_???????High Performance 2D/3D Tin-Lead Perovskite Solar Cells Achieved by Phenethylamine Acetate Post-Treatment

Environmentally friendly hybrid Sn-Pb-based perovskite solar cells (PCSs) have made great progress recently. However, the serious Sn (II)/I vacancy defects within perovskite film due to poor thermodynamic stability and strong reaction activity of Sn (II) still limit the efficiency and stability of Sn-Pb-based PSCs. In this work, we proposed a PEAAc post-treatment method to mitigate successfully this problem. Sn-Pb-based perovskite films were post-treated by phenethylamine acetate (PEAAc) to form a 2D layered structure on the surface of 3D perovskite film, which passivates the defects on the surface and at the grain boundary of the 3D perovskite and blocks the erosion of water and oxygen. In addition, the coordinate energy of Ac- with Sn2+/Pb2+ is larger than I-, which effectively inhibits the oxidation of Sn2+ and suppresses the ionic migration. Besides, the introduction of PEAAc also modifies the band energy alignment at the perovskite interface. Benefiting from these roles of PEAAc, the photovoltaic performance and long-term stability of the device are largely improved. As a result, the best device after PEAAc passivation achieves the open circuit voltage (VOC) of 0.79 V, the short-circuit current density (JSC) of 29.31 mA/cm2, and the fill factor (FF) of 0.75, and thus the PCE of 18.36% (the champion PCE of control device is only 14.75%). In addition, the PSCs treated by PEAAc can still maintain 60% of the initial efficiency stored in nitrogen after 700 h.