JPH10275926A - Photovoltaic device and module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the adhesion of a transparent conductive film to an electrode for avoiding the separation from the electrode by a method wherein an under side transparent conductive film is formed on an under side semiconductor layer on the opposite side to a light incident side of a semiconductor for partially interposing a metallic collector electrode on the interface between the under side semiconductor layer and the under side transparent conductive film. SOLUTION: A light receiving surface electrode 6 is interposed on the interface between a P type layer 3 on a surface semiconductor layer 4 and a surface transparent conductive film 5 of a substrate 1 made of n type single crystalline silicon semiconductor. Besides, a collector electrode 10 is interposed on the interface between an n type layer 7 on an under side semiconductor layer 8 and an under side transparent film 9. Furthermore, the electrode patterns of the collector electrode 10 and the electrode 6 are made almost similar i.e., is symmetrical with respect to plane, likewise, the surface transparent conductive film 5 and the electrode 6 as well as the under side transparent film 9 and the collector electrode 10 are made symmetrical with respect to plane. Through these procedures, the adhesion between respective transparent conductive films 5, 9 as well as between respective electrodes 6, 10 can be enhanced thereby preventing the separation of respective electrodes 6, 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic device provided with a junction of crystalline silicon and amorphous silicon as a semiconductor junction, and a module comprising the device.

[0002]

2. Description of the Related Art Conventionally, as a photovoltaic device having a semiconductor junction of a crystalline silicon semiconductor such as single crystal silicon or polycrystalline silicon and an amorphous semiconductor represented by amorphous silicon, for example, A photovoltaic device having a HIT structure described in Japanese Unexamined Patent Publication No. 4-130671 (H01L 31/04) is known.

In this photovoltaic device having the HIT structure, an intrinsic amorphous semiconductor layer is interposed between a single crystal semiconductor and an amorphous semiconductor having a relationship of opposite conductivity type to each other, so that the The electromotive force characteristics are greatly improved.

Meanwhile, in such a photovoltaic device using crystalline silicon, it has been studied to reduce the thickness of the crystalline silicon substrate to about 150 μm in order to reduce material costs.

However, in a conventional photovoltaic device using a transparent conductive film / light receiving surface electrode structure as a light incident side electrode and a metal film / collector electrode structure as a back side electrode,
As the thickness of the substrate is reduced, the effect of stress caused by the difference in the coefficient of thermal expansion between the transparent conductive film and the metal film increases, and the substrate is warped. In order to solve such a problem, studies have been made to make the rear electrode also have a transparent conductive film / collector electrode structure.

A conventional photovoltaic device of this type will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a substrate made of an n-type single crystal silicon semiconductor, and reference numerals 2 and 3 denote an i-type layer made of intrinsic amorphous silicon and a p-type layer made of p-type amorphous silicon. Are sequentially laminated on the light incident side, that is, the surface. 4 is a surface semiconductor layer composed of an i-type layer 2 and a p-type layer 3 and 5 is a surface transparent conductive film of ITO in which Sn is added to tin oxide (SnO ₂ ), indium oxide (In ₂ O ₃ ) or In ₂ O _3. And is formed on the p-type layer 3. Reference numeral 6 denotes a linear light-receiving surface electrode made of Ag, which is formed on the surface transparent conductive film 5.

On the opposite side of the substrate 1 from the light incident side, that is, on the back surface, an n-type layer 2 and an n-type amorphous silicon
A backside semiconductor layer 8 on which a mold layer 7 is laminated is formed, a backside transparent conductive film 9 is formed on the backside semiconductor layer 8, and a linear collector electrode 10 made of Ag is formed on the backside transparent conductive film 9. ing.

[0008]

In the case of the conventional device, the metal is oxidized, so that the adhesion between the front transparent conductive film 5 and the light receiving surface electrode 6 and between the rear transparent conductive film 9 and the collector electrode 10 is reduced. However, there is a problem that the two electrodes 6 and 10 are peeled off and the reliability is reduced.

The present invention has been made in view of the above points, and has as its object to provide a photovoltaic device and a module capable of improving adhesion between a transparent conductive film and an electrode, preventing separation of the electrode and improving reliability. Aim.

[0010]

According to a first aspect of the present invention, there is provided a photovoltaic device comprising a back transparent semiconductor film on a back semiconductor layer opposite to a light incident side of a semiconductor. And a collector electrode made of metal is partially interposed at the interface between the backside semiconductor layer and the backside transparent conductive film.

Therefore, the electrode is in direct contact with the semiconductor layer,
An extremely thin alloy layer is formed at the interface between the electrode and the semiconductor layer, and the adhesion between the electrode and the semiconductor layer is improved by the alloy layer, the separation of the electrode can be prevented, and the reliability can be improved. .

In the photovoltaic device according to a second aspect of the present invention, the light receiving surface electrode made of metal is provided on the surface semiconductor layer on the light incident side of the semiconductor in plane symmetry with the collector electrode on the side opposite to the light incident side. It is formed in.

According to a third aspect of the present invention, there is provided a photovoltaic device, wherein a front transparent conductive film and a light receiving surface electrode are provided on a surface semiconductor layer on a light incident side of a semiconductor, and a rear transparent conductive film on a side opposite to the light incident side. And the collector electrode is formed in plane symmetry.

Therefore, by forming the electrodes on both surfaces of the semiconductor in plane symmetry, warpage due to heat treatment can be eliminated.

A module according to a fourth aspect of the present invention comprises the photovoltaic device according to the first, second, or third aspect, and a highly reliable module having no electrode peeling. be able to.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment will be described with reference to FIG. 1 of a sectional view and FIGS. 2A, 2B and 2C of an explanatory view of a manufacturing process. In these figures, the same reference numerals as those in FIG. 3 indicate the same or corresponding elements, and the differences are as follows.

A light-receiving surface electrode 6 is interposed at the interface between the p-type layer 3 of the surface semiconductor layer 4 of the substrate 1 made of an n-type single crystal silicon semiconductor and the front transparent conductive film 5, and the n-type of the back surface semiconductor layer 8 is formed. The collector electrode 10 is interposed at the interface between the layer 7 and the back transparent conductive film 9, and the electrode patterns of the collector electrode 10 and the light receiving surface electrode 6 are made substantially the same pattern, that is, plane symmetrical. The light-receiving surface electrode 6 and the back transparent conductive film 9 and the collecting electrode 10 are plane-symmetrical, that is, both electrodes 6 and 10 are arranged on the substrate 1 side, and both transparent conductive films 5 and 9 are arranged thereon. I have.

Next, the manufacturing method will be described. First,
As shown in FIG. 2A, an i-type layer 2 and a p-type layer 3 are sequentially laminated on the surface of the substrate 1 by a plasma CVD method to form a surface semiconductor layer 4, and then, as shown in FIG. An i-type layer 2 and an n-type layer 7 are sequentially laminated on the back surface of the substrate by a plasma CVD method to form a back surface semiconductor layer 8.

Then, as shown in FIG. 2C, a paste-like light-receiving surface electrode 6 is formed on the p-type layer 3 by patterning using a screen printing method. The collector electrode 10 is formed and fired at a predetermined temperature. Thereafter, as shown in FIG. 1, front and rear transparent conductive films 5 and 9 are formed on the p-type layer 3 and the n-type layer 7 by a sputtering method.

In the case of the above-described embodiment, since the rear surface of the device has a light-transmitting property, the characteristics of the device alone are greatly reduced.

However, when actually used as a module, white polyvinyl fluoride (PVF), polyethylene terephthalate (PET),
By providing a high-reflection material made of a resin such as polyethylene naphthalate (PEN) or a metal, it is possible to prevent deterioration in characteristics.

In the above-described embodiment, the electrode is interposed at the interface between the semiconductor layer and the transparent conductive film of the photovoltaic device having the HIT structure. However, the present invention is applicable to a photovoltaic device having another structure. And is effective in improving reliability.

Further, a transparent conductive film made of ITO and Ag
Although the combination with the electrode consisting of is described as an example,
A combination using SnO ₂ and zinc oxide (ZnO) as the transparent conductive film and lead (Pb) and titanium (Ti) as the electrode may be used.

(Embodiment) Next, an embodiment will be described. Table 1 shows the conditions for forming the HIT structure semiconductor layer and the transparent conductive film formed on both surfaces of the substrate.

[0025]

[Table 1]

After the formation of the electrode, the transparent conductive film is
It was fired at a temperature of from about 250C to about 250C and formed using the conditions in Table 1.

Next, a thermal cycle test of the photovoltaic devices of FIGS. 1 and 3 was performed and compared. Thermal cycle is -40
After holding at 1 ° C. for 1 hour, the temperature was raised to + 90 ° C. over 2 hours, and then held at + 90 ° C. for 1 hour, and then lowered again to −40 ° C. over 2 hours, and this process was performed 200 times. Table 2 shows the results.

[0028]

[Table 2]

It is clear that the device of FIG. 1 suppresses the deterioration of the characteristics as compared with the device of FIG. 3, and the deterioration of the characteristics of the device of FIG. This is due to an increase in resistance due to peeling of the metal.

The electrodes 6 and 10 are usually formed by applying a paste-like resin, such as a silver paste, into which a metal is mixed, on the p-type layer 3 or the n-type layer 7, followed by a firing step. At this time, the resin material is formed on the p-type layer 3 or n
There is a possibility of being mixed into the mold layer 7.

When the resin material mixed into the p-type layer 3 reaches the interface with the substrate 1, the p / n junction is adversely affected and the photovoltaic characteristics may be deteriorated.

Therefore, especially when the thicknesses of the p-type layer 3 and the i-type layer 2 are reduced, the light receiving surface electrode 6 may be provided on the front surface transparent conductive film 5.

[0033]

Since the present invention is configured as described above, it has the following effects. In the photovoltaic device of the present invention, a transparent conductive film is formed on the semiconductor layer on the light incident side of the semiconductor or on the opposite side thereof, and an electrode made of metal is partially formed on the interface between the semiconductor layer and the transparent conductive film. ,
The electrode is in direct contact with the semiconductor layer, an extremely thin alloy layer is formed at the interface between the electrode and the semiconductor layer, and the adhesiveness between the electrode and the semiconductor layer is improved by this alloy layer, and peeling of the electrode can be prevented, Reliability can be improved.

Further, since the light receiving surface electrodes and the collector electrodes on both surfaces of the semiconductor are formed in plane symmetry, the warpage of the electrodes due to the heat treatment can be eliminated.

Further, by configuring a module using the above-described device, a module having improved reliability can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment of the present invention.

FIGS. 2A, 2B, and 2C are explanatory diagrams of the manufacturing process of FIG. 1;

FIG. 3 is a sectional view of a conventional example.

[Explanation of symbols]

 Reference Signs List 4 front semiconductor layer 5 front transparent conductive film 6 light receiving surface electrode 8 back semiconductor layer 9 back transparent conductive film 10 collector electrode

Claims (4)

[Claims] 1. A backside transparent conductive film is formed on a backside semiconductor layer opposite to a light incident side of a semiconductor, and a collector electrode made of metal is partially provided at an interface between the backside semiconductor layer and the backside transparent conductive film. A photovoltaic device characterized by being interposed. 2. A backside transparent conductive film is formed on a backside semiconductor layer opposite to a light incident side of a semiconductor, and a collector electrode made of metal is partially provided at an interface between the backside semiconductor layer and the backside transparent conductive film. A photovoltaic device, wherein a light receiving surface electrode made of a metal is formed on a surface semiconductor layer on the light incident side of the semiconductor in a plane-symmetric manner with the collector electrode. 3. A backside transparent conductive film is formed on a backside semiconductor layer opposite to a light incident side of a semiconductor, and a collector electrode made of metal is partially formed at an interface between the backside semiconductor layer and the backside transparent conductive film. A photovoltaic device interposed therebetween, wherein a front transparent conductive film and a light receiving surface electrode are formed in a surface semiconductor layer on the light incident side of the semiconductor in plane symmetry with the rear transparent conductive film and the collector electrode. . 4. A module comprising the photovoltaic device according to claim 1, 2, or 3.