Enhanced figure of merit in Pb(Zr,Ti)O3 nanorods for piezoelectric energy harvesting

Piezoelectric energy harvesting based on nanorod arrays has attracted attention owing to the simple structure that has the potential to generate large output power. The decreased density of the nanorod array, compared to that of typical piezoelectric films, should achieve a larger figure of merit (FOM). However, the effect of the density of the nanorod array has been scarcely validated by direct experiments. In this study, we fabricated Pb(Zr,Ti)O3 nanorods by using an elevated growth rate during pulsed laser deposition and compared them with the film. The nanorods have the a/c-domain structure, which is consistent with the reference film, leading to a similar piezoelectric response. The lowered density of the nanorods caused an appreciable reduction in the effective dielectric constant, which significantly increased the effective FOM. As a result, FOM and available energy of the nanorods were 61% improved, compared to those of the film. The enhanced FOM of the nanorod indicates the prospective application of piezoelectric energy harvesting in off-resonant vibration environments.