title: Fluorescence Concentric Triangles: A Case of Chemical Heterogeneity in WS2 Atomic Monolayer.
abstract: We report a novel optical property in WS2 monolayer. The monolayer naturally exhibits beautiful in-plane periodical and lateral homojunctions by way of alternate dark and bright band in the fluorescence images of these monolayers. The interface between different fluorescence species within the sample is distinct and sharp. This gives rise to intriguing concentric triangular fluorescence patterns in the monolayer. The novel optical property of this special WS2 monolayer is facilitated by chemical heterogeneity. The photoluminescence of the bright band is dominated by emissions from trion and biexciton while the emission from defect-bound exciton dominates the photoluminescence at the dark band. The discovery of such concentric fluorescence patterns represents a potentially new form of optoelectronic or photonic functionality.
authors.affiliation: Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542.|Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, 08-03, Singapore 138634.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542.|Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546.
authors.forename: Junpeng
authors.initials: J
authors.lastname: Lu
authors.affiliation: Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Ho
authors.affiliation: Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542.
authors.forename: Zhenliang
authors.initials: Z
authors.lastname: Hu
authors.affiliation: Department of Nanochemistry, Istituto Italiano di Tecnologia , Via Morego 30, 16163, Genova, Italy.
authors.forename: Zhiya
authors.initials: Z
authors.lastname: Dang
authors.affiliation: Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Carvalho
authors.affiliation: Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, 08-03, Singapore 138634.
authors.forename: Hui Ru
authors.initials: HR
authors.lastname: Tan
authors.affiliation: Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542.
authors.forename: Eng Soon
authors.initials: ES
authors.lastname: Tok
authors.affiliation: Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542.|Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546.
authors.forename: Chorng Haur
authors.initials: CH
authors.lastname: Sow
keywords: 2D materials; fluorescence; heterogeneity; homojunction; transitional metal dichalcogenides