Photoelectric conversion device

Batteries: thermoelectric and photoelectric – Photoelectric – Panel or array

Reexamination Certificate

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C136S246000, C136S256000, C136S259000, C136S261000, C136S252000, C257S432000, C257S433000, C257S436000, C257S461000, C257S443000, C438S063000

Reexamination Certificate

active

06563041

ABSTRACT:

This application is based on applications Nos. 2001-020624, 2000-362020, and 2001-005428 filed in Japan, the content of which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photoelectric conversion device. In particular, this invention relates to a photoelectric conversion device using numerous crystalline semiconductor particles.
2. Description of the Related Art
FIGS. 12-14
show photoelectric conversion devices using crystalline semiconductor particles that have been proposed so far.
FIG. 12
illustrates a solar cell in which a first conductive layer
33
is disposed over the surface of a substrate
32
which has been formed in a configuration with a periodically (regularly) indented pattern, and parts
31
a
of spherical or long cylindrical semiconductor crystals
31
are brought into electrical contact with the first conductive layer
33
, while the other parts
31
b
of the spherical or long cylindrical semiconductor crystals
31
are brought into electrical contact with a second conductive layer
34
. (Refer to Japanese Unexamined Patent Publication (Kokai) No. 2000-22184.) In
FIG. 12
, the numerals
35
,
36
, and
37
denote a high-reflection film, a spin-on-glass SOG
1
, and a spin-on-glass SOG
2
, respectively.
In the device shown in
FIG. 12
, since the spherical semiconductor crystals
31
are arranged according to the indented surface configuration of the substrate
32
, it is necessary to form an insulator
37
(for example, spin-on-glass SOG
2
) along the indented contours of the substrate
32
. Since such insulator formation cannot be performed by general printing methods, it has a problem of lowered productivity. In addition, since the device is arranged such that each of the recesses on the substrate
32
has one spherical semiconductor crystal
31
mounted thereon, mounting of the spherical semiconductor crystals
31
becomes difficult when they are reduced in size. It is therefore impossible in the above case to reduce the size of the spherical semiconductor crystals
31
. Accordingly, reduction in quantity of the semiconductor used as the raw material cannot be accomplished, which causes the problem of low productivity and high cost.
FIG. 13
illustrates another known photoelectric conversion device (U.S. Pat. No. 5,419,782). In this photoelectric conversion device, apertures are formed in a first aluminum foil
44
, and p-type silicon spheres
45
with n-type outer portions
46
are connected to the apertures. Then, the n-type outer portions
46
in the lower portions of the spheres are removed. An oxide coating
47
is applied to the surface of aluminum
48
and the oxide coating
47
in the lower portions of the spheres are removed so that the p-type silicon spheres
45
are joined to a second aluminum foil
48
. A transparent coating
49
is provided at the top surface. In this device, due to the coating
49
having a configuration which abruptly changes at the lowest point, light incident on locations where the p-type silicon spheres
45
are absent is directed to the p-type silicon spheres
45
, thereby improving the photoelectric conversion efficiency.
The photoelectric conversion device shown in
FIG. 13
intends to improve the photoelectric conversion efficiency by the arrangement being such that the coating
49
has a configuration which abruptly changes at the lowest point so as to form a V-shape. However, since forming such a coating having a configuration that changes abruptly at the lowest point is technically difficult, it would cause poor productivity. In addition, the material of the coating
49
deteriorates when exposed to sunlight for long duration of time, gradually lowering the photoelectric conversion efficiency.
FIG. 14
illustrates a photoelectric conversion device in which an aluminum film
52
is formed around a steel substrate
51
, and crushed silicon particles
54
are joined to the aluminum film
52
, over which an insulator layer
53
, n-type silicon portions
55
and a transparent conductive layer
56
are formed in succession (U.S. Pat. No. 4,514,580).
The disclosure of the photoelectric conversion device shown in
FIG. 14
lacks detailed descriptions regarding preferred arrangements of the crystalline semiconductor particles
54
and preferred shapes of peripheral regions around the crystalline semiconductor particles
54
. Accordingly, this device fails to efficiently utilize light incident on the peripheral regions around the crystalline semiconductor particles
54
, causing the problem of low photoelectric conversion efficiency.
It is an object of the present invention to provide a photoelectric conversion device with high efficiency and high productivity.
BRIEF SUMMARY OF THE INVENTION
(1) A photoelectric conversion device according to the present invention comprises: a lower electrode; numerous crystalline semiconductor particles of one conductivity type deposited on the lower electrode; an insulator formed among the crystalline semiconductor particles; and a semiconductor layer of the opposite conductivity type formed on the side of the upper portions of the crystalline semiconductor particles, wherein the insulator is formed of a translucent material, and the surface of the lower electrode comprises a roughened surface.
The above arrangement allows light that has been incident on the surface of the lower electrode to be scattered and directed to the crystalline semiconductor particles, thereby improving the photoelectric conversion efficiency, as well as it can enhance the adhesiveness between the lower electrode and the insulator formed thereon.
(2) Another photoelectric conversion device according to the present invention comprises: a lower electrode; numerous crystalline semiconductor particles of one conductivity type deposited on the lower electrode; an insulator formed among the crystalline semiconductor particles; and a semiconductor layer of the opposite conductivity type formed on the side of the upper portions of the crystalline semiconductor particles, wherein the insulator is formed of a translucent material, and a protruding portion comprising a reflective material is formed between the crystalline semiconductor particles.
The photoelectric conversion device according to the above arrangement allows incident light to be scattered by the protruding portion and directed to the crystalline semiconductor particles so that the photoelectric conversion efficiency is improved. Accordingly, a photoelectric conversion device with high efficiency and high productivity can be realized.
(3) Another photoelectric conversion device according to this invention comprises: a lower electrode; numerous crystalline semiconductor particles of one conductivity type deposited on the lower electrode; an insulator formed among the crystalline semiconductor particles; and a semiconductor layer of the opposite conductivity type formed on the side of the upper portions of the crystalline semiconductor particles, wherein the crystalline semiconductor particles are arranged such that a crystalline semiconductor particle is located on a straight line that perpendicularly crosses a line segment connecting central parts of other crystalline semiconductor particles that are adjacent to each other approximately at the midpoint of the line segment.
The photoelectric conversion device arranged as above enables light incident on peripheral regions around the crystalline semiconductor particles to contribute to the generation of electricity so that high photoelectric conversion efficiency can be achieved.
Structural details of these inventions are hereinafter described referring to the appended drawings.


REFERENCES:
patent: 3998659 (1976-12-01), Wakefield
patent: 4514580 (1985-04-01), Bartlett
patent: 4614835 (1986-09-01), Carson et al.
patent: 5419782 (1995-05-01), Levine et al.
patent: 6281427 (2001-08-01), Mitsuhiro et al.
patent: 6417442 (2002-07-01), Fukui et al.
patent: 6437234 (2002-08-01), Kyoda et al.
patent: 6441298 (2002-08-01), Thio
patent: 200

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