Multilayered heterojunction-based zinc oxide nanoneedles/polyaniline/titania nanoparticles as a self-powered ultraviolet light photodetector

Abstract

Nowadays, self-powered ultraviolet photodetectors (SPDs) with improved photoresponse features have attracted considerable attention due to their great pivotal applications in military and civilian fields. In the present work, for the first time, we investigate and report the construction and photoresponse features of a SPD based on multilayered heterojunction-based zinc oxide nanoneedles/polyaniline/titania nanoparticles (ZET). The structure, morphology, and optical properties of the ZET and its components were comprehensively investigated. A significant dependence was observed between the changes in I-V characteristics of the ZET-based SPD (SPZ) and the temperature change, resulting in a short reverse saturation current, proper ideality factor, and low dark current. I-V characteristics of the SPZ revealed nonlinear asymmetric rectifying behavior with the improved current under the influence and increase of power densities (PDiss) of ultraviolet (UV) light irradiation. Moreover, the self-powered feature of the SPZ was confirmed by the generation of short-circuit current and notable contrast ratio under UV light illumination at zero bias voltage. The device displayed remarkable photoresponsivity of 4.46A/W, high significant normalized detectivity of 63.1×1012Jones, good fill factor of 50.64%, and excellent external quantum efficiency of 1514% at the PDis of 0.77mW/cm2. In addition, the SPZ exposed a short rise time of 540 ms, a high maximum photocurrent of 99.9µA, and a significant gain dynamic range of 499.5 at PDis of 19.11mW/cm2. Finally, the imaginable mechanism of the current generation in our hand-made device was discussed in detail by exerting a standard thermionic emission-diffusion model and energy band diagram.