Defect passivation via incorporation of sodium thiocyanate for achieving high-performance MAPbI3-based perovskite solar cells with enhanced stability

The high density of defects in MAPbI 3 perovskite films brings about severe carrier nonradiative recombination, which lowers the photovoltaic performance and the stability of MAPbI 3 -based perovskite solar cells (PSCs). To tackle this issue, we prepared stable and efficient MAPbI 3 -based PSCs with incorporation of sodium thiocyanate (NaSCN). NaSCN can increase grain size and improve crystallization quality of the perovskite films due to an Ostwald ripening effect of SCN - and surface passivation of Na + which can effectively passivate the defect states and inhibit nonradiative recombination for an ultimate improvement of the device performance and stability. The excellent characteristics lead to a significant enhancement of the power conversion efficiency (PCE) from 18.1 % to 19.4 % both for MAPbI 3 -based and Cs 0.06 MA 0.15 FA 0.79 PbI 2.5 Br 0.5 -based PSCs, respectively. The unencapsulated NaSCN-treated PSCs also shows a improved stability after aging under a relative humidity of 40 ± 5 % for 15 days.