Triggering piezoelectricity directly by heat to produce alternating electric voltage

Piezoelectricity has proved itself a promising mechanism for energy conversion and signal sensing by taking advantage of its ability to convert mechanical energy into electricity. Here, we demonstrate that the piezoelectricity in free-standing non-centrosymmetric nanowires can also be triggered directly by heat to produce electricity. The feasibility of the idea is first analyzed by the dynamic theory of crystal lattices and then confirmed by molecular dynamics simulations. The most salient point is that the heat-induced voltage drop across the cross section of the free-standing nanowires alternates periodically with the vibration of the nanowire. Moreover, the electric potential induced by heat here (as large as 0.34 V) is proved to be comparable with the previously reported potentials induced by mechanical energy, and the maximum value can be tuned by controlling the size of the nanowire and the applied heat.