Solid-solid chemical bonding featuring targeted defect passivation for efficient perovskite photovoltaics

Solution-processed surface defect passivation has enabled perovskite solar cells (PSCs) to make remarkable progress in recent years. Here, different from solution processing, we proposed solvent-free solid-phase passivation (SPP) to bond surface uncoordinated Pb2+ defects using passivator molecules on pre-prepared solid-state films. The attentively selected passivator was found to anchor on the defect sites of the perovskite film surface even if the passivator film was removed, due to its strong coordination ability with the uncoordinated Pb2+ defects. This unique targeted defect passivation substantially reduces the carrier non-radiative recombination loss, delivering a high V-OC of 1.20 V (voltage loss is only 0.34 V). Consequently, the power conversion efficiency (PCE) of PSCs was greatly improved from 22.37% to certified 24.65%. The 1 cm(2) SPP-based PSC also exhibited a high PCE exceeding 23%. Moreover, the unencapsulated PSCs maintain 98% and 92% of their initial efficiency after storage under nitrogen for 2300 h and tracking at a maximum power point for 800 h.