JPS5833718B2 - Multilayer coaxial fibrous solar cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solar cell using Si, and particularly to a multilayer coaxial fibrous solar cell having a shape in which coaxial fibrous Si-containing semiconductor P-n junctions are twisted together and then knitted into a cloth. It is related to solar cells.

As is well known, a solar cell absorbs a component of sunlight incident on a semiconductor crystal having a P-n junction, which has an energy greater than the forbidden band width, and generates hole-electron pairs inside the crystal. The minority carriers flowing across the junction into the opposite conductive shadow region bias the junction in the forward direction, and the efficiency is usually expressed in terms of the power generated when a load is connected.

For example, the photo-electrical power conversion efficiency of a solar cell using a Si single crystal P-n junction is at most 12-13%.

On a clear day, the solar energy that falls on the earth's surface is approximately 1kW/m
Therefore, if the above-mentioned Si solar cell is used, approximately 100
Power of W/m or more can be obtained.

As described above, the electric power obtained by a solar cell is proportional to the surface area of the cell, so in order to effectively utilize sunlight as a power source, a solar cell with as large an area as possible is desired.

However, obtaining a single crystal with a large area is not only technically extremely difficult, but also increases the manufacturing cost, making it economically unviable.

Therefore, research is currently being conducted on the production of solar cells using polycrystalline semiconductors.

If it becomes polycrystalline, the crystallinity will naturally decrease and the conversion efficiency will naturally decrease to about 3 to 5 φ, but there is an advantage that the manufacturing cost will be considerably reduced.

However, even if such a method of manufacturing a polycrystalline solar cell is used, it is not easy to increase the area, and processing other than flat panels is extremely difficult.

The present invention was made to eliminate the drawbacks of the conventional Si solar cells described above, and is inexpensive and easy to mass produce.
The purpose of the present invention is to provide a solar cell that can be made to have a large area and has excellent workability and flexibility.

In order to achieve the above object, the present invention has a structure in which a Si layer is coated around a core wire and has one cylindrical P-n junction inside (i.e., a photoelectric conversion layer), and a Si layer is formed on the Si surface. A multilayer coaxial fiber with surface protection and insulation properties created by forming an oxide film, or a multilayer coaxial fiber with a structure in which a Si layer is coated on the inner surface of the core so as to include one cylindrical P-n junction. The present invention is characterized in that a multilayer coaxial fibrous solar cell is fabricated by forming a resistive electrode for the Pn junction at least at the end of a two-dimensionally expanded fabric by knitting it.

Hereinafter, the present invention will be described in detail based on examples.

(Part 1) A tungsten wire with a diameter of 100 μm is used as the core wire 1, and as shown in FIG. 1, it is immersed in a Si-saturated Sn solution 4 filled in a quartz container 3 heated in a nitrogen gas atmosphere.

The bottom of the quartz container 3 is filled with a polycrystalline Si block 2 doped with phosphorus (P) at a high concentration, which is held in place by a quartz partition plate 5 having a large number of small holes and in contact with the solution 4.

As shown in the figure, the solution 4 has a temperature gradient such that the temperature is high at the bottom of the container 3 and the temperature decreases toward the top.

The Sii layer is dissolved in the Sn solution in a saturated amount at the temperature T1, and is carried to the upper part of the container where the temperature is lower by the convection and diffusion of the solution, resulting in a supersaturated state.

The tungsten core wire 1 is wound around a quartz rotating shaft 11 provided relatively above the solution 4 as shown in the figure, and immersed in the solution 4.

At this time, the tungsten core wire 1 is at the temperature T2 (
〈T1), but n −S i in solution 4
Since Sn is in a supersaturated state, n-8i can be precipitated on the tungsten core wire 1 in an amount corresponding to the difference in the degree of saturation in Sn between T and T2.

The amount actually deposited can be adjusted by adjusting the immersion time of the tungsten core wire 1 in the solution 4, that is, the pulling speed of the core wire 1.

Usually, this pulling speed is adjusted so that the thickness of the n-Si layer on the core wire 1 is about 5μ.

In this case, the carrier concentration of the n-Si layer is approximately 5×10
The phosphorus concentration in the Si lump is adjusted so that it becomes 17cIrL-''.

The tungsten wire 1 with the n-Si layer deposited passes through a quartz rotating shaft 6 and is transferred to a second Si-saturated Sn solution-filled quartz container 7.
The quartz rotating shaft 12 is wound and immersed inside.

The bottom of the quartz container I is filled with a polycrystalline Si lump 8 doped with boron (B) at a high concentration, and is partitioned by a porous quartz partition plate 10.

The temperature T3 of the polycrystalline Si lump 8 at the bottom of the container 7 is T1
lower, and the temperature T at the rotating shaft 12 position, (<T
3) is kept lower than T2, so P- at the T4 position
8i is in a supersaturated state, and the n-Si layer deposited on the tungsten core wire 1 does not dissolve even when immersed in the solution 9, and a P-Si layer is deposited on the n-Si layer.

In this case, the boron concentration contained in the Si mass 8 and the temperature T3 are adjusted so that the thickness of the P-Si layer is about 4 μ and the carrier concentration is about 1×10 17 crIL″″3.

The tungsten core wire 1 coated with the Si layer including the 5iP-n junction in this way is once taken out into the air via the quartz rotating shaft 13, and then placed in the electric furnace 14 for approximately 105'
It passes through an oxygen atmosphere maintained at C.

As a result, the surface of the P-Si layer is thermally oxidized, and the S 1
02 film is formed.

The SiO2 film thickness is determined by the oxidation temperature and oxidation time, but it is approximately 300
It should be about 0 to 5000A.

In this way, n-8i on the tungsten core wire 1,
P-8i and 5i02 films are successively formed.

Therefore, if this Si and S t 02 coated tungsten core wire 1 is wound at a constant speed, the quartz container 3
As long as the Sii layer held at the bottom of 7 and 8 remain, a P-n bonded Si filament with a constant thickness is continuously formed.

That is, Si lost from the Sn solutions 4 and 9 by precipitation on the tungsten core wire 1 is replenished by the Sii layers and 8 through convection and diffusion.

Although the wound Si filament is polycrystalline, it is extremely thin (about 110 μm in diameter) and has great flexibility.
Since it is made of tungsten wire, it has sufficient mechanical strength.

By twisting these strands together and then knitting them alternately vertically and horizontally, a cloth (woven fabric) with a two-dimensional expanse is created.

For the n-Si layer, the tungsten core wire 1 acts as a resistive electrode, and for the p-Si layer,
If the Si02 film on the surface of the end is removed with hydrofluoric acid and then plated with gold or silver, it becomes a resistive electrode, so it is very easy to provide a resistive electrode only at the end of the fabric.

In addition, during the above process, immediately before forming the SiO2 film, the temperature was set at 1050°.
If steam containing S n C12 is flowed in an oxidizing atmosphere of
Since an n 02 layer is formed, it is also possible to use this as a resistive electrode for the P-Si layer.

The formation of the resistive electrode is shown in FIG. Figure a is Si0
The state in which two layers 51 are formed is shown, and the figure b shows the Si layer at the end 50.
02 layer 51 is removed with hydrofluoric acid, and FIG. 0 shows the removed portion plated with Au layer 52.

A lead wire is attached to a part of this Au layer by soldering using a known method.

Electromotive force can be extracted from this lead wire. According to the present invention, the 81 solar cell can be made into extremely thin filamentous fibers, which not only makes it highly flexible, but also uses only a few μm of Si, which is actually required to absorb sunlight, and allows for high-speed winding. By doing so, it is possible to mass produce and is extremely economical, and by knitting it as a fabric, it is possible to easily increase the area of Si solar cells and make them polymorphic.

In addition, the surface area is approximately 2πr/compared to the conventional flat panel type.
Since it is 2r×1/';l-1.5 times, there is also the advantage that the converted power in plane terms increases by about 50%.

This knitted fabric exhibited an output of about 80 W/m under direct sunlight.

(Part 2) A SiC fiber with a diameter of 50μ is used as the core wire 1, and it is immersed in a B-doped Si melt kept in a hydrogen atmosphere to coat the core wire 1 with a thickness of about 5μ and a carrier concentration of 1×1017 Crr.
A P-Si layer of L-3 was formed, and then the surface of the P-Si layer was thermally oxidized in a high temperature oxygen atmosphere to form a 5i02 film with a thickness of about 3000 nm.

The filamentous fibers were wound at a constant speed and then twisted into a fabric to create a heterojunction solar cell fabric.

SiC exhibits n-type conductivity, and the carrier concentration is approximately 5XIQ
It was 17crrL-s.

The SiO2, Si film on the edge of the fabric was removed with a mixture of hydrofluoric acid and nitric acid, and silver plating was performed on n-8i C.
It was heated to °C to form a resistive electrode.

Furthermore, the 8102 film on the other end was removed with hydrofluoric acid and PSi
The top was plated with gold to create a resistive electrode.

This fabric exhibited a power output of approximately 50 W/m under direct sunlight.

(Part 3) A quartz glass fiber with a diameter of approximately 30μ and whose surface is plated with Ni is used as the core wire 1, and an n-8i layer, a P-8i layer, and a SiO2 film are formed on it as shown in Fig. 1. After forming the fabric in this order and twisting it into a fabric, the Si02 film at one end was removed with hydrofluoric acid to expose the P-Si layer, which was then gold plated and a resistive electrode was attached to form a fabric solar cell. Ta.

Ni on the fused silica fiber acts as a resistive electrode for the n-8i layer.

This solar cell showed an output of about 85 W/- under direct sunlight.

(Part 4) Hollow quartz glass fiber 15 with inner diameter 1rfLrIL
Trimethylaluminum diluted with hydrogen is poured into one end of the tank, and the other end 18 is kept under reduced pressure.

This fiber 15 is heated to about 500° C. when passing through the electric furnace 14 shown in FIG.
61 is deposited.

Its thickness is adjusted to about 500 to 1000 thickness depending on the concentration of trimethylaluminum and the moving speed of the glass fiber 15.

Next, one end of this aluminum-coated glass fiber 15 is connected to the secondary side of a boron-doped monosilane (S i H4) gas cylinder that has been diluted with hydrogen gas, and the gas is injected into the fiber 15 at a high pressure of 1 atmosphere or more. At the same time as the gas is poured into the fiber 15, the pressure at the other end of the fiber 15 is reduced to one atmosphere or less, so that the gas continuously flows into the fiber 15.

An electric furnace 14 provided between the cylinder connection part of the fiber 15 and the decompression exhaust port is heated to about 700°C at the inlet and about 900°C at the center, and the fiber 15 is passed through the electric furnace 14. , a thermal decomposition reaction occurs, and a B-doped P-Si layer 162 is deposited on the aluminum thin film 161 on the inner wall of the fiber 15.

At this time, a small amount of thermal decomposition of SiH4 occurs even below 7000 C, and the Si precipitated layer suppresses the aluminum thin film 161, so that the aluminum does not melt and flow.

The thickness and carrier concentration of the Si film 162 are the same as that of the fiber 1.
5 passing through the electric furnace 14, B2H0 and S in the gas
It can be adjusted by adjusting the I H4 concentration, and in this case, the thickness of the P-Si layer 162 was selected to be about 4 μ, and the carrier concentration was selected to be I x 10 11 cyn-3.

Next, on the P-8i layer 162 of the fiber 15 on which the P-Si layer 162 was deposited on the inner wall, the same process as above was performed, using thermal decomposition of the AsH3;SiH4 mixed gas diluted with hydrogen. Thickness approximately 8μ, carrier concentration 1×101
An n-Si layer 163 of 7CrrL-3 is deposited.

Further, on the n-Si layer 163, an aluminum film 1 with a thickness of approximately 1 μm is formed using thermal decomposition of trimethylaluminum.
61 people were covered.

As a result, the P-S i layer 162゜n-S i layer 16
A thin aluminum film 161° on each layer acts as a resistive electrode for the respective Si layer.

This fiber 15 is knitted into a two-dimensionally spread cloth, the resistive electrode at the end of the cloth is exposed, a load is connected, and the power generated as a solar cell is measured under direct sunlight, approximately 75W.
/7F+" output was obtained.

In this case, the thin aluminum layer 161 directly under the quartz glass becomes translucent to sunlight, and most of the energy is transmitted to the Si layer, with only a small absorption loss.

Note that other conductive films, such as S, can be used instead of the aluminum film.
nO2 may also be used.

In the above embodiments, a case has been described in which quartz glass fiber is used as the insulating core wire, but the present invention is of course not limited to this, and for example, Al2O3, ceramics, etc. can be used.

It goes without saying that a material other than SiC can be used as the semiconductor core wire, and it is also obvious that a molybdenum wire, gold wire, carbon wire, etc., other than tungsten wire, can be used as the metal or conductor core wire.

Furthermore, although only 8102 was used as the insulating film for the semiconductor layer on the multilayer coaxial surface, other materials,
For example, it is naturally possible to use Al2O3 or a nitride film.

A conductor layer, such as a Sn 02 or aluminum film, may be uniformly formed on the surface of the semiconductor layer inscribed in this insulating film, and used for electrode extraction.

FIG. 3 is a diagram showing an example of the configuration of the solar cell end and explaining the electromotive force extraction.

The layer thickness relationships in this diagram are for illustration purposes only.
It is for convenience.

This solar cell is made up of two solar cell lines 100 and 101 and shows a simple example of parallel electromotive force extraction.

The two solar cell wires 100 and 101 were twisted together to form a longitudinal direction.

These two solar cell lines 100 and 101 are the solar cell lines shown in FIG.
A lead wire is fixed to the end of 1A with solder, and among the four conductive layers, two 161 are connected in common, and two 161
The common 161 lead wire and the common 161A IJ-do wire are connected to the two solar cell wires ioo and 1.
Forms a terminal for taking out the total electromotive force from oi.

FIG. 4 shows a plan view of a solar cell 200 formed into a cloth shape.

A large number of solar cell wires were twisted together to form a single wire, and this single wire was further woven vertically and horizontally into a cloth.

The positive and negative terminals of each of the lead wires for the total electromotive force from each single wire were used as common terminals 165A and 165B, respectively, forming two positive and negative terminals ◯ and ◯.

FIG. 5 shows an enlarged view of a single wire formed vertically and horizontally in a cloth-like manner.

The single wires 166° and 167 were woven in a vertical and horizontal lattice pattern.

The single wires 166° and 167 are ideally two or more solar cell wires, or may be just one.

Incidentally, when taking out the electromotive force above, an example of parallel extraction has been described, but an example of series extraction is also possible.

Parallel extraction as shown in FIG. 3 or series extraction (not shown) differs depending on the nature of the electromotive force extraction from the solar cell, and which one to adopt is arbitrary.

Moreover, it is not limited to Example (Part 4).

Furthermore, in the case where a conductive layer (Au or Ag) is formed at the end, since the semiconductor layer forms the conductive layer, the 8102 layer is slit in the longitudinal direction to prevent a decrease in the extraction electromotive force. Alternatively, a conductive layer may be formed on this portion.

The present invention has not only made it possible to reduce the price and increase the area of solar cells, but also, as already mentioned, has extremely high flexibility and sufficient mechanical strength, making it easy to process them into secondary products. It became extremely easy.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the manufacturing process of one embodiment of the solar cell according to the present invention, FIG. 2a is a diagram showing the manufacturing process of another embodiment of the solar cell according to the present invention, FIG. Figure 2 is a diagram showing the internal structure of the solar cell manufactured in the step of a, Figure 3 is an explanatory diagram of the electromotive force extraction of the present invention, Figure 4 is a diagram of the fabric configuration to which the present invention is applied, FIG. 5 is a partially enlarged view of the cloth structure to which the present invention is applied, and FIGS. 6 a, b, and c are diagrams illustrating electrode formation. In the figures, the same or equivalent parts are indicated by the same symbols, 1 is a core wire, 2 is a phosphorus-doped Si polycrystal, 3 is a quartz container, 4 is an n-Si saturated Sn solution, 7 is another quartz container,
8 is poron-doped Si polycrystal, 9 is P-S i saturated S
14 is an electric furnace, 15 is a hollow quartz glass fiber, 16 is a substance adhered to the inner wall of the hollow quartz glass fiber, 161 is an aluminum thin film, and 162 is a P-S i
The layers 163 are nSi layers, and 151 is a hollow portion of quartz glass fiber.

Claims (1)

[Scope of Claims] 1. A fibrous solar cell having a two-dimensional spread by knitting flexible multilayer coaxial fibrous solar cell wires having a multilayer coaxial structure, the multilayer coaxial fibrous solar cell wires having a two-dimensional spread. consists of an outermost transparent electrical insulating layer through which light from the outside enters, and a P-N junction type photoelectric conversion layer provided on the inner periphery of the insulating layer, which forms a P-N junction. a P-N junction type photoelectric conversion layer in which at least one of the layers or N layers is a Si layer; a conductive part located on both sides of the photoelectric conversion layer and provided in part or all of the photoelectric conversion layer; A multilayer coaxial fibrous solar cell comprising: means for extracting the electromotive force generated in the PN junction to the outside through the PN junction. 2. The multilayer coaxial fibrous solar cell according to claim 1, wherein the outermost insulating layer is made of a Sin film layer. 3. The multilayer coaxial fibrous solar cell according to claim 1, wherein the outermost insulating layer is made of quartz glass fiber. 4. The multilayer coaxial fibrous solar cell according to claim 1, wherein the conductive part is constituted by first and second conductive layers that are respectively formed in the upper layer and the lower layer of the photoelectric conversion layer in the longitudinal direction. 5 The conductive part has first and second conductive parts, one of the first and second conductive parts is a conductive layer formed along the longitudinal direction of the photoelectric conversion layer, and the other is a conductive layer formed along the longitudinal direction of the photoelectric conversion layer. It is a conductive layer laminated directly on the photoelectric conversion layer at the end of the conversion layer, and the first and second conductive layers are the upper layer (or lower layer) and the lower layer (or lower layer) of the photoelectric conversion layer. The multilayer coaxial fibrous solar cell according to claim 1, wherein the multilayer coaxial fibrous solar cell is formed as an upper layer). 6 The conductive part has first and second conductive parts, and the first and second conductive parts are the conductive layer laminated directly on the photoelectric conversion layer at the ends of the photoelectric conversion layer. The multilayer coaxial fibrous solar cell according to claim 1, wherein the first and second conductive portions are formed at an upper layer position and a lower layer position of the photoelectric conversion layer.