Enhanced emission intensity of vertical aligned flexible ZnO nanowire/p-polymer hybridized LED array by piezo-phototronic effect

Abstract

Flexible optoelectronic device arrays are critically desirable for next-generation digital display, seamless integration of optoelectronics with biomedical and human–machine interactive systems and many other applications. Here we report a flexible patterned ZnO nanowire/PEDOT:PSS LEDs array with very high light-emitting uniformity. A near band edge emission centered at 400nm and a broad defect-related emission covering the range from 450 to 780nm is observed in the electroluminescence spectra. Both anneal and H2O2 treatment of the ZnO NWs and the optimal thickness of PEDOT:PSS can improve the performance of the as-fabricated device. Furthermore, we demonstrate that the emission intensity of the ZnO nanowire/p-polymer LEDs can be enhanced by applying an external strain owing to the piezo-phototronic effect, which reduces the barrier height for hole transport, leads to an improved balance between electron contributed current and hole contributed current, owning to the piezoelectric charges on the ZnO side created by applying local strain. The simple fabrication process and excellent properties of the device pave the way to cost-efficient LED technology for potential applications in high-resolution optoelectronic device, biomedical implanted devices, artificial electronic skin and smart sensor systems.