A self-powered ultraviolet photodetector with van der Waals Schottky junction based on TiO2 nanorod arrays/Au-modulated V2CT MXene

A self-powered ultraviolet photodetector (UV PD) with van der Waals (vdW) Schottky junction based on TiO2 nanorod arrays/Au-modulated V2CTx MXene is reported. The Schottky junction enables the device to operate in self-powered mode. The dangling bond-free surface of V2CTx MXene reduces the charge recombination at the junction interface. Meanwhile, V2CTx MXene, with the work function (WF) increasing to 5.35 eV, forms a hole transport layer by contacting with Au electrode, which facilitates the carrier extraction. The electron lifetime in the device has prolonged to 8.95 μs. As a result, the responsivity and detectivity of the PD have achieved 28 mA/W and 1.2 × 1011 cm Hz1/2/W (340 nm, 65 mW/cm2, 0 V), respectively. In addition, the presence of the Au electrode prevents the vanadium from coming into contact with oxygen and oxidizing, preserving the properties of the V2CTx films. After 180 days of exposure to the atmosphere, the device performance remained at a particularly high level, indicating enhanced durability. This work points out an effective approach to modulate the properties of V2CTx to obtain the high performance and stability of the UV PD.