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.