title: Enhancing light emission efficiency without color change in post-transition metal chalcogenides.
abstract: Two-dimensional (2D) materials can take a large amount of mechanical deformation before reaching the fracture limit due to their high Young's modulus, and this in return, provides a way to tune the properties of 2D materials by strain engineering. Previous works have shown that the optical band gap of transition metal chalcogenides (TMDs) can be modulated by strain, resulting in a drift of the photoluminescence (PL) peak position and a decrease (or little change) in PL intensity. Here, we report a member of the post-transition metal chalcogenides (PTMCs), 2D-GaSe sheets, displaying vastly different phenomena under strain. Strained 2D-GaSe emits photons at almost the same wavelength as unstrained material but appears an order of magnitude brighter. In contrast to TMDs, optical spectroscopy measurements reveal that changes in the optical properties are mostly related to the colossal optical absorption anisotropy of GaSe, instead of commonly accepted strain-induced band renormalization. Results suggest that the light-matter interaction and the optical properties of 2D-GaSe can be controlled at will by manipulating the optical absorption.
authors.affiliation: The MOE Key Laboratory of Weak-Light Nonlinear Photonics, Taida School of Physics, Nankai University, Tianjin 300457, China.
authors.forename: Cong
authors.initials: C
authors.lastname: Wang
authors.forename: Shengxue
authors.initials: S
authors.lastname: Yang
authors.forename: Hui
authors.initials: H
authors.lastname: Cai
authors.forename: Can
authors.initials: C
authors.lastname: Ataca
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.forename: Xinzheng
authors.initials: X
authors.lastname: Zhang
authors.forename: Jingjun
authors.initials: J
authors.lastname: Xu
authors.forename: Bin
authors.initials: B
authors.lastname: Chen
authors.forename: Kedi
authors.initials: K
authors.lastname: Wu
authors.forename: Haoran
authors.initials: H
authors.lastname: Zhang
authors.forename: Luqi
authors.initials: L
authors.lastname: Liu
authors.forename: Jingbo
authors.initials: J
authors.lastname: Li
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Grossman
authors.forename: Sefaattin
authors.initials: S
authors.lastname: Tongay
authors.forename: Qian
authors.initials: Q
authors.lastname: Liu