Unifying Crystal Growth and Defect Passivation in Photovoltaic Perovskites: The Impact of Molecular Coordinating Strength

Perovskite solar cells (PSCs) are attractive due to their fast-increasing device efficiency, yet their further improvement is limited by their suboptimal morphology and intrinsic defects. To assess how the widely used additive engineering impacts crystal growth and defect passivation, we herein propose a simple but effective strategy to disentangle the influence of molecular coordinating strength on the above factors, respectively. By fine-tuning a single halide atom on the additive molecule, we can transform the functional role of the additive from only a normal passivator into a passivator plus crystal-growth modifier, rendered by the tailored competition between the precursor–solvent and precursor–additive interactions. Thus, optimized PSCs leveraged by the above strategy deliver a PCE of over 24% with improved stability. The unified crystal growth and defect passivation under the impact of molecular coordinating strength here provides new insights into designing additive molecules of interest to further push the envelope of PSCs' efficiency.