JP2000150929A - Photovoltaic element and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce shadow loss by more than a conventional photovoltaic element having grid electrodes and busbars, without reducing the current collecting efficiency on the side of a second electrode, and at the same time, to reduce the number of contact holes to a large extent as compared to the conventional photovoltaic element having a third electrode electrically connected with the second electrode via a multitude of contact holes instead of the grid electrodes, to reduce time and labor for the manufacture of a photovoltaic element and the cost of the element, and moreover, to reduce the photovoltaic loss due to contact holes which are dead spaces. SOLUTION: A semiconductor layer 2, a second electrode layer 3 and grid electrodes 4 are provided in this order on the surface of a conductive substrate 1a which is formed with a first electrode, and at the same time, a third electrode layer 6 is formed on the backside of the substrate 1a via an insulating film 5, and the grid electrodes 4 and the layer 6 are electrically connected with each other via a contact hole 7 which penetrates at least the layer 2, the substrate 1a and a layer 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic element having a semiconductor layer sandwiched between a first electrode located on a light incident side and a second electrode located on a light incident side, and a method of manufacturing the same. More specifically, the present invention relates to improving the conversion efficiency of the photovoltaic device and reducing the labor and cost of manufacturing.

[0002]

2. Description of the Related Art Among photovoltaic elements, a thin-film solar cell using an amorphous semiconductor can produce a solar cell having a larger area than a single-crystal or polycrystalline solar cell, and requires a thinner semiconductor layer. And it can be deposited on any substrate material.

An amorphous silicon solar cell is, for example, one in which a p-layer, an i-layer, and an n-layer made of thin amorphous silicon are stacked on one surface of a substrate. So-called double cells or triple cells in which two or more cells are stacked in series are also being studied. A lower electrode (first electrode) and an upper electrode (second electrode) are provided on the back side (substrate side) and light incident side (opposite substrate side) of the semiconductor layer, respectively. Usually, a metal is used as the first electrode. When a conductive substrate is used, the substrate itself is used as the first electrode. When an insulating substrate is used, a conductive film separately provided on the substrate is used. Are used as the first electrodes. In addition, as the second electrode, a transparent conductive film such as SnO ₂ or ITO, which also functions as an antireflection film, is usually used so as not to impede the incidence of light on the semiconductor layer.

Since the second electrode has a high sheet resistance, it is formed in a parallel line on the second electrode so as not to hinder the incidence of light in order to prevent power loss due to Joule heat. Usually, a grid electrode for current collection and a metal bus bar that electrically connects the grid electrodes and collects the current from each grid electrode are provided, thereby increasing the current collection efficiency. Improvements are being made. As the grid electrode, an electrode formed by screen printing silver paste in a line shape is usually used. It is also known that a highly conductive metal wire is used as a grid electrode (Japanese Patent Laid-Open No. 9-18034).

On the other hand, in a photovoltaic device in which a first electrode, a semiconductor layer, and a second electrode are sequentially laminated on one surface of an insulating substrate, after the first electrode is provided on one surface of the substrate, By providing a large number of contact holes penetrating both, then sequentially laminating a semiconductor layer and a second electrode on one side of the substrate, and further providing a third electrode on the other side of the substrate, It is also known that a photovoltaic element in which the third electrode and the third electrode are electrically connected via this contact hole (JP-A-6-342924). In this photovoltaic element, the electrical connection between the second electrode and the third electrode performed through a large number of contact holes is, so to speak, a substitute for the grid electrode, and the second electrode has a high sheet resistance. In this case, the current collection efficiency is improved by shortening the path of the current flowing through the third electrode, and the third electrode serves as a substitute for the bus bar.

[0006]

However, in the conventional photovoltaic element provided with the grid electrode and the bus bar, the grid electrode and the bus bar portion provided on the light incident side have a shadow loss portion which does not contribute to power generation. There is a problem. In particular, since the grid electrode formed by screen printing has a thickness of at most about 20 μm, it must be wide in order to obtain good conductivity, and there is a problem that the above-mentioned shadow loss portion becomes large. When using a grid electrode of metal wire, although the shadow loss portion is smaller than the grid electrode formed by screen printing, the grid electrode portion and the bus bar portion are the same as the shadow loss portion, in order to improve the conversion efficiency. In addition, it is required to further reduce this.

On the other hand, in a conventional photovoltaic element having a third electrode electrically connected to the second electrode via the contact hole, the grid electrode and the bus bar are not required, and shadow loss due to the grid electrode and the bus bar is eliminated. It has the advantage of no occurrence.

In order to improve the current collection efficiency by electrically connecting the second electrode and the third electrode via the contact hole and thereby shortening the path of the current flowing through the second electrode having a high sheet resistance, a number of methods are required. Contact holes densely,
It is necessary to electrically connect the second electrode and the third electrode with good conductivity through each contact hole.

However, a large number of contact holes are densely formed, and the connection between the second electrode and the third electrode with good conductivity through the contact holes requires a great deal of time and labor. There is an increasing problem. In addition, since the contact hole portion is a dead space that cannot contribute to power generation, when a large number of large-diameter contact holes are densely arranged, there is a problem that electromotive force loss due to the contact holes cannot be ignored.

It is conceivable that the contact holes have a coarse density and a small diameter. However, in this case, the power loss at the second electrode becomes large,
The intended purpose cannot be achieved. In addition, the smaller the diameter of the contact hole, the more difficult the operation of electrically connecting the second electrode and the third electrode with good conductivity, increasing the manufacturing cost and increasing the cost of the second electrode and the third electrode. It is difficult to perform reliable electrical connection between the electrodes, which may cause a connection failure.

The present invention has been made in view of the above-mentioned conventional problems, and has a lower shadow loss than a conventional photovoltaic element having a grid electrode and a bus bar without lowering the current collection efficiency on the second electrode side. At the same time, the number of contact holes is significantly reduced as compared with a conventional photovoltaic element having a third electrode electrically connected to the second electrode through a large number of contact holes instead of the grid electrode. It is an object of the present invention to reduce the labor and cost of manufacturing and further reduce the electromotive force loss due to a contact hole which is a dead space.

[0012]

A first aspect of the present invention is to provide a semiconductor device having at least one pin or pn semiconductor junction and a second electrode layer on one surface of a conductive substrate forming a first electrode. Grid electrodes and are provided sequentially,
A third electrode layer is formed on the other surface of the substrate with an insulating layer interposed therebetween, and the grid electrode and the third electrode layer are formed at least through a contact hole penetrating the semiconductor layer, the substrate and the insulating layer. Are electrically connected to each other.

According to a second aspect of the present invention, a semiconductor layer having at least one pin or pn semiconductor junction, a second electrode layer, and a grid electrode are sequentially provided on one surface of a conductive substrate, Between the substrate and the semiconductor layer,
Since the first electrode layer is provided with an insulating layer interposed between the substrate and the substrate, the substrate forms a third electrode, and penetrates at least the semiconductor layer, the first electrode layer, and the insulating layer. A photovoltaic element, wherein the grid electrode and the substrate serving as the third electrode are electrically connected via a contact hole.

A third aspect of the present invention is that at least one pi is formed on a first electrode layer formed on one surface of an insulating substrate.
A semiconductor layer having an n or pn semiconductor junction, a second electrode layer, and a grid electrode are sequentially provided, and a third electrode layer is formed on the other surface of the substrate, and at least the semiconductor layer, the A photovoltaic device, wherein the grid electrode and the third electrode layer are electrically connected via a contact hole penetrating one electrode layer and the substrate.

In the first to third aspects of the present invention, a plurality of any of the above photovoltaic elements may be provided with a substrate or a first electrode layer forming the first electrode between the adjacent photovoltaic elements. The third electrode layer or the substrate forming the third electrode is electrically connected in series, and at least the surface of the first electrode layer or the substrate forming the first electrode exposed on the inner surface of the contact hole. A short-circuit preventing layer is formed, and the electrical connection between the grid electrode and the third electrode layer or the substrate forming the third electrode through the contact hole is provided by the short-circuit preventing layer. The contact material filled in the contact hole having the layer, the contact material is a conductive resin filled in the contact hole having the short-circuit prevention layer, The electrode is a wire-shaped conductive material, the short-circuit prevention layer, and a contact material embedded in the contact hole, wherein the grid electrode is a wire-shaped metal wire coated with a conductive resin; The conductive material embedded in the contact hole as a contact material and the conductive resin coated on the metal wire as a contact material, and the conductive resin covering the metal wire Both the conductive resin and the conductive resin as the contact material are made of carbon,
The characteristic feature thereof is that at least one conductive particle selected from silver and copper is mixed with a binder resin.

Further, the fourth to eighth aspects of the present invention relate to the method of manufacturing a photovoltaic element having the short-circuit preventing layer, among the photovoltaic elements according to the first to third aspects of the present invention.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a photovoltaic device according to the present invention will be described with reference to the drawings.

FIG. 1 schematically shows an example of a photovoltaic element according to the first embodiment of the present invention. In the figure, reference numeral 1a denotes a conductive substrate serving as a first electrode, on one surface (surface) thereof. Is provided with a semiconductor layer 2, a second electrode layer 3, and a grid electrode 4. On the other surface (back surface) of the substrate 1a forming the first electrode,
The third electrode layer 6 is provided via the insulating layer 5.

Each grid electrode 4 is provided in the form of a parallel line as in the prior art.
The second electrode layer 3, the semiconductor layer 2, the substrate 1
a and a contact hole 7 is formed through the insulating layer 5. The inner peripheral surface of each contact hole 7 is covered with a short-circuit prevention layer 8, and each contact hole 7 surrounded by the short-circuit prevention layer 8 is filled with a contact material 9. The three electrode layers 6 are electrically connected.

FIG. 2 is a diagram schematically showing an example of a photovoltaic element according to the second embodiment of the present invention. The same reference numerals as in FIG. 1 denote the same members.

In the photovoltaic device shown in FIG.
Since the first electrode layer 10 is provided on the surface of the conductive substrate 1b via the insulating layer 5, the substrate 1b forms the third electrode. The insulating layer 5
The semiconductor layer 2 is provided on the first electrode layer 10 provided through
And a second electrode layer 3 and a grid electrode 4 are sequentially provided.

Each grid electrode 4 is also provided in the form of a parallel line as in the prior art, and the second electrode layer 3, the semiconductor layer 2,
First electrode layer 10, insulating layer 5, and substrate 1 forming third electrode
A contact hole 7 is formed penetrating through b.
The inner peripheral surface of each contact hole 7 is covered with a short-circuit prevention layer 8, and each contact hole 7 surrounded by the short-circuit prevention layer 8 is filled with a contact material 9. The substrate 1b forming three electrodes is electrically connected.

FIG. 3 is a diagram schematically showing an example of a photovoltaic device according to the third embodiment of the present invention. The same reference numerals as in FIG. 1 denote the same members.

In the photovoltaic device shown in FIG.
An insulating substrate 1c is used. The first electrode layer 10, the semiconductor layer 2, the second electrode layer 3, and the grid electrode 4 are sequentially provided on the surface of the insulating substrate 1c.
The third electrode layer 6 is provided on the back surface of the substrate 1c.

Each grid electrode 4 is provided in the form of a parallel line, similarly to the above-mentioned ones. Immediately below the center of each grid electrode 4, the second electrode layer 3, the semiconductor layer 2, and the A contact hole 7 is formed penetrating through one electrode and the substrate 1c. The inner peripheral surface of each contact hole 7 is covered with a short-circuit prevention layer 8, and each contact hole 7 surrounded by the short-circuit prevention layer 8 is filled with a contact material 9. Three electrode layer 6
Is also electrically connected to the above.

FIG. 4 shows a state in which a plurality of photovoltaic elements shown in FIG. 1 are arranged in series. In each of the photovoltaic elements, an insulating layer 5 is provided on the left end on the back side of the substrate 1a in the figure. And the substrate 1a which does not have the third electrode layer 6 and forms the first electrode.
Is exposed. The third electrode layer 6 protrudes from the substrate 1a to the right in the drawing. And
In each photovoltaic element, the third electrode layer 6 protruding from the substrate 1a is joined (usually soldered) to a portion where the back surface of the substrate 1a is exposed, and connected in series with each other. In such a series connection arrangement, in the photovoltaic element shown in FIGS. 2 and 3, for example, a metal foil or the like connected to the first electrode layer 10 is extended laterally, and this is adjacent to the first electrode layer 10. It can be performed by connecting to the back surface of the substrate 1b serving as the third electrode of another photovoltaic element or to the third electrode layer 6.

As described above, when the photovoltaic elements according to the present invention are arranged in series, there is no need to make a connection across the front and back surfaces of the photovoltaic element, and the connection is easy. There are advantages. The series connection in the photovoltaic elements shown in FIGS. 2 and 3 is a connection across the substrates 1b and 1c because the first electrode is on the substrates 1b and 1c. In particular, the light connection shown in FIG. The electromotive force is most easily connected in series because the series connection can all be performed on the back side of the substrate 1a.

Next, a method of manufacturing each of the photovoltaic elements shown in FIGS. 1 to 3 will be described.

The photovoltaic element shown in FIG. 1 is shown in FIG.
To (f).

First, as shown in FIG. 5A, a semiconductor layer 2 and a second electrode layer 3 are sequentially laminated on the surface of a conductive substrate 1a forming a first electrode. Next, as shown in FIG. 5B, a contact hole 7 is formed penetrating the laminated substrate 1a, semiconductor layer 2, and second electrode layer 3 all.
After the formation of the contact holes 7, the insulating layer 5 is formed on the back surface of the substrate 1a as shown in FIG.
At this time, the insulating material forming the insulating layer 5 is attached to the back surface of the substrate 1a and the inner peripheral wall surface of the contact hole 7 without closing the formed contact hole 7. Thereby, the contact hole 7 is extended to the insulating layer 5 to be formed, and at the same time, the short-circuit preventing layer 8 is formed on at least the surface of the substrate 1a which is the first electrode exposed on the inner surface of the contact hole 7.

Thus, the insulating layer 5 and the short-circuit preventing layer 8
5D, a third electrode layer 6 is formed on the insulating layer 5 as shown in FIG.
As shown in FIG. 5E, the contact hole 9 is filled with a contact material 9 so as to be connected to the third electrode layer 6, and then, as shown in FIG. The grid electrode 4 is formed on the second electrode layer 3 passing therethrough, and the grid electrode 4 and the third electrode layer 6 are contacted with the contact material 9.
By electrically connecting the devices, the photovoltaic element shown in FIG. 1 can be obtained.

The photovoltaic element shown in FIG.
It can also be manufactured by the procedures shown in (a) to (g).

First, as shown in FIG. 6A, a semiconductor layer 2 is laminated on the surface of a conductive substrate 1a serving as a first electrode. Next, as shown in FIG. 6B, a contact hole 7 is formed penetrating both the laminated substrate 1a and the semiconductor layer 2. After the formation of the contact hole 7, the insulating layer 5 is formed on the back surface of the substrate 1a as shown in FIG. At this time, the insulating material forming the insulating layer 5 is attached to the back surface of the substrate 1a and the inner peripheral wall surface of the contact hole 7 without closing the formed contact hole 7. Accordingly, the contact hole 7 is extended to the insulating layer 5 to be formed, and at the same time, the short-circuit preventing layer 8 is formed at least on the surface of the substrate 1a which is the first electrode exposed on the inner surface of the contact hole 7. Is the same.

Thus, the insulating layer 5 and the short-circuit preventing layer 8
6D, the second electrode layer 3 is formed on the semiconductor layer 2 without closing the contact hole 7, as shown in FIG. 6D.
6, a third electrode layer 6 is formed on the insulating layer 5, and further, as shown in FIG. 6F, a contact is formed in the contact hole 7 so as to be connected to the third electrode layer 6. After filling the material 9, as shown in FIG.
The grid electrode 4 is formed on the second electrode layer 3 passing over the contact material 9, and the grid electrode 4 and the third electrode layer 6 are electrically connected by the contact material 9, whereby the photovoltaic power shown in FIG. An element can be obtained. In the case of this method, if the formation of the second electrode layer 3 is performed so that the constituent material of the second electrode layer 3 does not adhere to the inner peripheral wall of the contact hole 7, the photovoltaic element having a configuration substantially as shown in FIG. When the constituent material of the two-electrode layer 3 is adhered also to the inner peripheral wall of the contact hole 7, the constituent material of the second electrode layer 3 is interposed between the short-circuit prevention layer 8 and the contact material 9 in the contact hole 7. Becomes

The photovoltaic element shown in FIG.
To (f).

First, as shown in FIG. 7A, an insulating layer 5 and a first electrode layer 10 are sequentially laminated on the surface of a conductive substrate 1b serving as a third electrode. Next, as shown in FIG. 7B, a contact hole 7 is formed penetrating through all of the laminated substrate 1b, the insulating layer 5, and the first electrode layer 10. After forming this contact hole 7, FIG.
As shown in (1), the semiconductor layer 2 is formed on the first electrode layer 10. At this time, the semiconductor material forming the semiconductor layer 2 is attached to the first electrode layer 10 and the inner peripheral wall surface of the contact hole 7 without closing the formed contact hole 7. Accordingly, the contact hole 7 can be extended to the semiconductor layer 2 to be formed, and at the same time, the short-circuit prevention layer 8 can be formed on at least the surface of the first electrode layer 10 exposed on the inner surface of the contact hole 7.

Thus, the insulating layer 5 and the short-circuit preventing layer 8
7D, the second electrode layer 3 is formed on the semiconductor layer 2 without closing the contact hole 7, as shown in FIG. 7D.
As shown in FIG. 7, after the contact hole 9 is filled with the contact material 9 so as to be connected to the substrate 1b forming the third electrode, the contact hole 7 passes over the contact material 9 as shown in FIG. A photovoltaic element shown in FIG. 2 is obtained by forming a grid electrode 4 on the second electrode layer 3 and electrically connecting the grid electrode 4 and a substrate 1 b forming a third electrode with a contact material 9. Can be. In the case of this method, if the formation of the second electrode layer 3 is performed such that the constituent material of the second electrode layer 3 is also adhered to the inner peripheral wall of the contact hole 7, the photovoltaic element having the configuration shown in FIG. When the constituent material of the two-electrode layer 3 is not attached to the inner peripheral wall of the contact hole 7, the constituent material of the second electrode layer 3 is not interposed between the short-circuit prevention layer 8 and the contact material 9 in the contact hole 7. Becomes

The photovoltaic element shown in FIG. 2 has an insulating layer 5, a first electrode layer 10, a semiconductor layer 2, and a second electrode layer 3 on the surface of a conductive substrate 1b forming a third electrode. After formation, it can also be manufactured by a procedure of forming a contact hole 7 that penetrates all layers except the substrate 1b. In this case, after the formation of the contact hole 7, an insulating paint is adhered to the inner peripheral wall surface of the contact hole 7 by screen printing or the like, and the short-circuit prevention layer 8 is formed. The short-circuit prevention layer 8 is formed by, for example, screen-printing an insulative paint in a donut shape having an outer diameter and an inner diameter smaller than the diameter of the contact hole 7, and forming the bottom surface of the contact hole 7 (substrate 1b surface).
By applying an insulating paint along the inner wall surface of the contact hole 7 without covering it.

After the short-circuit prevention layer 8 is formed, the contact hole 9 is filled with a contact material 9 and the grid electrode 4 is formed, whereby the photovoltaic element shown in FIG. 2 can be obtained. However, in this case, the film of the constituent material of the semiconductor layer 2 and the film of the constituent material of the second electrode layer 3 are not formed on the inner wall surface of the contact hole 7.

FIG. 8A shows the photovoltaic element shown in FIG.
To (f).

First, as shown in FIG. 8A, the first electrode layer 10 is laminated on the surface of the insulating substrate 1c. Next, as shown in FIG. 8B, the laminated substrates 1c
Through both the first electrode layer 10 and the contact hole 7
To form After forming the contact hole 7, the semiconductor layer 2 is formed on the first electrode layer 10, as shown in FIG. At this time, the contact hole 7 formed
The semiconductor material forming the semiconductor layer 2 is adhered to the first electrode layer 10 and the inner peripheral wall surface of the contact hole 7 without closing the substrate. Thereby, the contact hole 7 is extended to the semiconductor layer 2 to be formed, and at the same time, the first electrode layer 1 exposed at least on the inner surface of the contact hole 7 is formed.
The short-circuit prevention layer 8 can be formed on the surface No. 0.

Thus, the insulating layer 5 and the short-circuit preventing layer 8
8D, the second electrode layer 3 is formed on the semiconductor layer 2 without closing the contact hole 7, as shown in FIG. 8D.
8, a third electrode 6 is laminated on the back surface of the substrate 1 c, and further, as shown in FIG. 8 (f), a contact material is formed in the contact hole 7 so as to be connected to the third electrode layer 6. After filling 9, as shown in FIG.
By forming the grid electrode 4 on the second electrode layer 3 passing over the contact material 9 and electrically connecting the grid electrode 4 and the third electrode layer 6 with the contact material 9, the photovoltaic device shown in FIG. A power element can be obtained. In this case,
When the second electrode layer 3 is formed such that the constituent material of the second electrode layer 3 adheres to the inner peripheral wall of the contact hole 7 as well, FIG.
In the photovoltaic element having the structure shown in FIG. 2, when the constituent material of the second electrode layer 3 is not attached to the inner peripheral wall of the contact hole 7, the short-circuit preventing layer 8 in the contact hole 7 has The configuration is such that the constituent material of the two-electrode layer 3 does not intervene.

Next, each of the above components will be described.

(1) Substrates 1a to 1c The substrates 1a to 1c used in the present invention are members for mechanically supporting thin film layers such as the semiconductor layer 2 and the second electrode layer 3. It is used as an electrode or a third electrode. Conductive substrates are used as the substrates 1a and 1b forming the first and third electrodes, and electrically insulating substrates are used as the substrate 1c not used as the first and third electrodes.

The substrate 1a serving as the first electrode is a back electrode formed on the surface opposite to the light incident side for extracting power generated in the semiconductor layer 2 described later. The surface of the substrate 1a forming the first electrode is preferably a smooth reflection surface on which a reflection layer (not shown) made of, for example, an Al or ZnO film is laminated. You may make it.

In order to obtain good productivity, the conductive substrates 1a to 1c have heat resistance to withstand the heating temperature when forming a thin film layer such as the semiconductor layer 2 and the second electrode layer 3, It is preferable that the material is a long object that enables a continuous film-forming process by roll-to-roll, and that it has dimensional stability without stretching due to tension during winding.

Specific examples of materials for the conductive substrates 1a and 1b include, for example, Fe, Ni, Cr, Al, Mo, Au,
Examples include metals such as Nb, Ta, V, Ti, Pt, Pb, and Ti or alloys thereof, for example, thin plates such as brass and stainless steel and composites thereof, carbon sheets, galvanized steel plates, and the like. In particular, stainless steel has good heat resistance to the heating temperature during film formation, and is roll-to-roll.
This material is also suitable for continuous film formation using a roll. For example, it is a suitable material because of its strength and the like even when thinned to about 0.15 mm.

The specific material of the insulating substrate 1c is, for example, a heat-resistant synthetic material such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide and epoxy. Examples include a resin film or sheet, or a composite material film or sheet of these with glass fiber, carbon fiber, boron fiber, or the like, and a plate of glass, ceramic, or the like. Generally, a polyimide film or sheet, a glass plate, or the like is suitably used as the insulating substrate 1c.

(2) Semiconductor Layer 2 The semiconductor layer 2 is a layer having at least one pin or pn semiconductor junction, which generates power in response to the incidence of light, and generally has a pin semiconductor junction. . The semiconductor layer 2 is made of an amorphous or microcrystalline material, particularly amorphous or microcrystalline silicon, because it is easy to increase the area, has a small thickness, and has a wide choice of materials for the substrates 1a to 1c. Although preferred, a single crystal material or a polycrystalline material may be used.

In the semiconductor layer 2 of the pin type amorphous or microcrystalline silicon, for example, a-Si: H, a-Si: F, a-S
i: H: F, a-SiGe: H, a-SiGe: F, a
-SiGe: H: F, a-SiC: H, a-SiC:
So-called IV and IV, such as F, a-SiC: H: F
Group-alloy-based amorphous silicon semiconductors and microcrystalline silicon semiconductors. The semiconductor material forming the p-layer or the n-layer can be obtained by doping the semiconductor material forming the i-layer with a valence electron controlling agent. As a valence electron controlling agent for obtaining a p-type semiconductor, a compound containing an element of Group III of the periodic table is used. Elements of Group III of the periodic table include B, Al, Ga, and In.
As a valence electron controlling agent for obtaining an n-type semiconductor, a compound containing an element of Group V of the periodic table is used. P, N, As, Sb are mentioned as an element of the V group of the periodic table.

As a method of forming an amorphous silicon semiconductor or a microcrystalline silicon semiconductor, there are a vapor deposition method, a sputtering method, an RF plasma CVD method, and a microwave plasma CVD method.
Method, VHFCVD method, ECR method, thermal CVD method, LPCV
A film forming method such as a method D can be used. Industrially,
An RF plasma CVD method in which a source gas is decomposed and deposited by RF plasma is preferably used. Further, since the decomposition efficiency of the source gas can be increased and the volume velocity can be increased as compared with the RF plasma CVD, the microwave plasma CV
Attention has been paid to the D method and the VHF plasma CVD method.

As a reaction apparatus for performing the above film formation,
A batch type apparatus or a continuous film forming apparatus may be used. Further, in the photovoltaic element of the present invention, a so-called tandem cell semiconductor layer 2 in which two or more pn or pin semiconductor junctions are stacked can be used for the purpose of improving spectral sensitivity and voltage.

(3) First electrode layer 10 In the present invention, in addition to using the substrate 1a as the first electrode as in the first embodiment of the present invention, the first and second substrates 1b and 1c as in the second and third embodiments of the present invention. Separately, the first electrode layer 10 may be provided. The first electrode layer 10 provided separately from the substrates 1b and 1c is provided on the light incident side of the semiconductor layer 2 in order to take out the electric power generated in the semiconductor layer 2 like the substrate 1a forming the first electrode. The back electrode is formed on the surface opposite to the surface.

As a specific material of the first electrode layer 10, for example, Al, Ag, Pt, Au, Ni, Ti, M
o, W, Fe, V, Cr, Cu, stainless steel, brass, nichrome, SnO ₂ , In ₂ O ₃ , ZnO, ITO
Or a so-called metal simple substance or alloy, and a transparent conductive oxide (TCO). The surface of the first electrode layer 10 is preferably smooth, but may be textured in order to cause irregular reflection of light.

For providing the first electrode layer 10, a thin film forming method such as plating, vapor deposition, or sputtering is preferably used. Further, it can be attached by laminating foil materials such as copper foil and aluminum foil by a lamination method.

(4) Second Electrode Layer 3 The second electrode layer 3 provided on the light incident side is a transparent electrode provided on the light incident side of the semiconductor layer 2 in order to extract the electromotive force generated in the semiconductor layer 2. And a pair with the substrate 1a serving as the first electrode or the first electrode layer 10.

The second electrode layer 3 has a sheet resistance of 30 to facilitate taking out the electric power generated in the semiconductor layer 2.
It is desirably 0 Ω / □ or less.

The thickness of the second electrode layer 3 is set so that the resistance value is as low as possible and the transparency is not impaired. In some cases, it is designed such that reflection is minimized at the wavelength of light to be transmitted by using light interference conditions. For example, in order to minimize the reflection of 550 nm light using an ITO film, the thickness is preferably about 700 °. The second electrode layer 3 is used to efficiently absorb light from a light source such as the sun or a white fluorescent lamp into the semiconductor layer 2.
The light transmittance is preferably 85% or more.

Suitable materials having the above characteristics include, for example, SnO ₂ , In ₂ O ₃ , ZnO, CdO,
Metal oxides such as CdSnO ₄ and ITO (In ₂ O ₃ + SnO ₂ ) are exemplified. As a method for forming the second electrode layer 3, for example, a film forming method such as a vapor deposition method, a sputtering method, and a reactive sputtering method is used.

(5) Third Electrode Layer 6 In the present invention, the substrate 1b is used as a third electrode as in the second embodiment of the present invention, and the substrates 1a and 1c are connected to each other as in the first and second embodiments of the present invention. Separately, a third electrode layer 6 may be provided. When the substrate 1b is used as the third electrode,
The third electrode layer 6 provided separately from a and 1c also serves as a conventional bus bar (not shown) for further collecting the current collected by the grid electrode 4 described later. Therefore, in the present invention, there is no need to provide a bus bar as in the related art, and shadow loss due to the bus bar can be eliminated. Further, since the substrate 1b forming the third electrode and the third electrode layer 6 provided separately from the substrates 1a and 1c serve as bus bars, the substrate 1a forming the first electrode or the first electrode The electrode layer 10 is electrically insulated.

The third electrode layer 6 provided separately from the substrates 1a and 1c only needs to be at least immediately below a contact hole 7 described later (when the substrate 1b is used as a third electrode, it is inevitably directly below the contact hole 7). There is a substrate 1b as a third electrode), and a layer having a size covering the whole of the substrates 1a and 1c may be used. Alternatively, as shown in FIG. 9, the layer may be formed in a narrow band shape. The photovoltaic element shown in FIG. 9 is basically the same as the photovoltaic element shown in FIG. 1, but forms the first electrode in the photovoltaic element shown in FIG. Although the insulating layer 5 and the third electrode layer 6 are sequentially laminated on the entire back surface of the substrate 1a, in the photovoltaic element shown in FIG. 9, the back surface of the substrate 1a corresponding to the position of the contact hole 7 is provided. The difference is that the insulating layer 5 and the third electrode layer 6 are sequentially laminated in a strip shape crossing the central portion. That is, the insulating layer 5 and the third electrode layer 6 are formed in a narrower range than the photovoltaic element of FIG.
By providing the above, these materials can be saved. Also, in the photovoltaic element shown in FIG. 3, as in the photovoltaic element shown in FIG.
The material of the third electrode layer 6 provided on the back surface of the substrate c can be reduced by forming it into a band shape.

In addition, even when the substrate 1b is used as the third electrode or the third electrode layer 6 provided separately from the substrates 1a and 1c, the photovoltaic element according to the present invention can be easily connected in series. In addition, a part is extended outside the substrates 1a to 1c, or a part is cut out together with the insulating layer 5 or the insulating substrate 1c, so that the substrate 1a or the first electrode layer 10 forming the first electrode is formed. Can also be exposed.

As a specific material of the third electrode 10 provided separately from the substrates 1a and 1c, the same material as that of the first electrode layer 10 is suitably used. Can be attached. Further, the third electrode 10 provided separately from the substrates 1a and 1c may be made of, for example, a foil material formed in a strip shape or a mesh shape.

(6) Grid Electrode 4 The grid electrode 4 is formed as a low-resistance electrode on the second electrode layer 3 in a line shape in which shadow loss is suppressed. This is to prevent the current collection efficiency from being reduced by the series resistance of the second electrode layer 3 if the current collection is to be performed with the electrode layer 3 alone.

In the present invention, the second electrode layer 3 and the third electrode layer 6
Or, instead of densely arranging the electrical connection between the substrate 1b forming the third electrode and using the grid electrode 4 as a substitute,
The grid electrode 4 is used to collect current from the second electrode layer 3. Therefore, the electrical connection between the second electrode layer 3 and the third electrode layer 6 or the substrate 1b forming the third electrode via the contact hole 7 described later is performed from the grid electrode 4 which is a low-resistance electrode to the third electrode layer. It suffices if current can flow smoothly to the three-electrode layer 6 or the substrate 1b as the third electrode,
The number of contact holes 7 can be extremely reduced.

The arrangement of the grid electrodes 4 is performed by determining the electrode width, pitch and the like so as to minimize the electric resistance and shadow loss due to current collection. The grid electrode 4 is required to have a low specific resistance and not to have a large series resistance.
A preferable specific resistance value of the grid electrode 4 is 10 ⁻² Ωc.
m to 10 ^-6 Ωcm.

The grid electrode 4 is made of, for example, Ti, Cr, M
It can be formed using a metal such as o, W, Al, Ag, Ni, Cu, Sn, Pt, Cu, or an alloy or solder thereof.

The grid electrode 4 is formed by forming a layer of the above-mentioned metal or the like (the above-mentioned metal or an alloy or solder thereof) by a film forming technique such as a sputtering method, a resistance heating method and a CVD method using a mask pattern having a desired linear shape. It can be formed by attaching. In addition, a method in which a layer of the metal or the like is attached to the entire surface of the second electrode layer 3 by vapor deposition or the like and then etched to be patterned in a line shape, a method in which a linear pattern of the grid electrode 4 is directly formed by optical CVD,
It can also be formed by, for example, a method of forming a layer of the metal or the like by a plating method after forming a negative pattern mask of the grid electrode 4.

The grid electrode 4 can also be formed by screen-printing and curing a paste-like conductive resin. This screen printing method uses a screen obtained by subjecting a mesh made of polyester or stainless steel to a desired patterning, and a binder resin and a solvent for the binder resin are added to the powder of the metal or the like (preferably, carbon, silver or copper having low specific resistance). Is used as a printing ink using a conductive resin that is made into a paste by mixing the above-mentioned materials in an appropriate ratio, and the electrode width can be set to about 50 μm at a minimum. As the binder resin, for example, a thermosetting resin such as an epoxy resin, an acrylic resin, and a urethane resin is preferable. As the printing machine, a commercially available screen printing machine is suitably used. The screen-printed conductive resin is heated in a drying oven to crosslink the binder resin, volatilize the solvent, and cure. Hot air oven and I
An R oven or the like is used.

In the case where the grid electrode 4 is formed by printing the paste-like conductive resin, the conductive resin forming the grid electrode 4 can be used as the contact material 9. For example, after forming the short-circuit preventing layer 8 on the inner peripheral wall of the contact hole 7 as described with reference to FIGS. 5 to 8, the grid electrode 4 is formed by printing with a paste-like conductive resin. Along with the printing, a paste-like conductive resin is allowed to enter the contact holes 7, whereby electrical connection between the grid electrode 4 and the substrate 1 b or the third electrode layer 6 serving as the third electrode can be achieved.

The grid electrode 4 is preferably formed of a wire-shaped conductive material in order to obtain good conductivity with as little shadow loss as possible. Examples of the wire-shaped conductive material include Ti, Cr, Mo, W, Al, Ag,
Metal wires such as Ni, Cu, Sn, Pt, and Cu are preferably used. The diameter of the wire-shaped conductive material is 50 to 20
It is preferably 0 μm. The most preferred wire-shaped conductive material is a metal wire coated with a conductive resin. The wire-shaped conductive material obtained by coating the metal wire with a conductive resin can easily obtain good conductivity with a small diameter (large aspect ratio in cross section) and can prevent migration from the metal wire. .

When a wire-like conductive material in which a metal wire is coated with a conductive resin is used as the grid electrode 4, it is preferable to provide the grid electrode 4 by pressing it under heating. By doing so, it is possible to adhere and fix to the second electrode layer 3 using the conductive resin which is a coating material, and it is possible to achieve reliable integration with the contact material 9 in the contact hole 7. . In particular, when the contact material 9 is a conductive resin and further uses a binder resin that is compatible with the conductive resin covering the metal wire, reliable electrical connection can be easily achieved by integrating the two. .

The grid electrode 4 described with reference to FIGS.
Each of them has a linear parallel line shape. However, the form of the grid electrode 4 is not limited to this. For example, if the grid electrode 4 is arranged almost uniformly on the surface of the second electrode layer 3 while suppressing shadow loss, for example, The shape may be a grid or a meandering line.

(7) Contact Hole 7 The contact hole 7 is used to form a path for conducting the current collected by the grid electrode 4 to the substrate 1 b forming the third electrode or the third electrode layer 6. Things. This contact hole 7 does not need to penetrate through the substrate 1b forming the third electrode or the third electrode layer 6. Even if the contact hole 7 does not penetrate the second electrode layer 3, the grid electrode 4 is connected to the substrate 1 b serving as the third electrode or the third electrode layer 6 via the second electrode layer 3.
Can be connected to Therefore, contact hole 7
In the first embodiment of the present invention, it suffices that the material penetrates at least the semiconductor layer 2, the substrate 1a as the first electrode, and an insulating layer 5 described later. In the second embodiment of the present invention, at least the semiconductor Any material may be used as long as it penetrates through the layer 2, the first electrode layer 10, and the insulating layer 5 described later. In the third embodiment of the present invention, at least the semiconductor layer 2, the first electrode layer 10, and the substrate 1c are penetrated. Anything should do. However, in any of the first to third embodiments of the present invention, in order to secure the connection with the grid electrode 4,
As shown in FIGS. 1 to 3, it is preferable to penetrate the second electrode layer 3 as well.

The diameter of such a contact hole 7 is
The electrical connection between the grid electrode 4 and the substrate 1b serving as the third electrode or the third electrode layer 6 through the contact hole 7 can be performed with good conductivity such that resistance due to current can be ignored. Any size is acceptable. From the viewpoint of suppressing the electromotive force loss due to the provision of the contact hole 7, the diameter is preferably about 50 μm to 2 mm, and is approximately the same as or smaller than the width or diameter of the grid electrode 4 and Most preferably, the diameter is such that connection can be easily performed.

The number of the contact holes 7 is at least one for one independent region of the grid electrode 4 (region of the series of grid electrodes 4 separated from other grid electrodes 4). For example, in the case of parallel line-shaped grid electrodes 4 as shown in FIGS. 1 to 3, at least one contact hole 7 is provided for each grid electrode 4 since each one is an independent series. Is formed.
Further, for example, when the grid electrodes 4 are formed in a grid pattern, the entire grid electrodes 4 are connected to each other in a series, so that one contact hole 7 can be formed for the whole.

For example, in the case of parallel grid electrodes 4 as shown in FIGS. 1 to 3, if one contact hole 7 is provided for each grid electrode 4, the number of contact holes 7 can be minimized. It is preferable because it is possible. However, in the present invention, two or more contact holes 7 can be provided in one independent region of the grid electrode 4. When two or more contact holes 7 are provided for each parallel line-shaped grid electrode 4 as shown in FIGS. 1 to 3, it depends on the length and conductivity of the grid electrode 4.
Usually, four or less grid electrodes 4 are sufficient.

The contact hole 7 is preferably provided immediately below the grid electrode 4, for example, in the case of a parallel line grid electrode 4 as shown in FIGS. 1 to 3, at the center of each grid electrode 4. . When a plurality of contact holes 7 are provided in each grid electrode 4, it is preferable to provide the contact holes 7 at both ends of each grid electrode 4 or at positions where the grid electrodes 4 are divided at equal intervals.

For forming the contact hole 7, a well-known hole forming method such as drilling, etching, pressing, and laser can be used. If the contact hole 7 has a relatively small diameter of up to about 500 μm, drilling by a laser is suitable, and if the contact hole 7 has a relatively large diameter of more than 1 mm, drilling or etching is suitable. .

(8) Short-Circuit Prevention Layer 8 The short-circuit prevention layer 8 is formed by, for example, a metal wire or the like coated with an insulation coating, which connects the second electrode layer 3 to the third electrode layer 6 or the substrate 1b as the third electrode. Although it is not particularly necessary to establish an electrical connection between them, generally, the first electrode or the substrate 1a or the first electrode layer 10 and the third electrode layer 6 or the third electrode It is preferably provided to prevent a reduction in electromotive force due to a short circuit with a certain substrate 1b.

The short-circuit prevention layer 8 is formed so as to cover the surface of the first electrode layer 10 or the substrate 1a constituting the first electrode exposed on the inner surface of the contact hole. The short-circuit preventing layer 8 may cover only the exposed surface of the substrate 1a serving as the first electrode or the first electrode layer 10, or may cover other portions of the inner surface of the contact hole 7.

The short-circuit prevention layer 8 prevents short-circuit between the substrate 1a or the first electrode layer 10 as the first electrode and the third electrode layer 6 or the substrate 1b as the third electrode. The high-resistance material may be an insulating material such as an inorganic oxide such as SiO ₂ or TiO ₂ , a synthetic resin such as acryl or polyimide, or a semiconductor material ( For example, a semiconductor material constituting the semiconductor layer 2) can be used.

As a method for forming the short-circuit preventing layer 8, for example, printing, dispenser coating, electrodeposition, and a film forming technique such as sputtering can be used. When the short-circuit prevention layer 8 is formed by the method described with reference to FIGS.
In a state where a mask is applied to the front side of the substrate, the substrate is immersed in an electrodeposition coating liquid of the insulating material to form
Electrodeposition inside the insulating layer 5 and the short-circuit prevention layer 8
Can be formed. When the short-circuit prevention layer 8 is formed by the method described with reference to FIGS. 7 and 8, the short-circuit prevention layer 8 is formed by a film forming technique for forming the semiconductor layer 2. In particular, as described with reference to FIGS. 5 to 8, when the short-circuit prevention layer 8 is also formed at the same time as the formation of the insulating layer 5 or the semiconductor layer 2, the number of laminating steps is not increased, and it is not necessary to use an extra material. Therefore, it is possible to improve manufacturing efficiency and reduce manufacturing cost.

The above-described electrodeposition method can easily form the short-circuit prevention layer 8 selectively only in the contact hole 7. Apart from the formation of the insulating layer 5, the short-circuit preventing layer 8
Is effective in forming the short-circuit preventing layer 8 in the photovoltaic element of FIG. For example, when a photovoltaic element using a substrate 1b serving as a third electrode as shown in FIG. 2 is formed, an insulating layer 5, a first electrode layer 10, a semiconductor layer 2, and a second electrode layer 3 are laminated on the substrate 1b. Thereafter, a contact hole 7 is formed (the substrate 1b does not have to penetrate), and a short-circuit preventing layer 8 can be formed in the contact hole 7 by electrodeposition. When a photovoltaic element using an insulating substrate 1c as shown in FIG.
First electrode layer 10, semiconductor layer 2, second electrode layer 3 on substrate 1c
After forming the third electrode layer 6, a contact hole 7 is formed, and a short-circuit prevention layer 8 can be formed in the contact hole 7 by electrodeposition.

The thickness of the short-circuit prevention layer 8 is preferably about 5 to 20 μm so that irregularities on the inner peripheral surface of the contact hole 7 can be covered and good short-circuit prevention performance can be obtained.

(9) Contact Material 9 The contact material 9 is provided in the contact hole 7 for electrically connecting the grid electrode 4 and the third electrode layer 6 or the substrate 1b forming the third electrode. The contact hole 7 provided with the short-circuit prevention layer 8 is provided.
It is preferable to provide it inside.

It is desirable that the contact material 9 has a small electric resistance, specifically, a resistance value of 10 ⁻² to 10 ⁻⁶ Ω.
cm. The contact material 9 is
The contact hole 7 provided with the short-circuit prevention layer 8 can be provided as an adhesion layer or a filling material on the inner peripheral surface. Specifically, it can be provided by, for example, metal plating such as silver plating or copper plating, screen printing using a paste-like conductive resin, or dispenser application.

In order to obtain a reliable electric connection, it is preferable that the contact conductive material 9 is filled in the contact hole 7 provided with the short circuit prevention layer 8. In view of the ease of filling the contact holes 7, it is preferable to fill the paste-like conductive resin as the contact material 9 by screen printing, dispenser application, or the like. If the contact hole 7 cannot be sufficiently filled by a single printing or coating on the contact hole 7, the necessary amount of conductive resin can be filled by repeating the printing or coating a plurality of times. The conductive resin is provided on the grid electrode 4.
Is the same as that described in the section, but the contact material 9
A material containing at least one conductive particle selected from silver, copper, and carbon is preferably used.

(10) Insulating Layer 5 The insulating layer 5 is used in the case of the conductive substrates 1a, 1b.
Inorganic oxides such as TiO ₂ and TiO ₂ and synthetic resins such as acrylic and polyimide can be used. In addition, for forming the insulating layer 5, for example, a film forming technique such as printing, dispenser, electrodeposition, and sputtering can be used.

[0090]

EXAMPLE 1 A photovoltaic element having a pin junction type single cell configuration shown in FIG. 1 was manufactured by the steps shown in FIG.

First, SUS4 which has been sufficiently degreased and washed
A plate (thickness: 0.2 mm) made of 30BA is placed in a DC sputtering device (not shown), and a 4000-mm thick Al and a 400 mm thick
A reflective layer was formed by sequentially laminating ZnO at 0 ° to form a conductive substrate 1a. The substrate 1a is taken out of the sputtering apparatus and put in an RF plasma CVD film forming apparatus, where the n layer, i
A semiconductor layer 2 was formed by depositing layers in this order.

Then, the substrate was placed in a resistance heating evaporation apparatus and maintained at an internal pressure of 1 × 10 ⁻⁴ Torr while introducing oxygen.
An alloy of n and Sn is deposited by resistance heating, and a transparent IT having a function also as an anti-reflection effect is formed on the semiconductor layer 2.
A second electrode layer 3 of O was deposited to a thickness of 700 °. Said S
The plate made of US430BA is a belt-shaped plate wound in a long coil shape.
Forming was performed with two rolls.

After the obtained laminate was cut into a size of 10 cm square by a press cutter, YAG laser light (wavelength 1.
06 μm) was squeezed into a spot having a diameter of 300 μm, and oscillated in a pulse form to form a contact hole 7 having a diameter of 300 μm penetrating from the second electrode layer 3 to the substrate 1a. The contact hole 7 is a 10 cm square substrate 1a.
19 were formed in a horizontal line at an interval of 5 mm at the center. YAG
The laser light was emitted by moving the optical fiber to a predetermined position using an XY robot.

Next, the surface of the second electrode layer 3 is masked by bonding a plastic magnet sheet to the second electrode layer 3 side, and immersed in an electrodeposition coating solution made of acrylic resin. The electrodeposition coating liquid was prevented from adhering to the surface of the substrate 1a, and only the back surface of the substrate 1a and the inside of the contact hole 7 were brought into contact with the electrodeposition coating liquid. In this state, an electric field is applied, and an insulating layer 5 is formed on the back surface of the substrate 1a, and a short-circuit preventing layer 8 is formed on the inner peripheral wall of the contact hole 7 with an acrylic resin.
It was formed to 0 μm.

After the formation of the insulating layer 5 and the short-circuit preventing layer 8, a third electrode layer 6 was formed on the insulating layer 5 by pressing a 35 μm-thick copper foil against the insulating layer 5 with a heating roller and bonding them together.

Thereafter, the insulating layer 5 and the short-circuit preventing layer 8 were cured by heating at 200 ° C. for 30 minutes in a hot air oven.

The cured substrate 1a is set on a screen printing machine, and a dot-like printing of a paste-like conductive resin is performed on each contact hole 7 by screen printing. As No. 9, the conductive resin was filled. The conductive resin used in this example was obtained by dispersing carbon particles in an epoxy resin as a binder resin. After printing, set the temperature to 2
The conductive resin in the contact hole 7 was heated and cured in a hot air oven maintained at 00 ° C. The specific resistance of the conductive resin after heat curing was 10 Ωcm.

Further, the same conductive resin as described above is used, and the diameter is 1 mm.
A wire-shaped conductive material coated with a copper wire of 00 μm is used as a grid electrode 4, and one contact hole 7 is provided for each.
19 were arranged on the second electrode layer 3 in a parallel line of 5 mm pitch passing directly above and fixed by heating at 200 ° C. for 10 minutes while applying a pressure of 1 kg / cm ² .

As described above, the configuration of FIG.
Ten photovoltaic elements of cm × 10 cm square were produced.

Next, resin encapsulation of each photovoltaic element was performed as follows to obtain a sample.

First, EVA was laminated above and below the photovoltaic element. Then, after laminating a fluororesin film on the light incident surface side and laminating a metal plate on the back surface side, put in a vacuum laminator and hold at 150 ° C. for 60 minutes,
Vacuum lamination was performed. The surface on the light incident side of the obtained sample was sufficiently filled with the EVA resin.

The initial characteristics of the obtained sample were measured according to JIS C893.
The output was measured according to the method for measuring the output of the amorphous solar cell module of No. 5.

The conversion efficiency was determined by measuring the solar cell characteristics using a pseudo solar light source (hereinafter referred to as “simulator”) manufactured by SPIRE having a light intensity of 100 mW / cm ^{2 in} the AM1.5 global sunlight spectrum. 0.5% ± 0.
5%, good characteristics and little variation. The shadow loss was 4.5%.

Comparative Example l Next, for comparison, a photovoltaic element using a bus bar and the same wire-like grid electrode as in Example 1 was manufactured as follows.

On the same substrate as in Example 1, up to the second electrode layer was formed in the same manner as in Example 1, cut into a 10 cm square, and an insulating layer with an adhesive was applied over the entire length of both ends of the substrate. I stuck it. Thereafter, a grid electrode was attached in the same manner as in Example 1, and a bus bar made of copper foil having a thickness of 200 μm and a width of 1.8 mm was laminated at a position corresponding to the insulating layer.
Ten photovoltaic elements of 0 cm × 10 cm square were produced.

Next, encapsulation of each photovoltaic element was performed in the same manner as in Example 1 to obtain a sample.

When the initial characteristics of the obtained sample were measured in the same procedure as in Example 1, the shadow loss was as large as 8.0%, so that the conversion efficiency was 7.2% ± as compared with Example 1.
It was as low as 0.5%.

Example 2 A semiconductor layer 2 and a second electrode layer 3 were sequentially laminated on the surface of the same substrate 1a as in Example 1 in the same manner as in Example 1,
After cutting into an m-square, a contact hole 7 having a diameter of 500 μm penetrating the 10-cm-square laminate is formed at the same position as in the first embodiment by an NC drill, and the insulating layer 5 and the short circuit are formed in the same manner as the first embodiment The prevention layer 8 and the third electrode layer 6 were formed.

After the formation of the third electrode layer 6, a paste-like conductive resin made of an epoxy resin and silver particles was used in Example 1.
After screen printing in the same manner as described above and filling the contact holes 7 as the contact material 9, the same grid electrode 4 as in Example 1 was formed in the same manner as in Example 1, and 10 cm × 1
Ten photovoltaic elements having the configuration shown in FIG. 1 and having a size of 0 cm square were manufactured.

Next, encapsulation of each photovoltaic element was performed in the same manner as in Example 1 to obtain a sample.

The initial characteristics of the obtained sample were measured in the same manner as in Example 1. As a result, the conversion efficiency was as good as 7.3% ± 1.5%, and the variation was small.

Example 3 A semiconductor layer 2 and a second electrode layer 3 were sequentially laminated on the same surface of the substrate 1a as in Example 1 in the same manner as in Example 1,
After cutting into a 10 cm square, a contact hole 7 having a diameter of 800 μm penetrating the 10 cm square laminated body was formed at the same position as in the first embodiment by using a CO ₂ laser. The short-circuit prevention layer 8 and the third electrode layer 6 were formed.

After the formation of the third electrode layer 6, a paste-like conductive resin made of an epoxy resin and silver particles is used, and has a width of 500 μm and a thickness of 20 μm, each of which passes directly above one contact hole 7. Nineteen screen prints were formed in positions on the electrode layer 3 in parallel lines at a pitch of 5 mm. At the time of this printing, a part of the conductive resin forming the grid electrode 4 enters the contact hole 7 and the contact material 9
And the third electrode layer 6 was contacted and joined. The printed conductive resin was heated and cured to form the grid electrode 4, and ten photovoltaic elements of 10 cm × 10 cm square were manufactured.

Next, encapsulation of each photovoltaic element was performed in the same manner as in Example 1 to obtain a sample.

The initial characteristics of the obtained sample were measured in the same manner as in Example 1. As a result, the conversion efficiency was as good as 7.2% ± 0.8%, and the variation was small.

Example 4 A pin junction type single cell photovoltaic device having the structure shown in FIG. 2 was manufactured by the process shown in FIG.

The same plate made of SUS430BA as in Example 1 was used as the substrate 1b serving as the third electrode.
After depositing iO ₂ by a sputtering method to form an insulating layer 5, an Al having a thickness of 4000 °
The first electrode layer 10 was formed by sequentially laminating 000 ° of ZnO and cut into 10 cm squares.

Next, a contact hole 7 having a diameter of 200 μm penetrating the 10-cm square laminate is formed at the same position as in the first embodiment in the same manner as in the first embodiment.
The semiconductor layer 2 was formed on the first electrode layer 10 in the same manner as described above. During the formation of the semiconductor layer 2, the semiconductor material adhered to the inner wall surface of the contact hole 7, and the short-circuit prevention layer 8 was also formed.

After the formation of the semiconductor layer 2 and the short-circuit prevention layer 8,
In order not to close the contact hole 7, the second electrode layer 3
Is formed on the semiconductor layer 2 in the same manner as in Example 1, and then the conductive resin is filled as the contact material 9 in each contact hole 7 in the same manner as in Example 1 except that printing is performed from the back side of the substrate 1b. Then, a grid electrode 4 was formed on the second electrode layer 3 in the same manner as in Example 1, and a 10 cm × 1
Ten photovoltaic elements having the configuration shown in FIG. 2 and having a size of 0 cm square were manufactured.

Next, encapsulation of each photovoltaic element was performed in the same manner as in Example 1 to obtain a sample.

When the initial characteristics of the obtained sample were measured in the same manner as in Example 1, the conversion efficiency was as good as 7.9% ± 0.9%, and the variation was small.

Example 5 The same plate made of SUS430BA as in Example 1 was used as the substrate 1b serving as the third electrode, and SiO ₂ was deposited on the surface of the substrate 1b by sputtering to form the insulating layer 5, and then the insulating layer 5 was formed. 4000 mm thick Al and 4000 mm thick Z on layer 5
The first electrode layer 10 was formed by sequentially laminating nO, and the semiconductor layer 2 and the second electrode layer 3 were sequentially formed on the first electrode layer 10 in the same manner as in Example 1.

Next, the laminate was cut into 10 cm squares.
A contact hole 7 having a diameter of 200 μm is formed in the 10 cm square laminate with a second harmonic YAG laser (wavelength 0.53
μm) at the same position as in Example 1. This contact hole 7 does not penetrate through the substrate 1b, but the insulating layer 5,
It was formed as a hole penetrating only the first electrode layer 10, the semiconductor layer 2, and the second electrode layer 3.

After the formation of the contact holes 7, the short circuit prevention layer 8 was formed on the inner peripheral wall of each contact hole 7 by screen printing using an insulating paint.
In the same manner as described above, each contact hole 7 is filled with a conductive resin as a contact material 9,
Was formed on the second electrode layer 3 to manufacture ten photovoltaic elements of 10 cm × 10 cm square.

Next, encapsulation of each photovoltaic element was performed in the same manner as in Example 1 to obtain a sample.

When the initial characteristics of the obtained sample were measured in the same manner as in Example 1, the conversion efficiency was as good as 7.9% ± 0.9%, and the variation was small.

Example 6 Next, a photovoltaic element having a pin junction type single cell configuration shown in FIG. 3 was produced by the procedure shown in FIG.

The first electrode layer 10 was formed on the surface of the insulating substrate 1c made of polyimide in the same manner as in Example 4.
After cutting into a 0 cm square, a contact hole 7 having a diameter of 300 μm penetrating the 10 cm square laminate was formed at the same position as in Example 1.

After the formation of the contact hole 7, the semiconductor layer 2 and the second electrode layer 3 were sequentially formed on the first electrode layer 10 in the same manner as in Example 1 so as not to close the contact hole 7. At this time, the semiconductor material forming the semiconductor layer 2 also adhered to the inner peripheral wall of the contact hole 7, and the short-circuit prevention layer 8 was formed. Further, ITO constituting the second electrode layer 3 was also adhered on the short-circuit prevention layer 8. Thereafter, aluminum was deposited on the back surface of the substrate 1c to form the third electrode layer 6.

Next, a conductive resin was filled as a contact material 9 in each contact hole 7 in the same manner as in Example 1 except that printing was performed from the back side of the substrate 1c. The grid electrode 4 was formed on the second electrode layer 3, and ten photovoltaic elements having a size of 10 cm × 10 cm and having the configuration shown in FIG. 3 were manufactured.

Next, encapsulation of each photovoltaic element was performed in the same manner as in Example 1 to obtain a sample.

When the initial characteristics of the obtained sample were measured in the same manner as in Example 1, the conversion efficiency was as good as 6.5% ± 1.1%, and the variation was small.

Comparative Example 2 For comparison, a conventional photovoltaic element having a single cell structure of a pin junction type of a through-hole contact type shown in FIG. 10 was manufactured as follows.

First, a 200-cm thick insulating substrate 1c made of a 10 cm × 10 cm square polyimide film was
A first electrode layer 10 made of 0 ° aluminum is formed by a sputtering method, and has a diameter of 10
0 μm contact hole 7 is formed by YAG laser
19 × 19 pieces were formed in a grid pattern at mm intervals. Example 1
Although the diameter of the contact hole 7 was set to 300 μm,
In order to obtain the same efficiency as in Example 1, it was necessary to reduce the hole diameter, so that it was set to 100 μm.

After the formation of the contact hole 7, the amorphous silicon semiconductor layer 2 was formed by the CVD method so as not to close the contact hole 7. At this time,
The semiconductor material forming the semiconductor layer 2 is a contact hole 7
And the short-circuit preventing layer 8 was formed. Further, a second electrode layer 3 made of ITO was formed on the semiconductor layer 2 by a sputtering method. The ITO constituting the second electrode layer 3 also adhered on the short circuit prevention layer 8.

Screen printing of a conductive resin is performed on the back surface of the substrate 1c on which the second electrode layer 3 is formed, and the third electrode layer 6
And connection between the third electrode layer 6 at the bottom of the contact hole 7 and the second electrode layer 3 was performed. Thereafter, a copper foil is connected to the third electrode layer 6 to form a plus terminal, and a copper foil is also connected to the first electrode layer 10 to form a minus terminal, and ten 10 cm square photovoltaic elements are formed. Produced.

Next, encapsulation of each photovoltaic element was performed in the same manner as in Example 1 to obtain a sample.

When the initial characteristics of the obtained sample were measured in the same manner as in Example 1, the shunt resistance was lower by about 40% and the series resistance was higher by about 15% as compared with Example 1, so that the conversion efficiency was lower. It was as low as 7.1% ± 1.5%, and the variation was large. Analysis of the cause revealed that the reason for the high shunt resistance was that the diameter of the contact hole 7 was small, so that the semiconductor material was difficult to be formed on the inner wall of the contact hole 7, the coverage was insufficient, and the second electrode layer 3 and the first electrode It was found that the layer 10 was in direct contact, causing a short circuit. Also, when analyzing the cause of high series resistance,
Again, since the diameter of the contact hole 7 was small, it was found that ITO was difficult to be formed on the inner wall of the contact hole 7, and that a portion where the bonding between the second electrode layer 3 and the third electrode layer 6 was defective was generated.

As described above, as in Comparative Example 2, when the current is to be collected only through the contact holes 7 without providing the grid electrode 4 as in Example 1, the through holes 7 are formed as small and as many as possible. By doing so, the loss of efficiency can be reduced, but by making the contact hole 7 smaller, short-circuited portions or poorly connected portions are likely to occur.
It has been found that the conversion efficiency is reduced and the variation is increased.

[0140]

The present invention is as described above. Since the bus bar can be eliminated, shadow loss caused by the bus bar can be eliminated, and at the same time, only a very small number of contact holes 7 are required. Compared with the case where a large number of contact holes 7 are densely formed to achieve electrical connection, not only the electromotive force loss due to the contact holes 7 is extremely small, but also manufacturing is extremely easy, and electrical connection for each contact hole 7 is achieved. Variation due to unevenness can be prevented. When the short-circuit prevention layer 8 is formed on the inner wall surface of the contact hole 7, the insulating layer 5 or the semiconductor layer 2
Since the short-circuit prevention layer 8 can also be formed at the same time as the formation of the semiconductor device, the number of laminating steps is not increased, and there is no need to use an extra material, thereby improving the manufacturing efficiency and reducing the manufacturing cost. be able to.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an example of a configuration of a photovoltaic device according to a first embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating an example of a configuration of a photovoltaic element according to a second embodiment of the present invention.

FIG. 3 is a diagram schematically illustrating an example of a configuration of a photovoltaic element according to a third embodiment of the present invention.

FIG. 4 is a diagram schematically illustrating an example of a configuration in which the photovoltaic elements illustrated in FIG. 1 are serialized.

FIG. 5 is a diagram showing an example of a manufacturing procedure of the photovoltaic device shown in FIG.

FIG. 6 is a diagram showing another example of a manufacturing procedure of the photovoltaic device shown in FIG.

FIG. 7 is a diagram showing an example of a manufacturing procedure of the photovoltaic device shown in FIG.

FIG. 8 is a diagram showing an example of a manufacturing procedure of the photovoltaic device shown in FIG.

FIG. 9 is a diagram schematically showing another example of the configuration of the photovoltaic element according to the first embodiment of the present invention.

FIG. 10 is a diagram schematically illustrating a conventional photovoltaic element manufactured in Comparative Example 2.

[Explanation of symbols]

 1a Substrate (substrate forming first electrode) 1b Substrate (substrate forming third electrode) 1c substrate (insulating substrate) 2 semiconductor layer 3 second electrode layer 4 grid electrode 5 insulating layer 6 third electrode layer 7 contact hole 8 Short-circuit prevention layer 9 Contact material 10 First electrode layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshifumi Takeyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Koji Tsuzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside (72) Inventor Koichi Shimizu 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term (reference) 5F051 AA04 AA05 FA10 FA13 FA15 GA02 GA03 HA20 JA06

Claims (15)

[Claims] At least one semiconductor layer having a pin or pn semiconductor junction, a second electrode layer, and a grid electrode are sequentially provided on one surface of a conductive substrate forming a first electrode, A third electrode layer is formed on the other surface of the substrate with an insulating layer interposed therebetween, and the grid electrode and the third electrode layer are formed at least through a contact hole penetrating the semiconductor layer, the substrate and the insulating layer. Are electrically connected to each other. 2. A semiconductor substrate having at least one pin or pn semiconductor junction, a second electrode layer, and a grid electrode are sequentially provided on one surface of a conductive substrate, and the substrate and the semiconductor are provided. Between the layers, the substrate forms a third electrode by providing a first electrode layer with an insulating layer interposed between the substrate and the substrate, at least the semiconductor layer, the first electrode layer and A photovoltaic element, wherein the grid electrode and a substrate serving as a third electrode are electrically connected through a contact hole penetrating the insulating layer. 3. A semiconductor layer having at least one pin or pn semiconductor junction, a second electrode layer, and a grid electrode are sequentially provided on a first electrode layer formed on one surface of an insulating substrate. And a third electrode layer is formed on the other surface of the substrate, and the grid electrode and the third electrode are formed at least through a contact hole penetrating the semiconductor layer, the first electrode layer, and the substrate. A photovoltaic element characterized by being electrically connected to a layer. 4. A substrate or a first electrode layer and a third electrode layer or a first electrode, wherein a plurality of the photovoltaic elements according to any one of claims 1 to 3 is a first electrode between adjacent photovoltaic elements. A photovoltaic device in which substrates serving as three electrodes are electrically connected and arranged in series. 5. A short-circuit prevention layer is formed on at least a surface of the substrate serving as the first electrode or the first electrode layer, which is exposed on an inner surface of the contact hole. 3. The photovoltaic device according to claim 1. 6. The electric connection between the grid electrode and the third electrode layer or the substrate serving as the third electrode through the contact hole is made by a contact material filled in the contact hole. The photovoltaic device according to claim 5, characterized in that: 7. The photovoltaic device according to claim 6, wherein the contact material is a conductive resin. 8. The photovoltaic device according to claim 1, wherein said grid electrode is a wire-shaped conductive material. 9. The grid electrode is a wire-shaped conductive material obtained by coating a metal wire with a conductive resin, and further comprises a conductive resin filled in a contact hole as the contact material and a metal wire. The photovoltaic element according to claim 7, wherein the conductive resin and the conductive resin are integrally joined. 10. A conductive resin in which the conductive resin coating the metal wire and the conductive resin as the contact material are obtained by mixing at least one conductive particle selected from carbon, silver and copper with a binder resin. The photovoltaic device according to claim 9, wherein: 11. The manufacturing of the photovoltaic device according to claim 1, wherein a short-circuit preventing layer is formed on at least a surface of the substrate which is the first electrode exposed on an inner surface of the contact hole. In the method, after sequentially laminating the semiconductor layer and the second electrode layer on one surface of a substrate forming the first electrode, forming the contact hole penetrating all of them, and closing the contact hole. By forming an insulating layer on the other surface of the substrate without extending the contact hole to the insulating layer, by attaching an insulating material constituting the insulating layer to the inner peripheral wall of the contact hole, Forming the short-circuit preventing layer on at least the surface of the substrate which is the first electrode exposed on the inner surface of the contact hole; Forming a third electrode layer and a grid electrode connected to the photovoltaic element. 12. The photovoltaic device according to claim 1, wherein a short-circuit preventing layer is formed on at least a surface of the substrate that is the first electrode exposed on an inner surface of the contact hole. In, after laminating the semiconductor layer on one surface of the substrate constituting the first electrode, forming the contact hole penetrating both, on the other surface of the substrate without closing the contact hole At least the inner surface of the contact hole is exposed by forming the insulating layer and extending the contact hole to the insulating layer, and attaching an insulating material forming the insulating layer to the inner peripheral wall of the contact hole. Forming the short-circuit prevention layer on the surface of the substrate that is the first electrode to be formed, and then forming the second electrode layer and the contact hole. A method for manufacturing a photovoltaic element, comprising: forming a third electrode layer and a grid electrode which are electrically connected to each other. 13. The method for manufacturing a photovoltaic element according to claim 2, wherein a short-circuit prevention layer is formed on at least a surface of the first electrode layer exposed on an inner surface of the contact hole. After sequentially laminating an insulating layer and a first electrode layer on one surface of the substrate forming the third electrode, forming a contact hole penetrating all of them, and closing the contact hole without closing the contact hole. By forming the semiconductor layer on the electrode layer and extending the contact hole also to the semiconductor layer, by attaching a semiconductor material constituting the semiconductor layer to the inner peripheral wall of the contact hole, at least the contact hole Forming the short-circuit prevention layer on the surface of the first electrode layer exposed on the inner surface, and then forming the second electrode layer, via the contact hole Forming the grid electrode electrically connected to the substrate as the third electrode. 14. The method for manufacturing a photovoltaic element according to claim 2, wherein a short-circuit prevention layer is formed on at least a surface of the first electrode layer exposed on an inner surface of the contact hole. After sequentially laminating an insulating layer, a first electrode layer, a semiconductor layer, and a second electrode layer on one surface of the substrate forming the third electrode, all the layers other than the substrate forming the third electrode are penetrated. By forming a contact hole and applying an insulating paint to the inner peripheral wall of the contact hole without closing the contact hole, the short circuit to at least the surface of the first electrode layer exposed on the inner surface of the contact hole Forming a prevention layer, and then forming the grid electrode electrically connected to the substrate serving as the third electrode via the contact hole. Device manufacturing method. 15. The method for manufacturing a photovoltaic device according to claim 3, wherein a short-circuit prevention layer is formed on at least a surface of the first electrode layer exposed on an inner surface of the contact hole. After laminating a first electrode layer on one surface of the substrate, forming a contact hole penetrating both, forming the semiconductor layer on the first electrode layer without closing this contact hole The surface of the first electrode layer exposed at least on the inner surface of the contact hole by extending the contact hole to the semiconductor layer and simultaneously attaching a semiconductor material forming the semiconductor layer to the inner peripheral wall of the contact hole. Forming the short-circuit prevention layer on the third electrode layer, and then forming the second electrode layer and the third electrode layer electrically connected through the contact hole. And forming a grid electrode.