Interfacial Dipole Engineering With Taurine‐Modified SnO ₂ Electron Transport Layer for Efficient and Stable Perovskite Solar Cells

Organic‐inorganic metal halide perovskite solar cells (PSCs) are promising for photovoltaics due to their excellent optoelectronic properties. However, achieving high efficiency and stability remains challenging, mainly due to defects and energy losses at the electron transport layer (ETL)/perovskite interface. Although interfacial modifications have been tried, many approaches suffer from steric hindrance or poor conductivity, hindering charge transport. Herein, we tackle these critical challenges in n‐i‐p structured PSCs by introducing taurine (Tau), a zwitterion with a simple structure, as a surface modification layer for SnO 2 ETL. The SO 3− group of Tau passivates Sn 4+ dangling bonds, whereas the NH 3+ group interacts electrostatically with iodide ions at the perovskite buried interface, forming a chemical bridge that reduces interfacial energy losses. Furthermore, Tau creates a dipole layer on the SnO 2 surface, lowering its work function and enhancing the built‐in electric field, thereby facilitating charge extraction and suppressing carrier recombination. As a result, Tau‐modified PSCs achieve a remarkable power conversion efficiency of 23.94%, up from 21.87% for the control devices, alongside significantly improved operational stability. This work reveals the promise of zwitterionic compounds for serving as multifunctional interlayers in achieving both high efficiency and enhanced stability in PSCs.