Flexible Sandwich Piezoelectric Nanogenerators based ZnO Nanorods for Mechanical Energy Harvesting

Abstract

We present a flexible sandwich piezoelectric nanogenerators (PENGs) device with gold-coated ZnO nanorods (Au@ ZNRs) as an efficient top electrode; this device was used to harvest energy from the human walking motion. ZNRs were synthesised on the two-piece of ZnO seed layer coated gold/flexible polyethylene terephthalate (Au/PET) substrates through a simple hydrothermal method of low temperature and low cost at molar concentration (0.01M). X-ray diffraction and field emission scanning electron microscopy images revealed that the as-grown ZNRs have high crystallinity and apparent vertical growth with hexagonal shapes, the average diameter of NRs is 120 nm. Flexible sandwich PENGs based ZNRs was fabricated with gold-coated one piece of ZNRs by DC-sputtering method as an efficient top electrode, which was placed on the uncoated ZNRs as-grown on another piece of substrate. The maximum output potential voltage (Vmax) under a periodic of pressing and releasing of human walking is 5.76 V. The results confirmed the top efficient electrode has created more contact area with uncoated NR when it is pressed, which increases the transfer efficiency effectively of piezoelectric potential that generated from uncoated ZNRs.