Abstract: Various defects exist in tin-lead alloyed perovskites,and Sn²⁺is easily oxidized to Sn⁴⁺,which lead to poor power conversion efficiency（PCE）and stability of solar cells.It is found that the introduction of p-Coumaric acid modifies the surface morphology of the film,effectively improves the crystallinity,and inhibits the oxidation of Sn²⁺,which is conducive to the matching degree of energy levels between the perovskite layer and the transport layer.The photovoltaic characteristics of the device are significantly enhanced through passivating the defects in the perovskite layer.Ultimately,the open-circuit voltage of the tin-lead perovskite solar cell is enhanced by65 mV.The PCE is increased from 18.14%to 20.37%,and the stability of the device is effectively improved.