Multifunctional organic salts synergize interfacial passivation for efficient PSCs

Fully inorganic metal halide perovskite solar cells (PSCs) exhibit high efficiency and excellent thermal stability. However, the presence of surface traps caused by oxygen vacancies in the electron transport layer leads to significant non-radiative charge recombination, which limits both the short-circuit current density ( J SC ) and photoelectric conversion efficiency (PCE). In this study, we propose a dual-purpose strategy by incorporating the multifunctional organic salt dopamine hydrochloride (DACl) as an additive into the electron transport layer. Firstly, DACl acts as a Lewis base when added to TiO 2 films, facilitating improvements in electron transport properties and resulting in higher photovoltaic quality of subsequently deposited perovskite layers. This enhancement significantly improves overall photovoltaic performance . Secondly, DACl's electron-rich aromatic structure and -NH 2 functional group can anchor undercoordinated Pb 2+ ions and passivate defects within the perovskite film. Additionally, its -OH functional group and charged ion Cl - play crucial roles in improving perovskite grain size and crystallinity . As a result of these modifications, cell efficiency increased ∼35 %, from 9.37 % to 12.70 %, while short-circuit current density increased from 15.44 mA cm −2 to 17.80 mA cm −2 at an illumination intensity of 100 mW cm −2 . These findings suggest that introducing DACl into the ETL layer is a promising approach for achieving efficient and stable PSCs.