Microampere-level piezoelectric energy generation in Pb-free inorganic halide thin-film multilayers with Cu interlayers

Abstract Although asymmetric perovskite halides are known to possess viable piezoelectricity, their performance of energy harvesting has been limitedly reported. Herein, we propose the first Pb-free inorganic halide-based thin film harvester having strong capability of power-generation, particularly with additional efforts to enhance the device performance using an unprecedented multilayer structure incorporated with metallic interlayers. Representative high-quality CsSnI3 thin films were prepared by one-step spin coating, and up to four layers were stacked with alternating Cu interlayers. Impressive piezoelectric energy harvesting characteristics of ~22.9 V and ~1233 nA were attained for the four-layered halide structure after poling, which are highest values recorded thus far for perovskite halide thin films. The origin of the enhanced energy-generation is believed to be directly associated with the increased SnI6-octahedra distortion (with off-centering of Sn atoms) by poling and the extra space-charge polarization by Cu interlayers.