Fused Nanojunctions of Electron-Depleted ZnO Nanoparticles for Extraordinary Performance in Ultraviolet Detection

摘要

Zinc oxide nanoparticles (ZnO-NPs) with radius of the Debye length have the optimal electron depletion effect for high-performance optoelectronic devices. However, a major challenge remains in assembling ZnO-NPs into 3D interlinked networks for high-efficiency electron transport. Here an ultrafast thermal annealing process has been developed by exposing the ZnO-NPs to excessive heat for a short period of 2 s. This enables the formation of NP–NP interface nanojunctions, resulting in nearly two orders of magnitude decrease of the dark current IDark and more than an order of magnitude increase of the photocurrent IPh under ultraviolet (UV) illumination. Moreover, the UV photodetectors based on such 3D interlinked ZnO-NP networks exhibit extraordinary performance with high IPh/IDark ratio of 3.1 × 105, responsivity of up to 95.4 A W~(?1) at 340 nm UV power of 0.1 mW cm?2 (and up to 430 A W~(?1) at 0.003 mW cm?2), detectivity of 1.4 × 1013 Jones, and rise/decay time of 9.4 s/13.5 s. These results illustrate the critical importance of the NP–NP interface nanojunctions and provide a low-cost pathway for high-performance ZnO-NP optoelectronics.