High‐Performance Ultraviolet Photodetectors Enabled by van der Waals Schottky Junction Based on TiO<sub>2</sub> Nanorod Arrays/Au‐Modulated Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub> MXene
Guangcan Luo, Ziling Zhang, Jun Wang, Meng Huang, Yuchen Long, Yang Liu, Zixin Zeng, Yunfan Wang, Jihua Zou, Aobo Ren, Shengyun Luo, Yinye Yang, Wei Li, Lin Hong, Dewei Zhao
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.