High‐Performance Ultraviolet Photodetectors Enabled by van der Waals Schottky Junction Based on TiO2 Nanorod Arrays/Au‐Modulated Ti3C2Tx MXene

Abstract

AbstractTwo‐dimensional transition metal carbides and nitrides (MXenes) show tremendous potential for optoelectronic devices due to their excellent electronic properties. Here, a high‐performance ultraviolet photodetector based on TiO2 nanorod arrays/Ti3C2Tx MXene van der Waals (vdW) Schottky junction by all‐solution process technique is reported. The Ti3C2Tx MXene modulated by the Au electrode increases its work function from 4.41 to 5.14 eV to form a hole transport layer. Complemented by the dangling bond‐free surface of Ti3C2Tx, the Fermi‐level pinning effect is suppressed and the electric‐field strength of the Schottky junction is enhanced, which promotes charge separation and transport. After applying a bias of −1.5 V, the photovoltaic effect is favorably reinforced, while the hole‐trapping mechanism (between TiO2 and oxygen) and reverse pyroelectric effect are largely eliminated. As a result, the responsivity and specific detectivity of the device with FTO/TiO2 nanorod arrays/Ti3C2Tx/Au structure reach 1.95 × 105 mA W−1 and 4.3 × 1013 cm Hz1/2 W−1 (370 nm, 65 mW cm−2), respectively. This work provides an effective approach to enhance the performance of photodetectors by forming the vdW Schottky junction and choosing metal electrodes to modulate MXene as a suitable charge transport layer.