Plasmonic Pt nanoparticles triggered efficient charge separation in TiO2/ GaN NRs hybrid heterojunction for the high performance self-powered UV photodetectors

Abstract

Solar radiation, especially the UV-A light rays (320-400 nm) exposure causes severe health hazard such as skinrelated cancer and premature aging. Owing to the significance of UV-A photodetection, a high-performance UV-A photodetectors (PD) with high sensitivity, large detectivity and fast response time, have attracted great attention in various optoelectronic applications. Herein, we report a self-powered (SP) UV PD based on Pt nanoparticles (NP) decorated TiO2/GaN nanorods (NRs) hybrid heterojunction. The proposed Pt NP@TiO2/GaN NRs hybrid device demonstrates pronounced photoelectric performances including a large responsivity (44.6 A/W), superior detectivity (1.57 x 1014 Jones) and high electronic quantum efficiency (8.65 x 103 %) under the UV light intensity (lambda = 382 nm, 1.32 mW/cm2) at zero bias, which are relatively much higher as compare to the pristine counterparts. In addition, the hybrid PD showed a short response/recovery times of 180 ms/200 ms, with a remarkable reproducibility and long-term stability towards the UV light. The impressive photoresponse properties of the hybrid SP PD are ascribed to the large photon absorption endorsed by the localized surface plasmonic resonance effect of Pt NP and the adequate built-in potential at the TiO2 and GaN NRs heterojunction interface, which further endows the effective separation and transport of photogenerated charge carriers. Furthermore, the plausible mechanism for the high-performances of hybrid UV PD is demonstrated in detailed using the energy band diagram. Our work reveals that the integral advantages of hybrid heterostructures, have a significant potential for the practical applications of advanced optoelectronics and high-performance SP UV-A PD.