JPH11135817A - Photoelectric conversion element and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element which is capable of obtain a sufficient light diffusion effect, which is low-cost, and which is easily manufactured. SOLUTION: A translucent substrate 1 is coated with an ultraviolet curing acrylic resin which contains silica fine particles or with a polyimide resin which contains silica fine particles, and a light diffusion layer 2 which comprises uneveness is formed on the surface. A transparent conductive layer 3, a transparent layer 4, an a-Si layer 5, a rear electrode layer 6 and a rear metal reflection electrode layer 7 are laminated sequentially on the light diffusion layer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion element applied to a solar cell or the like.

[0002]

2. Description of the Related Art In recent years, in a photoelectric conversion element applied to a solar cell, in order to improve the energy conversion efficiency of the solar cell, incident light is diffused to increase the light absorption length. (Light diffusion effect). For example, a structure in which the surface of a transparent electrode such as SnO ₂ (tin oxide) formed on a glass substrate has a textured structure (a structure with fine irregularities) is often used (for example, JP-A-8-18084). Gazette,
See JP-A-7-115214. With such a texture structure, the incoming sunlight is irregularly reflected and confined, the short-circuit current density can be increased, and the sunlight can be effectively absorbed in the semiconductor.

However, in order to form such a texture structure, for example, a sputtering method or CV
Since the method D or the like is used, the cost increases for the manufacturing equipment. Also,
Since it is a glass substrate, it is not easy to handle and, in many cases, there are restrictions on its application to curved surfaces and the like.

[0004] In view of the above problems, an object of the present invention is to provide a photoelectric conversion element which can provide a sufficient light diffusion effect, is inexpensive and easy to manufacture.

[0005]

Means for Solving the Problems According to the present invention, a light diffusion layer, a semiconductor layer and an electrode layer having irregularities on the surface are provided on a substrate, and the light diffusion layer contains a photosensitive material containing fine particles. It is formed from resin. The fine particles are made of silicon oxide and have a particle size of 0.01 to 10
μm is desirable. Further, a polyimide resin may be used instead of the photosensitive resin.

According to this configuration, by incorporating fine particles into the photosensitive resin or the polyimide resin, irregularities can be formed on the surface of the light diffusion layer, and a sufficient light diffusion effect can be obtained by the irregularities. . In particular, when a photosensitive resin is used for the light diffusion layer, the light diffusion layer can be easily formed only by curing by irradiating ultraviolet light or visible light. Therefore, equipment costs can be reduced. Use of a polyimide resin having excellent heat resistance is also effective as a light diffusion layer. Further, when inexpensive silicon oxide is used for the fine particles, the above effects can be achieved at low cost.

The substrate is made of a light-transmitting electrically insulating film or glass, and a light diffusion layer is disposed on the substrate. Alternatively, the substrate is made of a metal plate, an electric insulator having a groove formed on the surface is provided on the substrate, and the light diffusion layer is disposed on the electric insulator. The former is a type in which light enters from the substrate side, and the latter is a type in which light enters from the surface opposite to the substrate. In the latter type, a light diffusion layer may be directly disposed without providing an electrical insulator on the substrate.

Thus, the substrate is made of an electrically insulating film,
With a glass or metal plate, a photoelectric conversion element can be manufactured at low cost. In particular, if an electrically insulating film is used,
It can also be applied to curved parts and the like. Further, the light diffusion layer is disposed on the electric insulator, and the unevenness is formed along the surface of the groove of the electric insulator, so that the light diffusion effect can be exhibited.

The groove is formed in a V-shape, and preferably has a pitch of 10 to 30 μm, a depth of 10 to 30 μm, and an opening angle of 45 to 120 degrees. If the value is smaller or larger than the above value, it is difficult to obtain a sufficient light diffusion effect.

In the method of manufacturing the photoelectric conversion element, in a type in which light enters from the substrate side, a photosensitive resin containing fine particles is applied on a translucent substrate, and light is applied to the photosensitive resin. Irradiation and curing to form a light diffusion layer having an uneven surface, and a transparent conductive layer, a semiconductor layer, and an electrode layer are sequentially laminated on the light diffusion layer.

In the type in which light enters from the surface opposite to the substrate, an electrical insulator having a groove on the surface is formed on the metal substrate, and the electrical insulator or the metal substrate alone is formed on the electrical insulator. On top, a photosensitive resin containing fine particles is applied, and the photosensitive resin is cured by irradiating the photosensitive resin with light to form a light diffusion layer having irregularities on the surface, and an electrode layer and a semiconductor layer are formed on the light diffusion layer. And a transparent conductive layer are sequentially laminated.

Alternatively, an electric insulator having a groove on the surface is formed on the metal substrate, and a polyimide resin containing fine particles is applied and formed on the electric insulator or on the metal substrate alone. A light diffusion layer having irregularities is formed, and an electrode layer, a semiconductor layer, and a transparent conductive layer are sequentially stacked on the light diffusion layer.

[0013]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

<First Embodiment> FIG. 1 is a diagram showing a configuration of a photoelectric conversion element according to a first embodiment of the present invention. This photoelectric conversion element includes a light-diffusing layer 2 having an uneven surface, a transparent conductive layer 3 made of ITO (indium tin oxide), a transparent layer 4 made of ZnO, and a p-layer (not shown) on a light-transmitting substrate 1. , An i-layer, and an n-layer, an amorphous silicon layer (hereinafter, referred to as an “a-Si layer”) 5, a back electrode layer 6 made of ZnO, and a back metal reflective electrode layer 7 made of Ag. ing. In the case of this photoelectric conversion element, light enters from the lower side of FIG.

The substrate 1 is made of a light-transmitting electrically insulating film such as a polyester film. By using a polyester film, the photoelectric conversion element can be reduced in weight and handling can be facilitated, and a low-cost photoelectric conversion element can be realized. The substrate 1 may be made of a polyimide film, glass, or the like.

The light diffusion layer 2 is formed of an ultraviolet curable acrylic resin containing silica (silicon oxide) fine particles, a so-called photosensitive resin. Thereby, as shown in FIG. 2, fine irregularities are formed on the surface of the light diffusion layer 2. Instead of the photosensitive resin, a polyimide resin or a polyimide resin having excellent heat resistance may be used. In the figure, 8 indicates fine particles.

As described above, the unevenness is formed on the surface of the light diffusion layer 2 by the photosensitive resin or the polyimide resin containing the silica fine particles, and is further laminated on the light diffusion layer 2 corresponding to the unevenness. Irregularities are also formed on the surfaces of the layers 3, 4, 5, and 6. Due to these irregularities, light incident on the photoelectric conversion element is scattered, and a light confinement effect in the a-Si layer 5 can be obtained. Therefore, the photocurrent density can be increased, and the energy conversion efficiency of the photoelectric conversion element can be improved. In addition, since inexpensive silica is used for the fine particles, a low-cost photoelectric conversion element can be manufactured. The fine particles were replaced with silica and TiO ₂
(Titanium oxide), Al ₂ O ₃ (aluminum oxide), ZrO
₂ (zirconium oxide), ITO (indium tin oxide), SnO ₂ (tin oxide), MgF ₂ (magnesium fluoride), or the like may be used.

The particle size of the silica fine particles is 0.01 to
It is desirable that the thickness is 10 μm, whereby irregularities having a height difference of about 0.005 to 5 μm can be formed on the surface of the light diffusion layer 2. It has been experimentally required that if unevenness with a height difference of 0.005 to 5 μm can be formed, it will be most suitable for light scattering in view of the wavelength of the incoming light.
On the other hand, when the particle diameter of the fine particles is smaller than 0.01 μm or larger than 10 μm, light is excessively transmitted or hardly transmitted. In addition, aggregation of the fine particles occurs, and the height difference of the unevenness becomes uneven.

The light diffusion layer 2 is formed by applying a photosensitive resin on the substrate 1 and curing it with ultraviolet rays. As a method of applying an ultraviolet curable acrylic resin on the substrate 1, a spin coating method, a dip coating method, a spray coating method, a bar coating method, a curtain coating method, or the like can be used.

As described above, the surface of the light diffusion layer 2 can be made uneven only by applying an acrylic resin on the substrate 1 and irradiating it with ultraviolet light to cure the resin. The texture structure can be easily formed as compared with the case of (1). Therefore, equipment costs can be reduced.

As the acrylic resin, specifically, polymers such as acrylic acid, acrylic acid ester, acrylamide, acrylonitrile, methacrylic acid, and methacrylic acid ester can be used. Further, as the material of the light diffusion layer, a polyester resin or the like may be used instead of the acrylic resin as long as the material has photosensitivity.

<Second Embodiment> FIG. 3 is a diagram showing a configuration of a photoelectric conversion element according to a second embodiment. The feature of this photoelectric conversion element is that a metal layer is formed on the light diffusion layer, and irregularities similar to the irregularities formed on the surface of the light diffusion layer are also formed on the surface of the metal layer, so that light incident from above is Is reflected to confine light in the a-Si layer formed on the metal layer. That is, the photoelectric conversion element includes a substrate 1 made of metal,
Electrical insulator 11 having grooves formed on the surface, light diffusion layer 2 having irregularities on the surface, metal reflective electrode layer 7 made of Ag, Zn
A transparent layer 4 composed of O, an a-Si layer 5 composed of an n layer, an i layer, and a p layer (not shown), a transparent conductive layer 3 composed of ITO, and a comb-shaped current collecting electrode layer 12 composed of Ag are laminated. I have. In the case of this photoelectric conversion element, light enters from the upper side of FIG. Other configurations are the same as in the first embodiment.

The electric insulator 11 is made of an electrically insulating polyimide resin, and the substrate 1 is made of stainless steel (SUS
430). Further, instead of the polyimide resin, an electrically insulating metal oxide such as alumina (aluminum oxide) or a plated steel material may be used.
In this case, aluminum or the like is used for the substrate 1. As described above, by using a metal plate in the form of a foil such as stainless steel, aluminum, or plated steel material, the thickness of the substrate 1 can be reduced. Therefore, the weight of the photoelectric conversion element can be reduced, and the handling becomes easy. Further, the cost of the photoelectric conversion element can be reduced.

The electric insulator 11 has a plurality of substantially V
A letter-shaped groove is formed. On the electrical insulator 11,
Light diffusion layer 2 made of photosensitive resin containing silica fine particles
Are formed. Therefore, as shown in FIG.
Irregularities are formed on the surface of the light diffusion layer 2 along the letter-shaped grooves. Then, the metal reflective electrode layer 7 is formed on the light diffusion layer 2. The metal reflective electrode layer 7 is formed on the interface with the transparent layer 4 by reflecting the same irregularities as the irregularities of the light diffusion layer 2. That is, in this case, the electric insulator 11 and the light diffusion layer 2 have a so-called mold role for forming irregularities on the surface of the metal reflective electrode layer 7.

With such a structure, light entering from above passes through the transparent conductive layer 3, the a-Si layer 5, and the transparent layer 4, and almost 100% of the unevenness formed on the surface of the metal reflective electrode layer 7. % Reflected. The incident light is reflected by these irregularities, and the light not absorbed by the a-Si layer 5 is again reflected by the a-S layer.
The light can be effectively used by returning to the i-layer 5. Further, the unevenness of the metal reflective electrode layer 7 is substantially
Since the letter-shaped groove and the unevenness of the light diffusion layer 2 are combined, the light diffusion effect is maintained and exhibited, and a-S
The light confinement effect can be obtained in the i-layer 5.

The specific size of the substantially V-shaped groove is as follows: the pitch is 10 to 30 μm, and the depth of the groove is 1
More preferably, the opening angle of the groove is from 45 to 120 degrees. It has a pitch and depth of 1
If it is smaller than 0 μm or larger than 30 μm, unevenness cannot be made uniform or a sufficient light diffusion effect cannot be obtained. On the other hand, if the opening angle is smaller than 45 degrees, it becomes difficult to process the electrical insulator 11, and
This is because a light diffusion effect cannot be sufficiently obtained when the degree is larger than the degree.

When this photoelectric conversion element is used for a large solar cell, the pitch of the substantially V-shaped groove is 0.5.
The depth of the groove may be 0.3 to 2 mm, and the opening angle of the groove may be 45 to 120 degrees. Further, the groove formed in the electric insulator 11 is not limited to the V-shape, but may be a substantially U-shape, a substantially semicircular shape, or the like.

Instead of the structure of the photoelectric conversion element shown in FIG. 3, a light diffusion layer is directly provided on the substrate 1 without providing an electric insulator 11 having a groove formed on the surface as shown in FIG. A photoelectric conversion element having a configuration in which 2 are arranged may be used. Alternatively, a substrate 1 having a substantially V-shaped groove directly formed on the surface may be used. Other configurations are the same as those shown in FIG.

Thus, the metal reflective electrode layer 7 has the same irregularities as the irregularities of the light diffusion layer 2 at the interface with the transparent layer 4 due to the irregularities formed on the surface of the light diffusion layer 2. Therefore, light entering from above is reflected by the unevenness, and a light diffusion effect is exhibited, and a light confinement effect can be obtained in the a-Si layer 5.

The present invention is not limited to the above embodiment, and many modifications and changes can be made to the above embodiment within the scope of the present invention. For example, the photoelectric conversion element described in the above embodiment is not limited to a solar cell, and may be applied to an optical sensor, a display element, and the like.

Further, the electric insulator described in the second embodiment is added to the structure of the first embodiment, for example, the substrate 1
And the light diffusion layer 2 may be formed. In this case, the electric insulator needs to have a light-transmitting property.

[0032]

EXAMPLES Examples of forming a photoelectric conversion element according to the present invention will be described below.

Example 1 An ultraviolet curable acrylic resin containing silica fine particles having an average particle size of 0.5 μm was applied on a polyethylene terephthalate film by a spray method using a roll coater. Next, after performing a heat treatment at 80 ° C. for 5 minutes, the coating film was cured by irradiating with ultraviolet rays for 2 minutes to obtain a light diffusion layer having fine irregularities on the surface. On top of this, the IT
The O layer was formed to have a thickness of 140 nm, and the ZnO layer was formed to have a thickness of 50 nm.

Further, an a-Si layer was formed thereon by a plasma CVD method in the order of a p-layer, an i-layer, and an n-layer. Table 1 shows the conditions for forming each layer.

[0035]

[Table 1]

The thickness of the p-layer is 10 nm and the thickness of the i-layer is 50
The thickness of the n-layer was set to 0 nm, and the thickness of the n-layer was set to 30 nm.

Next, a ZnO layer having a thickness of 60 nm was formed as a back electrode by a sputtering method, and an Ag layer was finally formed with a thickness of 500 nm as a back metal reflective electrode. Thus, a photoelectric conversion element having the structure shown in FIG. 1 was manufactured.

The photoelectric conversion element was irradiated with 100 mW / cm ² pseudo sunlight of AM 1.5 (standard sunlight spectrum) by a solar simulator. Then, the short-circuit current density J _SC , the open-circuit voltage V _OC , the fill factor FF (fill factor), and the conversion efficiency η were measured. Table 2 shows the obtained results.

[0039]

[Table 2]

Example 2 A polyimide resin having a substantially V-shaped groove having a pitch of 20 μm and an opening angle of 60 ° was formed on a stainless steel substrate having a thickness of 50 μm. An ultraviolet curable acrylic resin containing 0.5 μm silica fine particles was applied.

Next, after a heat treatment at 80 ° C. for 5 minutes, the coating film was cured by irradiating with ultraviolet rays for 2 minutes to produce a light diffusion layer having fine irregularities.

Next, the Ag layer was formed by sputtering to a thickness of 5 μm.
A ZnO layer was formed to a thickness of 100 nm and a thickness of 100 nm, respectively. Further, an a-Si layer was formed thereon in this order by a plasma CVD method in the order of an n-layer, an i-layer, and a p-layer. The conditions for forming each layer are the same as those described in Example 1 (see Table 1). The thickness of the n-layer is 30 nm, and the thickness of the i-layer is 5
The thickness of the layer was set to 00 nm and the thickness of the p layer was set to 10 nm.

Next, an ITO layer having a thickness of 60 nm was formed as a surface electrode by a sputtering method, and finally an Ag layer was formed as a comb-shaped current collecting electrode by a sputtering method.
It was formed to a thickness of 0 nm. Thus, a photoelectric conversion element having a structure shown in FIG. 3 was manufactured. The same measurement as in Example 1 was performed on this photoelectric conversion element. Table 2 shows the obtained results.

Embodiment 3 Aluminum having a thickness of 50 μm was used as a substrate, and an electrical insulator made of alumina having a substantially V-shaped groove having a pitch of 20 μm and an opening angle of 60 ° on the surface was formed thereon. For other configurations, a photoelectric conversion element was manufactured in the same manner as in Example 2, and similar measurements were performed. Table 2 shows the obtained results.

Example 4 A 150 μm thick stainless steel was used as a substrate, and a polyimide resin containing silica fine particles having an average particle diameter of 0.3 μm was applied thereon by a roll coater. For other configurations, a photoelectric conversion element having the structure shown in FIG. 5 was manufactured in the same manner as in Example 2.
Similar measurements were made. Table 2 shows the obtained results.

Example 5 Corning 7059 glass was used as a substrate. With respect to other configurations, a photoelectric conversion element was prepared in the same manner as in Example 1, and similar measurements were performed. Table 2 shows the obtained results.

The glass substrate which is in the textured structure <Comparative Example 1> SnO _2, ITO layer, ZnO layer, a-Si
A layer, a ZnO layer, and an Ag layer were formed, and a photoelectric conversion element was manufactured. The same measurement as in Example 1 was performed on this photoelectric conversion element. Table 2 shows the results.

Comparative Example 2 A Corning 7059 glass substrate was used, on which an ITO layer, a ZnO layer, and an a-Si
A layer, a ZnO layer, and an Ag layer were formed, and a photoelectric conversion element was manufactured. The same measurement as in Example 1 was performed on this photoelectric conversion element. Table 2 shows the results.

As described above, according to Table 2, it was found that the configuration of Example 5 in which the light diffusion layer was formed thereon using 7059 glass manufactured by Corning Co., Ltd. was the most excellent in fill factor and conversion efficiency. Examples 1, 2, 3, and 4
In this case, the fill factor and the conversion efficiency are equal to or higher than those of the photoelectric conversion element in which the SnO ₂ texture structure is formed on the substrate and the light diffusion layer is not formed. The effect can be obtained.

[0050]

As described above, according to the present invention, a light diffusion layer formed of a photosensitive resin or a polyimide resin containing fine particles is provided on a substrate, and irregularities are formed on the surface of the light diffusion layer. Therefore, a photoelectric conversion element capable of obtaining a sufficient light diffusion effect can be provided.

In particular, if a photosensitive resin is used, a light diffusion layer having irregularities on the surface can be formed simply by coating the photosensitive resin on a substrate and irradiating the photosensitive resin with light to cure the resin. Therefore, a photoelectric conversion element having a light diffusion effect can be easily manufactured without using a large-scale manufacturing facility.

When inexpensive silicon oxide is used for the fine particles, a photoelectric conversion element can be manufactured at low cost, and the particle size is 0.01.
If it is 10 μm to 10 μm, irregularities suitable for the light diffusion effect can be formed.

If an electrically insulating film, glass or metal plate is used for the substrate, a light-weight and low-cost photoelectric conversion element can be obtained.

Further, if an electric insulator having a groove formed on the surface and a light diffusion layer having an uneven surface are arranged in combination, the unevenness is formed along the groove of the electric insulator. Light can be effectively diffused.

[Brief description of the drawings]

FIG. 1 is a sectional view of a photoelectric conversion element according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the photoelectric conversion element.

FIG. 3 is a cross-sectional view of a photoelectric conversion element according to a second embodiment.

FIG. 4 is a sectional view of a main part of the photoelectric conversion element.

FIG. 5 is a sectional view showing a modified example of the photoelectric conversion element according to the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Light diffusing layer 3 Transparent conductive layer 5 a-Si layer 6 Back electrode layer 7 Back metal reflective electrode layer 8 Fine particles 11 Electrical insulator

Claims (11)

[Claims] 1. A photo-diffusion layer, a semiconductor layer, and an electrode layer having irregularities on a surface are provided on a substrate, and the light-diffusion layer is formed of a photosensitive resin containing fine particles. Conversion element. 2. A photoelectric conversion device comprising: a substrate, a light diffusion layer having an uneven surface, a semiconductor layer, and an electrode layer, wherein the light diffusion layer is formed of a polyimide resin containing fine particles. element. 3. The photoelectric conversion device according to claim 1, wherein the fine particles are made of silicon oxide and have a particle size of 0.01 to 10 μm. 4. The substrate according to claim 1, wherein the substrate is made of a transparent electrical insulating film or glass, and the light diffusion layer is disposed on the substrate. Photoelectric conversion element. 5. The substrate is made of a metal plate, an electric insulator having a groove formed on a surface thereof is provided on the substrate, and the light diffusion layer is arranged on the electric insulator. The photoelectric conversion element according to claim 1, wherein 6. The groove according to claim 5, wherein the groove is formed in a V-shape, and has a pitch of 10 to 30 μm, a depth of 10 to 30 μm, and an opening angle of 45 to 120 degrees. Photoelectric conversion element. 7. The photoelectric conversion element according to claim 1, wherein the substrate is formed of a metal plate, and the light diffusion layer is disposed on the substrate. 8. The photoelectric conversion element according to claim 5, wherein said substrate is made of stainless steel, aluminum or plated steel, and said electric insulator is made of polyimide resin or aluminum oxide. 9. A light-transmitting substrate is coated with a photosensitive resin containing fine particles, and the photosensitive resin is cured by irradiating light to form a light-diffusing layer having irregularities on the surface. A method for manufacturing a photoelectric conversion element, comprising sequentially laminating a transparent conductive layer, a semiconductor layer, and an electrode layer on a layer. 10. An electric insulator having a groove on the surface is formed on a metal substrate, and a photosensitive resin containing fine particles is applied on the electric insulator or on the metal substrate alone, A photoelectric conversion element comprising: irradiating a light on a conductive resin to cure it to form a light diffusion layer having an uneven surface, and sequentially laminating an electrode layer, a semiconductor layer, and a transparent conductive layer on the light diffusion layer. Manufacturing method. 11. An electric insulator having a groove on the surface is formed on a metal substrate, and a polyimide resin containing fine particles is applied and formed on the electric insulator or on the metal substrate alone. A method for manufacturing a photoelectric conversion element, comprising: forming a light diffusion layer having irregularities, and sequentially laminating an electrode layer, a semiconductor layer, and a transparent conductive layer on the light diffusion layer.