiconductor layer.

Furthermore, various methods such as a glow discharge method and a photo-CVD method can be employed to sequentially deposit the p-type valvus silicon layer, the l-type valvate silicon layer, and the n-type valvate silicon layer.

For example, if we take the case of adopting the glow discharge method as an example and explain it specifically, the temperature will be around 250℃ (200~350℃).
) The substrate on which the transparent electrode layer was formed was held in a holder heated to
5+000 ppr with silane and hydrogen diluted to about 0 mol%
A mixture of diborane diluted to about m [B2H6/ (S
iH4+ B2H6) = 0.1 to 0.6 mol%, preferably about 06363 mol%, is injected at a total flow rate of 11003 CC, and in that atmosphere, the holder is used as one electrode, and 13. 56MHz, I
A p-type crystalline silicon layer doped with boron is deposited to a thickness of 200 mm on the transparent electrode layer by applying high frequency power of approximately OW.

Subsequently, only hydrogen diluted silane was added at a total flow rate of 11008C.
An undoped i-type crystalline Schiffen layer was deposited in the same manner as described above under the atmosphere introduced at C, and further deposited with hydrogen-diluted silane and hydrogen for 5,000 nm.
A mixture of 7 osphin (PH3) diluted to 0 ppm [
P H3/ (S iH-+ P Hz) = 01~0
．． 6 mol%, preferably 0.3 mol%] at a total flow rate of 110
A phosphorus-doped n-type crystalline silicon layer is similarly deposited to a thickness of 500 nm under the atmosphere introduced in 08CC.

By the way, for convenience, p is used as a photovoltaic semiconductor layer.
-1-Although we have explained using the example of n-type amorphous silicon,
In addition to amorphous silicon, the p layer contains p-type amorphous silicon carbide (the film composition is 5ixC, -x, where X=0.6 to 0.
95, preferably with x=0.8 or so, noborane B2H,
membranes doped with etc.) can also be used. In this case, the carbonization source used is a saturated hydrocarbon such as methane or ethane, or an unsaturated hydrocarbon such as ethylene or propylene.

The molar ratio of silane (S iH4) or disilane (Si28s) used as the raw material gas and the above-mentioned hydrocarbons is determined as follows.

That is, for example, to produce a film with a film composition of S io, sCo, 2, the molar ratio of S i H+ and CH, 0.8N0.2 (
Also, 5i2Ha and CH, 0.4 vs. 0.2), SiH
, and 0.8 vs. 0.1 for C2H6, Si2Hg and C2H
, the molar ratio is determined from the number of Si atoms and the number of C atoms in the source gas, such as 0.4 to o, i.

In the present invention, a step (D) is performed in which a back electrode layer is further laminated on the semiconductor layer thus obtained.

The back electrode layer may be made of tin oxide, indium oxide, or a solid solution of both (ITO), etc., like the transparent electrode layer laminated between the substrate and the semiconductor layer, and may also be made of aluminum, It may be made of metal such as nickel, titanium, chromium, iron, stainless steel, nickel-chromium, or the like.

The back electrode layer is formed into a shape 1'# by a method such as a printing method, a sputtering method, or a vapor deposition method. For example, in the case of a vapor deposition method, it is carried out in a vacuum of 10<-4> to I Torr under the condition that the temperature of the vapor deposition source is near the melting point of the material used.

The thickness of the back electrode layer is not particularly limited, but it needs to be within a range that does not significantly reduce the flexibility of the entire flexible photoelectric conversion element and is at least thick enough to have the required conductivity. For example, in the case of an aluminum back electrode layer, approximately 0.1 μm is considered appropriate.

In this way, the support has heat resistant, flexible and electric J8
A charge conversion element (solar cell) is formed by laminating a transparent electrode layer, a semiconductor layer made of p-type-1-n-type valve crystalline silicon, and a back electrode layer on a substrate made of transparent plastic.

In this case, if the support is made of a transparent material, the characteristics of the charge conversion element can be evaluated by allowing light to enter from the support plate side at this stage.

In the present invention, next, on the surface of the back electrode layer formed in the above step (D), an electrical insulating layer having heat shrinkability equivalent to that of the above substrate, and having heat resistance and flexibility is provided. Step (E) of forming is carried out.

In the method for manufacturing a flexible photoelectric conversion element of the present invention, one of the important features is that from the above step (A) to the step (Il!l)
An electrical insulating layer is further laminated on the back electrode layer laminated through the steps except for the space for electrode terminal attachment.

This electrical insulating layer must have electrical insulation, heat resistance, and visibility, and must also have heat shrinkage characteristics equivalent to those of the substrate.

As described in a, this electrical insulating layer generates stress that curls in a direction that cancels the curl caused by the difference in thermal contraction rate between the substrate and the semiconductor layer due to the difference in thermal contraction rate between this and the semiconductor M. It is something.

That is, for example, in the case where the semiconductor layer is composed of a p-type-1-n-type crystalline silicon layer, curling of the flexible photoelectric conversion element or the semiconductor layer due to the difference in thermal shrinkage rate may occur. If the radius of curvature of becomes smaller than 40av+, cracks will occur in the semiconductor layer, so the coefficient of thermal expansion of the substrate is α, the coefficient of thermal expansion of the electrically insulating layer is α2, the sum of the thickness of the substrate and the thickness of the electrically insulating layer. If h(IIlm) is h(IIlm), the temperature difference between the amorphous silicon deposition temperature and room temperature is 8T, and the temperature difference between the electrical insulating layer formation temperature and room temperature is ΔT2, then it is necessary to satisfy the following.

Most preferably, the substrate and the electrical insulating layer are made of exactly the same material and have the same shape and size (same thickness).

For example, by casting the same polyimide precursor solution as when forming the substrate onto the back electrode layer to form a film and drying it with hot air to completely carry out the imidization reaction, it is possible to It is possible to form an electrically insulating layer 1&layer that has insulation, heat resistance, and flexibility, and also has heat shrinkage characteristics equivalent to that of the substrate.

In the present invention, finally, a step (F) is performed in which the support is removed from the visible photoelectric conversion element obtained through the above steps (A) to (E) by etching treatment.

In this step (F), the support is removed from the flexible photoelectric conversion element formed through the above steps by etching treatment, so that the transparent electrode layer, the semiconductor layer, and the back electrode layer are transparent on the transparent electrode layer side. A flexible photoconductive element having a laminated structure sandwiched between a plastic substrate and an electrically insulating layer on the back electrode side is obtained.

The thus obtained flexible photoelectric conversion element is prevented from curling by forming the electrically insulating layer.

The manufacturing method of the present invention has the greatest feature in etching treatment, that is, chemically removing the support, and the conditions for this etching treatment are usually those for etching fA foil or aluminum foil. ,used. For example, an acidic etching solution such as ferric chloride, copper chloride, or ammonium superphosphate, or an alkaline etching solution such as an ammonium salt or an ammonia complex may be sprayed onto the etching solution using a spray etcher. The support can be removed by immersion.

(e) Function As described above, the present invention has a laminated structure in which a transparent electrode layer, a semiconductor layer, and a back electrode layer are sandwiched between a transparent plastic substrate on the transparent electrode layer side and an electrical insulating layer on the back electrode layer side. V1 manufacturing method for a flexible photoelectric conversion element, in which the thus obtained flexible photoelectric conversion element is formed at a high temperature, and then when cooled to room temperature, the charge conversion element is attached to a substrate with a large coefficient of thermal expansion. In contrast to the internal thermal contraction force that tends to curl the substrate, by bonding the electrical insulating layer, which has almost the same coefficient of thermal expansion as the substrate, to the semiconductor layer via the back electrode layer at a high temperature, When the photoelectric conversion element is cooled down, a thermal contraction force is generated inside the photoelectric conversion element that tends to curl it toward the electrical insulating layer having a large coefficient of thermal expansion.

As a result of these thermal contraction forces trying to curl the visible photoelectric conversion element in opposite directions canceling each other out, the apparent thermal contraction force trying to curl the flexible photoelectric conversion element does not decrease. This has the effect of preventing curling of the flexible photoelectric conversion element.

Further, according to the method for producing a photoelectric conversion element of the present invention, in order to produce the photoelectric conversion element that prevents the occurrence of curling, a support having a suitably balanced rigidity is selected and used, and this is wound into a roll. It is possible to manufacture a visible photoelectric conversion element by continuously rolling out this element, and it also prevents the occurrence of curling during this manufacturing process, has excellent charge conversion efficiency, and is capable of producing highly reliable visible photoelectric conversion elements. This has the effect of providing a photoelectric conversion element with a high level of photovoltaic properties.

In addition, the manufacturing process of the present invention does not involve mechanically peeling off the support, but chemically removing it.
This has the effect of allowing the support to be removed without causing distortion or damaging the photoelectric conversion element body due to mechanical stress during removal of the support.

(f) Examples Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not limited thereto.

Example 1 Using N,N-trimethylacetamide as a solvent, 39
3'-97minodiphenylsul7one! For 3.3
'4.4'-biphenyltetracarboxylic dianhydride 1
A mo1 reaction was carried out to obtain a solution of a polyimide precursor. This solution was cast onto a support made of rolled copper foil with a thickness of 90 μm to form a film continuously, and this film was dried with hot air and further heated at 300°C for 1 hour to complete the imidization reaction. A transparent plastic substrate made of a polyimide film having a thickness of 50 μm was formed on the support.

The light transmittance (wavelength: 500 nm) of this film is 85%, and the degree of yellowness (yellow index) is 2.
It was 5.

Next, a film with a thickness of 600 mm was coated on the surface of the transparent polyimide film substrate with the support still attached by sputtering.
A transparent electrode layer made of ITO was continuously provided, and the substrate with the transparent electrode layer was subjected to an internal electrode type high frequency wave (13.
5 6MHz) It is held in a holder with a heater in a glow discharge device, and after keeping the temperature around 250℃, it is heated with hydrogen.
Silane diluted to 0 mol% and 5,000 ppm hydrogen
Mix noborane diluted to [B 2H a/ (S i
H 4+ B 2H g) = 0.

3 mol%] was introduced into a 100SCCM glow discharge device as a total flow rate, and high frequency power of IOW was applied in an atmosphere with a degree of vacuum of 0.2 Torr to form a sample of 200 people doped with boron on the substrate. A crystalline silicon layer was provided.

Subsequently, only the above hydrogen-diluted silane was introduced and a similar reaction was carried out to deposit a non-doped I-type valvous silicon thin film with a thickness of 4500 nm on the above-mentioned p-type valvate silicon layer, and further hydrogen dilution was performed. 5,000ppm of silane and hydrogen
EP Hs/
(S rH − 10 P Hz) = 0, 5 mol% 1, and a total flow rate of 1008 CCM was introduced into the glow discharge device to dope the i-type crystalline silicon thin film with phosphorus.
An n-type crystalline silicon thin film was formed. .

That is, IT is placed on a colorless and transparent polyimide film substrate.
A photoconductive semiconductor layer consisting of an n-type-n-n-type amorphous silicon thin film was formed via an O conductive thin film.

Next, this was held in a vacuum evaporation apparatus, and an aluminum back electrode layer having a thickness of 0.1 μm was laminated on the n-type crystalline silicon thin film by a normal evaporation method.

Next, with the support still attached, a polyimide precursor solution similar to the polyimide precursor solution for the substrate is cast on the back electrode layer, except for the electrode terminal portion, to a thickness similar to that of the substrate. An electrical insulating layer was formed by forming, drying with hot air, and further heating at a temperature of 200° C. for 5 hours to completely imidize.

Further, the support was removed by spraying and etching with a ferric chloride-based etching solution at 40°C, and a flexible structure consisting of the substrate, transparent electrode layer, semiconductor layer, back electrode layer, and electrical insulating layer was formed. A photoelectric conversion element was obtained.

The flexible photoelectric conversion element thus obtained had a completely flat appearance and no curling occurred.

This photoelectric conversion efficiency was 4.1%.

Further, this light receiving element was visible, and no decrease in photoelectric conversion efficiency was observed even when it was curved to a radius of curvature of 4 cm.

Example 2 Regarding the flexible photoelectric conversion element semi-finished product in which an aluminum back electrode layer was formed on the n-type crystalline silicon layer of Example 1, an epoxy resin having the following compounding ratio was applied to the back electrode layer side. was applied to a thickness of 50 μm using an applicator.

Compounding ratio Bisphenol A type epoxy resin 60 parts (Yuka Shell Epoxy Co., Ltd., Ebiko Co., Ltd.) 828) 1.6-hexanool diglycidyl ether 12 parts (Itamoto Yakuhin Co., Ltd. SR-16H) Flexible epoxy resin m s part (Itamoto Pharmaceutical Co., Ltd. SR-PTMG) Aromatic amine 20 parts (Itamoto Pharmaceutical Co., Ltd. SDA-07) Next, this was preliminarily dried with hot air at a temperature of 90°C for 2 hours, and then further A flexible charge conversion element obtained by keeping the epoxy layer in a hot air dryer set at a temperature of 150°C for 3 hours to harden the epoxy layer to form an electrical insulating layer, and then removing the support by etching in the same manner. The appearance was completely flat and no curls were observed.

Moreover, the content of this flexible photoelectric conversion element was 4.0%.

Further, even when this flexible photoelectric conversion element was curved to a radius of curvature of 4 cm, no decrease in charge conversion efficiency was observed.

Comparative Example 1 A conventional commercially available polyimide film (manufactured by DuPont, trade name: Kapton H) with a thickness of 50 μm was used as a substrate.
) was dried at a temperature of 110° C. for 30 minutes and then kept in a sputtering device to form a stainless steel back electrode layer with a thickness of 1000 μm on one side.

Next, the film was held in the same glow discharge device as used in Example 1 and heated to a temperature of 250°C. Since curling occurred, the film was held under tension and the phosphorus-doped E A layer of n-type crystalline silicon with a thickness of 500 mm, an undoped I-type crystalline silicon layer with a thickness of 4,500 mm, and a p-type crystalline silicon layer doped with boron and a thickness of 200 mm. The growth conditions for each layer were the same as in Example 1,
In addition, they were formed in the same order as in Example 1.

However, when the film in which the back electrode layer and the semiconductor layer were combined in this manner was taken out at room temperature, significant curling occurred with the polyimide film inside.

Next, the film was kept under tension in the same sputtering apparatus used in Example 1, and a transparent electrode layer of 600 nm thick ITO was formed on the p-type crystalline silicon layer.

The charge conversion element thus obtained was neatly curled with the substrate facing inside.

When this photoelectric conversion element was forcibly stretched and the photoelectric conversion efficiency was measured, cracks occurred in the amorphous silicon layer and internal wires were broken, indicating that most of the cells had no photovoltaic ability. could not be confirmed.

For some samples that escaped disconnection, the conversion efficiency was 1.3~
It was 2.1%.

Comparative Example 2 Regarding the photoelectric conversion element semi-finished product (semi-finished product with glass support) in which an aluminum back electrode layer was formed on the n-type crystalline silicon thin film of Example 1, Fi
, 75μ thick through 75μ thick acrylic adhesive layer
After laminating a polyethylene terephthalate film of 300 m in size, the film was immersed in water at room temperature for 1 hour and peeled off from the support to produce a photoelectric conversion element.

The photoelectric conversion element thus obtained had a radius of curvature of 3 cm.
The film was curled in a strange way, and when the film was forcibly stretched and the charge conversion efficiency was measured, most of the cells were A-line.

Example 3 The treatment was carried out under the same conditions as in Example 1, using an aluminum foil with a thickness of 150 μm as the support.

However, although the formation of the polyimide film substrate and the formation of the transparent electrode layer made of ITo were carried out continuously in the form of a roll, the formation of the amorphous silicon layer was carried out in the form of a single plate.

When the intermediate material laminate was cut into a single plate before being treated with a glow discharge device, it curled to a radius of curvature of about 100 cm when the force was released, but when heated to an amorphous deposition temperature of 250°C. It became flat.

Thereafter, the same treatment as in Example 1 was performed, and the photoelectric conversion efficiency was 4%.
A curl-free flexible photoelectric conversion element was obtained.

(g) Effects of the invention The present invention provides a flexible laminated structure in which a transparent electrode layer, a semiconductor layer, and a back electrode layer are sandwiched between a transparent plastic substrate on the transparent electrode layer side and an electrical insulating layer on the back electrode layer side. This is a method for manufacturing a flexible photoelectric conversion element, in which a flexible photoelectric conversion element is formed at high temperature and then cooled to room temperature, the thermal contraction force that tends to curl the photoelectric conversion element toward a substrate having a large coefficient of thermal expansion. occurs internally, whereas the electrical insulating layer, which has a coefficient of thermal expansion almost equal to that of the substrate, acts in a direction to cancel out the thermal contraction force, so that the appearance of curling the flexible photoelectric conversion element becomes worse. Thermal shrinkage force is reduced or eliminated, and curling of the flexible photoelectric conversion element is prevented. Therefore, a flexible photoelectric conversion element with excellent photoelectric conversion efficiency and high reliability can be produced. It has the effect that can be obtained.

Further, according to the method for manufacturing a flexible photoelectric conversion element of the present invention,
It is possible to manufacture a flexible photoelectric conversion element by winding the support into a roll and continuously unrolling the support, and moreover, it is possible to prevent curling of the flexible photoelectric conversion element during this manufacturing process. This has the effect of significantly improving productivity.

In addition, in the manufacturing process of the present invention, the support is not mechanically and forcibly peeled off or removed, but is chemically removed, so photoelectric conversion is performed when the support is removed. There is no distortion in the element body or damage to the photoelectric conversion element body due to mechanical stress, and from this point of view as well, a highly reliable flexible photoelectric conversion element can be obtained.

Claims (5)

[Claims] (1) Step of forming a transparent plastic substrate having heat resistance, flexibility and electrical insulation on the surface of the support (A
), a step (B) of laminating a transparent electrode layer on the surface of the substrate formed in the above step (A), a semiconductor having photovoltaic properties on the surface of the transparent electrode layer formed in the above step (B) a step (C) of forming a layer, a step (D) of forming a back electrode layer on the surface of the semiconductor layer formed in the above step (C), a step (D) of forming a back electrode layer on the surface of the back electrode layer formed in the above step (D); Step (E) of forming an electrically insulating layer having heat shrinkability equivalent to that of the substrate and having heat resistance and flexibility;
) to step (F) of removing from the flexible photoelectric conversion element obtained through step (E). (2) The method for manufacturing a flexible photoelectric conversion element according to claim 1, wherein the support is an aluminum foil. (3) The method for manufacturing a flexible photoelectric conversion element according to claim 1, wherein the support is a copper foil. (4) The method for manufacturing a flexible photoelectric conversion element according to claim 2, wherein the aluminum foil has a thickness of 5 to 500 μm. (5) The method for manufacturing a flexible photoelectric conversion element according to claim 3, wherein the copper foil has a thickness of 5 to 500 μm.