Lead-free NaNbO3 nanowires for a high output piezoelectric nanogenerator.

Perovskite ferroelectric nanowires have rarely been used for the conversion of tiny mechanical vibrations into electricity, in spite of their large piezoelectricity. Here we present a lead-free NaNbO(3) nanowire-based piezoelectric device as a high output and cost-effective flexible nanogenerator. The device consists of a NaNbO(3) nanowire-poly(dimethylsiloxane) (PDMS) polymer composite and Au/Cr-coated polymer films. High-quality NaNbO(3) nanowires can be grown by hydrothermal method at low temperature and can be poled by an electric field at room temperature. The NaNbO(3) nanowire-PDMS polymer composite device shows an output voltage of 3.2 V and output current of 72 nA (current density of 16 nA/cm(2)) under a compressive strain of 0.23%. These results imply that NaNbO(3) nanowires should be quite useful for large-scale lead-free piezoelectric nanogenerator applications.