High-performance, self-powered flexible MoS2 photodetectors with asymmetric van der Waals gaps

Xiaoqiu Tang; Shuai Wang; Yao Liang; Dongwei Bai; Jiyuan Xu; Yingying Wang; Chaoyu Chen; Xiang Liu; Sumei Wu; Yang Wen; Dayong Jiang; Zhihua Zhang

doi:10.1039/d1cp05602f

High-performance, self-powered flexible MoS₂ photodetectors with asymmetric van der Waals gaps

Phys Chem Chem Phys. 2022 Mar 23;24(12):7323-7330. doi: 10.1039/d1cp05602f.

Authors

Xiaoqiu Tang¹, Shuai Wang¹, Yao Liang¹, Dongwei Bai¹, Jiyuan Xu¹, Yingying Wang², Chaoyu Chen¹, Xiang Liu¹, Sumei Wu¹, Yang Wen¹, Dayong Jiang³, Zhihua Zhang¹

Affiliations

¹ School of Materials Science and Engineering, Dalian Jiaotong University, Dalian 116028, P. R. China. liangyao@djtu.edu.cn.
² Department of Optoelectronic Science, Harbin Institute of Technology at Weihai, Weihai 264209, P. R. China.
³ School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, P. R. China. dayongjiangcust@126.com.

PMID: 35262113
DOI: 10.1039/d1cp05602f

Abstract

With an urgent demand for low-energy-consumption and wearable devices, it is desirable to find an easy, effective, and low-cost method to fabricate self-powered flexible photodetectors with simple configurations and high-performance. Self-powered photodetectors are normally fabricated based on either two different materials or the same material in contact with two different metal electrodes. Here, a flexible MoS₂ photodetector with the same Au electrodes was fabricated on a polyethylene terephthalate (PET) substrate which exhibits self-powered properties. To our knowledge, its configuration is the simplest, and the fabrication process is easy to implement. At a bias of 0 V, the photodetector exhibits a high responsivity of 431 mA W^-1, a short response/recovery time of 40 ms/40 ms, and excellent flexibility. Compared with those at a bias of 2 V, a dark current is sufficiently suppressed, and the response/recovery speed is significantly improved. It is found that the driving force of the self-powered photodetector is provided by the asymmetric Schottky barriers originating from the spontaneous generation of two van der Waals gaps with different widths. The asymmetric barriers exist stably at the interfaces between the 2D material and Au electrodes as further observed for ReS₂ or GaSe flakes, which show the generality of asymmetric Schottky barriers between the 2D material and Au electrodes. The discovery here thus gives a new way to generate asymmetric Schottky barriers and develop high-performance self-powered photodetectors.