JP2002222976A - Photoelectric converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that a photoelectric converter which uses conventional crystalline semiconductor particles was low in conversion efficiency and productivity. SOLUTION: In a photoelectric converter, a plurality of granulated crystal semiconductors 2 are arranged on a lower electrode 1, and insulators 4 are filled between the granulated crystal semiconductors 2, and at least upper electrodes 5 are formed on the granulated crystal semiconductors 2. The insulator 4 and the upper electrode 5 are formed with translucent members, and a surface of the lower electrode 1 is made rough.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photoelectric conversion device, and more particularly to a photoelectric conversion device using a large number of semiconductor particles.

[0002]

2. Description of the Related Art FIGS. 4 and 5 show photoelectric conversion elements using crystalline semiconductor particles that have been conventionally proposed.

[0003] As shown in FIG.
According to Japanese Patent Publication No. 84, a plurality of spherical or rod-shaped semiconductor crystals 2 are provided with a structure arranged on a first substrate 13 having a periodic uneven structure. A first conductive layer 12 is disposed on the periodic uneven structure, and a part of the spherical or rod-shaped semiconductor crystal 2 is brought into electrical contact with the first conductive layer 12 to form the first conductive layer 12. A solar cell is disclosed in which a second conductive layer 9 that is in electrical contact with a part of the semiconductor crystal in a part different from the part of the spherical or rod-shaped semiconductor crystal 2 in contact with the layer 12 is disclosed. In FIG. 5, 8 is a high reflection film, and 10 is a spin-on glass S
OG1 and OG11 are spin-on glass SOG2.

[0004] As shown in FIG.
According to Japanese Patent Publication No. 2 (1993) -197, an opening is formed in the first aluminum foil 14, and the opening has an n-type skin portion 16 on a p-type in the opening.
The silicon ball 15 is joined to form an n-type skin 16 on the back side of the ball.
And oxide coating 1 on aluminum 18
7, the oxide 17 on the back side of the ball is removed, bonded to the second aluminum foil 18, and a transparent coating 19 is provided on the surface, and this coating 19 has a shape that changes rapidly at the lowest point. There is disclosed a photoelectric conversion device in which light incident on a position where no p-type silicon sphere 15 is provided is guided to the p-type silicon sphere 15 to improve conversion efficiency.

[0005]

However, in the photoelectric conversion device disclosed in Japanese Patent Application Laid-Open No. 2000-22184 shown in FIG. 4, since the spherical semiconductor crystals 2 are arranged in accordance with the uneven surface of the substrate 17, the insulator 11 (for example, Spin-on glass SO
G2) needs to be formed along the uneven surface of the substrate 13 and cannot be formed by a general printing method. In addition, since the spherical semiconductor crystal 2 is arranged on each of the irregularities of the substrate 13, assembling becomes difficult when the spherical semiconductor crystal is reduced in size.
There is a problem that the spherical semiconductor crystal 2 cannot be reduced in size, the amount of semiconductor used as a raw material cannot be reduced, and low productivity and high cost occur.

Further, US Pat. No. 5,419,782 shown in FIG.
In the photoelectric conversion device disclosed in Japanese Patent Application Laid-Open Publication No. H11-157, the conversion efficiency is improved by a coating 19 having a shape that rapidly changes in a V-shape at the lowest point, but a shape that rapidly changes in a V-shape at the lowest point is formed. However, there is a problem in that the productivity is low because it is technically difficult, and when exposed to sunlight for a long period of time, the coating material 19 deteriorates and the conversion efficiency gradually decreases.

The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide a photoelectric conversion device with high efficiency and high productivity.

[0008]

According to a first aspect of the present invention, there is provided a photoelectric conversion device comprising: a plurality of granular crystal semiconductors disposed on a lower electrode; In a photoelectric conversion device in which a body is filled and an upper electrode is formed on an upper side of the granular crystal semiconductor, the insulator and the upper electrode are formed of a translucent member, and the surface of the lower electrode is roughened. It is characterized by.

In the above-mentioned photoelectric conversion device, it is preferable that the arithmetic average roughness of the surface of the lower electrode is 0.01 to 10.

In the above-mentioned photoelectric conversion device, it is preferable that the lower electrode is made of aluminum or an aluminum alloy.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a view showing one embodiment of a photoelectric conversion device according to claim 1, wherein 1 is a lower electrode, 2
Is a first conductivity type semiconductor particle, 3 is a roughened surface of the lower electrode, 4 is a light-transmitting insulator layer, 5 is a second conductivity type semiconductor portion, 6
Is a protective layer.

The lower electrode 1 only needs to have conductivity and may also serve as a substrate. When an insulating material such as ceramic or resin is used as a substrate when not serving as a substrate, the lower electrode 1 serves as a conductive layer on the surface. It may be formed.

The surface of the lower electrode 1 is rough. By roughening the surface of the lower electrode 1, the light irradiated on the surface of the lower electrode 1 is scattered and guided to the semiconductor particles 2, so that the conversion efficiency is improved. This has the effect of improving the adhesion. As a method of roughening the surface of the lower electrode 1, a method of applying and firing an aluminum paste containing a filler or a glass frit on a substrate, or a method of forming fine particles of alumina or the like on a pressurized gas to form the lower electrode 1. Sand blast method, RIE method, which physically sprays on the surface
Etching with a chemical solution is available.

The arithmetic average roughness of the surface of the lower electrode 1 is 0.0
1 to 10 are preferred. When the arithmetic average roughness is 0.01 or less, the scattering of light is small, the effect of improving the conversion efficiency is small, and the adhesion is poor. Arithmetic average roughness is 1
When the value is 0 or more, it is not preferable because an insulator layer formed on the upper portion is difficult to form and the thickness may vary greatly or cause a short circuit.

The lower electrode 1 is preferably made of aluminum or an aluminum alloy. By using aluminum or an aluminum alloy, an inexpensive lower electrode with high reflectivity, low resistance, high reliability, and high reliability can be realized.

The first conductive type semiconductor particles 2 contain p-type B, Al, Ga, or the like in Si, Ge, or the like, and contain trace elements. Examples of the shape of the semiconductor particles 2 include those having a polygonal shape and those having a curved surface. The particle size distribution may be uniform or non-uniform, but if uniform, a process for adjusting the particle size is required, so that non-uniformity is advantageous in terms of cost. Further, by having a convex curved surface, the dependence on the light ray angle of light is small.

An example of a method for arranging the semiconductor particles 2 will be described below. Holes smaller than the diameter of the semiconductor particles 2 are arranged and formed in a box-shaped jig, and the inside of the box-shaped jig is depressurized by a pump.
The semiconductor particles 2 are adsorbed in holes smaller than the particle diameter. Substrate 1
After the jig is transported upward, the pressure inside the jig is increased, and the semiconductor particles 2 are arranged on the substrate 1. According to this arrangement method, the semiconductor particles 2 can be easily arranged in an appropriate arrangement by designing the arrangement of the holes formed in the box-shaped jig. Others
There is also a method of arranging the semiconductor particles 2 by applying vibration such as ultrasonic waves.

The insulator 4 is made of an insulating material for separating the positive electrode and the negative electrode, and has a light transmitting property. In particular, a material that has a transmittance of 50% or more of light having a wavelength of 400 to 1200 nm that contributes to power generation is preferable. For example, SiO ₂ , Al ₂ O ₃ ,
There are an insulating material using a glass slurry containing PbO, B ₂ O ₃ , ZnO or the like as an optional component, and a resin insulating material such as polycarbonate.

The second conductivity type semiconductor portion 5 is formed by a vapor phase growth method, a thermal diffusion method, or the like. For example, the second conductivity type semiconductor portion 5 is formed by introducing a small amount of a n-type phosphorus-based compound gas phase into a silane compound gas phase. The second conductivity type semiconductor portion 5 may be any of single crystalline, polycrystalline, microcrystalline, and amorphous. The concentration of the trace element in the second conductivity type semiconductor portion 5 is, for example, 1 × 10 ¹⁶ to 1
What is necessary is just about ²² atm / cm ³ . The second conductivity type semiconductor section 5 may also serve as the upper electrode. Further, an upper electrode such as tin oxide or zinc oxide may be formed between the second conductivity type semiconductor portion 5 and the protective film 6.

The protective film 6 preferably has the property of a transparent dielectric, and is made of, for example, silicon oxide, CVD or PVD.
Cesium oxide, aluminum oxide, silicon nitride, titanium oxide, SiO ₂ —TiO ₂ , tantalum oxide, yttrium oxide, or the like is formed on the second conductivity type semiconductor layer 5 in a single layer or in a single layer or in combination. It is more preferable that the protective layer 6 has an antireflection effect by adjusting the thickness to an appropriate thickness.

In order to reduce the resistance, auxiliary electrodes such as fingers and bus bars may be formed in an arbitrary pattern by a screen printing method or a vapor deposition method.

[0022]

Embodiment 1 Next, an embodiment of the photoelectric conversion device of the present invention will be described. First, the insulator layer 4 is formed on the lower electrode 1.
The lower electrode 1 was made of aluminum, and the surface was roughened by sandblasting to change the arithmetic average roughness, and the adhesion and conversion efficiency were evaluated. The results are shown in Table 1. A comparative example having an arithmetic mean roughness of 0.002 without performing the surface roughening treatment shown in FIG. 3 was also evaluated at the same time. The arithmetic average roughness was evaluated according to JIS, and the adhesion was evaluated at 85 ° C and 95% RH in an environment of 5%.
After 00 hours, evaluation was made based on the presence or absence of peeling between the lower electrode 1 and the insulator layer 4.も の indicates that no peeling was observed, Δ indicates a very small part, and X indicates that significant peeling occurred. The insulator layer 4 was formed to a thickness of 400 μm on this substrate using a glass paste. The glass used for the glass paste was a zinc oxide-based glass having a softening temperature of 550 ° C. and an average transmittance of 94% at a wavelength of 400 to 1200 nm. Next, p-type silicon particles 2 having an average diameter of 900 μm were arranged thereon. At this time, the p-type silicon particles 2
Was pressed from above, and the roughened surface irregularities were deformed and brought into contact with the lower electrode 1. Next, the glass paste was heated and fired. Next, an n-type silicon layer 5 having a thickness of 200 nm is formed on the silicon particles 2 and the insulating material layer 4 as an upper electrode layer.
Formed. The n-type silicon layer 5 also serving as the upper electrode layer had an average transmittance of 85% at a wavelength of 400 to 1200 nm. Further, 100 n of silicon nitride is used as the protective film 6.
m was formed.

[0023]

[Table 1]

From the above results, the roughened surface shows higher characteristics. The arithmetic average roughness is preferably from 0.01 to 10. When the arithmetic average roughness is less than 0.01, the effect of improving the conversion efficiency is small and the adhesion is poor, which is not preferable. If the arithmetic average roughness is larger than 10, the insulator on the lower electrode surface is partially thinned and short-circuiting occurs when a voltage is applied, which is not preferable. More preferably, the arithmetic average roughness is from 0.1 to 10.

Next, the results of evaluating the conversion efficiency by changing the transmittance of the insulator layer are shown in Table 2. The transmittance shown in Table 2 was shown as an average at a wavelength of 400 to 1200 nm. The arithmetic average roughness of the lower electrode surface was set to 1.

[0026]

[Table 2]

From the above results, the average transmittance of the insulator layer is 5
It is suitable when it is 0% or more. When the average transmittance is 50% or less, the conversion efficiency decreases, which is not preferable.

Next, the results of evaluating the conversion efficiency by changing the material of the lower electrode are shown in Table 3. The arithmetic average roughness of the lower electrode surface was set to 1, and the average transmittance of the insulator layer was set to 95%.

[0029]

[Table 3]

From the above results, the lower electrode material is preferably aluminum or an aluminum alloy. Aluminum or aluminum alloys are not preferred because of low conversion efficiency.

[0031]

Example 2 The lower electrode 1 was made of an aluminum-manganese alloy, the surface was roughened by etching with a chemical solution, and the conversion efficiency was evaluated by changing the arithmetic average roughness. Table 4 shows the results. An insulator layer 4 was formed on the lower electrode 1. This insulator layer 4 is formed on the lower electrode 1 by using a glass paste.
It was formed to a thickness of μm. The glass used for the glass paste is a boron oxide-based softening temperature of 500 ° C. and a wavelength of 400-12.
One having an average transmittance of 94% of 00 nm was used. next,
On top of this, p-type silicon crystal particles 2 having an average diameter of 400 μm 2
Was placed. Next, the glass paste was baked by heating. Next, an n-type silicon layer 5 was formed on the p-type silicon crystal grains 2 and the insulator layer 4 to a thickness of 50 nm, and a tin oxide upper electrode 7 was formed to a thickness of 200 nm. At this time, an upper electrode 7 having an average transmittance of 76% at a wavelength of 400 to 1200 nm was formed. Next, 100 nm of silicon nitride is used as the protection film 6.
Formed.

[0032]

[Table 4]

From the above results, the roughened surface shows higher characteristics. The arithmetic average roughness is preferably from 0.01 to 10. When the arithmetic average roughness is less than 0.01, the effect of improving the conversion efficiency is small and the adhesion is poor, which is not preferable. If the arithmetic average roughness is larger than 10, the insulator on the lower electrode surface is partially thinned and short-circuiting occurs when a voltage is applied, which is not preferable. More preferably, the arithmetic average roughness is from 0.1 to 10.

Next, the results of evaluating the conversion efficiency by changing the transmittance of the upper electrode are shown in Table 5. The transmittance shown in Table 5 was shown as an average at a wavelength of 400 to 1200 nm. The arithmetic average roughness of the lower electrode surface was set to 0.5.

[0035]

[Table 5]

From the above results, the average transmittance of the upper electrode is 5
A time of 0% or more is preferable. Top electrode transmittance is 50
% Is not preferable because the conversion efficiency is greatly reduced.

[0037]

As described above, according to the photoelectric conversion device of the present invention, a number of granular crystal semiconductors are provided on the lower electrode, and an insulator is filled between the granular crystal semiconductors. In a photoelectric conversion device in which at least an upper electrode is formed on a crystalline semiconductor, the insulator and the upper electrode are formed of a light-transmitting member, and light incident on the lower electrode surface is formed by roughening the lower electrode surface. The conversion efficiency is improved by being scattered and guided to the granular crystal semiconductor, and also has the effect of improving the adhesion to the insulator formed on the lower electrode.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the present invention.

FIG. 3 is a sectional view showing a comparative example of the present invention.

FIG. 4 is a cross-sectional view illustrating an example of a photoelectric conversion element of Conventional Example 1.

FIG. 5 is a cross-sectional view illustrating an example of a photoelectric conversion element of Conventional Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Lower electrode 2 ... 1st conductivity type semiconductor particle 3 ... Roughened surface of lower electrode 4 ... Translucent insulator layer 5 ... 2nd conductivity Semiconductor part 6 ... Protective layer 7 ... Transparent conductive layer 8 ... High reflection film 9 ... P electrode 10 ... Spin on glass SOG1 11 ... Spin on glass SOG2 12 ... Transparent electrode 13. First substrate (transparent glass) 14. First aluminum foil 15. p-type silicon sphere 16. n-type skin 17 oxide coating 18. second aluminum foil 19 transparent coating

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hisao Arimune 1166, Haseno, Snake-cho, Yokaichi City, Shiga Prefecture F term in the Kyocera Corporation Shiga Yokaichi Plant F-term (reference)

Claims (3)

[Claims] 1. A photoelectric conversion device comprising: a plurality of granular crystal semiconductors disposed on a lower electrode; an insulator filled between the granular crystal semiconductors; and an upper electrode formed on an upper side of the granular crystal semiconductor. A photoelectric conversion device, wherein the insulator and the upper electrode are formed of a translucent member, and the surface of the lower electrode is roughened. 2. The arithmetic mean roughness of the lower electrode surface is equal to 0.
The photoelectric conversion device according to claim 1, wherein the number is from 01 to 10. 3. The photoelectric conversion device according to claim 1, wherein the lower electrode is made of aluminum or an aluminum alloy.