title: Enhancement of Exciton Emission from Multilayer MoS2at High Temperatures: Intervalley Transfer versus Interlayer Decoupling.
abstract: It is very important to obtain a deeper understand of the carrier dynamics for indirect-bandgap multilayer MoS2and to make further improvements to the luminescence efficiency. Herein, an anomalous luminescence behavior of multilayer MoS2is reported, and its exciton emission is significantly enhanced at high temperatures. Temperature-dependent Raman studies and electronic structure calculations reveal that this experimental observation cannot be fully explained by a common mechanism of thermal-expansion-induced interlayer decoupling. Instead, a new model involving the intervalley transfer of thermally activated carriers from Λ/Γ point to K point is proposed to understand the high-temperature luminescence enhancement of multilayer MoS2. Steady-state and transient-state fluorescence measurements show that both the lifetime and intensity of the exciton emission increase relatively to increasing temperature. These two experimental evidences, as well as a calculation of carrier population, provide strong support for the proposed model.
authors.affiliation: Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory of UV-Emitting Materials and Technology, Ministry of Education, Northeast Normal University, Changchun, 130024, China.
authors.forename: Yuanzheng
authors.initials: Y
authors.lastname: Li
authors.affiliation: Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory of UV-Emitting Materials and Technology, Ministry of Education, Northeast Normal University, Changchun, 130024, China.
authors.forename: Haiyang
authors.initials: H
authors.lastname: Xu
authors.affiliation: Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory of UV-Emitting Materials and Technology, Ministry of Education, Northeast Normal University, Changchun, 130024, China.
authors.forename: Weizhen
authors.initials: W
authors.lastname: Liu
authors.affiliation: Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory of UV-Emitting Materials and Technology, Ministry of Education, Northeast Normal University, Changchun, 130024, China.
authors.forename: Guochun
authors.initials: G
authors.lastname: Yang
authors.affiliation: CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Shi
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University, Singapore, 639798, Singapore.|NOVTAS, Nanoelectronics Center of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Liu
authors.affiliation: CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China.
authors.forename: Xinfeng
authors.initials: X
authors.lastname: Liu
authors.affiliation: Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory of UV-Emitting Materials and Technology, Ministry of Education, Northeast Normal University, Changchun, 130024, China.
authors.forename: Zhongqiang
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory of UV-Emitting Materials and Technology, Ministry of Education, Northeast Normal University, Changchun, 130024, China.
authors.forename: Qingxin
authors.initials: Q
authors.lastname: Tang
authors.affiliation: Centre for Advanced Optoelectronic Functional Materials Research and Key Laboratory of UV-Emitting Materials and Technology, Ministry of Education, Northeast Normal University, Changchun, 130024, China.
authors.forename: Yichun
authors.initials: Y
authors.lastname: Liu
keywords: heat-induced interlayer decoupling; intervalley transfer of carriers; luminescence enhancement; multilayer MoS2