3‐Hydrazinylpyridine Hydrochloride Regulating Crystallization Kinetics of Tin‐Lead Perovskite Prepared by Two‐Step Method

Abstract Sn/Pb perovskite is an attractive photovoltaic material due to its low toxicity and ideal bandgap. However, the performance of Sn/Pb perovskite solar cells (PSCs) is lower than its Pb‐based counterpart. The main reason originates from the poor crystallinity of Sn/Pb perovskite film. To solve this problem, the crystallization kinetics of Sn/Pb perovskite prepared by the two‐step method is deeply explored and proposed an effective additive of 3‐Hydrazinylpyridine Hydrochloride (3‐HH) to regulate the crystallization process of Sn/Pb perovskite. The results indicate 3‐HH additive promotes fast nucleation, delays the formation and growth of perovskite microcrystals, balances the crystallization rate of Sn/Pb phase perovskite in the initial stage, and then accelerates perovskite microcrystal coalescence in the later stage. Furthermore, the perovskite surface is ameliorated by 3‐HH post‐treatment and a more matched energy level arrangement is attained. Simultaneously, 3‐HH doping and/or post‐treatment passivates perovskite defects and suppresses the oxidation of Sn 2+ . Benefiting from these effects of 3‐HH, the device with 3‐HH doping and post‐treatment obtains a PCE of 18.329%, which is higher than that of the control device (16.362%). The unencapsulated PSCs with 3‐HH‐modification retain 85% PCE after stored in the glove box for 1500 h, while the control device keeps only 66% PCE.