Unveiling Property of Hydrolysis-Derived DMAPbI3 for Perovskite Devices: Composition Engineering, Defect Mitigation, and Stability Optimization

Additive engineering has become increasingly important for making high-quality perovskite solar cells (PSCs), with a recent example involving acid during fabrication of cesium-based perovskites. Lately, it has been suggested that this process would introduce dimethylammonium ((CH3)2NH2+, DMA+) through hydrolysis of the organic solvent. However, material composition of the hydrolyzed product and its effect on the device performance remain to be understood. Here, we present an in-depth investigation of the hydrolysis-derived material (i.e., DMAPbI3) and detailed analysis of its role in producing high-quality PSCs. By varying the ratio of CsI/DMAPbI3 in the precursor, we achieve high-quality CsxDMA1-xPbI3 perovskite films with uniform morphology, low density of trap states, and good stability, leading to optimized power conversion efficiency up to 14.3%, with over 85% of the initial efficiency retained after ∼20 days in air without encapsulation. Our findings offer new insights into producing high-quality Cs-based perovskite materials.