Perovskite solar cells: a quantum leap in solar research

Organic–inorganic metal halide perovskites are recently proved to be suitable candidates for application in solar cells. Devices made of perovskite show efficiencies from 3.8% in 2009 to National Renewable Energy Laboratory (NREL) certified efficiency of 22.1% in 2016 making this the fastest-advancing solar technology to date. CH3NH3PbI3 and CH3NH3PbI3-xClx are currently the front-and-center materials for high efficiency perovskite solar cell. They are used as absorber materials, in combination with electron (electron transport layer (ETL)-TiO2, ZnO etc.) and hole (hole transport material (HTM) - spiro-OMeTad, P3HT etc.) selective contacts. The structural stability of perovskite solar cells depends on organic cation CH3NH3, while the electronic properties are largely influenced by metal and halide hybridized orbitals. Different device architectures are possible due to flexibility and simplicity of perovskite fabrication methods. In this review, the current status of perovskite materials is highlighted along with mention on the issues and future challenges.