JP2731314B2 - Translucent photovoltaic device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a translucent photovoltaic device and a method of manufacturing the same, and more particularly, it can reduce the production cost and the production time without impairing the uniformity of the transmitted light, and can increase the conversion efficiency. The present invention relates to a translucent photovoltaic device and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, as photovoltaic devices, for example, windows,
A so-called translucent cell that can be used for a transparent plate fitted into a sunroof or the like has been proposed. For example, Te
chnical Digest of the International PVSEC-3, Toky
The light-transmitting cell described in o, Japan, 1987, pp. 569 to 572, forms a myriad of micropores using a laser on the back metal electrode of an amorphous silicon (a-Si) solar cell. doing.

Further, for example, Technical Digest of the
701 of International PVSEC-3, Tokyo, Japan, 1987
As described on pages 704 to 704, there has been proposed a device in which the back electrode is formed of a transparent conductive film.

[0004]

However, in the conventional example in which innumerable minute holes are formed in the back metal layer, the distance between adjacent holes must be reduced (several mm) in order for transmitted light to be substantially uniform. Or less), which inevitably increases the number of holes, increases the manufacturing cost, and increases the manufacturing time. The problem is exacerbated when forming large area cells.

On the other hand, when a transparent conductive film is used for the back electrode, these problems can be solved. However, there is almost no light component reflected by the back electrode and returned to the photovoltaic layer again, and the conversion efficiency is low. Is low.

[0006] The present invention provides a translucent photovoltaic device with uniform transmitted light and high conversion efficiency.
It is an object of the present invention to provide a method of manufacturing a photovoltaic device capable of reducing the manufacturing cost and the manufacturing time without impairing the uniformity of transmitted light and improving the conversion efficiency.

[0007]

The translucent photovoltaic device of the present invention comprises a translucent support substrate, a first translucent electrode, a photovoltaic layer, a second translucent electrode, and a light reflecting film. In the photovoltaic device stacked in order, the second light-transmitting electrode has an uneven surface on the light-reflecting film side in which unevenness of the same shape is repeatedly formed continuously. The light reflecting film is laminated only on the inclined surface in one direction of the uneven surface of the surface.

Further, the method for manufacturing a translucent photovoltaic device according to the present invention comprises the steps of: translucent supporting substrate, first translucent electrode, photovoltaic layer, second translucent electrode, and light reflecting film. In the method for manufacturing a light-transmitting photovoltaic device to be laminated, after forming the surface of the second light-transmitting electrode on a concave and convex surface in which irregularities of the same shape are continuously repeated, a light reflecting film is formed by an anisotropic deposition method. It is characterized in that the light-transmitting support substrates are stacked in a state of being inclined with respect to the deposition direction.

[0009]

In the translucent photovoltaic device of the present invention, the light reflecting film is formed only on the one-way inclined surface of each of the irregularities on the surface of the second translucent electrode where the irregularities of the same shape are continuously repeated. Therefore, the distribution of the light reflection film that blocks the transmission of light becomes uniform, and light is transmitted uniformly.

The light path length of the light reflected by the light reflecting film and returning into the cell in the photovoltaic layer is such that the reflected light is transmitted obliquely through the photovoltaic layer because the light reflecting surface is inclined. Become longer.

In the translucent photovoltaic device of the present invention, in order to ensure the uniformity of transmitted light, the repetition pitch of each concave-convex shape of the second translucent electrode is preferably 0.1 to 10 μm. preferable.

If the repetition pitch exceeds 10 μm, the area of each light reflecting film dispersed becomes too large and the uniformity of the transmitted light is impaired, which is not preferable. Is not preferred because the surface roughness of the second light-transmissive electrode is significantly reduced due to excessively small irregularities. The most preferable result can be obtained when the repetition pitch of each uneven shape is in the range of 0.3 to 2 μm.

The material of the photovoltaic layer of the present invention may be any material as long as it has translucency and photovoltaic ability. Can be. Among these materials, it is recommended to use a-Si, which has particularly excellent translucency and photovoltaic ability.

The second light-transmitting electrode of the present invention has a light-transmitting and conductive material such as SnO ₂ , In ₂ O ₅ , IT
O, ZnO (zinc oxide) and the like can be used. Among them, MOCVD (Metalorganic Chemical Vapor
It is recommended to use zinc oxide which can form an uneven surface at a low temperature without damaging the base by applying a por deposition method.

In the translucent photovoltaic device of the present invention,
When depositing the light reflecting material, the unevenness of the surface of the second translucent electrode functions as a mask, and the light reflecting film is not deposited on a shadowed portion when viewed from the film deposition direction.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A photovoltaic device according to one embodiment of the present invention will be specifically described with reference to the schematic diagram of FIG.

In this photovoltaic device, a first translucent electrode 2 and a photovoltaic layer 3 are sequentially laminated on a translucent support base 1 made of, for example, glass according to a conventional method. 2 This is obtained by laminating a light-transmissive electrode 4 and a light reflecting film 5.

The first light-transmitting electrode 2 is made of a light-transmitting and conductive material such as SnO ₂ , In ₂ O ₅ , IT
O, ZnO (zinc oxide) or the like is used, and the photovoltaic layer 3 is amorphous silicon PIN-joined in parallel with the film surface,
It includes a semiconductor photoactive layer made of an amorphous silicon-based semiconductor film such as amorphous silicon carbide and amorphous silicon germanium.

The material forming the second light-transmitting electrode 4 is a light-transmitting and conductive material such as SnO ₂ ,
In ₂ O ₅ , ITO, ZnO (zinc oxide), or the like can be used, and various known methods can be used as a method for forming the same.

However, in the method of manufacturing the translucent electromotive device, for example, Japanese Journal of Applied Physics
As described in ics Vol. 3, 3B, March, 1991, pp. L441-L43, zinc oxide was used as a material for forming the second translucent electrode 4 and the forming conditions shown in Table 1 were used. MO below
A method was employed in which the surface was formed at a low temperature without damaging the underlayer at a low temperature without damaging the underlayer, and the unevenness was the same in shape.

[0021]

Table 1 Conditions for forming the second translucent electrode (MOCVD method)

The ZnO film thus formed had pyramid-shaped irregularities with an average particle size of about 0.5 μm, and its sheet resistance was 10 Ω / □.

Further, a light reflecting film 5 is formed on the surface of the second light transmitting electrode 4 using, for example, silver. The method of forming the light reflecting film 5 is not particularly limited. It is possible to use a known thin film forming method such as ion plating.

However, in the method of manufacturing a photovoltaic device according to one embodiment of the present invention, an anisotropic deposition method such as a vapor deposition method using resistance heating is adopted, and as shown in FIG. A method is adopted in which the conductive support substrate 1 (the first light-transmitting electrode 2, the photovoltaic layer 3, and the second light-transmitting electrode 4) is inclined with respect to the direction B in which the light reflecting film 5 is deposited.

The angle of inclination of the light-transmitting support substrate 1, the first light-transmitting electrode 2, the photovoltaic layer 3, and the second light-transmitting electrode 4 is different from the direction B in which the light reflecting film 5 is deposited. (2) It is sufficient that the angle on the surface of the translucent electrode 4 is such that a shadow is formed. For example, in this embodiment, the perpendicular A of the surface of the translucent support base 1 and the light reflecting film 5 are deposited. The included angle with the direction B may be about 30 ° to about 50 °. If the included angle is less than about 30 °, the light reflecting film 5 is deposited over the entire surface of the second light-transmissive electrode 4 and the light transmittance is remarkably reduced, and it is not preferable. If the included angle is more than about 50 °, It is not preferable because the shadow of the projections and depressions overlaps the next projections and depressions, and the adhesion area of the light reflecting film 5 becomes small, which is disadvantageous in increasing the conversion efficiency. In the case of this embodiment, the best results were obtained when the included angle was about 40 °.

According to this method, each concave / convex portion of the second translucent electrode 4 functions as a mask, and the light reflective film 5 is placed in a shadow of each concave / convex portion in the direction in which the light reflective film 5 is deposited. The light reflecting film 5 is not uniformly deposited on the surface of the second translucent electrode 4 and is formed so as to be evenly dispersed.

The light reflecting film 5 thus formed
Is about 30% of the total surface area of the second translucent electrode 4.

As a comparative example, a first light-transmitting electrode 2 and a photovoltaic layer 3 are sequentially laminated on a light-transmitting support substrate 1 made of, for example, glass in the same manner as in the above-described example according to a conventional method.
A second light-transmissive electrode having a flat surface and a thickness of 2 μm was formed of ITO, and the photoelectric conversion characteristics of this comparative example and the above-described one example were determined. Table 2 shows the results.

[0029]

[Table 2]

In the photovoltaic device according to the above-described embodiment, the light transmitting portion and the light non-transmitting portion are repeated at a repetition pitch of about 0.5 μm. The transmitted light looks quite uniform.

As described above, zinc oxide is used as a material for forming the second light-transmitting electrode 4, and the second light-transmitting electrode 4 is formed by MOCVD under the forming conditions shown in Table 1. By doing so, it is possible to form the second light-transmissive electrode 4 having an uneven surface having the same shape as the surface at a low temperature without damaging the base and to form the light reflecting film 5 by anisotropic deposition. The method is adopted, and the light-transmitting support base 1, the first light-transmitting electrode 2, the photovoltaic layer 3, and the second light-transmitting electrode 4 are inclined with respect to the direction in which the light reflecting film 5 is deposited. By adopting the method, the light reflecting films 5 can be formed on the surface of the second translucent electrode 4 by uniformly dispersing them without using a mask. Therefore, the light reflection film 5 uniformly dispersed on the surface of the second light-transmitting electrode 4 by a very simple method without using any steps such as laser patterning and etching.
And can greatly reduce manufacturing costs.
Manufacturing time can be greatly reduced.

Further, as is clear from Table 2, the embodiment has higher short-circuit current and conversion efficiency than the comparative example. This is because a part of the light is returned to the photovoltaic layer again by the light reflecting film 5 and the reflected light obliquely moves the photovoltaic layer 3 because the light reflecting film 5 is inclined. Depending on the transmission.

In the above embodiment, ZnO is used as the material of the second light-transmitting electrode 4 and the second light-transmitting electrode is formed by MOCVD. The method is not limited to the one shown in the above embodiment, and it is sufficient that the surface of the second permeable electrode 4 can be formed on the surface of the second permeable electrode 4 with the same shape as the surface.

The material of the light reflecting film 5 may be a material other than silver as long as the material has a high light reflectance. Any method can be used as long as it can be formed only on the inclined surface in the direction.

This embodiment is a so-called four-terminal cell in which a plurality of (usually two) photovoltaic devices are stacked and used except for the window or sunroof, which is the original use of the translucent cell. Can be used for the front cell. Especially,
When used as a front cell of a four-terminal cell, light transmitted through the first photovoltaic device is disturbed by irregularities on the surface of the second translucent electrode 4 and enters the cell. Has many components in the oblique direction, the path length in the second cell is increased, and the conversion efficiency of the second cell is increased.

[0036]

As described above, according to the translucent photovoltaic device of the present invention, the transmitted light can be made uniform and the conversion efficiency can be increased.

Further, according to the method for manufacturing a translucent photovoltaic device of the present invention, the production cost and the production time can be reduced without deteriorating the uniformity of the transmitted light, and the translucent light having high conversion efficiency is obtained. An electromotive device can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a photovoltaic device according to one embodiment of the present invention.

FIG. 2 is an explanatory view of a method for forming a light reflection film according to one embodiment of the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Translucent support base 2 1st translucent electrode 3 Photovoltaic layer 4 2nd translucent electrode 5 Light reflection film A Perpendicular direction of a support base plane B Film deposition direction

Continuation of the front page (56) References JP-A-63-34980 (JP, A) JP-A-61-218178 (JP, A) JP-A-2-81478 (JP, A) JP-A-62-90983 (JP, A) , A)

Claims (3)

(57) [Claims] 1. A photovoltaic device in which a light-transmitting support substrate, a first light-transmitting electrode, a photovoltaic layer, a second light-transmitting electrode, and a light-reflecting film are sequentially stacked. The electrode has an uneven surface on the side of the light reflecting film in which unevenness of the same shape is repeatedly formed continuously, and the light is applied only to the one-way inclined surface of the uneven surface of the surface of the second light-transmitting electrode. A translucent photovoltaic device, wherein a reflective film is laminated. 2. The translucent photovoltaic device according to claim 1, wherein the repetition pitch of each concave-convex shape of the second translucent electrode is 0.1 to 10 μm. 3. A method for manufacturing a light-transmitting photovoltaic device in which a light-transmitting support substrate, a first light-transmitting electrode, a photovoltaic layer, a second light-transmitting electrode, and a light-reflecting film are sequentially stacked. (2) A state in which the surface of the light-transmitting electrode is formed as a continuous uneven surface having the same shape as the surface, and the light-reflective film is tilted with respect to the film deposition direction by the anisotropic deposition method. A method for manufacturing a translucent photovoltaic device, comprising: