The Fabrication of Lead-Free Cs2SnI6 Perovskite Films Using Iodine-Rich Strategy for Optoelectronic Applications

摘要

Parallel to the booming of all-inorganic CsPbX_3 halide perovskites, the growth oflead-free perovskites is accelerating, with the efficiency values of over 10% beingrealized. Eco-friendly and stable halide double perovskites with superior stabilityare considered as an encouraging alternative to address the stability concernsrelated to the lead halide perovskites. Recently, Cs2SnI6 with defect perovskitestructure has appeared as a “superstar” material owing to its environmentalfriendliness and exceptional stability. Herein, an iodine-rich strategy (IRS) isdeveloped based on the modified two-step method for the fabrication of lead-freeCs_2SnI_6 films. In addition, the impact of the reaction temperature on theproperties of the resultant films is systematically investigated. The results revealthe improvement in the crystallinity and phase stability of the films, suggestingthat the proposed IRS successfully inhibits the decomposition of Cs_2SnI_6 films.The optical measurements confirm the n-type nature of Cs_2SnI_6 with bandgapvarying from 1.23 to 1.38 eV. The photoluminescence of the films increasesgradually with the addition of I_2, presumably owing to the reduction of nonrecombinationsites. The current work provides valuable direction for the fabricationof Cs2SnI6 devices for green energy applications.