There are two types of semiconductor materials: elemental semiconductors and compound semiconductors. The elemental semiconductor materials for the production of photovoltaic cells are mainly silicon and germanium, but silicon is the most used, accounting for more than 90% of the total consumption. Some compound semiconductors are also excellent materials for the production of photovoltaic cells. Currently known are gallium arsenide (GaAs), cadmium sulfide (CdS), cadmium telluride (CdTe), copper indium selenide (CIS), copper steel gallium selenide (CIGS) ), indium phosphide (InP), and gallium indium phosphide (GalnP).
(1) Silicon is an elemental semiconductor and can be divided into two types: crystalline and amorphous. Both crystalline and amorphous silicon can produce photovoltaic cells. Crystalline silicon is further divided into polycrystalline silicon and single crystal silicon. At present, monocrystalline silicon is the most used material in the production of photovoltaic cells. For more battery materials visit tycorun.com.
Monocrystalline silicon is widely used in industry, agriculture, aerospace, national defense, scientific research and other fields, and is currently the most important semiconductor material. Monocrystalline silicon is the earliest semiconductor material used in the production of photovoltaic cells, and it is also one of the most widely used semiconductor materials. It can be said that monocrystalline silicon is the most suitable material for the production of photovoltaic cells. The reason is that the monocrystalline silicon industry has developed to Economies of scale (reduce the cost per unit of product through high production capacity), and monocrystalline silicon has abundant raw material resources, mature production technology, low production cost, and does not cause any pollution to the environment. Because of the physical stress, it can be made into large-sized single-crystal silicon rods (now, the diameter of single-crystal silicon rods is about 300mm, while the maximum diameter of arsenide rods is only about 150mm). Polycrystalline silicon can not only be used alone to produce photovoltaic cells, but also is the raw material for the production of monocrystalline silicon. Therefore, polycrystalline silicon is used more than monocrystalline silicon and is the most used material in the production of photovoltaic cells.
(2) Germanium is an element semiconductor, and it is also the earliest used semiconductor. In recent years, it has also been used to produce photovoltaic cells, and amorphous silicon germanium thin film photovoltaic cells have been produced.
(3) Gallium arsenide (GaAs) is a compound synthesized by two elements, arsenic and gallium. It is also an important semiconductor material, used to make microwave integrated circuits [such as single crystal microwave integrated circuits (MMIC)], infrared light-emitting diodes and semiconductor lasers. In addition, gallium arsenide is also a semiconductor material for the production of photovoltaic cells. As a semiconductor, gallium arsenide has some better electronic properties than single crystal silicon, such as high saturation electron rate and high electron mobility, making gallium arsenide can be used in applications higher than 250GHz. Gallium arsenide will have lower noise if both the equivalent gallium arsenide and single crystal silicon components are operated at high frequencies at the same time. Also because gallium arsenide has a higher breakdown voltage, the arsenide image is more suitable for operating at high power than the same single crystal silicon element.
Another advantage of gallium arsenide is that it is a direct energy gap material, so it can be used to emit light. And single crystal silicon is an indirect energy gap material and can only emit very weak light. Furthermore, gallium arsenide is considered an ideal material for computer applications because of the fast switching speed of arsenide. Since gallium arsenide is a direct energy gap material, it is also a very suitable semiconductor material for the production of photovoltaic cells. The problem is that the toxicity of gallium arsenide has not been fully studied yet. Because it contains arsenic, studies have shown that arsenic is toxic and that arsenic is also a carcinogen. But because the crystal of gallium arsenide is very stable, if the body absorbs a small amount of arsenide, it can actually be ignored.
During the wafer polishing process (grinding GaAs wafers to make surface particles smaller), areas of the surface react with water, releasing or decomposing small amounts of arsenic. This has recently been pointed out when looking at gallium arsenide (like trimethylgallium and arsenic As) in terms of environmental, health and safety, and industrial hygiene monitoring studies of organometallic precursors.
(4) Cadmium sulfide (CdS) is an inorganic compound semiconductor of sulfur and cadmium, also known as cadmium yellow. High-purity cadmium sulfide is a good semiconductor. Since cadmium sulfide is a photoelectric material with a direct band gap, the gap energy band is about 2.4 eV, and it has a strong photoelectric effect on visible light, so it is a good N-type material for photovoltaic cells. It can form a heterojunction with cadmium telluride (CdTe) and copper indium selenide (CIS) materials with good performance, thereby becoming a cadmium telluride/cadmium sulfide thin film photovoltaic cell that can generate electricity.
(5) Cadmium telluride (CdTe) is an inorganic compound semiconductor of tellurium and cadmium. Cadmium telluride is an efficient, stable and relatively inexpensive photovoltaic cell material.
(6) Copper indium selenide (CulnSe2, which can be simplified as CIS) is an inorganic compound semiconductor of three elements: copper, indium and selenium. Copper indium selenide material is a direct band gap material, which is most suitable for thin-film solar cells. The thickness of the cell can be 2~3um, which can reduce the consumption of expensive materials. Its cost is 1/3~1/3 of that of crystalline silicon solar cells. 2. The energy repayment time is within one year, which is much lower than that of crystalline silicon solar cells.
(7) Copper indium gallium selenide (CIGS) is a compound semiconductor in which gallium is doped into the copper indium selenide material. Copper indium gallium selenide thin-film solar cells have the remarkable characteristics of low production cost, low pollution, no decay, and good low-light performance. 1/3, known as the next generation of very promising new thin-film solar cells, is a hot spot of research and development in recent years.
(8) Indium phosphide (InP) is an inorganic compound semiconductor of phosphorus and indium. It is a new generation of electronic functional materials after silicon and gallium arsenide. It has superior characteristics (such as electron mobility) that germanium and silicon do not have. It can be widely used in microwave and optoelectronic devices, and can also be used to produce indium phosphide thin film photovoltaic cells.
(9) Gallium indium phosphide (GalnP) is an inorganic compound semiconductor of phosphorus, gallium and indium. It is a new type of photovoltaic cell material and can be used to produce concentrated photovoltaic cells.