JPS606077B2 - photocell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photovoltaic cell, and to a device for converting light energy into electrical energy.

More specifically, it relates to a conversion system including a photoelectric effect and a photochemical reaction at the interface between a semiconductor and an electrolyte. 2. Description of the Related Art Solar cells have long been known as a means of converting natural light energy such as sunlight into electrical energy.

That is, this is a method in which light is incident on a PN junction of a semiconductor to generate pairs of holes and electrons, thereby extracting electrical energy. On the other hand, there is also a method in which a positive electrode or a negative electrode active material is generated through a photochemical reaction, and electrical energy is extracted by causing a normal chemical cell reaction with these materials. The former type of solar cell uses, for example, a diffused P-N junction of Si single crystal, but this requires expensive materials and a complicated process. . This requires a lot of processing and is expensive. On the other hand, photochemical cell systems are still inexpensive and reliable due to their complex system, and there are no small-sized ones available in the world. In view of the current situation, the present invention aims to provide a photovoltaic cell that can be manufactured at low cost, easily miniaturized, and has high conversion efficiency. That is, a semiconductor with an internal electric field formed therein and an electrolytic solution (for example, 0.1 MH
cl, etc.) to make light incident on the solid/liquid interface. The purpose is to utilize the photoelectric effect of such an interface. Compared to the conventional P-N junction method, this method does not necessarily require a single-crystal wafer or a diffusion process, and the electrolyte can be an aqueous solution, so it absorbs less light than the conventional P-diffusion layer. Since the amount of light is small, the light incidence efficiency is good. Furthermore, since there is a photosensitizing effect at the interface, it has the advantage of increasing conversion efficiency. Furthermore, the conversion efficiency is improved by forming an electric field inside the semiconductor. Since the present invention is easy to manufacture, the manufacturing cost is low, and it is easy to design into a 4-inch cell, it is suitable as an energy source for portable devices such as electronic watches and pocket calculators. explain.

Example 1 CdS is used as a semiconductor.

Figure 1 shows the structure of the cell. That is, an aluminum or chromium electrode 2 is attached on an alumina substrate 1 by vapor deposition or sputtering. This metal thin film 2 is a semiconductor lead electrode. Next, on this metal thin film 2, a C-type thin film 3 (n-type) having a resistivity of 1 to 100 is applied by vapor deposition or sputtering.

The thickness of the thin film is approximately 10 meters. Copper of about 100 Δ is deposited on the surface of this CdS thin film 3 and heat-treated at 250 to 30° for 10 minutes, so that about 2 Am of the surface of the CdS thin film becomes a high resistance layer and an internal electric field is formed from the surface toward the inside. Then about 1
A glass substrate 6 having a Nesa film 5 is placed opposite to the glass substrate 6 with a resin film of 0.00 French mm in between. At this time, a small hole 7 is prepared in advance in the glass substrate 6 for later injection of an electrolytic solution. After applying adhesive around the resin film to prevent the electrolyte from leaking, the electrolyte is injected from the injection port 7 and sealed using a potassium chloride solution containing a sodium acetate buffer. When this cell is irradiated with light from the direction of the arrow, a photovoltaic force is obtained such that lead wire 8 is positive with respect to lead wire 9. By creating an electric field inside the semiconductor, eight pairs of electrons and holes are generated by light inside the semiconductor, and the electrons are collected by the electric field on the electrode on the semiconductor side.On the other hand, the holes are collected on the surface of the semiconductor, and further Since the internal electric field is emitted inside, the light utilization efficiency becomes less than that without internal electric field.Under direct sunlight of about 10 hW, the open circuit voltage is 0.
A voltage of 9V and a short circuit current of 2 hA/h were obtained. It is possible to make a similar photovoltaic cell even if the semiconductor is not a polycrystalline thin film but a crystalline thin film. Example 2 The cell has exactly the same shape as in Fig. 1, but after depositing the CdS thin film 3, about 300△ of C or S was deposited on the surface of the CdS, and the Cu2S was heat-treated at 20,000 for 20 minutes.
Since it is a type semiconductor, a P-N junction is formed with CdS and Cu2S, and an internal electric field is generated in the semiconductor layer, resulting in the same effect as in Example 1.

Example 3 In a cell with the same shape as in Fig. 1, N-type Ga was used instead of CdS3.
As is deposited by R.F. sputtering.

The thickness is approximately 10vm. Te was thermally diffused over approximately 2 cm of this surface to form a PN junction and an internal electric field. Other steps are the same as in Example 1. In this photovoltaic cell, an open circuit voltage of 0.6V and a short circuit current of 200V were obtained under sunlight of 10V/ground. In the above explanation, CdS and G
Although aAs has been described, similar photovoltaic cells can be made using Si8 Ti02, GaAI, CaTe, and CdSe.

If the photovoltaic cells mentioned above are connected in series, the electromotive force will be added, so if you select an appropriate number of stages and combine it with a secondary battery, you can use it as an energy source for watches and pocket calculators. I can do it.

FIGS. 2 and 3 are examples in which the present invention is applied to clocks with an analog display and a digital display, respectively.

In FIG. 3, vines Qa and tortoises Qb are photovoltaic panels of the present invention, each having three stages of cells installed in series. In the Umbrella Diagram, the turtles and turtles are photovoltaic panels.

As mentioned above, the present invention is advantageous because the semiconductor provided on the electrode is made of a polycrystalline deposited film and is composed of a PN junction.
Since the N-junction is formed by thermal diffusion, the diffused impurities have a continuous distribution, so the internal electric field is also continuous, resulting in smooth carrier flow and good collection efficiency.

Furthermore, since it is a PN junction, the potential difference in the semiconductor electrode is large, and it has the effect of obtaining a large electromotive force.

[Brief explanation of the drawing]

FIG. 1 shows the photovoltaic cell of the present invention, and FIGS. 2 and 3 show the photovoltaic cell of the present invention applied to analog and digital wristwatches. Tatami...0 Insulator substrate, 2...Metal thin film electrode "3
...Semiconductor thin film, 4...Resin film 5M state membrane 6...Glass substrate, 4...W to the electrolyte sealing port 8...
Lead wire, 9... Lead wire, Kame oa, Qb... Photovoltaic panel 11... Photovoltaic panel. Younger brother' figure Younger brother 2 figure Younger brother 3 figure

Claims (1)

[Claims] 1 An electrolyte solution is sandwiched between opposing electrodes, a semiconductor thin film is formed on one of the electrodes, light is incident on the solid-liquid interface between the semiconductor and the electrolyte solution, and electrical energy is generated between the semiconductor and the opposing electrode. 1. A photovoltaic cell characterized in that the semiconductor is made of a polycrystalline vapor-deposited film and constituted by a PN junction.