Synergistic defect passivation and charge transport enhancement via thiosemicarbazide-functionalized carbon nanotubes for high-efficiency lead-free CsSnI₃ perovskite solar cells: A pathway to 23.34 % efficiency

Tin-based perovskite solar cells (PSCs) provide a lead-free alternative but suffer from Sn(II) instability. We introduce thiosemicarbazide-functionalized carbon nanotubes (TSBCNTs) to minimize defects and improve charge transport in all-inorganic CsSnI₃(PSCs. The S C N groups of TSBCNT interact with Sn²⁺, diminishing trap states, while CNTs enhance carrier extraction, resulting in a PCE of 23.34 % and a stability of 91.3 % after 800 hours under severe circumstances.