Lewis base governing superfacial proton behavior of hybrid perovskite: Basicity dependent passivation strategy

Proton behaviors in hybrid perovskites induced by Lewis base upon interfacial passivation have substantial impacts on perovskite lattice structure and the charge transfer kinetics in perovskite solar cells (PSCs). Herein, two Lewis base isomers with distinct basicity are used to investigate the basicity dependent proton behaviors and passivation effects. 2-aminopyridine with gentle basicity can effectively stabilize the superficial organic species of perovskite, whereas 4-aminopyridine (4A) with strong basicity would destructively despoil protons from the organic species in perovskite crystals and uncontrollably form low-dimensional perovskites above a layer of inorganic metal skeleton as a result of hindering the interfacial charge transport seriously. By virtue of regulation of the proton behavior through pre-protonation of 4A, boosted power conversion efficiency up to 23.3% and improved operational stability over 1000 h have been achieved. This work provides new insights into passivation strategy toward Lewis base as well as a basicity guidance for passivator selection.