SnO₂ nanorods arrays functionalized TiO₂ nanoparticles based UV photodetector with high and fast response

Abstract

TiO₂ nanoparticles (NPs) based ultraviolet (UV) photodetectors (PDs) present extremely slow response duo to the low electron mobility of TiO₂ (~ 0.1 to 1.0 cm² V⁻¹ S⁻¹) and electron loss in conspicuous interspace among the TiO₂ NPs. In this work, SnO₂ nanorods (NRs) arrays with high electron mobility are proposed to improve electron transfer in TiO₂ NPs by the highly oriented structure. Double layers of TiO₂ NPs are deposited on the SnO₂ NRs arrays by TiCl₄ hydrolysis reaction. The top layer is consisted of TiO₂ NPs clusters, which contributes to large UV light harvest and ensures high photoresponsivity. And the bottom layer of small TiO₂ NPs are distributed on and into SnO₂ NRs array, forming heterojunction between them, which favors for quick electrons transmit and ensures fast response rate. In contrast to most reported UV PDs based on other TiO₂ nanostructures, the present SnO₂ NRs arrays/TiO₂ NPs based UV PDs simultaneously exhibit a short response time and a high photoresponsivity, which are less than 0.2 s (rise and decay time) and 21.6 A W⁻¹, respectively. This response rate is almost one order of magnitude faster than that of pure-TiO₂ NPs, while the responsivity still remains much higher than the commercial values (0.1–0.2 A W⁻¹). The superior performance is ascribed to the large UV light harvest offered from the layer of TiO₂ NPs clusters, the directional electron transmission channel provided by SnO₂ NRs arrays and improved electrons transmit by heterojunctions formed between SnO₂ and TiO₂. Moreover, the present UV PDs with excellent UV light selectivity and fabulous detection sensitivity are competitive and highly applicable in UV detection.