High performance ultraviolet photodetectors based on ZnO nanoflakes/PVK heterojunction

Abstract

A high performance ultraviolet (UV) photodetector is receiving increasing attention due to its significant applications in fire warning, environmental monitoring, scientific research, astronomical observation, etc. The enhancement in performance of the UV photodetector has been impeded by lacking of a high-efficiency heterojunction in which UV photons can efficiently convert into charges. In this work, the high performance UV photodetectors have been realized by utilizing organic/inorganic heterojunctions based on a ZnO nanoflakes/poly (N-vinylcarbazole) hybrid. A transparent conducting polymer poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate)-coated quartz substrate is employed as the anode in replacement of the commonly ITO-coated glass in order to harvest shorter UV light. The devices show a lower dark current density, with a high responsivity (R) of 7.27 × 103A/W and a specific detectivity (D) of 6.20 × 1013 cm Hz1/2/W-1 at 2 V bias voltage in ambient environment (1.30 mW/cm2 at λ = 365 nm), resulting in the enhancements in R and D∗ by 49% and one order of magnitude, respectively. The study sheds light on developing high-performance, large scale-array, flexible UV detectors using the solution processable method.