High output performance of piezoelectric energy harvesters using epitaxial Pb(Zr, Ti)O3 thin film grown on Si substrate

Abstract

For a high power density in piezoelectric energy harvesters, both a large direct piezoelectric coefficient ( e31, f) and a small relative permittivity constant ( εr,33) are required. This study proposed an energy harvesting device made of an epitaxial Pb(Zr, Ti)O3 (PZT) thin film grown on a Si substrate. The epitaxial PZT thin film is deposited on the Si substrate by RF magnetron sputtering. The epitaxial PZT thin film grown on Si substrate has a εr,33 constant of 318. The output voltage as a function of input displacement was measured using a shaker to evaluate the direct e31, f coefficients and energy harvester output characteristics. According to the figure of merit defined as ( e31, f)2/ ε0 εr,33, the epitaxial PZT/Si cantilever is 32 GPa. At a resonant frequency of 373 Hz under an acceleration of 11 m/s2, the epitaxial PZT/Si cantilever has a high output power of 40.93  μW and power density of 108.3  μW/cm2/g2 without any damage, which is very promising for high power energy harvester applications.