Batteries: thermoelectric and photoelectric – Photoelectric – Cells
Reexamination Certificate
1999-10-07
2001-10-02
Diamond, Alan (Department: 1753)
Batteries: thermoelectric and photoelectric
Photoelectric
Cells
C136S258000, C136S262000, C136S252000, C136S265000, C257S053000, C257S103000, C257S615000, C257S447000, C257S448000, C257S460000, C257S461000, C257S431000, C438S085000, C438S093000, C438S096000, C438S097000, C438S098000
Reexamination Certificate
active
06297442
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a transparent solar cell comprising a transparent conductive substrate having thereon a novel photoconductor layer, a self-power-supply display device using the same, and a process for producing the solar cell.
BACKGROUND OF THE INVENTION
In recent years, clean energy has been demanded for protecting the global environment, such as prevention of harmful influence of CO
2
. A solar cell is one of the most expected energy sources because it can utilize the solar energy, which is substantially inexhaustible. A crystalline or amorphous silicon solar cell and a high-efficiency solar cell using a Group III-V compound semiconductor, such as GaAs and InP, have been subjected to practical use. In order to increase the proportion of clean energy in the whole-consumed energy, the consuming electric power should be substituted with a solar cell as much as possible. In order to spread a solar cell to various practical applications, it is important to widen the applicable field, as well as making the device itself to have a high efficiency. From such a point of view, what is receiving attention as an applicable field of a solar cell is, in addition to generation of electricity of relatively large-scale power such as electric power for home, to supply electric power from a solar cell to an apparatus used out of doors, such as a portable electronic apparatus and a portable personal computer.
However, since a large proportion of the surface of such an apparatus is occupied by a display device and an input device, there is no space for mounting a solar cell to the apparatus, and since a solar cell has a certain color, it is difficult to mount a solar cell to the apparatus from the standpoint of design. It is considered to utilize windows occupying a large proportion of an automobile and a building, as a space for mounting a solar cell. However, a solar cell currently available has a certain color and is not transparent since it utilizes a visible ray, and therefore lighting cannot be ensured. Furthermore, it is also considered to utilize other parts than the display device or the windows, but such is currently difficult from the standpoint of design.
The problems can be solved by a transparent solar cell. In other words, the problems can be solved when a high efficiency solar cell for ultraviolet rays can be formed on a transparent substrate.
Investigations of a solar cell have been made to improve the efficiency in a short wavelength region for increasing the sensitivity. However, it has been known that when, for example, the proportion of C in an amorphous Si
1-x
C
x
film is increased, the photoconductivity characteristics are rapidly deteriorated. That is, there is no material suitable as a photovoltaic material of a wide optical gap having a sensitivity in a short wavelength region, and there is no transparent solar cell of a high efficiency and a wide area.
On the other hand, a see-through type solar cell, through which the opposite side can be seen, is proposed, a large proportion of which is one having many minute holes therein. It is as if the opposite side is seen through a sieve, and cannot be applied to a display device, which is minute and should exhibit a sufficient brightness with a low electric power, or a window of an automobile, which requires both lighting and safety.
In recent years, a nitride series compound semiconductor receives attention as a semiconductor material of a wide optical gap. However, because such a semiconductor represented by GaN is produced through crystal growth at a temperature of from 800 to 1,000° C., and sapphire is frequently used as a substrate, it is difficult to apply to a solar cell from the standpoint of cost and size.
SUMMARY OF THE INVENTION
The invention has been developed to solve the problems described above and to attain the following objects.
An object of the invention is to provide a solar cell that can generate electricity with utilizing effectively harmful and useless ultraviolet rays, that can be used by accumulating with a display device to generate electricity simultaneously with utilization of the display function, and that is essentially transparent and exhibits less feeling of existence.
Another object of the invention is to provide a self-power-supply display device using the solar cell.
A further object of the invention is to provide a process for producing the solar cell.
In order to attain the objects described above, the invention relates to the following embodiments.
(1) A solar cell comprising a transparent conductive substrate having thereon a photoconductor layer that is transparent to a visible ray and has an absorbance of 0.8 or less at a wavelength of from 400 to 800 nm, and a transparent conductive electrode in this order.
(2) A solar cell as described in item (1), wherein the photoconductor layer contains at least one element selected from Group IIIA elements and at least one element selected from Group VA elements in the Periodic Table.
(3) A solar cell as described in item (1), wherein the photoconductor layer contains a metallic oxide semiconductor.
(4) A solar cell as described in item (3), wherein the metallic oxide semiconductor contains at least one of titanium oxide and zinc oxide.
(5) A solar cell as described in items (1), wherein the photoconductor layer has a laminated structure.
(6) A solar cell as described in item (5), wherein the laminated structure comprises a first photoconductor layer containing at least one element selected from Group IIIA elements and at least one element selected from Group VA elements in the Periodic Table, and a second photoconductor layer containing a metallic oxide semiconductor.
(7) A solar cell as described in items (1), wherein the photoconductor layer has an optical gap of 2.8 eV or more.
(8) A solar cell as described in items (1), wherein the solar cell has a photoelectric conversion efficiency for light of an ultraviolet region that is larger than a photoelectric conversion efficiency for light of a visible region.
(9) A self-power-supply display device comprising a solar cell as described in items (1), and a display device accumulated thereon.
(10) A process for producing a solar cell comprising a step of providing a photoconductor layer on a transparent conductive substrate by activating a compound containing a nitrogen element to an activated species (for example, a necessary energy condition or an excited species), and reacting the activated species with an organic metallic compound containing at least one element selected from Al, Ga and In; and a step of providing a transparent conductive electrode on the photoconductor layer.
(11) A process for producing a solar cell as described in items (10), wherein said reacting under an atmosphere containing hydrogen.
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patent: 4663495 (1987-05-01), Berman et al.
patent: 4695674 (1987-09-01), Bar-on
patent: 5078804 (1992-01-01), Chen et al.
patent: 5288700 (1994-02-01), McDowell
patent: 5652434 (1997-07-01), Nakamura et al.
patent: 5986285 (1999-11-01), Yagi
patent: 6180871 (2001-01-01), Campbell et al.
patent: 8-56007 (1996-02-01), None
patent: 10-256577 (1998-09-01), None
Mancini et al., Thin Solid Films, 124, pp. 85-92, 1985 (month unknown).*
K. Murata et al. “Features and application of amorphous Si solar cells—See-through and flexible modules”, Applied Physics, vol. 67, No. 10, 1998, pp. 1192-1198 (month unknown).
Suzuki Seiji
Torigoe Nobuyuki
Yagi Shigeru
Diamond Alan
Fuji 'Xerox Co., Ltd.
Oliff & Berridg,e PLC
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