Synthesis of zinc oxide microrod arrays and their performance as piezo-generators

Zinc oxide microrods were synthesized by aqueous chemical growth using zinc nitrate and zinc acetate solutions without seed layer. Rod length of around 10 mu m was obtained after 5hr at 95 degrees C. Solution replenishment led to a better alignment normal to the substrate; however, only zinc acetate solution resulted in bigger rods, reaching about 12 mu m in length and 5 mu m in diameter. X-ray diffraction revealed a pure hexagonal wurtzite structure with high crystallographic texture. Raman spectroscopy showed no evidence of lattice stress. The ZnO microrod arrays were used to fabricate piezoelectric generators, and the largest output was obtained from the generator with the higher density of rods. The use of a piezoelectric polymer in the generators led to an improved performance of at least 200% compared to reports that used a dielectric polymer.