High-Light-Tolerance PbI2 Boosting the Stability and Efficiency of Perovskite Solar Cells.

Excess lead iodide (PbI2) plays a crucial role in passivating the defects of perovskite films and boosting the power conversion efficiency (PCE) of perovskite solar cells (PSCs). However, the photolysis of PbI2 is easily triggered by light illumination, which accelerates the decomposition of perovskite materials and weakens the long-term stability of PSCs. Herein, the high light tolerance of lead iodide (PbI2) is reported by introducing an electron-donor molecule, namely, 2-thiophenecarboxamide (2-TCAm), to strengthen the [PbX6]4- frame. Characterization reveals that the retarded decomposition of PbI2 is attributed to the interactions between Pb2+ and the organic functional groups in 2-TCAm as well as the optimized distribution of PbI2. The crystallization and morphology of 2-TCAm-doped perovskite films are improved simultaneously. The 2-TCAm-based PSCs achieve a 16.8% increase in PCE and nearly 12 times increase in the lifetime as compared to the reference device. The demonstrated method provides insight into the stability of PbI2 and its influence on PSCs.