Linear regulation of perovskite work function through organic molecular layer surface modification

Abstract

Surface modification via organic molecular layers is an effective strategy for experimentally regulating the work function (Φ) of perovskites. However, achieving precise control over Φ of perovskites remains a significant challenge. In this study, Φ of the FAPbI3 perovskite surface is quantitatively regulated using anilinium (An) and its derivatives. Three factors contribute to the change in Φ (ΔΦ): surface structure relaxation, surface charge exchange, and modified layer potential difference (ΔV). After the modification of perovskite surface with anilinium (An) and its derivatives, ΔΦ of FAPbI3 correlates linearly with ΔV of the modified layer, as the contribution of surface structure relaxation to ΔΦ is negligible, and the contribution of interfacial charge exchange to ΔΦ remains constant. The experimental results also demonstrated that Φ of perovskite surface can be linearly regulated. In addition, the linear relationship between ΔΦ and ΔV applies to other organic groups and their derivatives, as well as other metal halide perovskites. This methodology offers a practical computational strategy to precisely regulate Φ of the perovskite surface by designing ΔV of the modified layer.