Single-atom effect on the regulation of the buried interface for self-assembled molecules in inverted perovskite solar cells

Abstract

Although self-assembled molecules (SAMs) have shown great potential in boosting the device performance of inverted perovskite solar cells (iPSCs) over the past years, their molecular design strategies are particularly varied, with ambiguous design principles due to their significantly different molecular structures and resultant properties. Herein, we designed and developed a series of SAMs with nearly identical structures, differing by only a single atom (from an O atom to S and Se atoms). It was found that the corresponding SAMs, POZ-PA, POT-PA and POSe-PA, exhibited distinct molecular configurations and properties. POZ-PA containing an O atom possessed a relatively planar structure, leading to a denser self-assembled film and superior interfacial properties, such as well-matched energy level alignment, excellent passivation capacity and optimized charge dynamics. Consequently, a champion power conversion efficiency of 22.23% was realized for POZ-PA-based PSCs, along with good storage and thermal stability. This work provides a more precise molecular design strategy to better investigate the structure–property–performance relationships and offers guidance for the development of efficient and stable hole-selective materials.