JP2775480B2 - Method of forming photovoltaic device - Google Patents

Description

The present invention relates to a photovoltaic device that collects electricity from a first back electrode layer and a second back electrode layer that is in contact with a transparent electrode layer through a through hole. The present invention relates to a method for forming an apparatus.

[Conventional technology]

Conventionally, a photovoltaic device such as a solar cell has a transparent electrode layer made of tin oxide [SnO ₂ ], ITO, or the like formed on a transparent insulating substrate made of glass or the like. And a metal electrode made of aluminum [Al], silver [Ag], or the like, are sequentially formed, and current is collected from the transparent electrode layer and the metal electrode, that is, an electromotive force is extracted to the outside.

However, since the transparent electrode layer generally has a low conductivity and a large resistance loss, which leads to a decrease in current collection efficiency, this is a major problem in improving photoelectric conversion efficiency.

Therefore, a photovoltaic device having a so-called through-hole contact structure as described in Japanese Patent Application Laid-Open No. 61-20371 (HO1L 31/04) has been proposed, and a further extension of the photovoltaic device to an integrated type has been proposed. In particular, in the case of the integrated type, in addition to the above-described prevention of the reduction of the current collection efficiency, the through-hole contact structure is effective in increasing the effective area. It is configured as shown in the figure.

In FIG. 2, reference numeral 1 denotes a light-transmitting insulating substrate such as glass;
Is a transparent electrode layer made of SnO ₂ , ITO, etc., formed on the substrate 1 and patterned in a predetermined pattern, and 3 is at least one pn formed on the transparent electrode layer 2 and on the exposed substrate 1.
A semiconductor junction forming layer 4 made of amorphous silicon or the like having a junction or a pin junction, 4 is a first back electrode layer,
It is made of Al, Ag, or the like, and is formed on the bonding layer 3.

Numeral 5 is formed by etching or patterning with a laser beam, and the like is formed through the first back electrode layer 4 and the junction forming layer 3 to reach the transparent electrode layer 2, and 6 is formed by etching or patterning with a laser beam. 1 Separation grooves for cell separation penetrating through the back electrode layer 4 and the junction forming layer 3 and reaching the substrate 1; 7 is an insulating layer made of an inorganic or organic insulating material;
It is formed on the first back electrode layer 4 and on the peripheral surface of the through hole 5.

At this time, after the insulating layer 7 is uniformly formed in the through hole 5, a part of the insulating layer 7 in the through hole 5 is removed by etching or patterning with a laser beam. The insulating layer 7 is formed only on the peripheral surface of the substrate 5.

Further, the insulating layer 7 on at least one end of the transparent electrode layer 2 is also removed at the same time, and a connection groove 8 for connecting between adjacent cells is formed.

Further, in FIG. 2, reference numeral 9 denotes a second back electrode layer, which is made of Al, Ag, conductive paste, or the like.
After that, after being formed on the insulating layer 7 and in the through hole 5, it is patterned into a predetermined pattern.

In the integrated photovoltaic device having the through-hole contact structure thus formed, when viewed from one cell, current is collected from the first back electrode layer 4 and the second back electrode layer 9, As can be seen from FIG.
Since the second back electrode layer 9 in the inside contacts the first back electrode layer 4 of the adjacent cell and each cell is connected in series, the first back electrode layer 4 or the second back electrode layer 9 of the first stage cell is formed. And the second back electrode layer 9 or the first back electrode layer 4 of the last stage cell.

[Problems to be solved by the invention]

The integrated photovoltaic device having the through-hole contact structure formed by the conventional method has a problem that the contact resistance between the transparent electrode layer and the second back electrode layer is large, and therefore, the current collection efficiency is low and the photoelectric conversion efficiency is low. There is a point.

This is because, as shown in FIG. 2, the adhesion insulating layer 10 adheres to the surface of the transparent electrode layer 2 in the through hole 5, and the contact resistance between the transparent electrode layer 2 and the second back electrode layer 9 increases. Because.

It is considered that the adhesion insulating layer 10 is formed and adhered by the following mechanism.

First, when the insulating layer 7 is formed only on the peripheral surface of the through hole 5 by patterning with a laser beam, only the central portion of the insulating layer 7 in the through hole 5 cannot be completely removed. The insulating layer 7 remains on the surface of the transparent electrode layer 2, and as a result, the adhered insulating layer 10 adheres.

When an organic insulating material is used for the insulating layer 7,
When the insulating layer 7 is formed only on the peripheral surface of the through hole 5 by etching, the adhesive insulating layer 10 adheres to the surface of the transparent electrode layer 2 in the through hole 5 during the etching process.

The adhesion insulating layer 10 is very thin, at most about 1000 °, but the adhesion insulation layer 10 increases the contact resistance between the transparent electrode layer 2 in the through hole 5 and the second back electrode layer 9, This causes a poor electrical connection between the two layers 2 and 9, and the generated electromotive force cannot be efficiently extracted to the outside.

This problem occurs not only in the integrated type but also in a photovoltaic device having a through-hole contact structure.

The present invention has been made in consideration of the above points, and is intended to improve the connection failure of a current collecting electrode layer of a photovoltaic device having a so-called through-hole contact structure by a simple method, and to improve photoelectric conversion efficiency. The purpose is to:

[Means for solving the problem]

In order to achieve the above object, a transparent electrode layer, a semiconductor junction formation layer, and a first back electrode layer are formed on a light-transmitting insulating substrate in a stacked manner, and the transparent electrode layer, the semiconductor junction formation layer, and the semiconductor junction formation layer penetrate through the first back electrode layer and the semiconductor junction formation layer. Forming a through hole reaching the transparent electrode layer; forming an insulating layer on the first back electrode layer and on a peripheral surface of the through hole; forming a second back electrode layer on the insulating layer and in the through hole. In the method for forming a photovoltaic device, the present invention is configured such that, after forming the second back electrode layer, removing the adhered insulating layer adhered to the surface of the transparent electrode layer in the through hole by pressing with a needle, It is characterized in that a second back electrode layer is connected to the transparent electrode layer.

[Action]

Therefore, the adhered insulating layer adhered to the surface of the transparent electrode layer in the through hole is removed by a simple method of pressing with a needle after the formation of the second back electrode layer, and the transparent electrode layer in the through hole and the second back electrode are removed. The electrical connection with the layer is improved by a simple method, the current collection efficiency is improved, and the photoelectric conversion efficiency of the photovoltaic device is improved.

〔Example〕

 One embodiment will be described with reference to FIG.

FIG. 1 is a sectional view of a photovoltaic device finally obtained, and the same symbols as those in FIG. 2 indicate the same or corresponding components.

In the apparatus of FIG. 1, through the same steps as those of the apparatus of the conventional method of FIG. 2, up to the second back electrode layer 9 is formed on the substrate 1, and at this time, Similarly, the adhesion insulating layer 10 remains.

Therefore, after the formation of the second back electrode layer 9, the upper side of the through hole 5 of the second back electrode layer 9 is pressed with a very fine needle,
By this pressing, the adhered insulating layer 10 is crushed and removed as shown in FIG. 1, and the second back electrode layer 9 and the transparent electrode layer 2 are electrically connected.

Then, by removing the adhered insulating layer 10 in the through hole 5, the fill factor of the obtained photovoltaic device is largely improved, and the output is improved as compared with the conventional one.

Although the contact resistance between the transparent electrode layer 2 and the second back electrode layer 9 in the through-hole 5 before pressurization was infinite, it is experimentally found that the contact resistance between the transparent electrode layer 2 and the second back electrode layer 9 is infinitely reduced by the above-described pressurization and removal. Was also confirmed.

By the way, in the above embodiment, the case where the present invention is applied to an integrated photovoltaic device is described. However, the present invention can be similarly applied to a single-cell type through-hole contact structure.

〔The invention's effect〕

Since the present invention is configured as described above,
The following effects are obtained.

After the formation of the second back electrode layer, the adhered insulating layer adhered to the surface of the transparent electrode layer in the through hole is removed by a simple method of pressing with a needle, and the transparent electrode layer in the through hole and the second back electrode layer are separated. Because the cause of the increase in contact resistance has been eliminated, the transparent electrode layer in the through hole and the second backside electrode layer are electrically connected well by a simple method to improve current collection efficiency and improve photoelectric conversion efficiency. Thus, the characteristics of the photovoltaic device can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of the present invention, and FIG. 2 is a sectional view of a conventional example. DESCRIPTION OF SYMBOLS 1 ... Transmissive insulating substrate, 2 ... Transparent electrode layer, 3 ... Semiconductor junction formation layer, 4 ... First back electrode layer, 5 ... Through hole, 7 ... Insulating layer, 9 ... Second Back electrode layer, 10 ... Adhesive insulating layer.

Continuation of the front page (56) References JP-A-60-149178 (JP, A) JP-A-62-11280 (JP, A) JP-A-61-6828 (JP, A) JP-A-61-20371 (JP, A) , A) JP-A-61-284974 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 31/04

Claims (1)

(57) [Claims] 1. A transparent electrode layer, a semiconductor junction forming layer and a first back electrode layer are formed on a light-transmitting insulating substrate in a laminated manner, and the transparent electrode layer penetrates the first back electrode layer and the semiconductor junction forming layer. Forming a through hole reaching the first back electrode layer, and forming an insulating layer on the first back electrode layer and the peripheral surface of the through hole; and forming a second back electrode layer on the insulating layer and in the through hole. In the method for forming a device, after forming the second back electrode layer, the adhesion insulating layer attached to the surface of the transparent electrode layer in the through hole is removed by pressing with a needle, and the second back electrode layer and the second back electrode layer are formed. A method for forming a photovoltaic device, comprising: connecting a transparent electrode layer.