The Chemical Design in High-Performance Lead Halide Perovskite: Additive vs Dopant?

Metal halide perovskite solar cells (PSCs) have attracted enormous attention as one of the most promising candidates for next-generation photovoltaics in the past few years. During the development of PSCs, various chemicals have been added to improve film quality and device performance. However, there are still debates about whether these chemicals are additives as removed from the final film or dopants incorporated into the crystal lattice. It is important to clarify whether these added chemicals are additives or dopants when designed for high-quality perovskite films' fabrications. Herein, we summarized several commonly used chemicals for hybrid and all-inorganic perovskites, such as MACl, DMAI, MAAc, and alkali metal cations. The underlying mechanism and their roles during the formation of perovskite films were discussed. In the end, we proposed some conclusive important factors to clarify additives and dopants, which would be helpful for the further chemical design for improving high-performance perovskite devices.