Two-dimensional InSe/WS$_2$ heterostructure with enhanced optoelectronic performance in the visible region
Abstract
Two-dimensional (2D) InSe and WS exhibit promising characteristics for optoelectronic and photoelectrochemical applications, e.g. photodetection and photocatalytic water splitting. However, both of them have poor absorption of visible light due to wide band gaps. 2D InSe has high electron mobility but low hole mobility, while 2D WS is on the opposite. Here, we design a 2D heterostructure composed of their monolayers and study its optoelectronic properties by first-principles calculations. Our results show that the heterostructure has a direct band gap of 2.19 eV, which is much smaller than those of the monolayers mainly due to a type-II band alignment: the valence band maximum and the conduction band minimum of monolayer InSe are lower than those of monolayer WS, respectively. The visible-light absorption is enhanced considerably, e.g. about fivefold (threefold) increase at the wavelength of 490 nm in comparison to monolayer InSe (WS). The type-II band alignment also facilitates the spatial separation of photogenerated electron-hole pairs, i.e., electrons (holes) reside preferably in the InSe (WS) layer. The two layers complement each other in carrier mobilities of the heterostructure: the photogenerated electrons and holes inherit the large mobilities from the InSe and WS monolayers, respectively.
Keywords
Cite
@article{arxiv.1808.01610,
title = {Two-dimensional InSe/WS$_2$ heterostructure with enhanced optoelectronic performance in the visible region},
author = {Lu-Lu Yang and Jun-jie Shi and Min Zhang and Zhongming Wei and Yi-min Ding and Meng Wu and Yong He and Yu-lang Cen and Wen-hui Guo and Shu-hang Pan and Xing-Lai Che and Xiong Li and Yao-Hui Zhu},
journal= {arXiv preprint arXiv:1808.01610},
year = {2020}
}