Highly Efficient Sn/Pb Binary Perovskite Solar Cell via Precursor Engineering: A Two‐Step Fabrication Process

Regulation of the crystallization of perovskite films and avoiding the oxidation of Sn2+ during the deposition process are very important for achieving Sn/Pb binary perovskite solar cells (PVSCs) with high power conversion efficiency (PCE) and producibility. In this work, a high‐quality HC(NH2)2Pb0.7Sn0.3I3 (FAPb0.7Sn0.3I3) film deposited from the two‐step solution process by introducing methylammonium thiocyanate (MASCN) as a bifunctional additive into the precursor solution containing PbI2 and SnI2 is reported. MASCN can not only tune the morphology of the perovskite film but also stabilize the precursor solution via retarding the oxidation of Sn2+ through a strong coordination between SCN− and Sn2+. The Sn/Pb binary inverted PVSCs based on FAPb0.7Sn0.3I3 present a high fill factor of 0.79 and the best PCE of 16.26% in the case of 0.25 MASCN addition. The device fabrication producibility is also greatly improved due to the stabilized precursor solution with the aid of MASCN. The PCE of the device is almost independent of the storage time of the precursor solution within 124 d in the N2‐filled glove box. These results indicate that the precursor engineering with multifunctionality additive is an effective approach toward highly efficient and producible PVSCs for future commercialization. The advantage of methylammonium thiocyanate (MASCN) addition inside the two‐step deposition process in forming high quality FAPb0.7Sn0.3I3 films is demonstrated. MASCN can tune morphology of the perovskite film and retard the oxidation of Sn2+. The power conversion efficiency of the device reaches 16.26%, and is almost independent of the storage time of the precursor solution in the glove box within 124 d.