Adjusting Microstrain via Interface Engineering for Efficient and Stable Perovskite Solar Cells

The presence of strain can affect the performance of perovskite solar cells, but strain is often unavoidable in the preparation of perovskite solar cells (PSCs). Herein, 4,5-dichloroaniline-2-sulfonic acid (DCSA) served as a passivator to treat the SnO2 electron transport layer, which led to a reduction of trap states in the SnO2 film and enhanced the energy level alignment between the SnO2 and perovskite layer. The −Cl in DCSA effectively interacts with the uncoordinated Sn4+ that fills the oxygen vacancy sites on the surface of SnO2. Meanwhile, the −SO3H functional group in DCSA interacts with the uncoordinated Pb2+ in perovskite, thus retarding the nonradiative recombination process. These interactions eventually contribute to the decrease in lattice strain within the device. The optimized device achieved a champion power conversion efficiency of 23.32% and retained above 90% of its initial PCE value after 1032 h of storage under ambient conditions without encapsulation.