Suppression of deep-level traps via semicarbazide hydrochloride additives for high-performance tin-based perovskite solar cells.

Tin perovskites with exemplary optoelectronic properties offer potential application in lead-free perovskite solar cells. However, Sn vacancies and undercoordinated Sn ions on the tin perovskite surfaces can create deep-level traps, leading to non-radiative recombination and absorption of nucleophilic O molecules, impeding further device efficiency and stability. Here, in this study, a new additive of semicarbazide hydrochloride (SEM-HCl) with a N-C=O functional group was introduced into the perovskite precursor to fabricate high-quality films with a low concentration of deep-level trap densities.