JP2003101046A - Photoelectric transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that the conversion efficiency of the conventional photoelectric transducer using crystalline semiconductor particles is low. SOLUTION: In this photoelectric transducer, a large number of crystalline semiconductor particles of a first conductivity are arranged on a substrate turning to one side electrode, an insulating substance is interposed between the particles, and a semiconductor layer of a second conductivity is formed on the particles. In the transducer, the insulating substance is constituted of a resin-insulating layer, where the refractive index is at least 1.4 and the transmittance of wavelength of 400-1,200 nm is at least 80%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion device, and more particularly to a photoelectric conversion device using crystalline semiconductor particles used for photovoltaic power generation.

[0002]

2. Description of the Related Art The advent of low-cost next-generation solar cells using silicon-saving raw materials is strongly desired. FIG. 3 shows a conventional photoelectric conversion device using grain-shaped or spherical silicon crystal particles advantageous for resource saving (see, for example, Japanese Patent No. 2641800). In this photoelectric conversion device, a low melting point metal layer 10 is formed on a substrate 1, crystalline semiconductor particles 3 of the first conductivity type are arranged on the low melting point metal layer 10, and the crystalline semiconductor particles 3 are formed.
There is disclosed a photoelectric conversion device in which an amorphous semiconductor layer 9 of the second conductivity type and a transparent conductive layer 8 are formed between the low melting point metal layer 10 and an insulating layer 2 therebetween.

Further, as shown in FIG. 4, a p-type silicon substrate 11a, an n-type silicon layer 11b and an outer electrode layer 11c.
There is disclosed a photoelectric conversion device in which a hemispherical solar cell 11 made of is formed on a conductive substrate 12 and a solder layer 14 is formed in a region between the hemispherical solar cells 11 via a polyimide resin layer 13 (for example, Japanese Patent Laid-Open No. 2001-177132
(See the official gazette).

[0004]

However, in the conventional photoelectric conversion device shown in FIG. 3, there is no specific description regarding the insulating layer 2, particularly about using a resin insulating layer.

In the conventional photoelectric conversion device shown in FIG. 4, the polyimide insulating layer 1 is provided between the hemispherical solar cells 11.
3 is formed, but the light that does not directly enter the hemispherical solar battery cells 11 and enters the polyimide insulating layer 13 is absorbed by the polyimide insulating layer 13 due to the low transmittance of the polyimide insulating layer 13, and thus power generation. There is a problem in that it cannot contribute and the conversion efficiency is low.

The present invention has been made in view of the above problems in the prior art, and an object thereof is to provide a photoelectric conversion device having high conversion efficiency and high reliability.

[0007]

In order to achieve the above object, according to the photoelectric conversion device of the first aspect of the present invention, the crystalline semiconductor particles of the first conductivity type are formed on the substrate to be one of the electrodes. In a photoelectric conversion device in which an insulating material is interposed between the crystalline semiconductor particles and a semiconductor layer of the second conductivity type is formed on the crystalline semiconductor particles. The resin insulating layer has a transmittance of 80% or more at a wavelength of 400 nm to 1200 nm.

In the above photoelectric conversion device, insulating particles are dispersed in the resin insulating layer, and the refractive index of the insulating particles is 0.9 times or less or 1.1 times or more the refractive index of the resin insulating layer. Is desirable.

In the above photoelectric conversion device, it is desirable that the insulating particles have a transmittance of 80% or more at a wavelength of 400 nm to 1200 nm.

According to the photoelectric conversion device of the fourth aspect of the present invention, a large number of first-conductivity-type crystalline semiconductor particles are provided on a substrate which is to be one of the electrodes, and insulation is provided between the crystalline semiconductor particles. In a photoelectric conversion device in which a second conductive type semiconductor layer is formed on the crystalline semiconductor particles with a substance interposed and a resin protective layer is formed on the semiconductor layer, the resin protective layer has a wavelength of 400 nm.
nm to 1200 nm has a transmittance of 80% or more, insulating particles are dispersed in the resin protective layer, and the refractive index of the insulating particles is 0.9 times or less the refractive index of the resin protective layer or 1. It is characterized by being more than 1 time.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of a photoelectric conversion device according to claim 1, 1 is a substrate, 2 is a resin insulating layer, 3 is granular crystalline silicon of the first conductivity type, and 4 is a second conductivity type. The semiconductor portion 5 is an upper electrode layer. FIG. 2 shows claim 4.
It is a cross-sectional view showing an embodiment of a photoelectric conversion device according to
1 is a substrate, 2 is a resin insulating layer, 3 is a first conductivity type granular crystalline silicon, 4 is a second conductivity type semiconductor part, 5 is an upper electrode layer, 6 is a resin protective layer, and 7 is an insulating particle.

As the substrate 1, metal, glass, ceramics, resin or the like is used. Preferably, a highly reflective metal such as silver, aluminum or copper is used. The large reflectance of the substrate 1 is preferable because the light can be reflected by the substrate 1 and more light can be guided to the granular crystalline silicon 3 and the conversion efficiency is improved. When an insulator is used as the substrate 1, a conductive layer 1a serving as a lower electrode is formed on the surface of the substrate 1.
Need to be formed. The conductive layer 1a is preferably made of a highly reflective material.

The resin insulating layer 2 is filled between the granular crystalline silicon 3 in order to separate the positive electrode and the negative electrode. The resin insulating layer 2 has a refractive index of 1.4 or more and a wavelength of 400 nm to 1200.
The transmittance of nm is 80% or more. This refractive index is wavelength 4
The average of the refractive indices of 00 nm to 1200 nm was used. When the refractive index of the resin insulating layer 2 is less than 1.4, the light incident on the resin insulating layer 2 is not largely refracted and is not guided to the granular crystalline silicon 3, which is not preferable because the conversion efficiency is lowered. More preferably, the refractive index is 1.5 or more. Also, the wavelength 40
When the transmittance of 0 nm to 1200 nm is less than 80%, the light incident on the resin insulating layer 2 is largely absorbed by the resin insulating layer 2, so that the light guided to the granular crystalline silicon 3 decreases and the conversion efficiency decreases. It is not preferable to do. More preferably, the transmittance is 90% or more. As the resin insulating layer 2, polyetherimide, polyether sulfone, polymethylpentene, polyallyl sulfone, benzocyclobutene, polyurethane, epoxy resin, phenoxy resin, or the like is used. The heat resistant temperature of the resin insulation layer 2 is preferably 150 ° C. or higher, particularly preferably 200 ° C. or higher.

Insulating particles 7 may be dispersed in the resin insulating layer 2. Dispersing the insulating particles 7 is preferable because the light incident on the resin insulating layer 2 is scattered and easily guided to the granular crystalline silicon 3. The refractive index of the insulating particles 7 is 0.9 times or less or 1.1 times or more the refractive index of the resin insulating layer 2. When the refractive index of the insulating particles 7 is more than 0.9 times and less than 1.1 times the refractive index of the resin insulating layer 2, the refraction / scattering effect of the light incident on the resin insulating layer 2 is small and the conversion efficiency is improved. It is not preferable because the effect is small. As the insulating particles 7, silicon oxide, aluminum oxide, boron oxide, polyester, air and synthetic materials thereof are used. Further, the transmittance of the insulating particles 7 at a wavelength of 400 nm to 1200 nm is 80.
% Or more is preferable. Insulating particle 7 wavelength 400
When the transmittance of nm to 1200 nm is less than 80%,
The light absorption of the insulating particles 7 becomes large and the granular crystalline silicon 3
This is not preferable because the amount of light guided to is reduced and the conversion efficiency is reduced. The particle size of the insulating particles is, for example, 0.5 μm or more 20
μm or less.

The resin insulation layer 2 is preferably concave. When the resin insulating layer 2 has a concave shape, the light incident on the resin insulating layer 2 is refracted in the direction of the granular crystalline silicon 3, so that the light guided to the granular crystalline silicon 3 increases and the conversion efficiency improves. preferable. When the resin insulating layer 2 has a flat shape, the refraction angle is small and the granular crystalline silicon 3
This is not preferable because the amount of light guided to is less than that of the concave shape and the conversion efficiency is low. The more preferable concave shape of the resin insulating layer 2 is such that the difference between the maximum thickness and the minimum thickness of the resin insulating layer 2 is 5
% Or more.

The first-conductivity-type granular crystalline silicon 3 is composed of silicon, and B, P, A as trace elements in silicon.
It may include 1, As, Sb. The granular crystalline silicon 3 can be formed by a vapor phase growth method, an atomizing method, a direct current plasma method or the like, but a melt dropping method of dropping the melt in a non-contact environment is preferable. Further, the first conductivity type granular crystalline silicon 3 is preferably p-type. For example, when added to silicon, B and Al exhibiting p-type are 1 × 10 ¹⁴ to 1
About 0 ²⁰ atm / cm ^{3 was} added.

The second conductivity type semiconductor portion 4 is formed by plasma doping method, thermal diffusion method, ion implantation method, VHF-CVD.
Method, plasma CVD method, catalytic CVD method, or the like. The trace element concentration of the second conductivity type semiconductor layer 4 is, for example, 1 × 1.
It is about 0 ¹⁴ to 10 ²² atm / cm ³ .

The upper electrode film 5 is formed of tin oxide, indium oxide or the like by a sputtering method or the like. It is also possible to provide an antireflection effect by adjusting the film thickness and the refractive index. Furthermore, an auxiliary electrode may be formed on it with a suitable pattern of silver or copper paste.

The resin protective layer 6 is used as a sealing member for suppressing corrosion and the like due to oxidation. The resin protective layer 6 has a transmittance of 80% or more at a wavelength of 400 nm to 1200 nm. When the transmittance of the resin protective layer 6 at a wavelength of 400 nm to 1200 nm is less than 80%, the light incident on the resin protective layer 6 is largely absorbed by the resin protective layer 6, so that the light guided to the granular crystalline silicon 3 is reduced. Then, the conversion efficiency is lowered, which is not preferable. More preferably, the transmittance is 90% or more. As the resin protective layer 6, polyetherimide,
Polyethersulfone, polymethylpentene, polyallylsulfone, benzocyclobutene, polyurethane,
Polyester, epoxy resin, phenoxy resin, EVA
Etc. are used.

Insulating particles 7 are dispersed in the resin protective layer 6. By dispersing the insulating particles 7, the light incident on the resin protective layer 6 is scattered and easily guided to the granular crystalline silicon 3. The refractive index of the insulating particles 7 is 0.9 times or less or 1.1 times or more that of the resin protective layer 6. When the refractive index of the insulating particles 7 is more than 0.9 times and less than 1.1 times the refractive index of the resin protective layer 6, the refraction / scattering effect of the light incident on the resin protective layer 6 is small and the conversion efficiency is low. It is not preferable because the improvement effect is small. As the insulating particles 7, silicon oxide, aluminum oxide, PET, air or the like is used. Further, the transmittance of the insulating particles 7 at a wavelength of 400 nm to 1200 nm is 80.
% Or more is preferable. Insulating particle 7 wavelength 400
When the transmittance in the range of nm to 1200 nm is less than 80%, the light absorption of the insulating particles 7 increases, the light guided to the granular crystalline silicon 3 decreases, and the conversion efficiency decreases, which is not preferable. The particle size of the insulating particles 7 is, for example, 0.5 μm or more and 20 μm or less.

The resin protective layer 6 preferably has a smaller refractive index than the insulating layer 2. When the refractive index of the resin protective layer 6 is smaller than that of the insulating layer 2, light is refracted in the direction of being guided to the granular crystalline silicon 3, which is preferable because the conversion efficiency is improved. The shape of the resin protective layer 6 is partially convex downward,
It is preferable that the silicon particles of the insulating layer 2 are partially concave.

[0022]

EXAMPLES Next, specific examples of the photoelectric conversion device of the present invention will be described. First, an average particle size of 4 on the aluminum substrate 1.
One layer of granular crystal p-type silicon 3 of 00 μm is densely arranged,
The substrate 1 and the granular crystalline silicon 3 were welded by heating. Next, a resin insulating material made of phenoxy resin is filled between the granular crystalline silicon 3 to form a resin insulating layer 2 having a thickness of 100 μm.
It was partially formed into a concave shape. Table 1 shows the results of evaluating the conversion efficiency by changing the refractive index and the transmittance by changing the material, forming temperature, etc. of the phenoxy resin. Next, the granular crystal p-type silicon 3 is doped with P by the plasma doping method.
Ions were diffused to form the n-type silicon portion 4. A protective film 5 made of tin oxide was formed thereon to a thickness of 100 nm.

[0023]

[Table 1]

As can be seen from the above results, the resin insulation layer 2
When the refractive index is 1.4 or more and the transmittance is 80% or more,
It is preferable because the conversion efficiency is improved. When the refractive index of the resin insulating layer 2 is 1.3 or less and the transmittance thereof is 70% or less, the conversion efficiency is lowered, which is not preferable. More preferably, the transmittance is 90% or more.

Next, the crystalline p-type silicon particles having an average particle diameter of 600 μm were converted into alumina ( correct?
You As a precaution, the case of an insulating substrate is included in the example.
Because it is. ) One layer was densely arranged on the substrate 1 having the aluminum electrode layer provided on the base material and heated to be welded to the substrate 1.
Next, a resin insulating material in which granular silicon oxide is dispersed in a polyetherimide resin is filled between the granular crystalline silicon 3,
The resin insulating layer 2 was formed in a partially concave shape with a thickness of 150 μm. The conversion efficiency was evaluated by changing the refractive index ratio of the polyetherimide resin and the granular insulating material and the transmittance of the granular silicon oxide by changing the material of the polyetherimide resin, the forming temperature, the material of the granular insulating material, the forming method, etc. Are summarized in Table 2. For the granular insulating material, air, silicon oxide, aluminum oxide and their composites were used. Next, the n-type silicon portion 4 was formed on the granular crystal p-type silicon 3 by the vapor phase growth method. On top of that, a protective film 5 made of zinc oxide 1
Was formed to a thickness of 00 nm.

[0026]

[Table 2]

( “More than”, “more”, and “less than” in Table 2
Use "and" exactly. In the claim
In relation to "above" and "below", the entire specification including tables is
Correct the "more than" and "exceed", "less than" and "less than"
Please use it properly. → From the table, the refractive index ratio of 1.0
Is outside the scope of the dependent claims, and in the claims 1.1 or more
Is 0.9 or less, but in the description and Table 2
Please check if there is any contradiction. As can be seen from the above results, it is preferable that the refractive index ratio of the resin material and the granular insulating material is 0.9 or less or 1.1 or more, because the conversion efficiency is high. More preferably, the refractive index ratio between the resin material and the granular insulating material is 0.8 or less or 1.2 or more. Further, when the transmittance of the granular insulating material is 80% or more, high conversion efficiency is obtained, which is preferable. More preferably, the transmittance of the granular insulating material is 90% or more.

Next, a resin protective layer 6 is provided on the protective film 5, and the conversion efficiency is evaluated by changing the transmittance of the resin protective layer 6 and the refractive index ratio with the granular insulating material. .

[0029]

[Table 3]

As can be seen from the above results, it is preferable that the resin protective layer has a transmittance of 80% or more and a refractive index ratio with the granular insulating material of 0.9 or less or 1.1 or more. The transmittance is more preferably 90% or more.

[0031]

As described above, according to the photoelectric conversion device of the first aspect, a large number of first-conductivity-type crystalline semiconductor particles are provided on the substrate that serves as one electrode, and the crystalline semiconductor In a photoelectric conversion device in which an insulating material is interposed between particles and a semiconductor layer of the second conductivity type is formed on the crystalline semiconductor particles, the insulating material has a refractive index of 1.4 or more and a wavelength of 400 n.
A photoelectric conversion device having high conversion efficiency can be realized by using a resin insulating layer having a transmittance of 80% or more for m to 1200 nm.

Further, according to the photoelectric conversion device of the fourth aspect, a large number of first-conductivity-type crystalline semiconductor particles are provided on the substrate that serves as one of the electrodes, and an insulating material is provided between the crystalline semiconductor particles. In a photoelectric conversion device in which a semiconductor layer of the second conductivity type is formed on the crystalline semiconductor particles and a resin protective layer is formed on the crystalline semiconductor particle, the resin protective layer having a wavelength of 400 n
The transmittance of m to 1200 nm is 80% or more, the insulating particles are dispersed in the resin protective layer, and the refractive index of the insulating particles is 0.9 times or less the refractive index of the resin protective layer or 1.
Since it is 1 time or more, a photoelectric conversion device with high conversion efficiency can be realized.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a photoelectric conversion device of the present invention.

FIG. 2 is a cross-sectional view showing a photoelectric conversion device of the present invention.

FIG. 3 is a cross-sectional view showing a conventional photoelectric conversion device.

FIG. 4 is a cross-sectional view showing another conventional photoelectric conversion device.

[Explanation of symbols]

1 ... substrate 2 ... Insulating layer 3 ··· First conductivity type granular crystalline silicon 4 ... Semiconductor part of the second conductivity type 5 ... Protective film 6 ... Resin protective layer 7 ... Insulating particles 8 ... Transparent conductive layer 9 ... Amorphous semiconductor layer 10 ... Low melting point metal layer 11 ... Hemispherical solar cells 11a ... p type silicon substrate 11b ··· n-type silicon layer 11c ... Outer electrode layer 12 ... Conductive substrate 13: Polyimide resin layer 14 ... Solder layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hisao Arimune             6 at 1166 Haseno, Jamizo-cho, Yokaichi-shi, Shiga               Kyocera Corporation Shiga Yokaichi Factory F term (reference) 5F051 AA02 CB18 CB30 DA03 DA20                       FA23 GA02 GA03 HA20

Claims (4)

[Claims] 1. A large number of first-conductivity-type crystalline semiconductor particles are provided on a substrate to be one electrode, an insulating material is interposed between the crystalline semiconductor particles, and a first semiconductor is formed on the crystalline semiconductor particles. In a photoelectric conversion device having a two-conductivity type semiconductor layer, the insulating material has a refractive index of 1.4 or more and a wavelength of 400 n.
A photoelectric conversion device comprising a resin insulating layer having a transmittance of 80% or more for m to 1200 nm. 2. Insulating particles are dispersed in the resin insulating layer, and the refractive index of the insulating particles is 0.9 times or less or 1.1 times or more the refractive index of the resin insulating layer. The photoelectric conversion device according to claim 1. 3. The wavelength of the insulating particles is 400 nm to 12
The photoelectric conversion device according to claim 2, wherein the transmittance at 00 nm is 80% or more. 4. A large number of first-conductivity-type crystalline semiconductor particles are provided on a substrate that serves as one of the electrodes, and an insulating material is interposed between the crystalline semiconductor particles. In a photoelectric conversion device in which a semiconductor layer of two conductivity type is formed and a resin protective layer is formed on the semiconductor layer, the resin protective layer has a transmittance of 80% or more at a wavelength of 400 nm to 1200 nm, and the resin protective layer is insulated. Particles are dispersed, and the refractive index of the insulating particles is 0.9 times or less or 1.1 times or more the refractive index of the resin protective layer.