DMSO-based PbI2 precursor with PbCl2 additive for highly efficient perovskite solar cells fabricated at low temperature

Using a dimethylsulfoxide (DMSO)-based PbI2 precursor solution and employing PbCl2 as an additive, organolead halide perovskite films were fabricated via a sequential solution deposition process. It is found that the PbCl2 additive in DMSO system dramatically improves the properties of the resultant perovskite films, including the crack-free morphology and enhanced light absorption, while its crystalline structure is not altered. Under the conditions of 30 mol% PbCl2 doping, the films exhibit a high uniformity and an optimum light harvesting capability; as-prepared solar cells achieve the highest power conversion efficiency of 14.42%, which is 36.3% higher than that of the pure PbI2-based one. The cells employ nanocrystalline rutile titania as the contact layer deposited by a chemical bath deposition method, contributing to preparing the devices at a low temperature less than or equal to 100 °C. This work provides a simple, low-cost but effective strategy to improve the power efficiency of the perovskite solar cells.