Batteries: thermoelectric and photoelectric – Photoelectric – Cells
Reexamination Certificate
1998-03-11
2001-05-01
Chapman, Mark (Department: 1753)
Batteries: thermoelectric and photoelectric
Photoelectric
Cells
C136S249000
Reexamination Certificate
active
06225552
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a solar cell produced by using a thin film, particularly a solar cell arranged on a dial face of a watch and a production method of the same.
BACKGROUND ART
The solar cell using the amorphous silicon film is known. This solar cell using the amorphous silicon film can be thinly produced in a high productivity and light weight. Thus, such solar cell has been used as a power source of portable devices such as a table calculator, watch or the like.
Particularly, once the solar cell is mounted on a watch, the watch has a merit of no cell or battery exchange, with the result that the solar cell can largely contribute to the spread of a quartz type wrist watch.
However, when a usually shaped solar cell is mounted on a watch, the problems occur that a design of the watch is limited and that not only appearance of the watch becomes bad, but also the whole size thereof is increased. Accordingly, incorporation of the solar cell with a shape matching the dial face in a wrist watch has been tried (Nikkei Business, Mar. 18, 1996, pages 71-73).
Such a shaped solar cell has, however, the problems that the production cost thereof is further increased over a conventional solar cell and its reliability is reduced.
Alternatively, in order to enhance the productivity of the solar cell there is a technology of forming the electrode by printing.
FIG. 1
a
is a cross-sectional view illustrating a part of a structure of a solar cell having electrodes formed by a printing process. In this case, the solar cell shown in
FIG. 1
a
is a type of solar cell that incident rays enter the surface (the surface of the device) side where a photoelectric conversion layer is formed.
In
FIG. 1
a,
the reference numeral
100
denotes a glass substrate, stainless steel substrate or resin substrate,
101
a first electrode formed of, for example, aluminum,
102
a photoelectric conversion layer of amorphous silicon layers deposited in order of P-I-N types or N-I-P types from the glass substrate
100
,
103
a second electrode of indium tin oxide (ITO) that is an electrode on a light incidence surface side,
104
a drawing electrode formed by using a printing process.
In the printing process, a conductive paste in which a conductive material generally composed of spherical, cigar shaped or rugby ball shaped metal particles is dispersed is printed in a desired pattern.
Thus, in a case where a printing process in which a pattern can directly be formed is utilized, the merit that production steps of electrodes can be simplified is obtained. However, there occurs the problem that pressure in a certain degree is locally applied to a portion to be printed. This pressure is particularly concentrated at a portion in which dispersed conductive materials are present.
An ITO film (second film)
103
having a structure shown in
FIG. 1
a,
is not so hard and strong, and has a thickness of only a few thousand angstroms or less. Further, the surface of the ITO film has significant concave and convex portions. And, amorphous silicon which forms the photoelectric conversion layer
102
also is not so hard.
Therefore, high pressure is locally applied to the photoelectric conversion layer
102
due to the pressure concentration during printing. As a result, damage, such as a crack or the like can occur in the photoelectric conversion layer
102
, whereby a conductive material in a conductive paste can penetrate into the crack or the like.
FIG. 1
b
shows the state where a conductive paste penetrates into the crack or the like. The reference numeral
105
denotes a thus formed short circuit. When such short circuit
105
is formed, the first electrode
101
is electrically connected to the second electrode
103
, whereby the photoelectric conversion layer does not fully function as a solar cell.
As described above, the simplification of the production steps can be accomplished by producing electrodes by using the printing process. However, the printing process damages the photoelectric conversion layer, and is likely to form a short circuit between the first electrode and the second electrode.
Therefore, the object of the present invention is to provide a solar cell for a wrist watch which can be produced at a low cost and has a high reliability, and the production method thereof.
Another object of the present invention is to provide a solar cell whose production steps can be simplified and which has high production yield.
DISCLOSURE OF INVENTION
The present invention to attain the above-mentioned objects provides a desired shaped plane type solar cell including a plurality of photoelectric conversion devices formed by dividing the plane, a plurality of conductive paths for connecting each of the photoelectric conversion devices to each other in series, the conductive path being provided adjacent to the plurality of photoelectric conversion devices, and two drawing electrodes exposed on an opposite surface to a light irradiated surface, the electrodes being connected to two photoelectric conversion devices on both ends of the photoelectric conversion device connected in series.
According to this constitution of the present invention, since an electrode portion for extracting the output can be provided on an opposite side of a light irradiated surface of a photoelectric conversion device, the structure of the extracting portion of the output can be simplified. Further, a surface area which contributes to the photoelectric conversion can be maximized. As a result, a solar cell to be incorporated into a wrist watch can be produced at a low cost, and thus produced solar cell can have a high reliability.
It is preferable that each of the photoelectric conversion devices includes a substrate, a first electrode layer deposited on the substrate, a photoelectric conversion semiconductor layer deposited on the first electrode layer, and a light transmitting second electrode layer deposited on the photoelectric conversion semiconductor layer, and that one of the two externally drawing electrodes is connected to the second electrode layer of the photoelectric conversion device on one end thereof, and the other of the two externally drawing electrodes is connected to the first electrode layer of the photoelectric conversion device on the other end thereof.
It is desirable that the solar cell further includes a first through-slot which electrically connects the second electrode layer to one of the externally drawing electrodes.
It is also desirable that the first through-slot is formed on a region where the first electrode layer and a part of the photoelectric conversion semiconductor layer is isolated from other portions.
It is preferable that the solar cell further includes a second through-slot which electrically connects the first electrode layer to the other externally drawing electrode.
It is preferable that the solar cell is circular, and that the plurality of photoelectric conversion devices are plurality of fan-shaped photoelectric conversion devices formed so that the circular plane is divided in radial directions.
It is also preferable that the plurality of conductive paths and the two externally drawing electrodes are provided on outer peripheral portions of the plurality of photoelectric conversion devices.
It is preferable that the plurality of conductive paths and the two externally drawing electrodes are provided on outer peripheral portions of the plurality of photoelectric conversion devices, the solar cell being polygonal, the plurality of photoelectric conversion devices being plurality of triangle-shaped photoelectric conversion devices formed so that the polygonal plane is divided in radial directions.
The plurality of conductive paths are provided between the plurality of photoelectric conversion devices and the two externally drawing electrodes are provided on outer sides of the photoelectric conversion devices on both ends, the solar cell being rectangular, the plurality of photoelectric conversion devices being plurality of rectangular photoelectric conversion devices formed
Hosokawa Makoto
Isobe Yukihiro
Ninomiya Hideaki
Nishi Kazuo
Arent Fox Kintner & Plotkin & Kahn, PLLC
Chapman Mark
Semiconductor Energy Laboratory Co,. Ltd.
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