Three Birds with One Stone: Construction of Highly Efficient Interfaces via Ammonium Sulfamate Doping SnO2

Interface engineering plays a crucial part in optimizing the device performance in perovskite solar cells (PSCs). Herein, ammonium sulfamate (ASA) is introduced as a multifunctional additive into SnO2 electron transport layer (ETL) with a “three birds with one stone” strategy. At first, the oxygen vacancy and hydroxyl ligand on the surface of SnO2 nanoparticles causing charge recombination is efficiently reduced by incorporating ASA into SnO2 colloidal dispersion. Second, the coordination bond of SO3− anion in ASA with SnO2 and the interaction between NH2 in ASA with Pb2+ construct a chemical bridging at the interface of ETL/perovskite. It significantly enhances the interfacial electron transport. Third, the introduction of ASA is conducive to form high‐quality perovskite films with larger crystallite size and improved crystallinity due to the optimization of buried interface. Consequently, by the integrated effects on both interfaces and the bulk, the ASA‐based device delivers an increased efficiency from 20.73% to 24.41%. Moreover, the ASA optimized device displays a remarkable retention of over 90% of its original power conversion efficiency after 1000 h under a controlled N2 atmosphere, demonstrating the stability is significantly enhanced.