title: Slow cooling and efficient extraction of C-exciton hot carriers in MoS2monolayer.
abstract: In emerging optoelectronic applications, such as water photolysis, exciton fission and novel photovoltaics involving low-dimensional nanomaterials, hot-carrier relaxation and extraction mechanisms play an indispensable and intriguing role in their photo-electron conversion processes. Two-dimensional transition metal dichalcogenides have attracted much attention in above fields recently; however, insight into the relaxation mechanism of hot electron-hole pairs in the band nesting region denoted as C-excitons, remains elusive. Using MoS2monolayers as a model two-dimensional transition metal dichalcogenide system, here we report a slower hot-carrier cooling for C-excitons, in comparison with band-edge excitons. We deduce that this effect arises from the favourable band alignment and transient excited-state Coulomb environment, rather than solely on quantum confinement in two-dimension systems. We identify the screening-sensitive bandgap renormalization for MoS2monolayer/graphene heterostructures, and confirm the initial hot-carrier extraction for the C-exciton state with an unprecedented efficiency of 80%, accompanied by a twofold reduction in the exciton binding energy.
authors.affiliation: State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China.|Department of Electrical &Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore.
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Electrical &Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore.|Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore.|The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ, UK.
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Wang
authors.affiliation: State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China.
authors.forename: Hai-Yu
authors.initials: HY
authors.lastname: Wang
authors.affiliation: The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ, UK.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Grinblat
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore.|Institute of Materials Research &Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis 138634, Singapore.
authors.forename: Yu-Li
authors.initials: YL
authors.lastname: Huang
authors.affiliation: State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Wang
authors.affiliation: Laser Materials Processing Research Center, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Xiao-Hui
authors.initials: XH
authors.lastname: Ye
authors.affiliation: State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China.
authors.forename: Xian-Bin
authors.identifier: 0000-0002-0046-2016
authors.initials: XB
authors.lastname: Li
authors.affiliation: Department of Materials Science and Engineering, Monash University, Clayton, Victoria 3800, Australia.
authors.forename: Qiaoliang
authors.identifier: 0000-0002-6971-789X
authors.initials: Q
authors.lastname: Bao
authors.affiliation: Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542, Singapore.
authors.forename: AndrewThye-Shen
authors.initials: AS
authors.lastname: Wee
authors.affiliation: The Blackett Laboratory, Department of Physics, Imperial College London, London SW7 2AZ, UK.
authors.forename: Stefan A
authors.initials: SA
authors.lastname: Maier
authors.affiliation: State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China.
authors.forename: Qi-Dai
authors.initials: QD
authors.lastname: Chen
authors.affiliation: Laser Materials Processing Research Center, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
authors.forename: Min-Lin
authors.initials: ML
authors.lastname: Zhong
authors.affiliation: Department of Electrical &Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583, Singapore.
authors.forename: Cheng-Wei
authors.initials: CW
authors.lastname: Qiu
authors.affiliation: State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China.|College of Physics, Jilin University, 2699 Qianjin Street, Changchun 130012, China.
authors.forename: Hong-Bo
authors.initials: HB
authors.lastname: Sun