Amidinium additives for high-performance perovskite solar cells

Abstract

Perovskite solar cells (PSCs) have developed rapidly and achieved power conversion efficiencies (PCE) of over 25% with diverse technical routes. However, defect is a major factor for device degradation, so a high-quality perovskite film with low defect density is critical to device performance. Here, we fabricate highly efficient and stable PSCs by introducing butyramidinium chloride (BRCl) into PbI₂ precursor solution. BRCl retards the nucleation and accelerates the crystal growth of perovskite by interacting with PbI₂, thereby obtaining high-quality crystalline perovskite films with large grains and few defects. In addition, BRCl effectively passivates the defects and reduces non-radiative recombination in the resultant film. Accordingly, planar n-i-p PSCs achieve a champion PCE of 23.27%. Importantly, the device stability under thermal, ambient and illumination stress is improved. Notably, non-encapsulated BRCl-assisted devices retained 93% of their initial PCE after over 1000 h under maximum power point tracking (MPP) in a N₂ atmosphere.