Types of Solar Cells

Types of Solar Cells


 As a device that directly converts solar energy into electrical energy by the photochemical or photoelectric effect. At present, the main development trend of solar cells is based on the principle of the photoelectric effect, and the principle of the photochemical effect is still in the initial period of research and development.
 
1. Photovoltaic solar cells
Photovoltaic solar cells include monocrystalline silicon solar cells, polycrystalline silicon solar cells, silicon-based solar cells, CIGS solar cells, cadmium sulfide (CdTe) solar cells, GaAs thin-film solar cells and IBM thin-film solar cells.
 
In the laboratory, the conversion efficiency of monocrystalline silicon solar cells can be as high as 24.7%, while that of polycrystalline silicon solar cells can be as high as 22.04%; the conversion efficiency of silicon-based thin-film solar cells after light attenuation can be as high as 14.04%. In thin-film solar cells, the conversion efficiency of CIGS and CdTe cells can reach 22.9%. Spire Semiconductor Corporation of the United States announced that the conversion efficiency of GaAs thin-film solar cells can be as high as 42.3% in October of 2010.
 
2. Photoelectrochemical solar cells
Photoelectrochemical solar cells are solar cells such as dyed perovskite solar cells, dye-sensitized solar cells (DSSC) and so on.
 
2.1 Dye-sensitized solar cells
Dye-sensitized cells mainly use relatively low-cost materials such as nanocrystalline TiO2 and photosensitizing dyes as raw materials, which are similar to the principle of photosynthesis using chlorophyll in imitation of green vegetation, and convert the energy of sunlight into electricity; the highest conversion efficiency is higher than 13.1%.
 
The role of sensitizers: When sunlight is irradiated on the photosensitive dye molecules, the dye molecules will transition the electrons from the ground state to a high-energy state after absorbing the energy of solar photons. The sensitizers can be classified into narrow bandgap semiconductors, organic dyes and polypyridine complex sensitizers.
 
2.2 Perovskite solar cells
All-solid-state perovskite structure is used as the light absorbing material for perovskite solar cells, which have a similar composition to DSSC. Replace the sensitizer in DSSC with ABX in the perovskite structure. A and B are generally composed of cations (inorganic Cs+ or organic FA/MA+) and cations (inorganic Pb2+). Anion X generally refers to Cl- and other halogen elements. At this stage, perovskite solar cells have reached a conversion efficiency of 24.2%.
 
Table 1 Comparative analyses of solar cells
Types of solar cells Highest conversion efficiency Advantages Disadvantages
Monocrystalline silicon solar cells 24.7% They have a long service life. They have high costs and complicated purification processes.
Polycrystalline silicon solar cells 22.04% This technology is the most mature, and the production cost is lower than that of monocrystalline silicon. They have lower conversion efficiency than those of monocrystalline silicon solar cells.
Silicon based thin-film solar cells 14.4% They can generate electricity even in low light and have low costs. They have low conversion efficiency.
CIGS thin-film solar cells 22.1% They have low costs. In and Ga are rare metals.
CdTe thin-film solar cells 22.9% Their production processes are relatively simple. The natural storage of Te is limited, and ed is highly toxic.
GaAs thin-film solar cells 42.3% They have large forbidden band width and high-temperature resistance. They have high costs. Ga is a rare metal and As is toxic.
Dye-sensitized solar cells 13.1% Raw materials are abundant; they have low costs and simple production. They have low conversion efficiency.
Perovskite solar cells 24.2% They have high conversion efficiency, low costs and simple production. They have poor stability. Pb is toxic and difficult to be encapsulated.
 
According to the comparative analysis of the above table, silicon-based thin-film solar cells are more suitable for large-scale production than other thin-film solar cells. At this stage, silicon is still the main material for solar cells, and crystalline silicon solar cells gain a leading market share.
 
According to the production material, solar cells can be divided into crystalline silicon solar cells, thin-film solar cells and dye-sensitized solar cells. They can be classified into rigid solar cells, soft solar cells and semi-rigid solar cells according to different packaging substrates. They can be divided into transparent solar cells and non-transparent solar cells based on the degree of light transmission. They can be divided into glass curtain wall solar cells, window eaves solar cells, roof solar cells, building-integrated solar cells, field placement solar cells and other solar cells according to the combination with the building.