JPH06283734A - Polycrystalline silicon solar cell and its manufacture - Google Patents

Abstract

PURPOSE:To form a solar cell in an arbitrary width by a method wherein a polycrystalline silicon layer is formed on a cloth constituted of a silicon diode fiber and an electrode is formed on the polycrystalline silicon layer. CONSTITUTION:A cloth 21 made of silicon dioxide is provided with a woven structure, polycrystalline silicon layers 22, 23 are formed on both faces or one face of the cloth, and a poly-crystalline silicon solar cell is former. Such a structure can be obtained by forming the polycrystalline silicon layers on the woven silicon dioxe cloth. In order to form an electrode on the surface part, As or the like is used as N-type impurities when the polycrystalline silicon layers are composed of a P-type bulk, B or the like is used as P-type impurities when they are composed of an N-type bulk, a P-N junction part is formed on the surface part by an ion implantation part, Al or the like is formed in the P-N junction part by a sputtering method, and a comb-shaped electrode is former. When a silicon dioxide fiber is formed to be a cloth shape, the restriction of the solar cell due to a width can be eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure and manufacturing method of a solar cell, especially a solar cell composed of polycrystalline silicon.

[0002]

2. Description of the Related Art Various non-fossil energy sources have been attracting attention as a result of the oil shock. Among them, the energy from the sun is considered promising as an energy source without fear of resource depletion, and development of its utilization technology is vigorous. Is being advanced to. The energy from the sun includes heat and light that can be used, but initially the development goal was to use thermal energy, but recently development of utilization of light energy has been developed from the viewpoint of simplicity of the equipment used. Has become the central goal of. Not only is this solar energy easy to use, but because it does not generate exhaust gas, it has recently been regarded as important as a clean energy without environmental pollution. Solar cells that directly convert electric power are becoming popular as solar batteries.

A semiconductor solar cell is used as the photoelectric conversion means of this solar cell, and among various semiconductors, silicon is used as a semiconductor material of the solar cell from the viewpoint of resource amount and material cost. Silicon solar cells are roughly classified into single-crystal solar cells, polycrystalline solar cells, and amorphous solar cells. In fields that are relatively large and need electric power, single-crystal silicon solar cells are small and electric power is small. Amorphous silicon solar cells are often used in fields that do not require them.

A single crystal solar cell has high photoelectric conversion efficiency and high performance in terms of power generation capacity and life, but it is very expensive because it is manufactured from a wafer or a single crystal ribbon cut from a single crystal ingot. Although it is evaluated in terms of performance, it is difficult to popularize in terms of price. In addition, the diameter of the single crystal ingot that is currently in practical use is 150 mm.
(6 inches), the size of a square wafer that can be cut from this ingot is about 106 mm (4.2 mm).
Inch) × 106mm, which has recently started to be used 2
Approximately 14 even with a 00 mm (8 inch) ingot
It is 1 mm (5.7 inches) x 141 mm. Therefore,
Currently, only 100 solar cells can be obtained.
mm × 100 mm, and at most 13
It is about 0 mm x 130 mm.

There are plate-shaped and ribbon-shaped polycrystalline solar cells, and the plate-shaped ones are manufactured by a casting method or a rotating disk method. In the casting method, molten silicon is put into a mold, and the temperature is sequentially lowered from the lower part of the mold to solidify the silicon and grow crystals. for that reason,
There are problems that molten silicon may react with the mold to dissolve impurities, and cracks may occur when solidifying. The rotating disk method is a method in which molten silicon is dropped on a graphite or quartz disk placed on a turntable, and is a polycrystal with a diameter of 10 cm and a thickness of about 0.3 to 0.4 mm. A silicon disc is produced.

In the ultra-quenching method shown in FIG. 1, the molten silicon 12 in the nozzle 11 is sprayed onto a roll 13 to be rapidly cooled to obtain a ribbon-shaped polycrystalline silicon 14. This method has a high production rate, but is large in size. You can't get the area.

As a method for producing a polycrystalline silicon ribbon, in addition to a super-quenching method in which molten silicon is sprayed on a roll and rapidly cooled to obtain a polycrystalline silicon ribbon, the molten silicon is brought into contact with a ribbon of a different material to form a polycrystalline silicon ribbon. There is a way to get. A method of using a ceramic ribbon as a different material ribbon is called SOC (Silicon on Ceramic) method developed by Honeywell (USA), and as shown in FIG. 2, a ceramic is formed on the molten silicon 16 on the gutter 15 made of quartz. By moving the ribbon 17 in contact with the ceramic ribbon 17, the thickness of the ceramic ribbon 17 is 0.1 to
A 0.2 mm polycrystalline silicon layer 18 is formed.

A method of using a carbon ribbon as a different material ribbon was developed by LEP in France, and the RAD (Ribbon Aga
Inst Drop) method, as shown in FIG. 3, molten silicon 20 is put in a crucible 19 and a carbon ribbon 22 of 50 mm width is passed through a narrow gap 21 provided at the bottom of the crucible 19 and pulled up. By contacting the molten silicon 20 with the carbon ribbon 22, the carbon ribbon 2
70 to 200 μm thick polycrystalline silicon layers 23, 2
4 is formed.

Amorphous silicon solar cells use silane (Si
Cl ₄ ) gas and hydrogen gas are caused to react with each other by plasma in a low pressure atmosphere, and amorphous silicon (a-S
i: H). Therefore, a reaction vessel for obtaining a low-pressure atmosphere is required, and because the size of the reaction vessel is limited, it is not possible to obtain a large area, and the currently available one is 1200 mm x 4
The maximum is 00 mm. In addition, there is also a method of producing amorphous silicon on a stainless thin plate or a plastic film in place of the glass substrate, and in the case of this method, it is possible to obtain a continuous long product,
The width limit is still around 400 mm. In addition, since amorphous solar cells do not have high light-to-electricity conversion efficiency, amorphous solar cells can be used in devices other than those with small size and low power consumption, such as electronic desk calculators, despite their low manufacturing costs. You can't use it to get high power.

The majority of the large-sized silicon solar cells currently in practical use are single crystal solar cells, and the size of the cell unit is 10 cm × 10 cm = 100 cm ² , 15 cm × 15 cm.
= 225 cm ² and 20 cm × 20 cm = 400 cm ² , and the rated output is 1.572 W, 1 for each 10 cm × 10 cm.
The size of 5 cm x 15 cm is 3.510 W, and the size of 20 cm x 20 cm is 6.228 W. Since the solar cell generates electricity by the light incident on the surface of the cell, a large area is required to obtain a large amount of electric power, and therefore a large number of solar cells must be arranged and used. Therefore, normally, this cell unit is combined to form a module panel, for example, 10 cm ×
Output of 51W by combining 36 10cm cell units
A total of 72 cell units of 15 cm × 15 cm are combined to obtain an output of 230 W.

As described above, a single crystal silicon solar cell is manufactured from a single crystal wafer or a single crystal ribbon, and a polycrystalline silicon solar cell is manufactured by using a mold in a casting method or a ribbon-shaped ultra-quenching method, Amorphous silicon solar cells are produced by the SOC method using a ceramic ribbon and the RAD method using a carbon ribbon, and an amorphous silicon solar cell is formed on a glass substrate, a stainless thin plate, or a plastic film surface. Therefore, the shape of the solar cell manufactured by these manufacturing methods is all flat regardless of its crystal form, and
It is not possible to obtain a large area due to the above-mentioned problems in manufacturing technology.

[0012]

SUMMARY OF THE INVENTION The invention according to the present application has these problems, that is, the conventional solar cell can obtain only a planar shape irrespective of its crystalline form and has a large area. The challenge is to solve the problem of not being able to get things.

[0013]

In order to solve the above-mentioned problems, the present inventor has noticed that a wide ribbon can be obtained by forming a cloth-like ribbon using a different fibrous material, A wide polycrystalline silicon ribbon can be obtained by forming polycrystalline silicon on a wide silicon dioxide ribbon by using silicon dioxide (SiO ₂ ) which is easy to be formed into a fiber and easily compatible with silicon as the different material. That is, in the present application, "a polycrystalline silicon solar cell characterized in that a polycrystalline silicon layer is provided on a cloth composed of silicon dioxide fibers, and electrodes are formed on the polycrystalline silicon layer" An invention comprising
“A silicon dioxide cloth is formed using a silicon dioxide fiber, the silicon dioxide cloth is immersed in molten silicon to form a polycrystalline silicon layer on the silicon dioxide cloth, and an electrode is formed on the polycrystalline silicon layer. And a method for manufacturing a polycrystalline silicon solar cell.
"Form a silicon dioxide cloth with silicon dioxide fibers, apply silicon paste to the silicon dioxide cloth, and form a polycrystalline silicon layer on the silicon dioxide cloth by baking the applied silicon paste, and then apply the electrode to the polycrystalline silicon. And a "composite silicon dioxide having a polycrystalline silicon layer on the silicon dioxide fiber by immersing the silicon dioxide fiber in molten silicon. Forming a fiber, forming a composite silicon dioxide cloth with the composite silicon dioxide fiber, and forming an electrode on the polycrystalline silicon layer on the composite silicon dioxide cloth. The invention of the constitution and "Silicon paste is applied to silicon dioxide fiber The coated silicon dioxide fiber is fired to form a composite silicon dioxide fiber having a polycrystalline silicon layer, the composite silicon dioxide fiber is formed into a composite silicon dioxide cloth, and an electrode is applied to the polycrystalline silicon layer on the composite silicon dioxide cloth. The present invention provides a method for manufacturing a polycrystalline silicon solar cell, which comprises:

[0014]

In the present invention having the above-mentioned structure, a polycrystalline silicon layer is formed on a cloth made of silicon carbide which is well compatible with silicon, and the polycrystalline silicon layer forms a solar cell.

[0015]

EXAMPLES Silicon dioxide is called silica, and in addition to crystalline silicon dioxide such as low temperature type trigonal quartz and high temperature type hexagonal quartz, amorphous silicon dioxide or fibrous silica W having a siloxane chain is used. is there. Of these, high temperature type hexagonal quartz is known as quartz and is used as an optical material or a piezoelectric material. Amorphous silicon dioxide is known as quartz glass, has a softening point of 1500 ° C. or higher, and has a very small coefficient of thermal expansion, and is therefore used as a heat resistant material and an optical material, especially an optical fiber material.

A specific embodiment of the present invention will be described with reference to the drawings. First, a manufacturing method will be described. FIG. 4 is a schematic view of the first method for manufacturing the polycrystalline silicon solar cell of the present invention. In this first method, the polycrystalline silicon solar cell of the present invention is manufactured by dipping a silicon dioxide fiber cloth 2 wound around a supply roll 1 into a molten silicon 4 in a crucible 3 to form a silicon dioxide fiber cloth. It is manufactured by forming polycrystalline silicon layers 5 and 6 having a thickness of 0.01 to 0.2 mm on the winding 2 and winding the polycrystalline silicon layers 5 and 6 on the winding side roll 4.

FIG. 5 is a schematic view of a second method for manufacturing the polycrystalline silicon solar cell of the present invention. This second
In the above method, the polycrystalline silicon solar cell of the present invention comprises a silicon dioxide fiber cloth 1 wound around a supply side roll 11.
2 is coated with a paste containing silicon powder in a coating device 13, and the paste is fired in a heating furnace 15 to form a polycrystal silicon layer 16 on the silicon dioxide fiber cloth 12.
Is manufactured and wound on the winding side roll 17.

The method of manufacturing the polycrystalline silicon solar cell of the present invention described above is based on forming a polycrystalline silicon layer on a silicon dioxide fiber cloth. However, as a method of manufacturing a solar cell using a combination of a silicon dioxide cloth and polycrystalline silicon, a polycrystalline silicon layer is formed on a silicon dioxide fiber, and the composite silicon dioxide fiber thus formed is woven. It is also possible to manufacture the polycrystalline silicon solar cell of the present invention by forming a cloth or a cloth shape by means and heating the cloth in a heating furnace to fuse the cloth.

FIG. 6 shows the internal structure of the polycrystalline silicon solar cell of the present invention obtained by these manufacturing methods. FIG. 6A is an external view of a polycrystalline silicon solar cell formed by ordinary weaving means, and FIG. 6B is a cross-sectional view of its internal structure. As is clear from this figure, the silicon dioxide cloth 21 has a woven structure, and the polycrystalline silicon layers 22 and 23 are formed on both sides or one side of the cloth 21 to form a polycrystalline silicon solar cell. . Such a structure can be obtained by forming polycrystalline silicon on a woven silicon dioxide cloth.

Further, FIG. 6 (c) is an external view of a polycrystalline silicon solar cell which does not use ordinary weaving means, and FIG. 6 (d) is a sectional view of its internal structure. As is clear from this figure, the silicon dioxide cloth 24 does not have a woven structure and the fibers in the same direction are arranged on the same plane, and the polycrystalline silicon layers 25 and 26 are provided on both sides or one side thereof. The formed polycrystalline silicon layers 25 and 26 are fused together to form a polycrystalline silicon solar cell. Such a structure can be obtained by arranging the silicon dioxide fibers on which the polycrystalline silicon layer is formed and fusing the polycrystalline silicon with each other.

In order to construct a solar cell from the polycrystalline silicon obtained as described above, it is necessary to form electrodes on both sides of the polycrystalline silicon. When the polycrystalline silicon layer is a P-type bulk, arsenic (As), antimony (Sb) or the like is used as an N-type impurity, and when the polycrystalline silicon layer is an N-type bulk, P
Type impurities such as boron (B) or indium (I
n) or the like is diffused or ion-implanted to form a PN junction on the surface, and aluminum (Al), nickel (Ni), copper (Cu), silver (Ag) is formed on the PN junction.
A comb-shaped electrode is formed by providing a conductive layer such as by vapor deposition or sputtering.

There are various methods for forming electrodes on the back surface, but aluminum (Al), nickel (Ni), copper (C
u), a method of forming a conductive metal layer such as silver (Ag) by vapor deposition or a sputtering method, a method of forming a high concentration layer by a diffusion method or an ion implantation method, and then forming a metal electrode,
A method in which a conductive paste such as copper is applied, dried and cured to form a metal electrode can be used.

[0023]

As described above, the silicon solar cell of the invention according to the present application has a polycrystalline silicon layer formed on a cloth made of silicon dioxide fiber which is well compatible with silicon, or a silicon dioxide layer having a polycrystalline silicon layer formed thereon. It is configured by forming fibers into cloth. Therefore, the polycrystalline silicon solar cell according to the present invention can be manufactured without using a special crucible or a low-pressure chamber, so that there is no restriction due to the width of the manufacturing apparatus. Therefore, an arbitrary width can be obtained. Further, when the molten silicon is cooled and solidified, it can be molded into an arbitrary shape.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a super-quenching method which is a conventional manufacturing technique.

FIG. 2 is a schematic explanatory diagram of an SOC method which is a conventional manufacturing technique.

FIG. 3 is a schematic explanatory view of a RAD method which is a conventional manufacturing technique.

FIG. 4 is a schematic explanatory view of a first manufacturing method of the present invention.

FIG. 5 is a schematic explanatory view of a second manufacturing method of the present invention.

FIG. 6 is a structural diagram of a polycrystalline silicon solar cell of the present invention.

[Explanation of symbols]

 1,11 Supply side roll 2,12 Silicon dioxide fiber cloth 3 Crucible 4 Molten silicon 5,6,16 Polycrystalline silicon layer 7,17 Winding side roll 13 Nozzle 14 Paste 15 Heating furnace

Claims (9)

[Claims] 1. A polycrystalline silicon solar cell in which a polycrystalline silicon layer is provided on a cloth made of silicon dioxide fibers, and an electrode is formed on the polycrystalline silicon layer. 2. The polycrystalline silicon solar cell according to claim 1, wherein a cloth composed of silicon dioxide fibers is woven. 3. The polycrystalline silicon solar cell according to claim 1, wherein a cloth made of silicon dioxide fibers is not woven. 4. A silicon dioxide cloth is formed using silicon dioxide fibers, the silicon dioxide cloth is immersed in molten silicon to form a polycrystalline silicon layer on the silicon dioxide cloth, and an electrode is formed on the polycrystalline silicon layer. A method for producing a polycrystalline silicon solar cell, which comprises: 5. A silicon dioxide cloth is formed from silicon dioxide fibers, a silicon paste is applied to the silicon dioxide cloth, and the applied silicon paste is baked to form a polycrystalline silicon layer on the silicon dioxide cloth. Then, a method for producing a polycrystalline silicon solar cell is characterized in that an electrode is formed on the polycrystalline silicon. 6. A silicon dioxide fiber is immersed in molten silicon to form a composite silicon dioxide fiber having a polycrystalline silicon layer on the silicon dioxide fiber, and the composite silicon dioxide fiber is used to form a composite silicon dioxide cloth. A method for manufacturing a polycrystalline silicon solar cell, comprising forming an electrode on a polycrystalline silicon layer on a silicon dioxide cloth. 7. The method for producing a polycrystalline silicon solar cell according to claim 6, wherein the polycrystalline silicon layer is fused by heating the composite silicon dioxide cloth. 8. A silicon dioxide fiber is coated with a silicon paste, and the silicon dioxide fiber coated with the silicon paste is fired to form a composite silicon dioxide fiber having a polycrystalline silicon layer. A method of manufacturing a polycrystalline silicon solar cell, comprising forming a silicon dioxide cloth and forming an electrode on the polycrystalline silicon layer on the composite silicon dioxide cloth. 9. The method for producing a polycrystalline silicon solar cell according to claim 6, wherein the polycrystalline silicon layer is fused by heating the composite silicon dioxide cloth.