The principle of solar cell power generation is mainly the photoelectric effect of semiconductor. Silicon material is a kind of semiconductor material. The principle of solar cell power generation is mainly to use the photoelectric effect of semiconductor. When other impurities, such as boron and phosphorus, are added into the silicon crystal, when boron is added, the boron element can capture electrons, and there will be a hole in the silicon crystal. This hole becomes very unstable due to the absence of electrons and is easy to absorb electrons and neutralize. It becomes a hole type semiconductor, called p-type semiconductor. Similarly, after the phosphorus atom is doped, because the phosphorus atom has five electrons, one electron will become very active to form an electronic semiconductor, which is called an n-type semiconductor. P-type semiconductors contain more holes and n-type semiconductors contain more electrons. In this way, when p-type and n-type semiconductors are combined together. A special thin layer will be formed in the interface region of the two semiconductors. The p-type side of the interface is negatively charged and the n-type side is positively charged, resulting in a concentration difference. The electrons in the N region will diffuse to the p region, and the holes in the p region will diffuse to the N region. Once diffused, an "internal electric field" from n to P will be formed, so as to prevent the diffusion. After reaching equilibrium, such a special thin layer is formed to form potential difference, so as to form PN junction. When the wafer receives light, in the PN junction, the holes of the n-type semiconductor move to the p-type region, and the electrons in the p-type region move to the n-type region, thus forming a current from the n-type region to the p-type region. Then a potential difference is formed in the PN junction, which forms the power supply.
Thin film solar cells and concentrating solar cells are used to reduce the dependence on raw materials. The conversion rate of common thin-film batteries is low, so the new high-power concentrating battery system has attracted the attention of researchers. The concentrating solar cell focuses the sunlight several times, dozens of times, hundreds of times or even thousands of times with a convex lens or paraboloid mirror, and then projects it onto the solar cell. At this time, the solar cell may produce a corresponding multiple of electrical power. They have the advantages of high conversion rate, small battery floor area and less consumables. Gallium arsenide (GaAs) solar cells are representative of high power concentrating cells.
GaAs is a III-V compound semiconductor material. Its energy gap matches the solar spectrum and can withstand high temperature. Compared with silicon solar cells, GaAs solar cells have better performance.
So the si and gaas are used in solar cell.