JP2000196120A - Manufacture of thin-film solar battery, the solar battery, and solar battery attaching structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible lightweight solar battery at a low cost. SOLUTION: A main boy 2 of a thin-film solar battery is formed on a substrate 3 for a thin-film solar battery, having fine ruggedness sections 7 on its surface which is brought into contact with a support body 8, having fine ruggedness sections 12 on its support surface after the substrate 3 is supported by the support body 8, by engaging the fine ruggedness sections 7 and 12 of the substrate 3 and body 8 with each other. Since the front ends of the ruggedness sections 7 and 12 adhere strongly to each other by friction in a state where the front ends intersect each other, the substrate 3 hardly melts nor is deformed by heat, even if the substrate 3 is subjected to heat treatment at forming of the main body 2 of the solar battery, when the main body 2 is formed on the substrate 3 in this manner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a thin-film solar cell, a solar cell, and a structure for mounting the solar cell.

[0002]

2. Description of the Related Art A thin-film solar cell is characterized in that it can be manufactured with a smaller amount of raw materials as compared with a crystalline solar cell, and that the integration provides a degree of freedom in designing output voltage and current. Has features. Further, by selecting a base material on which the solar cell main body is mounted, light weight and flexibility can be obtained as compared with a crystalline solar cell. Furthermore, it has the feature that it can be installed in a wide range without choosing a place, and the degree of freedom of installation is increased.

Conventionally, there are a first configuration and a second configuration as a thin-film solar cell having such features. The first configuration is such that a thin-film solar cell base made of a light-transmitting insulating substrate such as glass is disposed at a cell end where light is incident (hereinafter, referred to as a light incident end), A thin-film solar cell body composed of a transparent electrode layer, an amorphous semiconductor layer, and a back electrode layer is arranged on a base material in a forward direction of a light incident direction in the described order.

[0004] In a second configuration, a base material for a thin-film solar cell made of a film substrate or a metal substrate is arranged at a battery end located on a side opposite to the light incident end, and is arranged along a direction opposite to the light incident direction. The thin-film solar cell main body including the back electrode layer, the amorphous semiconductor layer, and the transparent electrode layer is arranged on the thin-film solar cell substrate in the described order.

[0005] Solar cells are expected to be used not only for power on the ground but also as power sources for artificial satellites and airships. There is a demand for higher flexibility to be attached to members (artificial satellites and airships), and there is a demand for further weight reduction because these solar cell mounting members are flying objects.

[0006] In response to such a demand, a thin-film solar cell having the above-mentioned second configuration is considered promising.

[0007]

By adopting the above-mentioned second structure, it is possible to achieve a certain degree of weight reduction and flexibility, but to promote higher flexibility and further weight reduction. In this case, it is important to reduce the thickness of the thin-film solar cell substrate, and to promote the thinning of such a thin-film solar cell substrate, a film substrate is used as the thin-film solar cell substrate. It is desirable that the film substrate used be thinner.

However, when a thin film solar cell having the second structure is manufactured using a film substrate as a base material for the thin film solar cell, the heat generated during the formation of each layer constituting the thin film solar cell main body is used for forming the thin film solar cell. There are problems such as melting of the base material (film substrate) and deformation of the base material for thin-film solar cells due to heat and film stress during film formation. The more significant it becomes.

Conventionally, in order to solve such a problem, a method such as a roll-to-roll method for forming a thin-film solar cell main body in a state where tension is applied to a thin-film solar cell substrate composed of a film substrate is generally used. However, it is difficult to reduce the thickness of the thin-film solar cell substrate by forming each layer of the thin-film solar cell main body under a tension.

Further, in order to obtain a high conversion efficiency in a thin-film solar cell, the formation of an amorphous semiconductor layer requires 150 nm.
A high processing temperature, such as about 200 degrees to 200 degrees, is required. On the other hand, a film substrate that can be used as a base material for a thin-film solar cell and does not deform under a temperature condition of about 150 degrees under tension is a part of a polyimide-based film or a fluorine-based film. However, such a resin film is very expensive, and therefore has a disadvantage of increasing the manufacturing cost of the thin-film solar cell. For the above reasons,
Methods such as the roll-to-roll method have not substantially solved the problem.

In order to solve such problems, a thin film solar cell substrate (film substrate) is attached to a support such as glass or a metal plate, and then a thin film solar cell body is formed. It is possible to do. Then, the thin film battery substrate (film substrate) lined with the support is less likely to be melted or deformed by the heat during film formation. However, when a thin film solar cell substrate (film substrate) is attached to a support using a general adhesive,
Since it is impossible to peel the base material for the thin-film solar cell and the support, the completed solar cell is in a state where the support is attached, which makes it impossible to obtain flexibility and weight reduction. Therefore, even in this configuration, it cannot be said that the problem has been substantially solved.

[0012]

The present invention achieves the above-mentioned object by the following means.

In the invention according to claim 1 of the present invention, a support having fine irregularities formed on a support surface and a base material for a thin film solar cell having fine irregularities formed on a surface in contact with the support are provided. Is prepared, and the minute irregularities are engaged with each other,
After supporting the thin-film solar cell substrate with the support,
The present invention is characterized in that a thin film solar cell main body is formed on the thin film solar cell base material, and thereby has the following operation. That is, in the state where the contact surfaces of the thin film solar cell substrate are in contact with the support surface of the support, pressure is applied to these surfaces in the contact direction, so that the tips of the minute irregularities are brought together. They cross each other and adhere strongly by friction. In this state, if the thin-film solar cell main body is formed on the thin-film solar cell base material, even if a heat treatment is performed at the time of forming the thin-film solar cell main body, melting and deformation of the thin-film solar cell base material due to the heat do not occur. Less likely to happen.

According to a second aspect of the present invention, there is provided the method for manufacturing a thin-film solar cell according to the first aspect, wherein the base material for the thin-film solar cell comprises a resin to which fine particles are added. While using a substrate, on the thin film solar cell substrate, a back electrode layer, an amorphous semiconductor layer, and characterized in that a thin film solar cell body composed of a transparent electrode layer is formed in this order, This has the following effect. That is, on the surface of the base material for a thin film solar cell made of a resin to which fine particles are added, extremely small irregularities smaller than the aforementioned minute irregularities are present. If each layer of the thin-film solar cell main body is formed on the thin-film solar cell substrate having such minimal irregularities, similar minimal irregularities are formed on the surface of each layer, especially on the back electrode layer. . On the other hand, if a thin film solar cell body composed of a back electrode layer, an amorphous semiconductor layer, and a transparent electrode layer is formed in this order on a thin film solar cell substrate, such a thin film solar cell can be formed from the transparent electrode layer side. Light that has not been absorbed by the amorphous semiconductor layer after being incident is reflected by the back electrode layer and then absorbed again by the amorphous semiconductor layer. Here, as described above, extremely small irregularities are formed on the back electrode layer, so that the reflected light is diffused by the extremely small irregularities at the time of reflection, and the optical path length is extended. The light absorption efficiency of the layer is improved and the short-circuit current value is increased, resulting in high conversion efficiency.

According to a third aspect of the present invention, there is provided a method of manufacturing a thin film solar cell according to the first or second aspect, wherein the thin film solar cell body is formed on the thin film solar cell substrate. The feature is that the support is separated from the base material for the thin-film solar cell against the engagement of the fine irregularities, thereby having the following effects.
In other words, since the tips of the microscopic irregularities only alternately cross each other and are bonded by friction, it is not possible to separate the support from the thin-film solar cell base material against the adhesive force. It can be done relatively easily. The thin-film solar cell separated from the support is less likely to be melted or deformed, so that the thin-film substrate can be made thinner, so that the weight is reduced and the flexibility is improved.

The invention according to claim 4 of the present invention is characterized in that minute irregularities are formed on the external bonding surface to constitute a solar cell, and thereby has the following effects. That is, if a member having fine irregularities similar to the above minute irregularities is used as the solar cell mounting target member, the solar cell can be easily and reliably attached and detached by engaging the minute irregularities. Can be attached to the solar cell attachment target member.

According to a fifth aspect of the present invention, there is provided a solar cell according to the fourth aspect, wherein the external bonding surface is provided on a cell end located on a side opposite to a light incident end of the solar cell. This has the following effects. That is, since the minute unevenness is not arranged on the light incident end side, the incidence of light is not hindered by the minute unevenness.

According to a sixth aspect of the present invention, there is provided a solar cell mounting target member having fine irregularities on a surface, and a solar cell having fine irregularities on an external bonding surface in contact with the solar cell mounting target member. The feature is that the solar cell is attached to the solar cell attachment target member by engaging the minute unevenness with each other, thereby having the following operation. In other words, by engaging the small irregularities, the solar cell can be easily and reliably attached to the solar cell attachment target member in a detachable manner. In addition, the solar cell can be securely mounted even on a solar cell mounting target member having a curved mounting surface.

According to a seventh aspect of the present invention, there is provided the solar cell mounting structure according to the sixth aspect, wherein each of the fine irregularities has a height difference between a top and a bottom of 50 μm to 2 μm.
mm, which has the following effect. That is, by setting the height difference between the top and the bottom of the minute unevenness in such a range, the solar cell can be securely mounted on the solar cell mounting target member.

[0020]

An embodiment of the present invention will be described below in detail with reference to the drawings.

A thin-film solar cell 1 according to one embodiment of the present invention
Is a light incident end 1a of the thin-film solar cell 1 as shown in FIG.
And a thin film solar cell main body 2 and a thin film solar cell substrate 3 along the forward direction of the light incident direction α. The thin-film solar cell main body 2 includes a transparent electrode layer 4, an amorphous semiconductor layer 5, and a back electrode layer 6 along the forward direction of the light incident direction α. The transparent electrode layer 4 is made of, for example, ITO, SnO ₂ , and ZnO. Although not shown, the amorphous semiconductor layer 5 is configured by laminating a p-layer, an i-layer, and an n-layer. The back electrode layer 6 is made of, for example, A
g or a laminate of Al and ZnO. As the thin film solar cell substrate 3, for example, a film substrate made of a vinyl chloride-based, polyester-based, polyimide-based, fluorine-based, or acrylic-based resin material can be used. Since the substrate is relatively expensive, it is desirable to select a film substrate made of another resin material. Thin-film solar cell substrate 3 facing solar cell end 1b facing light incident end 1a
Are formed on the end surface (which will be a contact surface to a support 8 described later and an external bonding surface). As shown in FIG. 2, minute irregularities 7 are innumerably (eg, 100 to 100 per cm ²⁾ on the end surface of the thin film solar cell substrate 3.
The height difference 7a between the top and the bottom is set to about 50 μm to 2 mm.

Next, an example of a method for manufacturing the thin-film solar cell 1 will be described.

First, a thin film solar cell substrate 3 is prepared.
The thin film solar cell substrate 3 can be formed of a film substrate made of a resin such as a vinyl chloride-based, polyester-based, polyimide-based, acrylic-based, or fluorine-based resin. In this example, the base material 3 is formed of an acrylic-based resin. Use a film substrate. One surface of the thin-film solar cell substrate 3 (a contact surface to the support 8 described later and an external adhesive surface)
The minute unevenness 7 is formed in advance. The minute irregularities 7
The thin film solar cell substrate 3 can be formed simultaneously with the precision molding. As described above, the height difference 7a between the top and the bottom of the minute unevenness 7 is preferably about 50 μm to 2 mm. This is because if the thickness is 50 μm or less, or 2 mm or more, sufficient adhesiveness cannot be obtained between the support 8 and a member to which the solar cell is to be described later.

On the other hand, the support 8 is prepared in advance. The support 8 is formed by bonding a film material 10 on a glass substrate 9 with an adhesive 1
1 is attached. Further, fine irregularities 12 are previously formed on the surface of the film material 10 constituting the support surface of the support 8. The minute irregularities 12 have the same height difference 12a and formation density as the minute irregularities 7. Here, the glass substrate 9 is used as the base material on which the film material 10 is attached, but a metal substrate such as SUS or aluminum can also be used.

The thin-film solar cell substrate 3 is supported and fixed to the support 8 thus prepared. This supporting and fixing is performed by bringing the fine irregularities 7 of the thin film solar cell substrate 3 into contact with the minute irregularities 12 of the support body 8 and then contacting these minute irregularities 7, 1.
This is performed by uniformly applying pressure from outside to rollers 2 and the like. FIG. 3A is a cross-sectional view in this state.

After the thin-film solar cell substrate 3 is supported and solidified by the support 8, a substrate setting temperature 18 is applied to one surface 3 a of the thin-film solar cell substrate 3 (the surface opposite to the surface on which the fine irregularities 7 are formed).
By sputtering performed in an atmosphere of 0 degrees, a film thickness of about 5
A 00 nm Ag film is formed. Further, a 50 nm-thick ZnO film is formed on the formed Ag film to form the back electrode layer 6. In the present embodiment, the back electrode layer 6 is formed by sputtering, but may be formed by an evaporation method.

After that, the amorphous semiconductor layer 5 is formed on the back electrode layer 6 by a plasma CVD apparatus. Amorphous semiconductor layer 5
Is formed of a p-layer, an i-layer, and an n-layer, and the thicknesses of the respective layers are set, for example, to 20 nm, 400 nm, and 30 nm, respectively. Table 1 shows an example of the conditions for forming each layer. The substrate setting temperature is 170 degrees, and the amorphous semiconductor layer 5 having sufficient characteristics can be obtained by such setting.

[0028]

[Table 1]

Thereafter, the thin-film solar cell main body 2 is formed on the thin-film solar cell substrate 3 by forming the transparent electrode layer 4 on the amorphous semiconductor layer 5 by a sputtering method. The method for producing the transparent electrode layer 4 includes a vapor deposition method and a plasma CV method.
Method D may be used. As the transparent electrode layer 4, ITO,
SnO ₂ and ZnO can be used. The substrate set temperature at this time is 150 degrees. FIG. 3B is a cross-sectional view of the thin-film solar cell 5 formed by such a method.

As described above, the temperature at the time of forming the thin-film solar cell main body 2 is 150 ° C. or more, and when the thin-film solar cell main body 2 is formed on the thin-film solar cell base material 3 made of an acrylic resin film alone. Melting of the film or deformation due to thermal stress or film stress occurs. However, the thin film solar cell substrate 3
Is attached to the support body 8, even when the thin film solar cell substrate 3 is formed of a film having low heat resistance, it is possible to suppress the deformation of the film substrate and the like when the thin film solar cell body 2 is formed. Become.

When the fine irregularities 7 are formed on the entire surface of the thin film solar cell substrate 3 and supported and fixed by the support 8, the deformation of the thin film solar cell substrate 3 can be more reliably prevented. However, when the base material 3 for a thin-film solar cell is made of a resin film having high heat resistance and being hardly thermally deformed,
It is not always necessary to provide the fine unevenness 7 on the entire surface of the thin film solar cell substrate 3, and the fine unevenness 7 may be formed in a part of the area.

After the thin-film solar cell main body 2 is manufactured as described above, the support 8 is separated from the thin-film solar-cell base material 3 to complete the thin-film solar cell 1 shown in FIG. The support 8 can be separated by peeling the support 8 from the thin-film solar cell substrate 3 against the engagement between the minute unevenness 7 and the minute unevenness 12. Since the support 8 is not adhered to the thin film solar cell substrate 3 using an adhesive, it can be used repeatedly and is economical.

The thin-film solar cell 1 is manufactured as described above. In such a manufacturing method, the following method may be used. That is, with respect to the material of the thin film solar cell substrate substrate 3 (acrylic resin in the above-described embodiment),
Fine particles are added before molding. As the fine particles to be added,
Al ₂ O ₃ , SiO ₂ , TiO _{2 and the} like can be used.
The particle diameter of the fine particles is preferably about 200 to 500 nm.
If it is less than 200 nm, it tends to aggregate into fine particles larger than the desired size. Also, in the case of 500 nm or more, relatively large fine particles tend to be formed. When the fine particles are contained in the thin film solar cell substrate 3, short circuit of the thin film solar cell may be caused, which is inconvenient. For these reasons, the particle size of the fine particles is preferably about 200 to 500 nm.

Therefore, for example, SiO ₂ fine particles having a particle size of about 300 nm
Add t%. As described above, by adding fine particles to the material of the thin film solar cell substrate 3, the surface of the formed thin film solar cell substrate 3 'has extremely small irregularities corresponding to the particle diameter of the fine particles (as described above). 13), which has an extremely small size as compared with the minute unevenness 7 and the minute unevenness 12).

When the thin film solar cell main body 2 'is formed on the thin film solar cell base material 3' having such extremely small irregularities 13, as shown in FIG. The same minimal unevenness 14 (backside electrode layer 6 '), 15 (amorphous semiconductor layer 5'), and 16 (transparent electrode layer 4 ') are also formed on the surface of each layer constituting 2' (particularly, backside electrode layer 6 '). ) Is formed.

In the thin-film solar cell 1 'manufactured in this manner, light which is not absorbed by the amorphous semiconductor layer 5' after being incident from the transparent electrode layer 4 'side is reflected by the back electrode layer 6'. However, at the time of reflection, light is diffused by the very small irregularities 14 provided on the surface of the back electrode layer 6 ', and the optical path length increases, so that the short-circuit current value increases, and as a result, high conversion efficiency is obtained.

The thin-film solar cell 1 ′ in which the very small irregularities 14 are formed on the back electrode layer 6 ′,
The thin film solar cell 1 having no 4 was manufactured for each of 10 samples, and the characteristics were measured. As a result, the results shown in Table 2 were obtained. The values in Table 2 are average values. As is clear from Table 2, higher conversion efficiency can be obtained by adding the fine particles and forming the minimum unevenness 14 on the back electrode layer 6 '.

[0038]

[Table 2]

The thin-film solar cell 1 manufactured as described above
Is attached to an airship or a balloon (in this example, an airship), which is an example of a thin-film solar cell mounting target member.
As shown in FIG. 5, first, fine irregularities 23 having the same size as the fine irregularities 7 described above are formed on the surface of the outer wall material 21 of the airship 20 made of a vinyl chloride film (which does not transmit helium gas) or the like. To form The minute irregularities 23
It is formed in the thin film solar cell bonding area 22 on the surface of the outer wall material 21.

Then, the thin-film solar cell 1 is adhered to the thin-film solar-cell forming region 22 in which such fine irregularities 23 are formed. The sticking can be easily performed by applying a certain amount of pressure in a state where the fine unevenness 7 is brought into contact with the minute unevenness 23 and engaging the two unevennesses 7 and 23 with each other. Thereby, the thin-film solar cell 1 can be simply and inexpensively attached. In addition, this bonding structure is a thin-film solar cell 1
Can be directly adhered to the surface of the outer wall material 21 which has become a phase, so that an airship equipped with a lightweight power source can be manufactured. This solar cell installation structure is a simple, low-cost, and lightweight installation method not only for airships, balloons, and artificial satellites, but also for ground installation of thin-film solar cells.

In the above-described embodiment, the resin film (acrylic resin film) is used alone as the base material 3 for the thin-film solar cell. However, as shown in FIG.
A resin film 30 having a metal substrate 32 with an adhesive 31
The thin-film solar cell 34 may be configured to have the thin-film solar cell base material 33 attached to the substrate. Even with such a configuration, it can be simply and easily attached to the thin film solar cell mounting target member.

[0042]

According to the first aspect of the present invention, the tips of the fine irregularities cross each other and strongly adhere to each other by friction. In this state, the thin film solar cell is placed on the thin film solar cell substrate. If the main body is formed, even if heat treatment is performed during the formation of the thin-film solar cell main body, the heat does not cause the thin-film solar cell base material to be easily melted or deformed. for that reason,
Since the melting and deformation of the base material for thin film solar cells are less likely to occur, the base material for thin film solar cells can be made thinner. Moreover,
An inexpensive resin film having low heat resistance can be used as the base material for the thin-film solar cell, and the manufacturing cost can be reduced accordingly.

According to the second aspect of the present invention, since minimal irregularities are formed on the surface of each layer of the thin-film solar cell main body, particularly on the back electrode layer, light reflected on the formed back electrode layer can be reduced. At the time of reflection, the light is diffused by extremely small irregularities and the optical path length is extended. Therefore, the thin-film solar cell manufactured by this manufacturing method can obtain high conversion efficiency as a result.

According to the third aspect of the present invention, by separating the support from the thin film solar cell base material against the adhesive force, the weight of the thin film solar cell can be reduced, and the flexibility can be improved. Will also improve.

According to the fourth aspect of the present invention, when the member having the fine irregularities similar to the minute irregularities is used as the solar cell mounting target member, the solar cell can be easily and reliably attached and detached. The solar cell can be attached, the installation cost can be reduced, and the installation structure of the solar cell can be reduced in weight because it is not necessary to use an adhesive or the like.

According to the fifth aspect of the present invention, since the minute unevenness is not arranged on the light incident end side, light incidence is not hindered by the minute unevenness, and the power generation efficiency of the solar cell is reduced accordingly. Without this, the solar cell can be installed.

According to the sixth aspect of the present invention, the solar cell can be easily and reliably formed by engaging the minute unevenness with each other.
Furthermore, it can be detachably attached to the solar cell attachment target member. In addition, the solar cell can be securely mounted on the solar cell mounting target member having a curved mounting surface. As a result, the installation cost can be reduced, and the weight of the solar cell installation structure can be reduced because no adhesive or the like is required.

According to the seventh aspect of the present invention, by setting the height difference between the top and bottom of the fine unevenness in such a range, the solar cell can be securely mounted on the solar cell mounting target member. Become like

As described above, according to the present invention, it is possible to obtain a solar cell having high flexibility, light weight, and easy attachment and detachment. Further, since the transportation cost and the installation cost are reduced, the production cost of the thin-film solar cell can be reduced. In addition, when a thin film solar cell is formed, an inexpensive resin film having low heat resistance can be used, so that the manufacturing cost can be reduced accordingly. Furthermore, since the thin-film solar cell body can be formed in a state where the thin-film solar cell base material is supported and fixed by the support, the conventional production line using a glass substrate or the like can be used as it is. It is not necessary to make a capital investment, and the manufacturing cost can be reduced by that much.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a structure of a thin-film solar cell according to one embodiment of the present invention.

FIG. 2 is a perspective view showing a main part of the thin-film solar cell of the embodiment.

FIG. 3 is a cross-sectional view showing each step of a method for manufacturing a thin-film solar cell according to an embodiment.

FIG. 4 is a cross-sectional view illustrating a structure of a thin-film solar cell according to a modification of the present invention.

FIG. 5 is a diagram showing an example of installation of a thin-film solar cell according to an embodiment.

FIG. 6 is a cross-sectional view showing a structure of a thin-film solar cell according to another modification of the present invention.

[Explanation of symbols]

1 Thin-film solar cell 1a Light incidence end
1b Solar cell end 2 Thin-film solar cell body 3 Thin-film solar cell base material 3a One surface of thin-film solar cell base material 3 (surface opposed to surface on which minute irregularities 7 are formed) 4 Transparent electrode layer 5 Amorphous semiconductor layer
6 Back electrode layer 7 Minute irregularities 7a Height difference
8 support 9 glass substrate 10 film material
11 Adhesive 12 Irregularity 12a Height difference
DESCRIPTION OF SYMBOLS 13 Tiny unevenness 14 Tiny unevenness of the back electrode layer surface 15 Tiny unevenness of an amorphous semiconductor layer 16 Tiny unevenness of a transparent electrode layer 20 Airship 21 Outer wall material 22 Thin film solar cell formation region 23 Fine unevenness 30 Resin film
31 adhesive 32 metal substrate 33 base material for thin film solar cell
34 Thin-film solar cell α Incident light 2 'Thin-film solar cell main body with very small unevenness 3' Thin-film solar cell base material with very small unevenness 4 'Transparent electrode layer with very small unevenness 5' Formation of very small unevenness Amorphous semiconductor layer 6 'Backside electrode layer with extremely small irregularities

Claims (7)

[Claims] 1. A support having fine irregularities formed on a support surface and a base material for a thin-film solar cell having fine irregularities formed on a surface in contact with the support are prepared. By supporting the thin-film solar cell substrate with the support, and then forming a thin-film solar cell main body on the thin-film solar cell substrate. . 2. The method for manufacturing a thin-film solar cell according to claim 1, wherein a base made of a resin to which fine particles are added is used as the base for the thin-film solar cell, and the base for the thin-film solar cell is used. A method for manufacturing a thin-film solar cell, comprising: forming a thin-film solar cell main body including a back electrode layer, an amorphous semiconductor layer, and a transparent electrode layer in this order. 3. The method for manufacturing a thin-film solar cell according to claim 1, wherein after the thin-film solar cell main body is formed on the thin-film solar cell base material, the thin unevenness is engaged with each other. A method for manufacturing a thin-film solar cell, comprising separating the support from the base material for the thin-film solar cell. 4. A solar cell, wherein minute irregularities are formed on an external bonding surface. 5. The solar cell according to claim 4, wherein the external bonding surface is provided at a cell end located on a side opposite to a light incident end of the solar cell. 6. A solar cell mounting target member having fine irregularities on the surface, and a solar cell having fine irregularities on an external bonding surface abutting on the solar cell mounting target member, wherein the fine irregularities are fixed to each other. A solar cell mounting structure, wherein the solar cell is mounted on the solar cell mounting target member by engaging. 7. The mounting structure for a solar cell according to claim 6, wherein each of the minute irregularities has a height difference between a top and a bottom of 50 μm to 2 mm. .