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 NaNbO3 nanowire-based piezoelectric device as a high output and cost-effective flexible nanogenerator. The device consists of a NaNbO3 nanowire–poly(dimethylsiloxane) (PDMS) polymer composite and Au/Cr-coated polymer films. High-quality NaNbO3 nanowires can be grown by hydrothermal method at low temperature and can be poled by an electric field at room temperature. The NaNbO3 nanowire–PDMS polymer composite device shows an output voltage of 3.2 V and output current of 72 nA (current density of 16 nA/cm2) under a compressive strain of 0.23%. These results imply that NaNbO3 nanowires should be quite useful for large-scale lead-free piezoelectric nanogenerator applications.