DMSO-Free Tin Halide Perovskites for Indoor Photovoltaics

Indoor photovoltaic (IPV) technology has emerged as an effective strategy to sustainably power batteryless Internet of Things (IoT) devices. Though tin perovskite solar cells offer competitive IPV performance, their effectiveness is often compromised by Sn²⁺ oxidation, particularly when processed with dimethyl sulfoxide (DMSO) solvent. This work explored the IPV performance of DMSO-free tin perovskites FASnI_3-x Br _x by tuning the halide composition. Notably, X-ray photoelectron spectroscopy confirms no traces of Sn⁴⁺, highlighting the critical role of eliminating DMSO. Under 1000 lx indoor illumination, the power conversion efficiency (PCE) increases with Br content, reaching a maximum of 11.1% for FASnI₂Br without introducing any reducing agent. Remarkably, after six months of storage, it exhibited an impressive indoor PCE of 11.9%, demonstrating the effectiveness of the DMSO-free processing route for the intrinsic stability of the tin perovskite. These findings provide crucial insights for developing high-performance, lead-free perovskite materials for sustainable energy applications and IoT devices.