Oxide nanowire arrays for light-emitting diodes and piezoelectric energy harvesters

As an outstanding member in the oxide nanowire family, ZnO nanowire is widely studied for its optical, semiconductive, and piezoelectric properties. PbZrxTi1-xO3 (PZT), usually in the form of polycrystalline thin films, is known for its high piezoelectric coefficient and is an ideal material as actuator. In this review, we first briefly introduce the rational growth of ZnO and PZT nanowire arrays by seedless wet chemical methods. Utilizing the ordered ZnO nanowires grown on p-type substrates, we next present an array of single ZnO nanowire-based blue/near-UV light-emitting diodes (LEDs), including their fabrication process, electroluminescence (EL) spectra, and external quantum efficiency. Finally, we discuss the piezoelectric ZnO and PZT nanowire-enabled three-dimensionally integrated direct- and alternating-current nanogenerators, and their primary roles in self-powered nanosystems and for powering personal microelectronics.