Strontium Chloride-Passivated Perovskite Thin Films for Efficient Solar Cells with Power Conversion Efficiency over 21% and Superior Stability.

Industrialization of perovskite solar cells is constrained by adverse stability in the air. Herein, we report effective strontium chloride (SrCl2) passivation upon HC(NH2)2-CH3NH3 (FA-MA)-based perovskite thin films for the suppression of nonradiative recombination. Moreover, the recombination dynamics, crystallinity, carrier transport, morphology, and the elemental stoichiometry of this film were systematically studied. By optimizing the concentration of SrCl2, the corresponding devices exhibited an increased open-circuit voltage (1.00 V vs 1.09 V), consistent with the enhanced photoluminescence lifetime. The champion passivated device showed an ascendant power conversion efficiency (PCE) about 21.11%, with over 90% retention of the primal PCE in dry air after 1000 h of aging with 20-30% humidity. A superior stability and an accelerated electron/hole-extraction ability were further observed by time-resolved photoluminescence spectroscopy.