118-119 Chapter 5 Solar cells, modules and array
Author: Source: Datetime: 2017-01-22 17:12:28
Chapter 5 Solar cells, modules and solar array
5.1 Solar cells
5.2 Solar cell components and phalanx
5.1 Solar cells
As mentioned above, solar cells is a use of photovoltaic effect of light energy into electrical energy devices, also known as photovoltaic devices. Electromotive force generated by the phenomenon of absorption of light energy, known as the photovoltaic effect. This phenomenon occurs both in liquid and solid matter. However, only in the solid, especially in the semiconductor, have a higher energy conversion efficiency. Therefore, it is often referred to as solar cells, semiconductor solar cells.
Solar cells are made of semiconductor materials, the development so far, has a wide range of various forms.
(1) by structure classification
Solar cells in accordance with the different structure can be divided into five categories as follows.
① homojunction solar cell homojunction solar cells are composed of the same semiconductor materials, one or more P-N junction of solar cells. Such as silicon solar cells, gallium arsenide solar cells.
② heterojunction solar cell heterojunction solar cells with two different band gap of semiconductor materials at the interface to form a heterogeneous junction of PN junction solar cells, such as indium tin oxide / silicon solar cells, copper sulfide / Cadmium sulfide solar cells. If the lattice structure of two heterogeneous materials is similar, the interface of the lattice match is better, called heterogeneous surface solar cells, such as AlGaAs / GaAs heteroplane solar cells.
③ Schottky junction solar cells Schottky junction solar cells are made of metal and semiconductor contact to form a "Schottky barrier" of solar cells, also known as MS solar cells. The principle is based on certain conditions under the metal - semiconductor contacts can produce a Schottky effect of rectifier contact. Metal-insulator-semiconductor solar cells, i.e., MIS solar cells, such as molybdenum / silicon Schottky junction solar cells, aluminum / silicon solar cells, such as aluminum / silicon solar cells, Silicon Schottky junction solar cells.
④ multi-junction solar cells formed by a number of P-N junction of solar cells, known as multi-junction solar cells, also known as complex junction solar cells, a vertical multi-junction solar cells, multi-junction solar cells and other points.
⑤ liquid junction solar cells by immersion in the electrolyte composition of the semiconductor solar cell called liquid junction solar cells, also known as photoelectrochemical cells.
According to the structure of solar cells to classify, the physical meaning of more clear, which has been adopted by the state as the basis for naming solar cells.
(2) by material classification
Solar cells in accordance with the different materials can be divided into the following categories.
① silicon solar cell This battery is based on silicon solar cells, such as monocrystalline silicon solar cells, polycrystalline silicon solar cells, amorphous silicon solar cells and so on. Production of polycrystalline silicon solar cells, available purity is not too high solar silicon. Polysilicon materials and ribbon silicon, cast silicon, thin film polysilicon and other. Solar cells made with them have two kinds of film and sheet.
(1) Compound semiconductor solar cell This solar cell means a solar cell made of a compound material having semiconductor properties composed of two or more kinds of elements. Such solar cells can be divided into crystalline inorganic compounds, amorphous inorganic compounds and organic compounds, oxide semiconductor and other four categories. The former has 3-5 group compound semiconductor gallium arsenide, gallium phosphide, indium phosphide, indium antimony, etc., 2-6 compound semiconductor cadmium sulfide, zinc sulfide, and its solid solution (such as gallium aluminum arsenic, gallium arsenic phosphorus Etc.), and the latter are, for example, glass semiconductors, organic semiconductors, oxide semiconductors (such as MnO, Cr2O3, FeO, Fe2O3, Cu20).
② organic semiconductor solar cells that contain a certain number of carbon-carbon bonds and the conductivity between the metal and insulator between the organic semiconductor materials made of solar cells, there are naphthalene, anthracene, pyrene and other molecular crystals, aromatics - halogen complex Aromatic hydrocarbon-metal halide and other charge transfer complexes and polymers.
(1) by shape classification
Figure 5-1 shows the solar cells according to the thickness of the semiconductor is divided into two kinds of massive and thin film solar cells. Bulk-like solar cells, refers to monocrystalline silicon, polycrystalline silicon made of massive crystals, and then processed into flakes as a sheet-like semiconductor for solar cells. Bulk crystalline silicon solar cells are widely used in electricity. In the bulk crystal, GaAs, InP and other 3-5 groups of semiconductors for the amorphous silicon system is expected to achieve 30% to 40% conversion efficiency of compelling. This kind of material substrate and processing costs are high, so the current mainly in aerospace and concentrating batteries as the focus.
Figure 5-1 Types of solar cells
The thin-film solar cell means a solar cell having a semiconductor layer with a thickness of 50 m or less. The thin-film solar cell has a silicon-based thin-film solar cell, a 2-6 compound thin-film solar cell, and a chalcopyrite-based solar cell. Silicon thin-film solar cells on behalf of amorphous silicon (a-Si) solar cells, both at home and abroad have long been mass production. The thickness of the amorphous silicon solar cell is only 0.3 m. In addition, the amorphous silicon advantage, but also to make up for its shortcomings, so look forward to the use of polysilicon and microcrystalline silicon thin film solar cells, amorphous silicon solar cell conversion efficiency has been a leap; also on the amorphous silicon And polycrystalline silicon stack of multi-junction thin film solar cells placed high expectations. In the compound thin film system, small-scale Cu (InGa) Se2 (CIGS) solar cells also have products to sell. In addition, with CdTe thin-film solar cells made of large area components, has also entered the residential area. As well as the future of new materials as organic materials and dye-sensitized batteries.
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