Origin of high piezoelectricity of inorganic halide perovskite thin films and their electromechanical energy-harvesting and physiological current-sensing characteristics

Halide perovskite materials have been recently recognized to possess potentially strong ferroelectricity and piezoelectricity even though the experimental evidence is very limited. Herein, we report high piezoelectricity of representative inorganic halide CsPbBr3 thin films and their energy harvesting and current-sensing characteristics with an optimization process. This is the very first report of introducing an effective piezoelectric coefficient and energy-harvesting performance for inorganic halide perovskites. A record high piezoelectric coefficient of ∼40.3 pm V-1 was obtained for the optimized CsPbBr3, which was attributed to the extended bonding angles of Pb-Br-Pb and Br-Pb-Pb arising from the applied electric field according to structural simulations. As expected from the high piezoelectricity, the electromechanical energy-harvesting performance was very competitive with excellent values of a ∼16.4 V output voltage and ∼604 nA output current achieved for a large-scale harvester of 5 cm2. Highly strain-sensitive devices were also successfully exemplified to identify specific body-motion from the detected current values in the sensitive inorganic halide patches.