JPS5896777A - Solar battery - Google Patents

Abstract

PURPOSE:To improve the V-I characteristics and the photoelectric conversion coefficient of the titled solar battery by a method wherein the solar battery having an P-N junction is formed by thinly diffusing a conductive layer which is different from that of the surface layer part of a semiconductor substrate, and an Ag paste, whereon 5-10% of Ni paste was added as an electrode material, is used when a grid electrode is provided on the light-receiving surface of the solar battery. CONSTITUTION:A P-N junction is grown by forming a shallow N type layer 2 on the surface layer part of a P type Si substrate 1 by diffusion and the surface of the layer 2 is used as a light-receiving surface. Then, a grid electrode 3a is formed on the light-receiving surface, and at this time, excellent ohmic characteristics are maintained between the grid electrode 3a and the layer 2. Subsequently, a light-reflection preventing film 5 is provided in the intervals of the electrodes 3a, and a back face electrode 4 is coated on the whole surface of the back side of the substrate 1. Thus, the characteristics of the solar battery is increased and the cost of its manufacture is also cut down.

Description

[Detailed description of the invention] This invention relates to solar cells.

An example of the structure of a conventional silicon single crystal solar cell is shown in FIG. That is, in FIG. 1, (1) is a P-type silicon semiconductor substrate, e2) is an n-type layer formed by shallowly diffusing n-type impurities on one main surface of this substrate (1), and is a light-receiving layer. In addition, (3) is a grid electrode that extracts negative potential from the light-receiving surface of the substrate, and (4) is a back surface that is provided on the other main surface of the substrate α) and that extracts positive potential. The electrode (5) is an antireflection film on the light receiving surface.

In this way, this type of solar cell with the conventional configuration is manufactured using a P-type single-crystal silicon substrate (
1) An n-type diffusion region (about 0.3 to 0.5 μm) is formed on the surface of
2) to form a light-receiving surface, and 30θμ,
Grid electrodes with a width of approximately 4 to 5 times apart are formed by screen printing, for example, Ag paste manufactured by Engelhard, and furthermore, Ag paste is applied to the entire back surface of the substrate.
The At paste was formed by screen printing in the same manner, and the substrate was baked in the air at 600 to 620°C for about 10 to 15 minutes, and Ties, Si@N4.
An antireflection film (5) such as TBmOa is formed.

In such conventional solar cells, since the grid electrode (3) is fired in the atmosphere, the ohmic relationship with the n-type layer (2) is poor, v-r characteristics, and light conversion efficiency. was bad.

In view of the above drawbacks of the conventional method, this invention was developed by adding 5 to 10% of Ni paste to Ag paste as the material for the grid electrode.
By using an additive mixture of about 10%, the light-mixing properties are improved and the V-total characteristics and light conversion efficiency are greatly improved.

Hereinafter, one embodiment of the solar cell according to the present invention will be described in detail with reference to FIGS. 2 and 3.

FIG. 2 is a cross section showing the configuration of this embodiment. In this FIG. 2, the same reference numerals as those in FIG. 1 indicate the same or corresponding parts. )'' A-4162) and about 5 to 10% Ni paste (for example, Engelhard A-41).
07) is added and mixed to form an n-type layer 0.
) with good ohmic properties. .

Further, FIG. 3 shows the V-4 characteristics of the conventional solar cells and the solar cells of this example, when the light-receiving surface is irradiated with light equivalent to AMI. That is, the curve (a), ←) is the V-I characteristic during dark current and during light irradiation in the conventional example, and the curve (c), ←) is the V-I characteristic during dark current and during light irradiation in this embodiment. This is an I characteristic.

As is clear from FIG. 3, by using a material mixed with Ag paste and 5 to 10% Ni paste for the grid electrode (3a) as in this example, the forward bias voltage drop is significantly reduced. Moreover, the ohmic properties of the electrode are significantly improved, the V-1 characteristics during light irradiation are improved, and the light conversion efficiency can be dramatically improved. After using the electrode material in this example, the firing conditions at 610°C for about 10 minutes were sufficient, and as a result, the ohmic properties and light conversion efficiency were improved as described above. It is.

Although the above embodiments have been described with respect to silicon single crystal solar cells, similar effects can be obtained with other solar cells.

As detailed above, according to the present invention, A paste material containing Ni is used as the grid electrode of the light receiving surface formed by thinly diffusing a different conductive layer on the silicon semiconductor substrate. Ohmic properties can be improved, light conversion efficiency can be improved, and manufacturing yields can also be improved.
It also has the advantage of helping to reduce costs.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the general structure of a solar cell according to a conventional example, FIG. 2 is a cross-sectional view showing a general structure of a solar cell according to an embodiment of the present invention, and FIG. FIG. 2 is an explanatory diagram showing the VI characteristics of a solar cell when irradiated with light. (1)...P-type single crystal silicon substrate, (2)-...
-n-type layer, (3), (3a), m-, grid electrode, (4), back electrode, (5), anti-reflection film. Agent Makoto Kuzuno (1 other person) Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A solar cell in which a thin conductive layer different from the above is diffused on a semiconductor substrate to form a Pn junction near the light-receiving surface, characterized in that an Ag paste material containing Ni is used at least for the electrode on the light-receiving surface side. solar cells.