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.