High-responsivity self-powered UV photodetector performance of pristine and V-doped ZnO nano-flowers

Abstract

Wurtzite ZnO nanostructures are suitable for high-performance, self-powered photodetectors (PDs) because of their attractive optoelectronic properties. In this study, highly sensitive ultra-violet self-powered PDs with high responsivity/detectivity and large external quantum efficiency was developed by V-doped ZnO nanoflower samples onto an ITO glass substrate. Highly faceted pristine and V-doped ZnO nanoflowers were produced using a simple, low-cost co-precipitation method. The presence of Na+ ions in the precursor solution appeared to control the morphology of the nanomaterial. Various physicochemical characterizations showed that the variation of the Na+ ion concentration inhibits the reaction at selected regions, causing the branching of nanostructures to form ZnO nanoflowers. Room- and low-temperature photoluminescence studies showed that V-doping increases the extrinsic carrier density and produces many intrinsic and extrinsic defect states, which reduce the e−–h+ recombination rate significantly and produce a large photocurrent under UV illumination. The V-ZnO-based self-powered UV PD device showed a 156 % increase in photocurrent compared to pristine ZnO-based PDs, with very short response/recovery times of 0.22/0.23 s under 382 nm UV illumination of 1.14 mW/cm2, and excellent responsivity (5.1 × 103 mA/W), very high external quantum efficiency (5.5 × 104 %), and large detectivity (4.0 × 1013 Jones). Therefore, the current work presents a simple way to obtain high-performance self-powered UV PDs that can open up a new horizon to fabricate new-generation optoelectronic devices for diverse applications.