Deep level defect passivation for printable mesoporous CsSnI3 perovskite solar cells with efficiency above 10%

The lead-free inorganic perovskite CsSnI 3 is considered as one of the best candidates for emerging photovoltaics. Nevertheless, CsSnI 3 -based perovskite solar cells experience a significant drop in performance due to the nonradiative recombination facilitated by trapping. Here, we show an electron donor passivation method to regulate deep-level defects for CsSnI 3 perovskite with electron donor pyrrole. Experimental observations combined with theoretical simulations verify that the saturation of Tin dangling bonds with pyrrole on the CsSnI 3 surface via a Lewis acid-base addition reaction can significantly reduce the density of deep-level defects. Consequently, the printable mesoporous perovskite solar cells with an FTO/compact-TiO 2 /mesoporous-TiO 2 /Al 2 O 3 /NiO/carbon framework device structure penetrated with CsSnI 3 achieve a power conversion efficiency of up to 10.11%. To our knowledge, this represents the highest efficiency reported to date for lead-free perovskite-based printable mesoporous solar cells. Furthermore, the unencapsulated devices demonstrated remarkable long-term stability, retaining 92% of their initial efficiency even after 2400 h of aging in a nitrogen atmosphere.