JPH0456474B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an amorphous solar cell formed on the inner wall of a transparent hollow body, and particularly to stabilization thereof.

Amorphous solar cells are attracting attention as a new energy conversion material. However, its energy conversion efficiency decreases over time.

Conventionally, solar cells have been formed by placing their substrates in expensive equipment for forming amorphous semiconductors. For example, the glow discharge tank of glow discharge equipment,
Sputtering tank of sputtering equipment, CDV
This is a method in which a substrate is placed in a CVD tank of equipment, and an amorphous semiconductor is formed using each method. As a result, the solar cells are exposed to the outside, and it is difficult to protect them, especially to stabilize them against moisture.

From this point of view, various stabilization methods have been studied in the past, and methods such as embedding an amorphous solar cell in a case using epoxy resin or silicone resin have been proposed.

One of the objects of the present invention was made in view of this point, and is to provide a stabilized amorphous solar cell without using these embedding resins or cases.

Furthermore, another object of the present invention is to provide a technique for simplifying an amorphous silicon layer forming means in a process for forming an amorphous silicon layer.

According to the present invention, there is no need for the above-mentioned expensive equipment, and the substrate of the solar cell itself becomes a reactor, which can be used as a glow discharge tank, for example, as shown in FIG. Stable amorphous solar cells can also be easily produced by glow discharge.

That is, the present invention is an amorphous solar cell in which electrodes and photovoltaic regions are formed on the inner wall of a transparent hollow body in the order of a transparent first electrode, a photovoltaic region, and a second electrode, and preferably The inside of the hollow body is in a substantially dry state, and is more preferably a photovoltaic region, an amorphous silicon layer, preferably an amorphous solar cell formed by glow discharge.

In the amorphous solar cell of the present invention, a substantially dry state is a state in which gas with a moisture content of 5 ppm or less is enclosed, particularly preferably hydrogen or an inert gas with a moisture content of 3 ppm or less is enclosed. It is also what is being done.

FIG. 1 is an example of an external view of a preferable amorphous solar cell of the present invention, and FIG. 2 is a schematic diagram showing an example of a cross-sectional view taken along line A-A in FIG. 1. In FIG. 2, 1 is a transparent hollow body, 2 is a first electrode formed on the inner wall of the transparent hollow body 1, 3 is a photovoltaic region, 4 is a second electrode, and 5 is an internal space of the hollow body. It shows. In FIG. 1, 6 and 7 are external lead wires, which are connected to the first electrode 2, respectively.
and is connected to the second electrode 4.

The transparent hollow body is not limited to having a circular cross section as shown in Figure 2, but may also be square, rectangular, oval, etc., and is not particularly limited; however, in terms of manufacturing and handling, the cross section must be circular. is preferred. In short, the hollow body may have any shape as long as it can maintain a substantially dry state in the internal space, and the hollow body may be an integral body or may be composed of parts. In FIG. 1, the device is composed of a hollow cylinder 1 as a transparent hollow body and sealing materials 8 and 9. The hollow cylinder 1 and the sealing material are integrated by welding or adhesion. The gas introduction or evacuation portions are sealed by heat sealing, for example, as shown in 13 and 14. The material of the sealing members 8 and 9 is not particularly limited, but from the viewpoint of manufacturing and maintenance, it is preferable that the material is the same as or similar to that of the transparent hollow body 1.

The first electrode 2 is a light-transmitting conductor.
For example, ITO (Indium−Tin−Oxide), In ₂ O ₃ ,
It is made of a thin film such as SnO ₂ . The second electrode 4 can of course be formed using the electrode material used for the first electrode, but an opaque metal electrode can also be effectively used. When a light-transmitting conductor is used as the second electrode, the light that has passed through the photovoltaic region on the light irradiation side can reach the photovoltaic region on the opposite side to the light irradiation side, so sunlight This is preferable in terms of effective utilization.

The photovoltaic region consists of an amorphous silicon layer.
Gaseous silicon compounds such as SiH ₄ , Si ₂ H ₆ , Si ₃ H ₈ and the like, PH ₃ , B ₂ H ₆ , AsH ₃ , CH ₄ , C ₂ H ₆ , NH ₃
It is formed by glow discharge or thermal decomposition in an atmosphere of a raw material gas with or without addition of appropriate gases such as. One of the features of the present invention is this deposition method. That is, conventional deposition methods require expensive equipment to generate glow discharge and thermal decomposition, which is not necessary with the present invention. For example, when using glow discharge, a hollow body is heated,
The inside thereof is connected to a vacuum means and a raw material gas introduction means, and the raw material gas is introduced while being evacuated, and a high frequency electric field is applied. As a result, amorphous silicon is deposited on the inner wall of the hollow body, and a photovoltaic region can be easily formed.

The amorphous silicon layer is formed by depositing, for example, P-type, i-type, and n-type silicon layers in this order from the first electrode side.

The thickness of the p-type amorphous silicon layer is 50 to 1000 Å. The p-type amorphous silicon layer contains p-type impurity gas,
For example, it is formed by mixing B ₂ H ₆ with a gaseous silicon compound at a ratio of 10 ^-4 to 10 ^-1 . The i-type amorphous silicon layer has a thickness of 5000 Å-1 μm,
It is formed from a raw material gas with or without adding p-type impurities to a gaseous silicon compound at a ratio of 10 ^-5 or less. The n-type layer has a film thickness of 50 to 1000 Å and is formed by mixing an n-type impurity gas, such as PH ₃ or AsH ₃ , with a gaseous silicon compound at a ratio of 10 ^-4 to 10 ^-1. be done. The deposition of these amorphous silicon layers can also be carried out in an atmosphere to which a gas such as He, Ar, _H2, etc. is added 0 to 1000 times as much as the gaseous silicon compound.

A second electrode is deposited on top of the amorphous silicon. Glow discharge or vacuum deposition can be effectively used for the deposition. For example, it is useful to introduce a gaseous tin compound and an oxygen-containing gas after depositing amorphous silicon and deposit tin oxide by glow discharge, or to deposit aluminum by heating it in a vacuum. be. As an external lead wire,
Of course, wires and plates made of aluminum, copper, silver, etc. can be effectively used, but it is also convenient to use conductive paints such as silver paste, copper paste, etc.

After connecting the external lead wires to the first and second electrodes, introducing hydrogen gas or inert gas,
Move on to the sealing process. For example, in FIG. 4, the gas introduction section 11 and the vacuum evacuation section 12 are
and evacuation means 16 for evacuation and introduction of hydrogen. Preferably exhaust-
Perform the introduction three or more times. Next, the inside of the hollow body can be brought into a substantially dry state by sealing the gas introduction part and the gas exhaust part in a vacuum state of less than atmospheric pressure, preferably 100 Torr.

When the photovoltaic region has a large area, a thin film electrode for current collection can be provided between the first electrode and the inner wall or on the second electrode.

Another feature of the present invention is that the solar cell of the present invention has no distinction between front and back, and a photovoltaic region exists over almost the entire surface. Therefore, not only directly incident light but also transmitted light, scattered light, and reflected light can be effectively used. Naturally, it is also effective as a solar cell for condensing light.

As described above, in the present invention, the electrodes and photovoltaic region are sealed inside a transparent hollow body, which is not only isolated from the outside world but also maintained in a hydrogen or inert gas atmosphere. It prevents the intrusion of water, corrosive gases, and oxidizing gases from the outside, making its performance extremely stable, and its manufacturing method and photoelectric conversion efficiency are also excellent.

A more specific explanation will be given below with reference to Examples.

Embodiment In FIG. 3, a transparent hollow body 1 whose inner wall is coated with ITO and SnO ₂ is prepared by evacuation means 18 and flanges 19 and 20 (flange 19 does not deposit amorphous silicon) having a vacuum evacuation means 18 and a movable gas introduction means 17. (has a collar 21 that serves as a mask for the purpose of the test) via an O-ring. Further, a heating means 22 and a coil-shaped electric field applying means 23 for glow discharge are added. The glass cylinder was heated to 300° C. by the heating means 22 while flowing hydrogen gas. A mixed gas of B ₂ H ₆ /SiH ₄ =1/100 (volume ratio) was introduced, and a p-type amorphous silicon layer of 100 Å was formed by glow discharge. Then, only SiH ₄ was introduced,
An i-type layer was formed with a thickness of 5000 Å. Then PH ₃ /SiH ₄ =
Introduce a mixed gas of 1/1000 (volume ratio) to form an n-type layer.
150 Å was formed. Further, a mixed gas of SnCl ₂ and O ₂ was introduced, and a SnO ₂ layer was deposited by glow discharge to form a second electrode. As shown in FIG. 4, the external lead wire 6 is connected with silver paste to the portion 24 where the first electrode exists in a bare state. A grit-like current collecting electrode is provided on the second electrode, and an external lead wire 7 is connected to this current collecting electrode using silver paste. External lead wires are taken out to the outside of the sealing materials 8 and 9, and the sealing material and the glass cylinder are bonded and integrated with epoxy resin. Next, the gas introduction section 11 and evacuation section 12 of the sealing material are connected to the gas introduction means 15 and the evacuation means 16. After drawing a vacuum below 10 ^-2 , hydrogen gas is introduced. After repeating this three times, the gas introduction part and the vacuum exhaust part were sealed with an oxyhydrogen flame while the pressure was reduced to 1 Torr. It was found that the thus obtained solar cell had hydrogen gas sealed inside and was isolated from the outside world, and its performance was extremely stable.

[Brief explanation of the drawing]

FIG. 1 is an example of an external view of a preferable amorphous solar cell of the present invention, and FIG. 2 is a schematic diagram showing an example of a cross-sectional view taken along line A-A in FIG. 1. FIG. 3 is a schematic diagram of an apparatus in which a vacuum means and a gas introduction means are attached to a transparent hollow body, and FIG. 4 is a diagram showing an example of the state of the solar cell during gas introduction and melting. 1... Transparent hollow body, 2... First electrode, 3...
Photovoltaic region, 4... second electrode, 5... internal space of transparent hollow body.

Claims (1)

[Scope of Claims] 1. An electrode and a photovoltaic region are formed on the inner wall of an integrally formed cylindrical transparent hollow body, and a translucent first electrode, a photovoltaic region, and a second an amorphous material, characterized in that the interior of the hollow body is substantially dry, and the photovoltaic region includes an amorphous silicon layer formed by glow discharge. solar cells. 2 Claim 1 in which the internal space of the hollow body is in a dry state filled with hydrogen gas or inert gas
The described amorphous solar cell. 3. The amorphous solar cell according to claim 1, wherein at least the i-type layer in the photovoltaic region is formed by glow discharge.