JPS58130578A - Selenium optical battery - Google Patents

Abstract

PURPOSE:To obtain the highly efficient selenium optical battery, by laminating and forming a transparent conductive layer, a thin film comprising metal or a semiconductor, a selenium crystal film, and high work function metal layer on a substrate of a transparent material to which light is inputted, and attaching a pair of external lead wires to the transparent conductive layer and the high work function metal layer, respectively. CONSTITUTION:A material layer 2 having high conductivity and high light transmittance is deposited on the surface opposite to the light incident surface of the glass substrate 3, which is the transparent material layer. On the layer 2, the super thin film 4 with a thickness of about 100Angstrom , which comprises the metal or the semiconductor for improving the conductive property of the selenium layer 1, is deposited. Thereafter, an amorphous selenium layer with a thickness of 2- 5mum is deposited on the film 4. Heat treatment is performed at 160-200 deg.C and the amorphous selenium is transformed into a crystal. Then an ohmic electrode 6 is deposited thereon by using the high work function metal, and the external lead wires 5a and 5b are attached to the electrode 6 and the exposed surface of the layer 2, respectively. Thus the battery having the same response time as a silicon optical battery 1 is obtained by using inexpensive selenium.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an FC photovoltaic cell using selenium, a Group I element, as a matrix material.

Conventionally, selenium photovoltaic cells have played a role in sensor elements as photoelectric conversion elements, but their low energy conversion efficiency has limited their field of application despite their low cost and high reliability. The cause of the low conversion efficiency is an increase in the series resistance inside the photovoltaic cell due to the low conductivity of the dry selenium monoxide film that is the base material of the photovoltaic cell and the electrode material used.

It was obvious. The simplest and most reliable way to reduce series resistance is to reduce the thickness of the crystallized selenium film formed on the substrate of the photovoltaic cell.

When a selenium film is formed on a substrate by vacuum evaporation, etc., it is amorphous, and it is possible to make it thinner, but heat treatment is required to increase the conductivity of selenium by 5 to 6 orders of magnitude. During crystallization, selenium peeled off or became discontinuous from the substrate, making it impossible to form a crystallized selenium thin film 9 that would allow a technically stable photovoltaic cell to be produced.

The present invention uses a substrate with high conductivity and high transmittance as one electrode material, forms a technically stable crystallized selenium thin film on the substrate, and utilizes this to create a highly efficient 2RL structure. The purpose of the present invention is to provide a selenium photovoltaic cell. According to the present invention, high-efficiency selenium photovoltaic cells can be provided as sensors and energy conversion elements in fields where conventional selenium photovoltaic cells cannot be used, and furthermore, the effective use of abundant selenium substances can be expanded.

Examples of the present invention will be described in detail, and the photoelectric characteristics thereof will also be explained.

An example of the structure of a highly efficient selenium photovoltaic cell according to the present invention is shown in FIG. Selenium layer 1 used in this example
was vacuum-deposited on the surface of the glass substrate 3, which is a transparent material on which the material layer 2 having high electrical conductivity and high light transmittance is coated, and which is located on the side opposite to the light incident surface of the material layer 2. The selenium layer 1 was heat treated at a temperature of 160° C. to 200° C. to convert it from amorphous to crystalline. In a typical selenium battery, the thickness of the selenium layer that contributes to power output is approximately several tens of micrometers.

In the selenium battery shown in FIG. 1, the JIJ of selenium layer 1 is
The thickness is 2 to 5 μm, typically 4 μm. Such thin layers are necessary to reduce the series resistance of the photovoltaic cell. Furthermore, ultra-thin films of certain metals or semiconductors (
A layer (having a thickness of about 100 A) 4 is deposited on a light-transmissive substrate (2° 3) by vacuum deposition or sputtering to improve the conductivity of the selenium layer 1. The installation of an ohmic electrode (; on the back side of the selenium layer 1 is carried out using a high work function metal -C). are connected to each other.

FIG. 2 shows the current (I)-(V) characteristics of the selenium photovoltaic cell of the present invention under the incident light of the AMI using a sunlight simulator. Open end voltage, closed circuit short, SUI)v; current density, and fill factor (F, F) are respectively 77.0.4 ~
0.5 V, 9-10 mA/cm", 0.4~
It was 0.5.

The average conversion efficiency was 2.5% without an antireflection coating.

AMI efficiency is about 10 times higher than conventional photovoltaic cells! υN
It was. According to the present invention, selenium has been successfully used in solar cells to achieve the desired efficiency, but the main reason for the efficiency improvement is due to the II thickness of the selenium layer and the series This is a decrease in resistance and an increase in photocurrent due to the mirror effect at the counter electrode 6.

FIG. 3 shows an example of the IV characteristics of this photovoltaic cell in the dark. White circles indicate forward characteristics, and black circles indicate reverse characteristics. In the forward direction, the n value indicating the deviation from the ideal diode is approximately 1.7 between 0.3V and 0.5V. This n value is believed to be due to carrier recombination at grain boundaries within the selenium layer.

An advantage of using selenium material is that large area photovoltaic cells can be easily manufactured. Furthermore, it is thought that the effect V will reach nearly 14% by creating a selenium film and improving the film quality.

The conventional selenium photovoltaic cell has an illuminance of 1000 l.

Although the response time τ and τd at a load resistance 1 of Ω and a repetition frequency of 100 Hz were slow as shown in Figure 4, the selenium photocell of the present invention had a slow response time as shown in Figure 5 under the same measurement conditions. τ2. τd becomes about 1/2,
It has become equivalent to the non-condensed photocell. It shows the possibility of being used as an optical sensor or for converting light and electrical signals.

Furthermore, as described above, instead of depositing selenium, a selenium layer can be formed by sputtering if selenium is added and the surface of the selenium is kept at a predetermined temperature or lower. In this case, since the selenium layer formed is sequentially crystallized, crystallization by heat treatment at 160° C. to 200° C. can be omitted, which has the advantage of simplifying the manufacturing process.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIGS. 2, 3, 4, and 5 are characteristic diagrams and waveform charts showing characteristic examples of selenium photovoltaic cells according to the conventional and the present invention. . 1...Selenium crystal film, 2...Transparent conductive layer (electronic V
i), 3...Glass substrate, 4...Metal or cow conductor thin, 1.5a, 5b...External conductor, 6...
- High work function gold + r5 ran (electrode). Patent applicant Country Akio Oka Agent Otsuka 1 off-campus person No. II ¥1 3rd Seki V (Vl Ya 4 Figure 5 Flash 0.4m9 0.45m!ii Procedural amendment (voluntary) Showa) March 1, 157 Japan Patent Office Commissioner Shima 1) Haruki Tono Indication of the case Patent Application No. 1987-011747 2 Name of the invention Selenium photocell 3 Person making the amendment Relationship to the case Applicant Akio Oka 4 Agent Nishi, Shinjuku-ku, Tokyo Shinjuku 1-23-1 5, column 6 of "Detailed Description of the Invention" of the subject specification of the Supplementary IE, the statement in the description of the contents of the amendment is corrected as follows. (1) Page 3, lines 12 and 14 [Selenium battery]
selenium photocell]. (2) Page 4, line 6 [Current (I)-] is followed by [1iL
b].

Claims (1)

[Claims] A substrate made of a transparent material through which light enters, a transparent conductive layer formed on the substrate, a metal or semiconductor thin film formed on the transparent conductive layer, and a selenium crystal film formed on the metal or semiconductor thin film. A selenium photovoltaic cell comprising: a high work function metal layer formed on the selenium crystal pattern; and a pair of external conductive wires respectively provided on the transparent conductive layer and the high work function metal layer.