ZnO Quantum Dot/MXene Nanoflake Hybrids for Ultraviolet Photodetectors

Abstract

Efficacious utility of fugacious photons within a limited dimension of photoactive semiconductor thin films provides a facile approach to break through the obstacle for the sensitivity improvement of photodetection. Herein, we demonstrate a facile way to fabricate ZnO quantum dot (QD)/MXene nanoflake photodetectors by uniformly blending various ratios of two-dimensional (2D) Ti3C2Tx nanoflakes into ZnO QD thin films, which can establish a carrier transportation highway and light confinement centers within the photoactive layers. The light absorption of hybrid thin films is obviously enhanced because of the localized surface plasmon resonance effect of MXene nanoflakes, resulting in an expressively enhanced external quantum efficiency by 35 times for the device with 0.1 mg/mL 2D Ti3C2Tx nanoflakes (150.0%) in comparison with that of the pristine photodetector (4.3%). Under 350 nm light illumination (1.72 mW cm–2), the carrier transportation in ZnO thin films is significantly accelerated with the hot electron injection from the high-conductivity 2D Ti3C2Tx nanoflakes and thereby the optimal responsivity of 425 mA/W with an improved response speed at 10 V. Furthermore, ZnO QD/MXene nanoflake photodetectors also exhibit an excellent long-term stability. This work provides an efficient method to fabricate high-performance ZnO UV photoelectric devices in the military and civilian fields at low light intensities.