Facile Synthesized Acetamidine Thiocyanate with Synergistic Passivation and Crystallization for Efficient Perovskite Solar Cells

Further performance enhancement of perovskite solar cells (PSCs) is limited by the defect‐assisted recombination losses. The approaches employed to decrease the losses contain defect passivation, perovskite crystallization control, interface engineering, etc. Herein, a new material of acetamidine thiocyanate (AASCN) via a facile method is synthesized, which exhibits dual functions combining a cation with passivation and an anion with crystallization. The iodine vacancies in the perovskite can be effectively passivated through hydrogen bonds formed by the NH bonds of the polar cation AA+. Furthermore, the pseudo‐halide anion SCN− can coordinate the Pb–I octahedrons, improving the perovskite film crystallization. Through vaporing the AASCN on perovskite films during the secondary crystal growth process, the defects mitigation and crystallization improvement are synergistically achieved. As a consequence, the FA0.25MA0.75PbI3 PSCs with AASCN achieve a power conversion efficiency of 23.17%, which is higher than that (21.43%) of untreated PSCs. In detail, the open‐circuit voltage has also a significant advancement from 1.095 to 1.167 V after the AASCN treatment. The design and synthesization of the multifunctional materials are supposed to provide a feasible approach for the performance improvement of PSCs.