High‐Performance Ultraviolet Photodetectors Enabled by van der Waals Schottky Junction Based on TiO₂ Nanorod Arrays/Au‐Modulated Ti₃C₂T_x MXene

Abstract

Abstract Two‐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 TiO 2 nanorod arrays/Ti 3 C 2 T x MXene van der Waals (vdW) Schottky junction by all‐solution process technique is reported. The Ti 3 C 2 T x 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 Ti 3 C 2 T x , 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 TiO 2 and oxygen) and reverse pyroelectric effect are largely eliminated. As a result, the responsivity and specific detectivity of the device with FTO/TiO 2 nanorod arrays/Ti 3 C 2 T x /Au structure reach 1.95 × 10 5 mA W −1 and 4.3 × 10 13 cm Hz 1/2 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.