Piezoelectric nanogenerator using CdS nanowires

Vertically grown cadmium sulfide (CdS) nanowire (NW) arrays were prepared using two different processes: hydrothermal and physical vapor deposition (PVD). The NWs obtained from the hydrothermal process were composed of alternating hexagonal wurtzite (WZ) and cubic zinc blende (ZB) phases with growth direction along WZ ⟨0001⟩ and ZB [111]. The NWs produced by PVD process are single crystalline WZ phase with growth direction along ⟨0001⟩. These vertically grown CdS NW arrays have been used to converting mechanical energy into electricity following a developed procedure [Z. L. Wang and J. Song Science 312, 242 (2006)]. The basic principle of the CdS NW nanogenerator relies on the coupled piezoelectric and semiconducting properties of CdS, and the data fully support the mechanism previously proposed for ZnO NW nanogenerators and nanopiezotronics.