Surface Potential Homogenization Improves Perovskite Solar Cell Performance

The synthesis of multicomponent metal halide perovskites (MHPs) by cationic and/or halide alloying allows band gap tuning, optimizing performance and improving stability. However, these multicomponent materials often suffer from compositional, structural, and property inhomogeneities, leading to uneven carrier transport and significant non-radiative recombination losses in lead halide perovskites. While many researchers have focused on the aggregation of perovskite halide ions, the impact of the surface potential has received relatively less attention. In this study, the multifunctional ionic liquid 1-allyl-3-methylimidazole dicyanamide (AMI) is introduced into the perovskite precursor to effectively regulate the surface potential of the perovskite layer. This approach inhibits non-radiative recombination, enhances carrier injection, and improves device performance. Surface potential homogenization within the perovskite layer leads to simultaneous improvements in both the efficiency and stability of perovskite solar cells. For wide-bandgap perovskites (1.81 eV), the optimal power conversion efficiency (PCE) reaches 20.44%, with an open-circuit voltage (V_oc) of 1.339 V, a short-circuit current density (J_sc) of 17.92 mA cm⁻², and a high fill factor (FF) of 85%. This strategy also proved effective for conventional bandgap perovskite solar cells (PSCs) (1.53 eV), leading to a significant increase in performance, with the PCE increasing from 23.22% to 25.41%.