Methanesulfinate Modifier for Printable Mesoscopic Perovskite Solar Cells with Enhanced Performance

High-performance perovskite solar cells require the modification of grain boundaries in the polycrystalline light absorbing layer and salt modifiers have contributed a lot toward this requirement. Herein, the application of the sodium methanesulfinate (SMSI) as the modifier for the hole-conductor-free printable mesoscopic perovskite solar cell (p-MPSC) with a carbon electrode is reported. It is found that SMSI prevents the oxidization of iodine ions in the precursor and methanesulfinate coordinates more strongly than methanesulfonate with perovskite. The interaction between SMSI and perovskite brings improved crystallinity and reduced defects, and thereby suppresses nonradiative recombination in p-MPSCs. At the same time, SMSI also shifts the Fermi level of perovskite downward and contributes to an optimized energy-level alignment for promoted charge injection. By introducing the SMSI modifier, the power conversion efficiency of p-MPSCs from 16.6% to 18.1% is successfully improved. The research indicates that the methanesulfinate anion is a promising candidate for salt modifier design serving high-performance PSCs.