Differential impact of a-Nb₂O₅ and a-TiO₂ ETL on the photoelectric performance of Cs₃Sb₂I_9-xCl_x perovskite solar cells

Recently, the stable all-inorganic lead-free Cs3Sb2I9-xClx perovskite-like solar cells have attracted enormous attention where the electron transport layer (ETL) is extremely important. Herein, the amorphous Nb2O5 (a-Nb2O5) ETL was prepared by sputtering technology at room temperature to increase the optical band gap of a-Nb2O5 layer, improve its conduction band minimum (CBM), suppress charge recombination at the a-Nb2O5/Cs3Sb2I9-xClx interface, and reduce leakage current of Cs3Sb2I9-xClx solar cells. More importantly, the a-Nb2O5-based Cs3Sb2I9-xClx solar cell presents a higher efficiency (1.75 %) compared with Cs3Sb2I9-xClx device containing a-TiO2 ETL (0.69 %). Additionally, the a-Nb2O5 ETL increases the device stability in air. This study highlights the great effect of a-Nb2O5 ETL as a carrier controller on enhancing performance of Cs3Sb2I9-xClx solar cells.