Batteries: thermoelectric and photoelectric – Photoelectric – Cells
Reexamination Certificate
2000-05-17
2002-04-30
Diamond, Alan (Department: 1753)
Batteries: thermoelectric and photoelectric
Photoelectric
Cells
C136S251000, C136S249000, C136S255000, C257S432000, C257S437000, C257S436000, C257S434000, C428S426000, C428S428000, C428S432000, C428S220000
Reexamination Certificate
active
06380480
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a photoelectric conversion device such as a solar cell or the like, more particularly, to a photoelectric conversion device having a low reflectance with respect to incident light with a wavelength in the vicinity of a wavelength allowing a photoelectric conversion unit to have an optimal spectral sensitivity characteristic so as to improve the conversion efficiency of the photoelectric conversion device. The present invention also relates to a substrate for a photoelectric conversion device.
BACKGROUND OF THE INVENTION
In a thin film photoelectric conversion device such as a thin film solar cell, a glass sheet with a transparent conductive film (a transparent electrode) may be used in some cases. This thin film photoelectric conversion device is manufactured by forming, on a glass sheet, a transparent conductive film containing tin oxide as a main component, a photovoltaic unit including a photovoltaic layer, and a back electrode of aluminum or the like in this order.
As the transparent conductive film, a fluorine doped tin oxide (hereinafter referred to as “SnO
2
:F”) film has been used in many cases. This film is more excellent in chemical stability such as plasma resistance or the like compared to a tin doped indium oxide (ITO) film. Therefore, the SnO
2
:F film does not deteriorate greatly in forming a photovoltaic layer by using a plasma CVD method. A thin film photoelectric conversion device in which an undercoating film is formed between a transparent conductive film and a glass sheet also has been known. This undercoating film functions as a barrier film for preventing an alkaline component from diffusing into the transparent conductive film from the glass sheet. As the barrier film, a silicon oxide film has been used in many cases.
A glass sheet with a transparent conductive film also is used as window glass for buildings. The glass sheet with a transparent conductive film formed thereon suppresses the outflow of heat from an opening of a building as so-called Low-E glass. In this application field, it is important that a natural appearance as window glass is provided. A tin oxide film also is one of the typical transparent conductive films in this field. However, when the tin oxide film is formed to have a thickness effective in suppressing the heat loss from an opening, the problem of interference colors (iridescence) of reflected light comes up. Therefore, JP 3-72586 B discloses the formation of two intermediate layers between a glass sheet and a transparent conductive film. Specifically, it discloses that a tin oxide film with a thickness of about 18 nm and a silicon-silicon oxide mixed film with a thickness of about 28 nm are formed sequentially from a glass sheet side and further a SnO
2
:F film with a thickness of about 200 nm is formed on those films as a transparent conductive film.
On the other hand, the transparent conductive film used for the thin film photoelectric conversion device is required to have the compatibility between a high light transmittance and a high conductivity. However, these two properties show reciprocal tendencies and thus the compatibility cannot be obtained easily. Thus, a thin film photoelectric conversion device using a transparent conductive film itself as an antireflection film by adjusting the thickness of the transparent conductive film so that a large quantity of light reaches a photovoltaic layer also has been proposed (for instance, “Amorphous Solar Cell” by Kiyoshi Takahashi and Makoto Konagai, published by Shokodo).
However, when the transparent conductive film itself is intended to be used as an antireflection film, the thickness of the transparent conductive film is limited, which causes difficulty in controlling the conductivity. Therefore, the improvement in characteristics of the photoelectric conversion device as a whole cannot be expected. Furthermore, in a photoelectric conversion device including a plurality of photovoltaic layers having different spectral sensitivity characteristics, it is difficult to exert an antireflection effect on the plurality of photovoltaic layers merely by adjusting the thickness of the transparent conductive film.
As described in JP 3-72586 B, in the field of window glass for buildings, it also has been proposed to insert a plurality of films between a glass sheet and a transparent conductive film. However, it has not been studied yet to improve the characteristics of a photoelectric conversion device by using an intermediate film between a glass sheet and a transparent conductive film. In order to improve the characteristics of the photoelectric conversion device, consideration also must be given to the spectral sensitivity characteristics of a photovoltaic layer.
SUMMARY OF THE INVENTION
The present invention is intended to provide a photoelectric conversion device such as a photovoltaic device in which conversion efficiency is improved by employing a film structure including an intermediate film between a transparent substrate and a transparent conductive film. The present invention also is intended to provide a substrate for a photoelectric conversion device that has the above-mentioned film structure and is effective in improving the conversion efficiency.
In order to achieve the above-mentioned object, a first photoelectric conversion device of the present invention includes a transparent substrate, a transparent conductive film, a photoelectric conversion unit including a photoelectric conversion layer, and a back electrode, which are stacked sequentially from the side on which light is incident. Further, an intermediate film is formed between the transparent substrate and the transparent conductive film. The first photoelectric conversion device satisfies the relationship of R
1
<R
2
×0.8, wherein R
1
represents an average reflectance of the photoelectric conversion device in the wavelength region between (&lgr;−50) nm and (&lgr;+50) nm, where &lgr; (nm) indicates a wavelength of the light allowing the photoelectric conversion layer to have an optimal spectral sensitivity characteristic, and R
2
denotes an average reflectance, in the wavelength region, of the photoelectric conversion device that does not include the intermediate film.
A second photoelectric conversion device of the present invention includes a transparent substrate, a transparent conductive film, at least two photoelectric conversion units, and a back electrode, which are stacked sequentially from the side on which light is incident. The at least two photoelectric conversion units include two photoelectric conversion layers in which wavelengths &lgr; of the light allowing optimal spectral sensitivity characteristics to be obtained are different from each other. Further, an intermediate film is formed between the transparent substrate and the transparent conductive film. The second photoelectric conversion device satisfies the relationships of: R
11
<R
12
, wherein R
11
represents an average reflectance of the photoelectric conversion device in a first wavelength region between (&lgr;−50) nm and (&lgr;
1
+50) nm, where &lgr;
1
(nm) represents one of the wavelengths &lgr; in one of the two photoelectric conversion layers, and R
12
denotes an average reflectance, in the first wavelength region, of the photoelectric conversion device that does not include the intermediate film; and R
21
<R
22
, wherein R
21
represents an average reflectance of the photoelectric conversion device in a second wavelength region between (&lgr;
2
−50) nm and (&lgr;
2
+50) nm, where &lgr;
2
(nm) represents the other of the wavelengths &lgr; in the other of the two photoelectric conversion layers, and R
22
denotes an average reflectance, in the second wavelength region, of the photoelectric conversion device that does not include the intermediate film.
According to the photoelectric conversion devices of the present invention, since the average reflectances are low in the wavelength regions allowing the photoelectric conversio
Fujisawa Akira
Hirata Masahiro
Norimatsu Hodaka
Otani Tsuyoshi
Sueyoshi Yukio
Diamond Alan
Merchant & Gould P.C.
Nippon Sheet Glass Co., Ltd
LandOfFree
Photoelectric conversion device and substrate for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Photoelectric conversion device and substrate for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Photoelectric conversion device and substrate for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2913274