JP4131474B2 - Microparticle layer type high efficiency solar cell - Google Patents

Description

The present invention not only achieves high efficiency by forming n-type and p-type silicon into n-type microparticles and p-type microparticles and forming pn microjunction layers by pn microjunction, The present invention relates to a solar cell characterized in that high efficiency is achieved by using a light diffusing material.

Conventional solar cells intended to be made by the photoelectric effect, which is irradiated with light to n-type silicon having a pn junction surface, electron-hole pairs are generated near the pn junction surface by interband transitions, etc., It utilizes the phenomenon that positive and negative electrodes can be formed by the drift effect of the depletion layer.

However, since the energy density of sunlight is low, conventional solar cells can be broadly divided into a flat plate type that uses sunlight as it is, and a concentrator that uses an optical system or the like to increase the density and then enter the solar cell. There are two types of light.

Usually, the flat plate type that obtains electric power by the structure of a pn junction formed of n-type and p-type silicon with the former sunlight as it is is the most common solar cell, most of which is an ingot silicon solid Therefore, it is a method of manufacturing a crystal plate (wafer).

  Among them, there is a product developed by Kyosemi Corporation having a spherical pn junction under the name of “spherical micro solar cell” (for example, see Non-Patent Document 1).

  The contents are as follows: "A small silicon single crystal having a diameter of about 1 to 2 mm is used to diffuse impurities from the surface of silicon to a depth of about 1 micrometer to form a pn junction having a spherical surface. A cell is formed by providing a pair of electrodes opposed to the surface of the cell.

  That is, a silicon ball having a diameter of 1 to 2 mm is made, and for each of them, the content is P-type silicon and the outside is n-type silicon, thereby creating a pn junction surface at the boundary between the content and the outside. In this case, positive and negative electrodes are attached to each spherical end and end.

  On the other hand, some solar cells are simply made using spherical semiconductors. This is a method in which a second type semiconductor layer and a transparent conductive film are stretched together on the surface of a first type semiconductor formed into a spherical shape so as to form a pn junction, and individual spherical semiconductors are connected by a thin conductor ( For example, see Patent Document 1)

Furthermore, there is a spherical solar cell that is modularized with a configuration in which a thread-like conductor in contact with the p-type and n-type regions is a weft and a defective conductor is a warp (see, for example, Patent Document 2).
"Kyosemi Corporation Internet HP Spherical Micro Solar Cell" JP 2001-156315 A JP 09-162434 A

In the conventional solar cell, since the energy density of sunlight is low, the conversion efficiency is as low as about 15 to 19% even in the case of a pn junction of a crystalline silicon solar cell. I could not say. For example, in order to obtain 1 KW of electric power, a light receiving area (Pn junction surface) of about 7 m ² is required, and the module is also large-scale and the manufacturing cost is high. In addition, it was difficult to receive light along the sun's orbit, and it was difficult to obtain light of stable intensity.

This is because the principle of a conventional solar cell is made by the photoelectric effect, because the width of the pn junction plane is most influential to generate electron-hole pairs.

Therefore, in the pn junction causing photoelectric effect by sunlight, increasing the pn junction area per unit area, and possible to realize a solar cell more realistically to allow miniaturization and a high conversion efficiency that Do not.

The present invention is intended to solve such a problem. The formation of a pn microjunction layer by micronization of p-type and n-type silicon significantly increases and improves the pn junction area per unit area. The purpose is to realize a solar cell with high conversion efficiency that can be realized and a flexible and highly efficient solar cell.

In order to achieve the above object, the present invention achieves a three-dimensional structure by forming n-type and p-type silicon into, for example, n-type microparticles and p-type microparticles at a pn junction of a solar cell and combining them together. By forming a “pn micro-junction layer” with an appropriate thickness, the electromotive force is greatly increased and improved as a result. By greatly increasing the pn junction area per unit area, downsizing and cost reduction can be achieved. It is intended.

First, n-type silicon is made into micro-level particles (n-type micro-particles), and they are stacked, for example, so as to load a baseball ball in a cardboard box (the baseball is taken as an example, so it is expressed as stacked).

Next, p-type silicon is used as micro-level fine particles (p-type micro fine particles), and the p-type micro fine particles are integrally combined so that gaps between the layers of the n-type micro particles are filled. ”. In addition, the method of combining the layers naturally includes the case of p-type microparticles and n-type microparticles as described in claim 3.

In this state, when the smaller p-type microparticles are closely bonded to the spherical surface portion of the n-type microparticle, the pn junction area is approximately increased by the spherical surface portion compared to the plane.

The pn micro junction layer is sandwiched between the p-type and n-type silicon layers from both sides, and an electrode or the like (such as anti-reflection thin film) is provided, so that a basic micro particle layer type high-efficiency solar electric field can be obtained. It ’s done.

In addition, when the pn micro junction layer is thickened or more incident light is required, n-type silicon is arranged as n-type microparticles in the n-type silicon layer serving as the light receiving surface, and a gap formed there It is sufficient to fill the light diffusion material (crystal, glass and quartz glass; hereinafter abbreviated) finely formed from the n-type microparticles and combine them together to form the light-receiving surface of the micronized n-type silicon layer. It becomes possible to cope with.

This is because sunlight is induced to the deep part of the pn micro junction layer by reflection and refraction action by the light diffusing material, so that the pn micro junction layer can be made thicker or incident light can be obtained from more angles. Because it becomes.

The effect | action by these solutions is as follows.

First, the principle of a solar cell is that when a semiconductor cathode is irradiated with light, pairs of electrons and holes of generated carriers are generated from the vicinity of the pn junction due to interband transition or the like. However, electrons and holes generated by recombination of electrons and holes disappear at a location away from the pn junction surface, but a built-in electric field region called a depletion layer is created near the pn junction surface, and drift effects and the like occur. Thus, electrons and holes are polarized without being recombined, and a potential difference is generated to generate an electromotive force.

That is, in order to improve the conversion efficiency, it is necessary to generate and polarize more pairs of electrons and holes generated near the pn junction surface.

Therefore, by using the conventional pn junction surface as the pn micro-junction layer of the present invention, the pn junction area per unit area is approximately increased as compared to the conventional plane, and the spherical surface portion is increased. The pair of electrons and holes can be generated and polarized.

Further, by using a light diffusing material for the n-type silicon layer as the light receiving surface and repeating reflection and refraction in the layer, sunlight can be guided to the deep part of the pn micro junction layer, and as a result, the pn micro junction layer Can be made thicker or incident light can be obtained from more angles.

Further, by combining the n-type and p-type silicon layers as micro-level (including nano-level) particles with the pn micro-junction layer, all junction points are mechanically close to pin junctions, It seems that a slightly flexible form is possible as compared with the conventional solar cell.

As described above, by using the conventional pn junction surface as the pn micro junction layer of the present invention, an increase in the pn junction area is realized without any loss of the photoelectric effect of the conventional pn junction surface. 7m to get the conventional 1KW power ² What required a light receiving area of a certain level can be covered by a smaller light receiving area.

In other words, not only high conversion efficiency but also the scale required for the conventional solar cell can be greatly reduced, which not only facilitates transportation and installation work, but also greatly increases construction costs and maintenance costs. Reduced.

Moreover, since the selling price is also reduced, more solar power generation (solar cells) is expected to become popular. For example, downsizing will lead to widespread use in household and commercial electrical products or automobiles.

BEST MODE FOR CARRYING OUT THE INVENTION

It will be described below with reference to embodiments of the present invention in FIGS. However, the present invention is not limited to these.

  1 to 3, 1a is a microparticle layer type high efficiency solar cell (basic type), 1b is a microparticle layer type high efficiency solar cell (light diffusion type), and 1c is a microparticle layer type high efficiency solar cell. It is the content of a battery (flexible type).

First, in FIG. 1, n-type stacked microparticles 5 to about several layers to several tens of layers in order to increase the pn junction area per unit area, by filling a p-type micro-fine particles 6 in the gap created when the formation The pn micro junction layer 4 is bonded so as to be sandwiched between the n-type silicon layer 2a on the light-receiving surface side and the p-type silicon layer 3a on the back surface side, thereby generating a pair of electrons and holes as generated carriers. It will be.

Then, place the anti-reflection film 9 to the outside of the n-type silicon layer 2a, the solar cell of the 1a by placing the respective n-type silicon layer 2a and the p-type silicon layer 3a electrodes 7 serving as both ends of the solar cell ( Basic type) is formed .

In FIG. 2, the pn micro junction layer 4 and the p-type silicon layer 3a are not changed, but the n-type silicon layer (light diffusion type) 2b on the light-receiving surface side is made to receive not only the normal incident light but also more scattered light and weak light. In order to guide to the deep part of the pn micro junction layer 4, the n type micro particles 5 and the light diffusion material 8 are combined together.

The antireflection film 9 is disposed outside the n-type silicon layer (light diffusion type) 2b, and the electrodes 7 are disposed at both ends in the same manner as described above, whereby the solar cell 1b (light diffusion type) is formed. .

In FIG. 3, the n-type silicon layer 2a on the light-receiving surface side and the p-type silicon layer 3a on the back surface side are made into microparticles without changing the pn micro junction layer 4, and first, the n-type silicon layer on the light-receiving surface side. The n-type microparticles 2a are filled with n-type microparticles 10 smaller than the n-type microparticles 5 and combined together to form an n-type silicon layer (particle type) 2c.

Similarly, the p-type silicon layer 3a on the back side is formed on the p-type silicon layer (particle type) 3b. That is, the pn micro junction layer 4 is sandwiched between the n-type silicon layer (particle type) 2c on the light-receiving surface side and the p-type silicon layer (particle type) 3b on the back surface side, and the electrodes 7 are arranged at both ends. A solar cell (flexible type) is formed.

Sectional drawing of the microparticle layer type | mold high efficiency solar cell (basic type) which shows the form of the Example of this invention Sectional view of the microparticle layer type high efficiency solar cell (light diffusion type) Sectional view of the microparticle layer type high efficiency solar cell (flexible type)

Explanation of symbols

1a Microparticle layer type high efficiency solar cell (basic type)
1b Same (light diffusion type)
1c Same (Flexible type)
2a n-type silicon layer
2b Same (light diffusion type)
2c Same (Particle type)
3a p-type silicon layer
3b Same (Particle type)
4 pn micro junction layer
5 n-type microparticles
6 p-type micro fine particles
7 electrodes
8 Light diffusing material (crystal, quartz glass, etc.)
9 Anti-reflective coating
10 n-type micro particle
11 p-type microparticles

Claims (1)

In a pn junction (including a pin junction, hereinafter omitted) by n-type and p-type silicon (including single crystal, polycrystalline, microcrystalline, amorphous silicon, and a compound semiconductor), for example, n-type silicon is converted to a micro level. Particles (hereinafter referred to as “n-type microparticles”, those finer than p-type microparticles as “n-type microparticles”, including nano-level particles, hereinafter abbreviated), and stacked in several layers. P-type silicon micro-level particles finer than n-type microparticles (hereinafter referred to as “p-type microparticles”, and “p-type microparticles” having the same size as n-type microparticles are used as gaps. All of which are filled, and the n-type microparticles and the p-type microparticles are integrally assembled to form a planar pn junction surface. It is formed into a pn junction layer (hereinafter referred to as “pn micro junction layer”, including a combination of p-type microparticles and n-type microparticles and a pin junction, hereinafter abbreviated). Not only the bonding layer but also the n-type silicon layer serving as the light receiving surface and the p-type silicon layer serving as the back surface, all of which are molded into micro-level particles and fine particles (including nano-level) and integrally combined A solar cell characterized by that.

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