JP3209700B2 - Photovoltaic device and module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an HI having a junction of crystalline silicon and amorphous silicon as a semiconductor junction.
The present invention relates to a photovoltaic device (solar cell) having a T structure and a module including 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,
With the thinning of the substrate, the influence of stress due to the difference in thermal expansion coefficient between the transparent conductive film and the metal film increases,
Its Ri there is a problem that is caused. 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 consideration of the above points, and has a light receiving surface electrode.
To prevent exfoliation of the collector electrode and warpage due to heat treatment.
The lost, and to provide a photovoltaic device and a module for HIT structure with improved reliability.

[0010]

According to another aspect of the present invention, there is provided a photovoltaic device comprising an n-type photovoltaic device.
A substrate made of crystalline silicon, provided on the light incident side of the substrate
A p-type layer made of p-type amorphous silicon,
N-type amorphous silicon layer provided on the opposite side of the plate from the light incident side.
An n-type layer made of a con, and on the p-type layer and
A front transparent conductive film and a rear transparent conductive film on the n-type layer, respectively.
Is formed, and an interface between the p-type layer and the surface transparent conductive film is formed.
Surface, and at the interface between the n-type layer and the back transparent conductive film,
The light receiving surface electrode and collector electrode made of metal, respectively, are plane symmetric
Are formed in substantially the same pattern .

Therefore, the light receiving surface electrode and the collector electrode are p
Direct contact with the mold layer and the n-type layer, very thin alloy layer is formed at the interface between the electrodes and the two layers improves the adhesion between the electrodes and the two <br/> layer by the alloy layer, both it is cut with <br/> to prevent peeling of the electrode.

[0012]

[0013]

In addition, by forming both electrodes in substantially the same pattern with plane symmetry , warpage due to heat treatment can be eliminated. Therefore, a highly reliable HIT photovoltaic
A force device can be provided.

Further, the module according to a second aspect of the present invention has been constructed from the photovoltaic device according to claim 1 Symbol placement, its due to peeling and heat treatment of the light-receiving surface electrode and a collector electrode
Ri but not, it is possible to obtain a highly reliable module.

[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.

[0022]

Then , 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 SnO2 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 was formed using the conditions shown 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. you formed.

[0031]

[0032]

[0033]

Since the present invention is configured as described above, it has the following effects. The photovoltaic device of the present invention is made of amorphous silicon on the light incident side of the substrate.
Between the p-type layer and the surface transparent conductive film thereon and the substrate
N-type layer made of amorphous silicon on the side opposite to the light incident side of
A light receiving surface electrode and a collector electrode made of metal are respectively provided on the interface with the transparent conductive film on the back surface on the same pattern in a plane symmetrical manner .
Since in the formation, in contact with the electrodes directly to both layers, very thin alloy layer is formed at the interface between the electrodes and the two <br/> layer improves the adhesion between the electrodes and the two layers by the alloy layer The separation of the light receiving surface electrode and the collecting electrode can be prevented, and the light receiving surface electrode
And the collector electrode are formed in almost the same pattern with plane symmetry.
And eliminates electrode warpage due to heat treatment
It is possible to provide a photovoltaic device having a high-performance HIT structure .

[0034]

Further, by configuring a module using the above-described device, a highly reliable HIT structure module 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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 31/04-31/078

Claims (2)

(57) [Claims] A substrate made of n-type single crystal silicon;
P-type amorphous silicon provided on the light incident side of the substrate
And a p-type layer formed on the side opposite to the light incident side of the substrate.
An n-type layer made of n-type amorphous silicon.
For example, each surface transparent electrode on the p-type layer and the n-type layer
A film and a back transparent electrode film are formed , and an interface between the p-type layer and the front transparent conductive film;
Metal at the interface between the mold layer and the back transparent conductive film
The light-receiving surface electrode and the collecting electrode are
A photovoltaic device characterized by being formed of a photovoltaic device. 2. A photovoltaic device according to claim 1.
A module characterized by the following.