Boosting Photovoltaic Efficiency: The Role of Functional Group Distribution in Perovskite Film Passivation

The utilization of small organic molecules with appropriate functional groups and geometric configurations for surface passivation is essential for achieving efficient and stable perovskite solar cells (PSCs). In this study, two isomers, 4-sulfonamidobenzoic acid (4-SA) and 3-sulfamobenzoic acid (3-SA), both featuring sulfanilamide and carboxyl functional groups arranged in different positions, are evaluated for their effectiveness in passivating defects of the perovskite layer. The calculation and characterization results reveal that 3-SA, with its meta-substitution, offered superior passivation compared to the para-substituted 4-SA, leading to enhanced charge carrier dynamics and extraction efficiency. The devices treated with 3-SA demonstrates a notable increase in power conversion efficiency from 21.50% to 23.30%. Moreover, these devices maintain over 90% of their initial efficiency after 2000 h in a 30% relative humidity environment, showcasing exceptional long-term stability. This research advances strategic design approaches for small molecule passivation, providing critical insights for the enhancement of perovskite optoelectronic applications.