Inhibiting Ion Migration and Oxidation in Sn–Pb Perovskite by Multidentate Chelating Additive Strategy
Tianjun Ma, Xinzhao Zhao, Xuke Yang, Jun Yan, Dingfu Luo, Mingyu Li, Xiong Li, Chao Chen, Haisheng Song, Jiang Tang
Abstract
Abstract Currently, all‐perovskite tandem solar cells have achieved power conversion efficiencies exceeding 29%. The further improvement is limited by mixed Sn–Pb narrow‐bandgap perovskite subcells. The facile oxidation of Sn 2+ to Sn 4+ poses an inherent challenge that limits the efficiency and stability of Sn–Pb perovskite solar cells. In this study, a multi‐dentate chelating additive, 3‐amino‐2‐chloroisonicotinamide (ACPC), is developed. Its amino group could anchor I − of the perovskite lattice by hydrogen bonds, thereby preventing I − migration and oxidation. On the other hand, the carbonyl group of ACPC as a Lewis base group could coordinate with Sn 2+ , effectively protecting Sn 2+ from oxidation. Ultimately, the multi‐dentate chelating effect of ACPC helps to suppress the oxidation of Sn–Pb perovskite and its related nonradiative recombination. The resulting Sn–Pb perovskite solar cells obtain a top power‐conversion efficiency (PCE) of 23.09% and a high open‐circuit voltage ( V OC ) of 0.902 V while the control values only reach 19.11% and 0.825 V. As a result of the improved performance of the Sn–Pb perovskite solar cells, the corresponding all‐perovskite tandem solar cells achieve a PCE of 27.60%, retaining 85.7% of initial PCE after 500 h continuous 1 sun illumination.