JPS6149482A - Photovoltaic device - Google Patents

Abstract

PURPOSE:To avoid scattering of broken pieces of a light-receiving plate and a substrate of a photovoltaic device when broken by shock, by inserting a transparent bonding layer between a light-transmitting light-receiving plate which defines a light incident surface and a light-transmitting substrate, the bonding layer being adapted to bond them together. CONSTITUTION:A plurality of photoelectric conversion films 3 are formed on the reverse surface 2S1 of a light-transmitting substrate 2 made of light-transmitting glass, ceramic or the like. Each film 3 is formed from a laminated structure 10 consisting of a light-transmitting electrically conductive oxide electrode 7, an amorphous Si photoactive layer 8 and an Al rear electrode 9, these layers being laminated in that order from the reverse surface 2S1. An output electrode 13 is provided at one end of the electrode 7, and a connecting electrode 12 is provided within an adjacent spacing area 11 so as to extend from the other end of the electrode 9 to the electrode 7. Thereafter, the surface 2S2 of the substrate 2 is coated with a sheet-like transparent bonding layer 6, and a transparent light-receiving plate 5 of tempered glass is secured to the surface 2S2 through the bonding layer 6 so as to define a light incident surface. In this arrangment, the respective refractive indexes of the light-receiving plate 5, the bonding layer 6 and the substrate 2 are made uniform to enable light to pass therethrough to reach the film 3 in a satisfactory state.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a photovoltaic device that directly converts light energy such as sunlight into electrical energy, and is mainly used as a commissioned solar cell.

(b) Conventional technology A photovoltaic device in which a photoelectric conversion film that performs photoelectric conversion upon irradiation with light is directly formed on a supporting substrate is already known, and by making the substrate translucent, the substrate can receive light. A surface-side photovoltaic device is also disclosed, for example, in U.S. Pat. No. 4,281,
Existing as disclosed in No. 208. Glass is practically used for the above-mentioned light-transmitting substrate;
Ceramics that have been made translucent by increasing the degree of sintering are also used, as disclosed in Japanese Patent Publication No. 59-6074.

However, since the photoelectric conversion film of the above-mentioned photovoltaic device is in the form of a film, the support substrate that supports the conversion film is indispensable.
Although the above-mentioned glass or translucent ceramic is a useful substrate material, both have the risk of being destroyed by impact.
In particular, pocket radios incorporating such photovoltaic devices (solar cells).

In consumer appliances such as wristwatches and trains, it is dangerous if the above-mentioned supporting substrates are damaged by impact and scattered.

Problems that the Invention Attempts to Solve The present invention attempts to solve the problem that such a transparent support substrate breaks when an impact is applied to it, and its fragments are scattered.

B) Means for Solving the Problems In order to solve the above-mentioned problems, the present invention aims to solve the above-mentioned problems by using a light-transmitting support substrate that supports a photoelectric conversion film that performs photoelectric conversion on one main surface. The surface side is the light-receiving surface side, and a light-transmitting light-receiving plate is disposed on the light-receiving surface side with a transparent adhesive layer having an optical refractive index substantially equal to that of the support substrate. The light-transmitting light-receiving plate is made of tempered glass (e) Function: As described above, the light-transmitting light-receiving plate has a transparent adhesive layer on the light-transmitting light-receiving surface side having a light refractive index almost equal to that of the supporting substrate. By arranging the light-receiving plate, the transparent adhesive layer prevents fragments from scattering even if the light-receiving plate is damaged due to collision (9). Furthermore, when tempered glass is used as the light receiving plate, the impact resistance itself increases.

(f) Embodiment FIG. 1 is an exploded perspective view of the present light-emitting electromotive device. FIG. 1 is an enlarged cross-sectional view of the main parts. In Figures 1 and 2, (1
A photovoltaic element is a photovoltaic element that generates an electromotive force when exposed to sunlight or other light. One main surface (
2111) side, and a passivation film [4] covering the main surface of the photoelectric conversion film (3) on the side opposite to the substrate (2''). .

(6 ) is a sheet-like transparent adhesive layer that is placed between the light receiving plate (5) and the supporting substrate (2) and bonding them together; ) has a refractive index that is approximately equal to the refractive index of ().For example, if so-called plate glass for ordinary window glass is used as the supporting substrate (2) and the light receiving plate (5), the glass material is soda lime glass). Polyvinyl butyral (PVB) and ethylene vinyl acetate (EVA) with a refractive index of 1.48 exist as transparent adhesive layers (6) that have a refractive index of about 1.45 to 160 and are almost equal to this refractive index. do. Both PVB and EVA are available in sheet form with a thickness of about 11 to several IM, for example, from DuPont in the United States.
] and the light receiving plate (5), for example, 1QTor.
Heating temperature 80-170"C under reduced pressure below r
By hot pressing at a pressure of 0.5 to 5/-, air bubbles were removed from the cloudy sheet material and the transparent adhesive layer 6) was bonded to the light receiving plate [5] and the supporting substrate ( 2) are integrally combined.

On the other hand, in general, when light is incident perpendicularly from a substance with a refractive index n1 to a substance with a refractive index n2, the light reflectance R generated at the interface is
It is a well-known convention that R=()nl+n2. Therefore.

In order to make the refractive index of the adhesive layer (6) almost equal to the refractive index of the support substrate (2) and the light receiving plate (5), the photoelectric conversion film]3
Although the light must pass through three layers, the light receiving plate (5), the transparent adhesive layer (6), and the support substrate (2), before reaching the incident surface of the light receiving plate (5), the initial atmosphere and the light receiving plate (5) ) The reflections at each interface can be almost ignored, except for the large reflection at the interface with . That is, the light receiving plate (5) and the supporting substrate (
When using the most common window glass material as 2), the refractive index of the glass material is approximately 152, and the refractive index of PVB or EVA located in between is approximately 148 as mentioned above, so photoelectric conversion is difficult. The total reflectance RsH1 is the total reflectance of light that is reflected until it reaches the film (3), and the reflectance R1 is the reflectance R1 when the supporting substrate (2) is directly irradiated with light as in the conventional case.

Considering this, the increase in reflectance due to the three-layer structure is only 0.0004.

Referring again to FIG. 2, the specific structure of the photoelectric conversion film (3) will be explained. One main surface (2) of the support substrate (2)
81), that is, the photoelectric conversion film (3) provided on the back side when viewed from the light incident side is selectively formed using electron beam evaporation, or formed on the entire surface and then formed into multiple pieces using photolithography or laser scribing. A translucent conductive oxide electrode (hereinafter referred to as TCO electrode) (7) with a single layer or laminated structure made of tin oxide, indium tin oxide, etc., and a glow discharge in an atmosphere of a reactive gas such as silane. A single layer of light flooded amorphous silicon semiconductor (8
) and an ohmic back electrode such as aluminum (9)
and a laminated structure with a film thickness on the order of microns to submicrons, at their adjacent interval [11] Vc, through a coupling electrode α21 that includes a laminated structure Vc of titanium or titanium and aluminum, VcVi, and titanium. electrically connected in series as much as possible. The above-mentioned coupling electrode 0 has a back electrode (9) made of aluminum directly adjacent to the space αυ
TCO electrode (7) of the adjacent laminated structure 11G exposed to
When in contact with the TCO electrode (7) at the contact interface
The oxygen inside is the aluminum r of the back electrode (9) material.
This is to prevent the laminate from oxidizing and forming a resistance layer. Therefore, the bonding surface material of the bonding electrode [+21] need not be limited to titanium as long as it is resistant to oxidation.

The amorphous silicon-based photoactive layer (8) is equipped with well-known semiconductor junctions such as pins parallel to the film surface, and includes a light receiving plate (5), a transparent adhesive layer (6), a support substrate (2) and a TC.
When light is irradiated through the O electrode (7), photocarriers of free electrons and holes are generated mainly in the thick type 1 layer, and these photocarriers are transferred to the TCO electrodes (71 and 71). Photovoltaic force is generated by collecting current to the back electrode (9).

The generated photovoltaic force is added to the photovoltaic force of the adjacent laminated structure exposed through the coupling electrode 1, and the output arranged in a row of holes in the area between the laminated structures is taken out from the terminal electrode (13). .

In such a structure, when an impact is applied to the light incident surface of the light receiving plate (5), the light receiving plate (5) breaks and its fragments try to scatter, but the transparent adhesive layer +61 Since the scattering force of the fragments is absorbed, the fragments of the light receiving plate (5) are not scattered.

Furthermore, in the photovoltaic device of the present invention [6], it is possible to use thick tempered glass, which has a mechanical strength about 3 to 8 times that of ordinary plate glass of the same thickness, as the light receiving plate (5). It becomes possible. That is, as 1 tempered glass, after uniformly heating ordinary plate glass to around the softening temperature (500 to 700 ° C.),
When this is quenched by uniformly blowing cooling gas onto it, the internal contraction is inhibited by the surface layer that has already been cooled and hardened, creating tensile stress, which is strengthened by inducing compressive stress in the surface layer. There are two types: chemical strengthening, in which potassium is incorporated into the surface layer by immersing it in a potassium aqueous solution to chemically strengthen it. The common drawback of these two types of tempered glasses is that they cannot be cut into any shape after being strengthened, and furthermore, in order to increase the transparency of the TCO electrode (7) of the photoelectric conversion film (3), a
The support substrate (2) is heated to around 0°C, and then an amorphous silicon-based semiconductor film is formed by glow discharge of silane as described above as a photoactive layer (8).
Tempered glass, which had to be heated to temperatures between 00 and 350 degrees Celsius, can be strengthened by reverting to normal plate glass. Therefore, photovoltaic devices that conventionally required heat treatment are Even if tempered glass is used as a supporting substrate, it will only have the same mechanical strength as ordinary plate glass after manufacturing, and even if tempered glass is rarely used, it will not fit into a pocket on a large substrate of 10 sides x 10 to 40 cs x 40 countries. Assuming that a large number of solar cells for use in small consumer devices such as radios, calculators, and wristwatches are manufactured at the same time, if scribe grooves are formed on the surface layer to cut each individual module, -
Because the glass would instantly shatter due to internal stress, it was not possible to use tempered glass with such high mechanical strength.

Also, as the light receiving plate (5), it is the same as using tempered glass.
It becomes possible to use a photovoltaic device equipped with an antireflection film, which has conventionally required heat treatment at 200° C. or higher.

(G) Effects of the Invention As is clear from the above description, the photovoltaic device of the present invention has a transparent adhesive layer between the light-transmitting light-receiving plate forming the light incident surface and the light-transmitting support substrate to bond them together. By disposing the transparent adhesive layer, the transparent adhesive layer acts to prevent the scattering of fragments due to impact destruction of the light-receiving plate, thereby avoiding the danger of scattering of such fragments. Since both are substantially equal, the increase in light reflectance caused by the transparent adhesive layer can be substantially ignored and does not cause a decrease in photoelectric conversion efficiency.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of the photovoltaic device of the present invention, and FIG. 2 is an enlarged cross-sectional view of the main parts of FIG. Photoelectric conversion film, (5
)...Light receiving plate, (6)...Transparent adhesive layer.

Claims (2)

[Claims] (1) A photoelectric conversion film that performs photoelectric conversion upon irradiation with light is supported on one main surface. A photovoltaic device characterized in that a light-transmitting light-receiving plate is disposed through a transparent adhesive layer having substantially the same thickness as the support substrate. (2) The photovoltaic device according to claim 1, wherein the light-transmitting light-receiving plate is made of tempered glass.