Natural Antioxidant-Inspired Interfacial Engineering for Stable and High-Performance Perovskite Solar Cells

Abstract

Although perovskite solar cells (PSCs) have recently achieved high certified power conversion efficiencies (PCEs), operational instability remains a critical obstacle to commercialization. In particular, superoxide (O2∙−) generated at metal-oxide charge-transport layers rapidly decomposes perovskites by deprotonating the organic cations (FA⁺ and MA+) and therefore must be suppressed. Nevertheless, under operating illumination, the formation and diffusion of O2∙− are unavoidable as long as metal oxides are employed in PSCs. To address this, we introduce the natural antioxidant taurine at the SnO2/FAPbI3 interface to suppress O2∙− diffusion via chemical radical quenching. We elucidate the taurine-mediated O2∙− quenching mechanism through density functional theory (DFT) calculations supported by experiments. In addition, we find that I2 is concomitantly reduced to I- during the quenching process. This antioxidant interface prevents O2∙− induced perovskite decomposition under strongly oxidizing conditions. Moreover, the multifunctional groups of taurine form a chemical bridge between SnO2 and FAPbI3, reducing interfacial defect density, enhancing carrier mobility, and suppressing non-radiative recombination. Consequently, the taurine-buried interface enables an improved PCE with increased open-circuit voltage (VOC) and fill factor (FF), while markedly enhancing the light-soaking and operational stability of PSCs.