Perovskite solar cells (PSCs) have achieved power conversion efficiencies (PCEs) exceeding 25% over the past decade and effective passivation for the interface with high trap density plays a significant role in this process. Here, two organic molecules are studied as passivators, and it is demonstrated that an advantageous molecular geometry and intermolecular ordering, aside from the functional moieties, are of great significance for effective and extensive passivation. Besides, the passivation molecules spontaneously form a uniform passivation network adjacent to the bottom surface of perovskite films during a top-down crystallization via liquid medium annealing, which greatly reduces defect-assisted recombination throughout the whole perovskite/SnO2 interface. The champion device yields an in-lab PCE of 25.05% (certified 24.39%). The investigation provides a more comprehensive understanding of passivation and a new avenue to achieve effective bottom-interface engineering for perovskite photovoltaics.
Keywords: bottom-interface engineering; interface passivation; molecular geometry; molecular ordering; perovskite solar cells.
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