JPH0637343A - Solar cell device - Google Patents

Abstract

PURPOSE:To give a design property to a solar cell device constructed by juxtaposing a plurality of solar cell elements on a plane and thereby to increase a value added as a commodity. CONSTITUTION:Solar cell elements 30A of a group A having light-receiving surfaces 33A of a first color and solar cell elements 30B of a group B having light-receiving surfaces 33B of a second color are used in a plurality respectively, and a solar cell device 50 having a prescribed two-dimensional lithographic pattern is obtained by disposing the solar cell elements 30A and 30B belonging to the groups A and B respectively in the shape of a mosaic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell device (solar cell assembly) constructed by arranging a plurality of solar cell elements (solar cell elements) in a plane, and particularly The present invention relates to an improvement for not only having a photoelectric conversion function as a function but also making it usable as a design article.

[0002]

2. Description of the Related Art A photoelectric conversion element generally called a solar cell element has already been very well known in its photoelectric conversion principle, and many concrete examples of its structure are well known. Therefore, a detailed description is omitted, and a comparatively basic cross-sectional structure example of the conventional solar cell element 10 is given in FIG.

First, there is a semiconductor region 11 which is generally a semiconductor wafer or a semiconductor substrate, and a barrier forming layer for forming an energy barrier with the semiconductor region 11 on one main surface side thereof.
Twelve are provided. There are several methods of forming an energy barrier by the semiconductor region 11 and the barrier forming layer 12, and a semiconductor of opposite conductivity type or a thin layer formed by introducing an impurity is applied to the p-type or n-type semiconductor region 11. In addition to the most general classical structure provided as the barrier forming layer 12, for example, a SnO ₂ layer is provided as the Schottky barrier forming layer 12 for the Si substrate 11, or
Even a metal film can transmit light with little loss as long as it has a film thickness of approximately 100 Å or less, so a suitable metal film may be provided as the Schottky barrier forming layer 12 for the semiconductor region 11, and further, a semiconductor film may be provided. In some cases, the region 11 and the barrier forming layer 12 form a so-called heterojunction. The barrier forming layer 12 itself may be composed of a plurality of laminated structures, but in the group of drawings attached to this specification, the barrier forming layer 12 is shown as a single layer including such a case. As will be clarified, the present invention provides a photoelectric conversion mechanism of such a photoelectric conversion function part (11, 12) including a semiconductor region 11 and a barrier forming layer 12, and physical properties of the semiconductor region 11 and the barrier forming layer 12. This is because the relationship and the like may be in accordance with a known place and is not directly limited.

A protective film 13 is formed on the surface of the barrier forming layer 12, and light is normally incident on the photoelectric conversion function section (11, 12) through the protective film 13. Therefore, the protective film
13 is often made so as to function as an antireflection film against incident light, and in some cases, a fancy one may have a single layer structure or a plurality of laminated structures. However, since this point also has no direct relation to the present invention, it is shown as a single-layer film in the drawings attached to this specification. Photocurrent generated by light incident on the photoelectric conversion function section (11, 12) from the outside through the protective film or antireflection film 13 is applied to the surface of the barrier forming layer 12 by, for example, a comb-shaped first electrode. 14 and the second electrode 15 provided on the back side of the semiconductor region 11
Can be taken out to an external load circuit (not shown) connected between and.

However, FIG. 6 shows a single solar cell element 10, that is, a unit solar cell element 10. However, for example, various types such as a tabletop or a portable computer, a portable shaver, a portable radio, etc. When incorporated into office or daily home appliances, a plurality of such solar cell elements 10 are used in parallel or series, or connected in parallel series according to the required current capacity and voltage.
Therefore, the actual geometric arrangement pattern of the plurality of elements is as shown in FIG. 7, for example.

FIG. 7 shows a portable or desk-top calculator 20. The keyboard portion 21 used by the user for calculation and the calculation result are visually displayed according to a very general arrangement on the main body surface. A display 22 is provided. Although a gothic type is shown in FIG. 7 for the sake of convenience, the alphanumeric display on the display 22 is usually made using a well-known 7-segment liquid crystal element or the like. The solar cell element 10 serving as a power source for driving the calculator 20 is arranged in a four-dimensional, one-dimensional array so as to expose its light receiving surface to the window 23 opened on the surface of the calculator main body. ing. window
A cover (not shown) made of transparent plastic or the like is fitted on the 23, and the part visible to the human through this cover is shown in each figure as a small dot pattern. Protective film or antireflection film 13 that constitutes the light-receiving surface of the battery element 10.
And the surface electrode (first electrode described above) 14 provided between the surface of the solar cell and the adjacent solar cell element. The four solar cell elements 10 provided in FIG. 7 are normally connected in series with each other in this application, but more solar cell elements 10 are used in electronic devices that require more power, and some of them are used. It may be used by connecting those connected in series in parallel. In addition, in consideration of use in a dark place, in addition to the illustrated solar cell element 10,
Some devices have a built-in primary battery or a built-in secondary battery that can be charged by surplus power of the solar cell element 10 when it is bright.

[0007]

However, regardless of the number of solar cell elements 10 to be used, at least the above-mentioned various electronic equipments using the solar cell elements 10 are always present in the main body of the equipment. A window 23 that exposes the light-receiving surface of the solar cell element 10 is required in the surface portion that is easily exposed to light.
This point has no room for modification in principle, but on the other hand,
The light-exposed portion is, after all, the surface portion that is best viewed by the user for operating the device. In the example shown in FIG. 7, the solar cell element 10 is provided on the same surface of the device body as the keyboard 21 and the display 22.
Is also provided.

However, as can be seen by looking at the light receiving surface of the ordinary solar cell element 10, most of the things are mostly dark blue, and depending on how the light hits, it appears that dark gray is close to black. It may appear to be a color, but in any case, it gives only a uniformly dark visual feeling.

The present inventor initially considered this to be a problem. This is because many solar cell-using devices of this kind, including the computer shown in FIG. 7, have only functional factors such as high performance and excellent cost performance when viewed as products offered on the market. However, it does not necessarily mean that the market competitiveness is increased, and looking at recent market trends, having a good design is becoming a major factor. Even if the performance is a little inferior, products with unusual or sophisticated designs may sell better.

From this point of view, the solar cell device up to now does not contribute to the design of the product in which it is used. It can be said that there are many cases in which the sense of design is impaired. Looking at the calculator shown in FIG. 7, the solar cell element 10 having a dark-colored light-receiving surface such as dark blue is randomly
Moreover, in a fairly large area, four are lined up on the operation surface, which is an important design surface of the device body. From a design standpoint, this is an undigested feeling. Nevertheless, it can be said that there is no conventional example in which the design feeling of the solar cell device itself has been deeply studied so far.

In view of such circumstances, the inventor of the present invention generally has to provide a solar cell device in a conspicuous portion even in an electronic device using the solar cell device. We wondered if it would be possible to provide a solar cell device that is not only a functional component but also a design article by giving the product its own design. In other words, the provision of such a solar cell device is the main object of the present invention. On the other hand, if the main purpose of the present invention is such, the above-mentioned main purpose is achieved, and for this type of solar cell device, a new added value is added in a design sense.
The photoelectric conversion function, which is its basic function, may be damaged to some extent. However, of course, the smaller the degree, the more desirable it is, and further, if the device is not inferior in performance to the existing solar cell device, it is better than that. In the present invention, disclosure of such a structural device is also another purpose.

[0012]

In order to achieve the above main object, the present invention firstly has a photoelectric conversion function having a light receiving surface having a predetermined planar shape with a predetermined area and a back surface facing the light receiving surface. In a solar cell device having a plurality of solar cell elements, each of which has a plurality of solar cell elements and generates a potential difference between the first and second electrodes when light is incident on the photoelectric conversion function section through a light receiving surface. , Prepare a predetermined number of solar cell elements with different colors when looking at the light-receiving surface for each light-receiving surface color, and arrange the solar cell elements of each light-receiving surface color in a mosaic pattern according to the planned planar layout pattern. We propose a solar cell device that is installed in parallel.

Further, when the surface electrode as described with reference to FIGS. 6 and 7 is provided on the light receiving surface side of each solar cell element,
In some cases, the design design may be hindered. Therefore, the present invention also proposes a configuration in which such a surface electrode may be unnecessary. That is, the barrier forming layer that forms an energy barrier on the light-receiving surface side of the semiconductor region of each solar cell element is further configured to have a side surface portion extending along at least one side surface portion of the semiconductor region. It is also possible to have a back surface portion which is continuous with the side surface portion and extends around even a part of the back surface of the semiconductor region. Then, of the first and second electrodes for extracting the photoelectric conversion current to the outside, the first electrode is provided on the side surface portion or the back surface portion of the barrier forming layer, and the second electrode is formed on the back surface of the semiconductor region. Provide on the side. When the first electrode is provided on the side surface of the barrier forming layer, this electrode may be extended to the insulating film on the back surface of the semiconductor region.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic plan structure of a solar cell device 50 as an embodiment constructed according to the present invention. In the case shown, a total of 75 squares are drawn in a matrix arrangement of 5 rows and 15 columns.
Each of these squares represents a unit solar cell element or its light-receiving surface. In this example,
A solar cell element 30A belonging to the first group A having a light-receiving surface 33A with a fine dot pattern in the figure, and a solar cell element belonging to the second group B in which the light-receiving surface 33B is shown by white squares. Two types of solar cell elements 30A, 30B of 30B
, The fine dot pattern represents the first color, and the open squares represent the second color. Looking at the figure as it is, the light receiving surface 33 with the dot pattern
The color of A appears to be lower than the color of the white light-receiving surface 33B in its lightness, that is, darker, and in fact, it may be, but it is not limited thereto. In short, in order to clearly show in the monochrome drawing that the first color and the second color are different, a fine dot pattern and a white outline were used to distinguish them. The light-receiving surface 33B may have a really dark color, and the light-receiving surface 33A having a fine dot pattern may have a lighter color.
The reference numerals 33A and 33B refer to the light-receiving surface that exhibits each color as described above, and also refer to the surface film that is visible when the surface of the solar cell element 30 is viewed.

In the following description, in the case where the description is applicable to any group that does not particularly require color grouping, the subscripts A and B indicating that each code belongs to each group A and B are omitted. , For example, simply referred to as the solar cell element 30 and the like, in the case of the embodiment of FIG. 1, 5 × 15 =
The entire rectangular planar shape of the solar cell device 50 itself, which is composed of the total set of the light-receiving surfaces 33 of the 75 solar cell elements 30, constitutes a two-dimensional drawing area of a desired pattern as a so-called “canvas”. In the rectangular drawing area, the English character "ETL" is drawn as a desired pattern by utilizing the color difference of the light receiving surface 33 of each solar cell element 30. That is, each light receiving surface 33 of each solar cell element 30 constitutes a “pixel” which is a minimum drawing area unit for drawing a desired pattern, and in the illustrated case, is a first pixel belonging to the first group A. Of the thirty solar cell elements 30A having a color, for example, a dark blue light-receiving surface 33A, the first is thirteen solar cell elements.
30A is used to draw the letter "E" on the left side of the rectangular canvas with the square light-receiving surface or a set of pixels 33A, and a row of pixels is provided to the right of which nine solar cells are similarly arranged. The letter "T" is made by the group of the light-receiving surface 33A of the element 30A, and the column "L" is made by the group of the pixels of the light-receiving surface 33A of the eight solar cell elements 30A at the right next to the pixel row. The remaining area of the rectangular canvas, which is the background area for emphasizing each character, is drawn as a sun with a light receiving surface 33B of a second color belonging to the second group B, for example, red or yellow. It is filled with the battery element 30B.

As is apparent from such an embodiment, in the present invention, the individual solar cell elements constituting the solar cell device 50 are
By using the light receiving surface 33 of 30 as a pixel of a unit having a predetermined area and a predetermined color, and arranging solar cell elements 30A and 30B having light receiving surfaces 33A and 33B of different colors in a mosaic pattern, respectively. Since a desired pattern is drawn by a set of light receiving surfaces 33A and 33B of different colors, the total number of solar cell elements 30 to be used, the number of different kinds of colors (the number of groups described above), the individual solar cell elements There is no particular limitation on the planar shape and area of the light-receiving surface, the size, the planar shape, and the like of the “canvas” formed by the collection of the light-receiving surface groups of all the solar cell elements.
It can be changed as needed.

Specifically, for example, in the use example of the solar cell device so far shown in FIG. 7, the individual solar cell elements are
The area of the light receiving surface 13 of 10 is approximately 10 mm square (10 mm square), and therefore, the area occupied by the window 23 for the solar cell device in the computer 20 shown in FIG. Even if the width of the first electrode 14 provided therebetween is taken into consideration, the area is approximately 10 mm in length and 40 mm in width. Therefore, in the apparatus of the embodiment of the present invention shown in FIG. 1, if the size of the light receiving surface 33 of each solar cell element 30 is set to, for example, about 2 mm square, the window area is called "ETL" in a window area similar to the above. Since it is possible to obtain a solar cell device 50 having a desired pattern notation and having a colorful light incident surface, if this is incorporated in place of the solar cell device of the computer 20 shown in FIG. Up until now, there was only a dark blue window 23, that is, an area that was completely meaningless in terms of design could be used as a meaningful area for transmitting English character information "ETL". it can. If "ETL" is a general company name, for example, the computer 20 as shown in FIG. 7 having a solar cell device having such a pattern notation indicates that the source of the product is ETL company. The area of the window 23 where the solar cell element 50 can be seen can be intuitively understood by the consumer and is never a useless area in terms of design.

On the contrary, the solar cell device, which has been apt to be pushed to one corner of the main body of various electronic devices up to now, is positively utilized by the solar cell device according to the present invention. However, it can be considered that it will be installed in a more conspicuous position, or it may be intentionally made larger. Depending on the individual designer, if it is judged that a large area is desirable for design, or if the number of pixels in a unit is increased and a more complicated pattern is intended to be drawn, it will result. In consideration of the basic photoelectric conversion function, the light receiving area of the entire solar cell device increases, so that it becomes easy to increase the total output current capacity and output voltage.

If this idea is promoted, the solar cell device 50 of the present invention is constructed so as to have a large-area drawing region with an extremely large number of unit solar cell elements, and further, each light-receiving surface 33 which is a unit pixel. By increasing the number of types of colors that should be given, it is possible to provide the market with things like "power generation murals". Moreover, various application ranges are widened depending on the size of the area of the unit pixel. For example, each solar cell element that constitutes this type of solar cell device is usually cut out into individual solar cell elements after a large number are formed on one wafer, but it is not enough to reduce the area. , 1mm even with existing technology
Since it is possible to obtain a solar cell element having a light-receiving surface of a corner or less with sufficient reliability, the entire drawing area, that is, the total area of the solar cell device 50 is not so large, but is considerably complicated. You can draw patterns. Therefore, by using the solar cell device of the present invention as a power supply device for various kinds of desktop or portable small electronic devices, it is possible to express considerably interesting pictorial expressions, numbers and characters. On the other hand, when considering the direction of increasing the area of the unit pixel, one large solar cell element is formed on one circular wafer, or a plurality of solar cell elements are individually cut out. It is also possible to obtain a considerably large mural-like drawing pattern by making all of them into unit pixels without using them. In addition to the power generation murals mentioned above, this is an improved product that has been further improved in design as a solar battery panel as a household auxiliary power source that has already been put into practical use, or as a solar car solar battery panel. Can be applied to provide.

The planar shape of the unit pixel, that is, the planar shape of the light receiving surface 33 of each solar cell element 30 is not limited to the square shown in FIG. 1, but other rectangular shapes such as rectangles, triangles, hexagons, etc. In the same manner as in the case of using the entire circular wafer as one pixel in the above, including the polygonal shape, the case where each of the light receiving surfaces of the individual small solar cell elements is circular is also allowed. In the case of circular pixels, there are gaps between neighboring objects, but if you draw some pattern with many circular pixels and see it from a little distance, you can still get a drawing pattern with an interesting design sense. it can. Furthermore, in order to make the line pattern of the boundary surface between the adjacent solar cell elements interesting, the light receiving surface shape of each solar cell element may be shaped like an individual piece of a jigsaw puzzle. If the color of the light receiving surface of the adjacent solar cell element is different, even if it is not an expression with intelligent meaning, such as letters or numbers, it is a kind of abstract image, which is enough visual,
A pattern with a design value can be obtained. Although a two-dimensional drawing area is formed in the case of FIG. 1, the present invention can be applied to a one-dimensional drawing area. By changing the colors of the light-receiving surfaces of a large number of solar cell elements arranged in a line in accordance with predetermined patterns, it is possible to provide a significant value in terms of design only by such a change in the color pattern.

Looking again at FIG. 1, this is a schematic diagram, but as seen in the solar cell device in the conventional example of FIG. 7, surface electrodes (first electrode) provided between adjacent solar cell elements are used. The electrode corresponding to electrode 14) is not drawn.
This is not omitted because it is a schematic view, and this is because the embodiment shown in FIG. 1 uses the solar cell element 30 having the sectional structure as shown in FIG.

As shown in FIGS. 2A and 2B, FIG. 2 shows two solar cell elements 30, 30 having a slight difference in surface film structure on the light receiving surface. However, the main components are the same. Therefore, first, to explain from a point common to them, the unit solar cell element 30 shown in the center in the illustrated cross section shows one of a plurality of solar cell elements simultaneously formed in one wafer. Therefore, a part of the adjacent solar cell element is also shown on both sides thereof.

The photoelectric conversion function portion of the solar cell element 30 is composed of the semiconductor region 31 and the barrier forming layer 32, but the semiconductor region 31 may originally be a semiconductor wafer or a semiconductor substrate. In both main surfaces of the semiconductor region 31, the upper surface side in the figure is the light receiving surface side, and the energy barrier forming layer 32 is formed on this light receiving surface side. As already described with reference to FIG. 6, the photoelectric conversion function part (31+) including the semiconductor region 31 and the barrier forming layer 32 is formed.
In order for 32) to perform the photoelectric conversion function, the semiconductor region 31
The barrier forming layer 32 must form a pn junction, a Schottky junction, or a hetero junction. The solar cell element used in the present invention may be of any type, but in the case of the solar cell element shown in FIG. 2, the semiconductor region 31 is a p-type semiconductor and a barrier is formed in accordance with a manufacturing example described later. Layer 32
Is n-type, particularly preferably high-concentration n-type (n ⁺ ) having high conductivity
Has become a semiconductor.

In one cross section of FIG. 2, a groove cut from the back surface side of the semiconductor region 31 toward the front surface side (that is, the light receiving surface side), particularly V in this case, is provided between the adjacent solar cell elements 30, 30. Separated by a groove cut into a cross section, so that
At least in the cross section shown in the drawing, a pair of side surface portions facing each other is formed in the semiconductor region 31 of each solar cell element 30. Particularly in the case of the structure shown in the drawing, as a result of forming the V-shaped cross-section groove, the pair of side surface portions are inclined toward the back surface side in a linear taper shape that is close to each other. As shown by the portion 36, the barrier forming layer 32 extends along the pair of side surface portions of the semiconductor region 31 and further ends at the portion 37 that extends to the back surface side of the semiconductor region 31.

The side surface portion 36 of the barrier forming layer 32 and the surface of the back surface portion 37 which is continuous with the side surface portion 36 and extends to the back surface side of the semiconductor region 31 are both made of an appropriate insulating film or protective film.
38, and the exposed back surface of the semiconductor region 31 is also covered with an appropriate protective film or insulating film 39, which are provided with contact openings of appropriate areas at appropriate places, and through these openings. , The back surface of the barrier forming layer 32
37, 37 have the first electrodes 34, 34, respectively, and the semiconductor region
A second electrode 35 is provided on the back surface of 31.

The structure up to this point is the same in any of the solar cell elements 30 and 30 shown in FIGS. 2A and 2B, but the difference between the two is that the surface of the barrier forming layer 32 on the light receiving surface side is covered. It is recognized in the structure or arrangement pattern of the surface film 33. First, the element of FIG. 2 (a) will be described. The thickness t of the surface film 33 in the unit solar cell element 30 shown in the center is also shown in the unit solar cell elements 30, 30 partially shown on both sides. The thicknesses t of the surface films 33, 33 are also the same. In other words, the surface film 33 is formed so as to cover the light receiving surfaces of all the unit solar cell elements 30 formed on the common wafer or the common semiconductor substrate with the uniform thickness t. In a sense, the surface film 33 protects the light receiving surface of the solar cell element 30 like the protective film or the antireflection film 13 found in the basic structure of this type of solar cell element described with reference to FIG. It may be a thin film of a material and a structure suitable for increasing the incident light rate of light.
Therefore, as described above, the structure is not limited to the single layer structure, and may be a multilayer structure. However, what is more important to the present invention is that the thickness t of the surface film 33 is an element that determines the color of the light receiving surface of the solar cell element 30 (that is, the surface film 33) when viewed from above. It is that.

To explain this, for example, a semiconductor region
When the material 31 and the barrier forming layer 32 are usually made of a material suitable for this type of solar cell element (eg, silicon-based, gallium arsenide-based, etc.), the silicon nitride film is a film formed on the surface region of the silicon nitride film in terms of physical properties in manufacturing. It is also one of the suitable films. However, when such a silicon nitride film is used as the surface film 33 shown in FIG. 2, the color seen when the silicon nitride film 33 is viewed from above differs depending on the thickness t, and is considerably large. It has a distinctive color. This is based on a known principle of generating interference light, but in the case of a silicon nitride film, the color of navy blue, yellow, red, green, or the like is changed greatly depending on the thickness t. The relationship between the specific film thickness and the color to be exhibited at that time will be described together with the production example described later. In any case, by utilizing this feature, as described through the embodiment shown in FIG.
It is possible to obtain the solar cell elements 30A, 30B having different light-receiving surface colors necessary for constructing the solar cell device 50 according to the present invention. For example, if a solar cell element group of dark blue and red is required, a silicon nitride film 33A having a film thickness t that looks like dark blue is formed on the barrier forming layer 32 of the solar cell element 30A formed on a certain wafer. , Solar cell element 30 formed on another wafer
It is sufficient to form a silicon nitride film 33B having a film thickness t that appears red on the barrier forming layer 32 of B, and the required number of individual solar cell elements 30A, 30B cut out from these wafers for each color are obtained. If only two are used one by one and two-dimensionally arranged according to a predetermined pattern by the mosaic drawing method, the solar cell device 50 having a desired design expression can be provided. Of course, if you need more colors,
The solar cell elements 30A, 30B, ... With various changes in the thickness t of the silicon nitride film may be produced for each wafer.

In the method shown in FIG. 2 (a) described above, the light receiving surfaces of the plurality of solar cell elements 30 simultaneously formed on one wafer have the same color. On the other hand, when it is desired to make only the light receiving surface of the solar cell element 30 at a specific location on one wafer different from the other colors, as shown in FIG. The thin film 33 'such as a silicon oxide film formed uniformly on the barrier forming layer 32 of the solar cell element 30 is removed or thinned at the solar cell element 30 (in the case shown, it remains thin) Then, the silicon nitride film 33 may be formed thereon again to the thickness t exhibiting a predetermined color. This also applies to the thin film 33 'on the other solar cell elements.
Is replaced with a silicon nitride film having a different film thickness t,
It also indicates the possibility of manufacturing solar cell elements having different light-receiving surface colors on the same wafer. Such a selective manufacturing method is used, for example, when the number of solar cell elements of a specific color required is small, or when a relatively large two-dimensional pattern is drawn with one wafer as a unit pixel. It is also effective in giving a special design feeling. That is, either a single wafer is used as it is, or the periphery is cut so as to leave only the effective manufacturing region of the solar cell element group and formed into a rectangular shape, which is then used as an extremely large “canvas” that constitutes a mural or the like. When a two-dimensional pattern is drawn in a mosaic pattern by using several other wafers or a group of cut wafers as a unit pixel to be used in contrast, a large unit pixel called a wafer already has a predetermined linear pattern or the like in a small unit pixel. Since it can be drawn, more complicated drawing is possible.

On the contrary, if the thin film 33 'in FIG. 2 (b) is considered to be an oxide film or the like which is intentionally formed or is formed by an oxidizing environment in any of the solar cell element manufacturing steps. Similarly, in the case of the structure shown in FIG. 2A, the silicon nitride film 33 for imparting color to the light-receiving surface is not formed directly on the barrier forming layer 32 but on the oxide film. It may be formed. Rather, Fig. 2 (a), (b)
In any of the above cases, after forming a thin film having a single layer or a laminated structure suitable as a protective film for the barrier forming layer 32 or as an antireflection film, silicon nitride is used only for the purpose of giving a good color to the light receiving surface. The film 33 may be further laminated.

Further, as described above, the silicon nitride film is effective for exhibiting a clear and desired color as described above, but other thin films such as tin oxide, indium oxide, zinc oxide, tantalum oxide, and titanium oxide are also available. Is also possible to express a fairly clear color tone. Even if it is a silicon oxide film, the color is not so clear, but a phenomenon occurs in which the color changes depending on the film thickness.Therefore, a predetermined film is provided to give color to the light receiving surface of the solar cell element. Thickly formed surface film
These thin films can also be used as 33. It is understood that the material of the thin film 33 for giving the light-receiving surface color may be different for each solar cell element used for each unit pixel, and naturally, the film thickness of the thin film 33 made of different materials from each other. May be different.

By the way, in the solar cell element 30 of the sectional structure example shown in FIGS. 2 (a) and 2 (b), the surface electrode is not visible, so that the solar cell device 50 of the present invention is constructed in addition to the excellent designability. The workability of the assembly work (mosaic arranging work) for this purpose is excellent, and the original photoelectric conversion function is also excellent. That is, according to the existing structure shown in FIG. 6, the first electrode 34 to be formed with respect to the barrier forming layer 32 is located on the light receiving surface side. Therefore, the area area occupied by the electrode becomes a dark field area with respect to the incidence of light, and the effective area area that can be called a light receiving surface is reduced. On the other hand, as in the structure example shown in FIG. 2, the first electrode 34 is not electrically connected to the back surface portion 37 through the high-concentration n ⁺ type side surface portion 36 to the barrier formation layer 32 on the light receiving surface side. Is provided,
Since the entire surface area of the barrier forming layer 32 on the light receiving surface side can be used as an effective light receiving surface, the photoelectric conversion efficiency is surely increased accordingly. Of course, for this function,
As shown in FIG. 6, the side surface portion 36 and the back surface portion 37 of the barrier forming layer 32 do not need to be paired, and are provided only on one side surface portion of the semiconductor region 31 and a part of the back surface portion continuous with the side surface portion. I'm good. However, as can be seen from the manufacturing example described later, it is rather troublesome to form the semiconductor regions on both side surfaces.

On the other hand, in order to construct the solar cell device 50 of the present invention, the solar cell device 50 is separated at the center of the V-shaped groove between the adjacent solar cell elements 30 (since there is a groove, this separation operation itself is easy. ) Even after the individual solar cell elements 30 are cut out and the solar cell elements 30 each having a predetermined number of light-receiving surface colors in accordance with a predetermined pattern are assembled into predetermined positions one by one, the first electrode 34 And the second electrode 35 connected to the semiconductor region 31 are in a juxtaposed relationship with each other in the same plane,
A printed circuit board is used as a physical support substrate (not shown), and the first and second electrodes 34 and 35 are usually soldered to a predetermined portion on a conductive pattern formed on the printed circuit board with a predetermined pattern. You can fix it with. That is, electrical predetermined connection wiring between a plurality of solar cell elements and physical fixing and supporting of these individual solar cell elements can be performed at the same time, and automation is easy. If this is a structure having the surface electrode 14 as in the element structure illustrated in FIG. 6, for example, a separate lead wire or the like is required for connection wiring work with another solar cell element. , Becomes extremely complicated, and disconnection accidents easily occur.

FIG. 3 shows a specific example of a manufacturing process for obtaining the solar cell element 30 having the sectional structure shown in FIG. First, as shown in FIG. 3A, in order to form the silicon oxide films 41, 41 on both front and back main surfaces of the p-type silicon wafer 31, and to form a groove at a predetermined position of the silicon oxide film 41 on the back surface side. Open the etching openings 42 ,. Then, hydrazine etching is performed to form a groove 43 extending from the back surface to the front surface of the semiconductor region 31, as shown in FIG. 3 (b). At this time, the back surface of the starting wafer is the (100) surface, and one side of the opening 42 is <11.
0> direction, grooves formed by etching
As shown in the figure, 43 has a V-shaped groove whose side surface is a (111) plane.

Next, as shown in FIG. 3 (b), the silicon oxide films 41, 41 in predetermined regions on the front and back surfaces are removed,
By depositing and diffusing n ⁺ impurities with the entire wafer standing, or by depositing and diffusing n ⁺ impurities once while removing the oxide film 41 on the front and back surfaces, respectively, as shown in FIG. as shown (c), the to form the n ⁺ barrier layer 32 in the surface region of the semiconductor region 31, n ⁺ side in succession to the barrier-forming layer 32 along the V-groove of the semiconductor region 31 A portion 36 and an n ⁺ back surface portion 37 that is continuous with the side surface portion 36 and extends to the back surface side of the semiconductor region 31 are formed.

After this step, a silicon oxide film is newly deposited in the opening for introducing the n ⁺ impurity, but if necessary, it is removed in a predetermined region or the barrier forming layer 32 is formed. For protection, a silicon nitride film 33 having a predetermined thickness t is formed on the barrier forming layer 32 in order to give a predetermined color to the light receiving surface of the solar cell element to be manufactured while leaving it thin. At this time, the silicon nitride film 44 also grows in the openings on the side surface side and the back surface side of the semiconductor region 31, and generally the silicon oxide film left in the previous step.
Although it is also deposited on 41, the silicon nitride film 44 that may be formed on the silicon oxide film 41 on the back surface side is omitted for simplicity.

Here, the relationship between the thickness t of the silicon nitride film 33 formed on the barrier forming layer 32 and the obtained color is
According to the results of experiments conducted by the present inventor, the film thickness t is approximately 950.
At Å, it becomes blue or navy blue, and at about 1500 Å yellow, almost 18
It became red at 00Å and magenta at about 2000Å. As described above, such a change in film thickness vs. color also occurs in the silicon oxide film, and although it is not unusable in the present invention, a clear color can be obtained and it is easy to handle. The silicon nitride film is optimal as the material of the surface film 33 because it has little adverse effect on the photoelectric conversion function that the device should originally have. Of course, the other materials described above also exhibit a color change with respect to a change in film thickness. By the way, another example of zinc oxide is as follows. In the case of this material, when the film thickness t is about 900Å, it is light blue, about 1200Å
Became yellow, and when it became thicker up to about 1900Å, it became red.

In any case, if the surface film 33 having a required film thickness t is formed in this way, each oxide film 4 on the back surface side is formed.
Openings 45 and 46 are opened at predetermined positions with respect to 4 and 41 to form the first electrode 34 and the second electrode 35. Further, as described above, in order to perform automatic soldering, the electrodes 34 and 35 are formed. Solder coat the surface of. After such a series of steps, the remaining insulating film is the insulating film 3 shown in FIG. 2 (b).
8 and 39. Although there is a pair in the illustrated case, the first electrode 34
Of course, only one may be used.

In the process of FIG. 3 (b) described above,
In the figure, not only the solar cell element formation area shown in the center but also after removing the silicon oxide film on the entire surface of the wafer, the subsequent steps are followed, as shown in FIG. A solar cell element 30 having a silicon nitride film 33 having a film thickness t is obtained. In addition, since no etching stopper is provided in the above process, the bottom of the V-shaped groove (which is the upper end portion in the figure is usually etched from top to bottom) when forming the V-shaped groove. It penetrates to the surface of the semiconductor region, forming a kind of through hole. If necessary, the existing technology can be used to provide an etching stopper, but even if it is not provided and a through hole is formed, the length of the groove in the direction orthogonal to the drawing sheet is kept at an appropriate length. When viewed from the surface of the semiconductor region 31, if the plane pattern for forming the solar cell element on the wafer is determined so that the groove opened on the surface has, for example, a discontinuous perforation shape, it is sufficiently durable to the subsequent steps. Only the strength of the wafer can be secured.

In producing a cross-sectional structure having a V-shaped groove as shown in FIG. 2 or 3, Japanese Patent Publication No. 54-26475 can be referred to as a publicly known example concerning the production method. Although this publication differs from the process of FIG. 3 in that the V-shaped groove is formed from the front surface side to the back surface side of the semiconductor region, various considerations regarding the method itself can be equally applied. Of course, any other known existing method may be used, and the shape of the through hole or groove is not limited to the V shape, and the side surface portion of the semiconductor region in the direction orthogonal to the drawing sheet may be used. Similarly, such grooves may be provided.

More specifically, the materials of the barrier forming layer 32 and the side surface portion 36 and the back surface portion 37 along the side surface of the semiconductor region 31 are
In principle, the barrier forming layer 32 may be different,
It suffices if the first electrode 34 provided on the back surface side can be conducted with high conductivity. However, after applying the insulating film to the side surface and the back surface of the semiconductor region 31, it is troublesome to purposely laminate the high-conductivity layer thereon, and as described above,
This is not suitable for the convenience of forming the barrier forming layer 32 at the same time.

However, if the element shown in FIG. 2 is slightly modified to form an element having a sectional structure as shown in FIG. 4, the back surface portion 37 of the barrier forming layer 32 itself may be unnecessary. Only parts different from those of the device shown in FIG. 2 will be described, and the other parts will be referred to as already described. However, the barrier forming layer 32 has only the side surface part 36. One electrode 34 is formed. However, desirably, the first electrode 34 is formed on the back surface side insulating film 39 of the semiconductor region 31.
Has a portion extending to the upper side, and this extending portion also has a side-by-side relation with the second electrode 35 in a plan view. Therefore, the various effects of this element are the same as those of the element shown in FIG.
Rather, the device of this structure is easier to manufacture.

As described above, the solar cell element 30 having the structure shown in FIG. 2 or 4 is the solar cell element 50 of the present invention.
It has a very desirable structure in constructing. Since there is no surface electrode, if the adjacent solar cell elements are arranged in close contact, the unit pixels forming a predetermined two-dimensional drawing pattern are also in close contact with each other and a fine pattern can be drawn. In addition, since the coloring method for effectively using all of the light-receiving surface and giving color to the light-receiving surface is also made depending on the film thickness of the light-receiving surface film and the material, it is possible to select other than dark blue with less loss. Even when colored, the film is extremely thin, so that the loss of the amount of incident light there can be suppressed within a range that does not pose a problem.

However, in order to achieve the main object of the present invention, as described above, the photoelectric conversion function may be sacrificed to some extent, so that the solar cell having the structure shown in FIG. Element 30 can also be utilized in the present invention. First, in FIG. 5A, the structural portion 10 has the same structure as the existing solar cell element 10 shown in FIG. 6, as indicated by the same reference numeral. Therefore, the description of the constituent elements 11 to 15 is based on the description of FIG. 6, but in order to obtain the solar cell element 30 used in the present invention, the coloring of the thickness t is formed on the surface of the structural portion 10. A surface film 33 '' is provided. This colored surface film 33 '', like the surface film 33 mentioned in the previous embodiment,
It may be an insulating film having different colors depending on the change in the film thickness t, but in this embodiment, a resin film intentionally colored in a desired color is considered. If the surface film 33 '' is such a resin film 33 '', the performance may be slightly deteriorated for the photoelectric conversion function, but in exchange for that, there is an advantage that any color can be obtained. .

However, when suitable fluorescent fine particles are mixed in the colored resin film 33 '', the wavelength of incident light is shifted, and light in the wavelength region that has not contributed to photoelectric conversion is also converted to photoelectric conversion. By doing so, the disadvantages of the structure shown in FIG. 5 are alleviated. Of course, in contrast to the structure having no surface electrode as shown in FIG. 2, a structure in which a colored resin film 33 ″ is provided instead of the surface film 33 such as a silicon nitride film can be constructed. When the colored resin film 33 ″ containing the fluorescent fine particles is provided as described above, it is conceivable that the photoelectric conversion characteristics of the colored resin film 33 ″ are even higher than those of the conventional structure.

FIG. 5B shows, as a simple modification of FIG. 5A, a case where the colored surface film 33 ″ is provided only on the surface of the barrier forming layer 12 except on the surface electrode 14. However, when the colored surface film 33 '' is directly provided on the surface of the barrier forming layer 32 as shown in the drawing, this is as shown in FIGS. It is more desirable that it is a protective film that protects the surface of 12. When a resin film is used, it is better to sandwich a protective film such as an oxide film, or preferably an antireflection film, between the resin film 33 ″ and the surface of the barrier forming layer 12.

[0046]

According to the present invention, a solar cell device which has been a mere electronic functional component until now can be provided to the market with added value as a designed article. In practice, this effect is considerably large, and the design principle of various solar cell power source-using devices is largely changed, and a considerably free design design is allowed. In some cases, the most prominent part of the device may be the solar cell device part. Also, when used as a "power generation mural", it was never possible to install a large panel of dark blue in a public area in the public place until now. Depending on the content, it will be highly welcomed by people, and there is the possibility that they will be able to benefit from solar energy in various places without any damage to their living environment.

[Brief description of drawings]

FIG. 1 is a schematic plan configuration diagram of an embodiment of a solar cell device manufactured according to the present invention.

FIG. 2 is a schematic cross-sectional configuration diagram of a solar cell element suitable for use in the solar cell device of the present invention.

FIG. 3 is a schematic explanatory diagram of a manufacturing process for obtaining the solar cell element of FIG.

FIG. 4 is a schematic cross-sectional configuration diagram of another solar cell element that can be used in the solar cell device of the present invention.

FIG. 5 is a schematic cross-sectional configuration diagram of still another solar cell element that can be used in the solar cell device of the present invention.

FIG. 6 is an explanatory diagram related to a basic structure of a conventional solar cell element.

FIG. 7 is an explanatory diagram of a usage example of a conventional solar cell device.

[Explanation of symbols]

 10,30 Solar cell element, 11,31 Semiconductor region, 12,32 Energy barrier forming layer, 13 Protective film or antireflection film, 14,34 First electrode, 15,35 Second electrode, 33,33 '' Surface film , 36 side surface continuous with barrier forming layer, back surface continuous with 37 side surface, 43 groove or through hole.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshiki Mae Yashiki 3-3-12 Fujihashi, Ome, Tokyo Ome Cosmos Electric Co., Ltd. (72) Inventor Osamu Ichiki 2-10- Shinkawa, Chuo-ku, Tokyo 6 Kayanuma Building 604 Co., Ltd. in the integrated resource system

Claims (13)

[Claims] 1. A photoelectric conversion function section having a light receiving surface having a predetermined planar shape with a predetermined area and a back surface facing the light receiving surface, and light is transmitted to the photoelectric conversion function section via the light receiving surface. A solar cell device comprising a plurality of solar cell elements that generate a potential difference between a first electrode and a second electrode when they are incident on each other, and the colors are different when the light receiving surface is viewed. A predetermined number of solar cell elements are prepared for each light-receiving surface color; the solar cell elements having the respective light-receiving surface colors are arranged side by side in a mosaic according to a predetermined planar arrangement pattern. . 2. The solar cell device according to claim 1, wherein the difference in the color of the light-receiving surface of the solar cell element is obtained by the difference in the coloring of the surface film formed on the light-receiving surface. A solar cell device. 3. The solar cell device according to claim 1, wherein the difference in the color of the light receiving surface of the solar cell element is obtained by the difference in the thickness of the surface film formed on the light receiving surface. A solar cell device. 4. The solar cell device according to claim 1 or 2, wherein the difference in the light-receiving surface color of the solar cell element is:
A solar cell device characterized by being obtained by a difference in material of a surface film formed on the light receiving surface. 5. The solar cell device according to claim 3 or 4, wherein the surface film also serves as a protective film for the light-receiving surface. 6. The solar cell device according to claim 3, 4 or 5, wherein the surface film also serves as an antireflection film for reducing light reflection on the light receiving surface. Battery device. 7. The solar cell device according to claim 1, 2, 3, 4, 5 or 6, wherein the photoelectric conversion function section of each of the solar cell elements is a semiconductor region and a semiconductor region with respect to the semiconductor region. And a barrier forming layer forming an energy barrier, wherein the light receiving surface is a surface on the side where the barrier forming layer is provided; and the barrier forming layer further extends along at least one side surface portion of the semiconductor region. Has a lateral portion extending through;
The solar cell device, wherein the first electrode is provided on the side surface portion of the barrier forming layer; and the second electrode is provided on the back surface side of the semiconductor region. 8. The solar cell device according to claim 7, wherein the first electrode provided on the side surface portion of the barrier forming layer is on an insulating film provided on the back surface of the semiconductor region. To the second electrode, and the extended portion is in a juxtaposed relationship with the second electrode. 9. The solar cell device according to claim 7, wherein the barrier forming layer has a pair of side surface portions extending along a pair of side surface portions facing each other of the semiconductor region. A solar cell device. 10. The solar cell device according to claim 9, wherein the pair of side surface portions of the semiconductor region in which the side surface portion of the barrier forming layer is formed extends from the light receiving surface side to the back surface side. A solar cell device, which is tapered so as to approach each other as it goes. 11. The solar cell device according to claim 1, 2, 3, 4, 5 or 6, wherein the photoelectric conversion function part of each solar cell element is a semiconductor region and a semiconductor region with respect to the semiconductor region. And a barrier forming layer that forms an energy barrier,
The light-receiving surface is a surface on the side where the barrier forming layer is provided; the barrier forming layer is further continuous with a side surface portion extending along at least one side surface portion of the semiconductor region, and the side surface portion. The semiconductor region also has a back surface portion that extends to part of the back surface; the first electrode is provided on the back surface portion of the barrier forming layer; and the second electrode is the back surface. Provided on the semiconductor region in a side-by-side relationship with the first electrode. 12. The solar cell device according to claim 11, wherein the barrier forming layer is continuous with a pair of side surface portions extending along a pair of opposing side surface portions of the semiconductor region. And a back surface part that extends around a part of the back surface of the semiconductor region, respectively. 13. The solar cell device according to claim 12, wherein the pair of side surface portions of the semiconductor region in which the side surface portion of the barrier forming layer is formed extends from the light receiving surface side to the back surface side. A solar cell device, which is tapered so as to approach each other as it goes.