Anti-solvent engineering enables efficient ambient-processed halide perovskite solar cells

Organic-inorganic metal halide perovskite thin film formation is one of the major challenges for solution-processed perovskite optoelectronic and photovoltaic devices, in particular, in ambient conditions due to their hygroscopic nature. Therefore, to improve the quality, optical properties, and performance of ambient processed metal halide perovskite thin films, it is necessary to have control over the fabrication process. We demonstrate how compositional and morphological control of ambient-processed perovskite films can be achieved using anti-solvents. We compare how exposing the film to anti-solvents, including dichlorobenzene, ethanol, and chlorobenzene, affects the crystallization and device performance of ambient-processed planar heterojunction perovskite solar cells. We also analyzed the charge carrier dynamics of the devices and found that including dichlorobenzene leads to reduced charge carrier recombination. The incorporation of dichlorobenzene results in densely packed grains without voids, leading to the best-performing device with a reproducible power conversion efficiency of ∼20%. These findings open the possibility of developing low-cost, highly reliable perovskite solar cells for commercial applications in the future.