Enhanced Size-Dependent Piezoelectricity in Nanostructured Films

We have developed a nanogenerator that is driven by mechanical forces to produce continuous direct-current output. The nanogenerator was fabricated with titanium dioxide nanoparticle arrays forming a Schottky barrier with a conducting electrode with a small gap. Under uniaxial mechanical compression, nanogenerators have shown repeatable and consistent electrical outputs with energy-conversion efficiency of order of magnitude at least comparable to similar nanogenerators based on piezoelectric materials. Flexoelectricity due to inhomogeneous strain induced in the nanostructured TiO2 film has been identified as one possible mechanism of the high apparent piezoelectricity in the nanoparticles. The approach presents an adaptable, mobile, and cost-effective technology for harvesting mechanical energy from the environment. At the present stage it offers a potential solution for powering nanodevices.