A Natural Antioxidant Organic Material Modifying the Buried Interface To Regulate the Photovoltaic Performance and Stability of Pure Tin-Based Perovskite Solar Cells.

Despite showing great potential in lead-free green energy, tin-based perovskite materials still face challenges such as inherent material instability and energy level misalignment with the hole transport layer (HTL), which limits the advancement of tin-based perovskite solar cells (Sn-PSCs). In this work, a natural antioxidant organic small molecule, thiolactic acid (TA), is used to modify the interface between PEDOT:PSS and the tin-based perovskite film. The TA molecule can cross-link to form a network polymer and regulate the microstructure and photoelectrical characteristics of PEDOT:PSS. Meanwhile, TA contains C═O and C─S groups, which can interact with Sn to inhibit its oxidation. Moreover, the introduction of TA interfacial modification effectively improves the morphology of the perovskite film, suppresses interfacial charge recombination, and promotes carrier transport. Thus, TA-modified Sn-PSCs achieve a champion power conversion efficiency of 9.03%, surpassing 6.92% of the control PSCs. Even after being stored for 1000 h in a nitrogen atmosphere, the unencapsulated devices with TA modification still maintain 95.4% of their original PCE, compared to only 66.5% of the control devices. This study demonstrates the significance of the PEDOT:PSS/tin-perovskite interfacial modification on the efficiency and stability of Sn-PSCs.