Lead-Free Perovskites: Metals Substitution towards Environmentally Benign Solar Cell Fabrication

Perovskite solar cells have attracted significant attention during the current decade owing to their efficacy and photovoltaics performance, which has reached a new milestone in the thin-film category. Perovskite solar cells have witnessed a remarkable 25.2 % light-to-electricity conversion efficiency; however, the toxicity of the commonly employed Pb counterpart towards humans as well as the environment, in addition to material instability, are current bottlenecks towards commercial application. The scientific community has explored other metal ions as substitutions for Pb, while preserving the unique properties of the material, to produce environment-friendly perovskites. In this Review, we highlight the recent developments and challenges of Pb-free halide perovskite-based light harvesters for solar cell applications. This summary is intended to aid in the further development of a materials library for this sustainable technology.