Synchronous defect passivation strategy via Lewis base for efficient and stable perovskite solar cells

The power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs) are affected by the presence of Pb-I antisite and I vacancy defects. Here, we propose a strategy for synchronous passivation of defects by Lewis bases D-Tryptophan methyl ester hydrochloride (D-TMe·HCl). The results show that the amino and carboxyl groups in D-TMe·HCl could synchronously passivate the Pb-I antisite and I vacancy defects through ionic and hydrogen bonding. In addition, the inhibition of ion migration of Pb 2+ and I − effectively suppresses charge recombination and promotes interfacial carrier extraction. As a result, the PCE of the device with D-TMe·HCl increased to 20.59% with a fill factor of 79.8%. Furthermore, the introduction of D-TMe·HCl promotes the crystallinity of the perovskite and obtains a more dense and uniform film, thus the stability of the device is enhanced. The device with D-TMe·HCl retains more than 94% of its initial PCE after aging in a glovebox for 500 h under nitrogen conditions. This work opens up a new avenue for achieving efficient and stable PSCs by forming high-quality films, synchronously passivating defects, and inhibiting ion migration.