Perovskite Solar cells
The pervoskite solar cells are those cells with perovskite structured compound. It is an organic or inorganic tin based material. Some of the other perovskite materials are methylammonium lead halides and cesium lead halide. They are inexpensive and simple to manufacture.
An Australian – Chinese research team has found perovskite solar cell with conversion efficiency of 22.6%. The fill factor of the cell is 85.3%. The device was fabricated using nitrogen doped titanium oxide. With this the scientists have increased the charge transport between perovskite absorber and the electrodes.
The efficiency of solar cells have increased from 3.8% in 2009 to 25.7% in 2022 due to these materials. They are mainly known for their cheap production costs. This is mainly due to their easy fabrication.
The absorption coefficient of perovskite materials is high. This helps in the formation of ultra thin films. The perovskite films are 500 nm thin. In such minute thickness, the material is capable of absorbing the entire visible spectrum. These features help in building light weight, high efficiency, low cost and thin solar modules.
The perovskite solar cells are mainly used to power Internet of Things and wireless electronics. It also helps to mitigate climate change.
Structure of Perovskite
It is derived from ABX3 crystal structure. Here A is a cation and B is an anion. X is a halogen. The bandgap of the structure is 2.3 eV. Band gap is the energy required to transit an electron from the valence band to conduction band. Lesser the band gap, higher the electrical conductivity.
Some of the perovskite solar cells are made of lead. This strains the public acceptance of the technology. The WHO says that lead level of 5 micro gram per deci litre of lead is safe for humans. Scientists are working to replace lead halides with tin halides. Germanium halide perovskites are unsuccessful mainly because of very low efficiencies.
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