A Facile and Effective Ozone Exposure Method for Wettability and Energy-Level Tuning of Hole-Transporting Layers in Lead-Free Tin Perovskite Solar Cells

Lead-free perovskite solar cells (PSCs) have attracted interest among scientists searching for eco-friendly energy harvesting devices. Herein, the effects of ozone exposure on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) in lead-free tin halide PSCs as a facile and low-cost process for improving device performance are analyzed. Two types of tin-based PSCs and one typical lead-based PSC were fabricated. The ozone exposure on PEDOT:PSS increases the short-circuit current density ( J SC ) and the fill factor (FF) of PSCs in all cases with perovskite grain enlargement and hole-mobility enhancement of the devices, respectively. For open-circuit voltage ( V OC ), the outcome depends on the band gap and the energy levels of the perovskite films. While ozone exposure treatment is favorable for PEA 0.15 FA 0.85 SnI 3 -based tin PSCs, V OC decreases with ozone exposure in the…