biostudies-literatureUnknown14(1)Wu TShanghai Jiao Tong UniversityLead-free tin perovskite solar cells (PSCs) have undergone rapid development in recent years and are regarded as a promising eco-friendly photovoltaic technology. However, a strategy to suppress charge recombination via a built-in electric field inside a tin perovskite crystal is still lacking. In the present study, a formamidinium tin iodide (FASnI₃) perovskite absorber with a vertical Sn²⁺ gradient was fabricated using a Lewis base-assisted recrystallization method to enhance the built-in electric field and minimize the bulk recombination loss inside the tin perovskites. Depth-dependent X-ray photoelectron spectroscopy revealed that the Fermi level upshifts with an increase in Sn²⁺ content from the bottom to the top in this heterogeneous FASnI₃Nano-micro letters99https://www.ebi.ac.uk/biostudies/studies/S-EPMC8993987biostudies-literatureHeterogeneous FASnI₃ Absorber with Enhanced Electric Field for High-Performance Lead-Free Perovskite Solar Cells.PMC8993987Liu XOno LKHan LSegawa HZhang YQi YWu TLuo XTong GfalseHeterogeneous FASnI₃ Absorber with Enhanced Electric Field for High-Performance Lead-Free Perovskite Solar Cells.Lead-free tin perovskite solar cells (PSCs) have undergone rapid development in recent years and are regarded as a promising eco-friendly photovoltaic technology. However, a strategy to suppress charge recombination via a built-in electric field inside a tin perovskite crystal is still lacking. In the present study, a formamidinium tin iodide (FASnI₃) perovskite absorber with a vertical Sn²⁺ gradient was fabricated using a Lewis base-assisted recrystallization method to enhance the built-in electric field and minimize the bulk recombination loss inside the tin perovskites. Depth-dependent X-ray photoelectron spectroscopy revealed that the Fermi level upshifts with an increase in Sn²⁺ content from the bottom to the top in this heterogeneous FASnI₃2022-01-01T00:00:00Z2022 Apr2026-07-14T13:03:56.29Z2024-10-17T22:05:58.248ZS-EPMC89939873539456810.1007/s40820-022-00842-4