title: Correlated fluorescence blinking in two-dimensional semiconductor heterostructures.
abstract: 'Blinking', or 'fluorescence intermittency', refers to a random switching between 'ON' (bright) and 'OFF' (dark) states of an emitter; it has been studied widely in zero-dimensional quantum dots and molecules, and scarcely in one-dimensional systems. A generally accepted mechanism for blinking in quantum dots involves random switching between neutral and charged states (or is accompanied by fluctuations in charge-carrier traps), which substantially alters the dynamics of radiative and non-radiative decay. Here, we uncover a new type of blinking effect in vertically stacked, two-dimensional semiconductor heterostructures, which consist of two distinct monolayers of transition metal dichalcogenides (TMDs) that are weakly coupled by van der Waals forces. Unlike zero-dimensional or one-dimensional systems, two-dimensional TMD heterostructures show a correlated blinking effect, comprising randomly switching bright, neutral and dark states. Fluorescence cross-correlation spectroscopy analyses show that a bright state occurring in one monolayer will simultaneously lead to a dark state in the other monolayer, owing to an intermittent interlayer carrier-transfer process. Our findings suggest that bilayer van der Waals heterostructures provide unique platforms for the study of charge-transfer dynamics and non-equilibrium-state physics, and could see application as correlated light emitters in quantum technology.
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore.
authors.forename: Weigao
authors.initials: W
authors.lastname: Xu
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany.
authors.forename: Jan F
authors.initials: JF
authors.lastname: Schmidt
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore.
authors.forename: Weijie
authors.initials: W
authors.lastname: Zhao
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore.
authors.forename: Xin
authors.initials: X
authors.lastname: Lu
authors.affiliation: Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany.
authors.forename: Timo
authors.initials: T
authors.lastname: Raab
authors.affiliation: Laboratoire Pierre Aigrain, Ecole Normale Supérieure, PSL Research University, CNRS, Université Pierre et Marie Curie, Sorbonne Universités, Université Paris Diderot, Sorbonne Paris-Cité, 24 Rue Lhomond, 75231 Paris Cedex 05, France.|MajuLab, CNRS-UNS-NUS-NTU International Joint Research Unit, UMI 3654 Singapore.
authors.forename: Carole
authors.initials: C
authors.lastname: Diederichs
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore.
authors.forename: Weibo
authors.initials: W
authors.lastname: Gao
authors.affiliation: Department of Physics and Center for Applied Photonics, University of Konstanz, D-78457 Konstanz, Germany.
authors.forename: Denis V
authors.initials: DV
authors.lastname: Seletskiy
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore.|MajuLab, CNRS-UNS-NUS-NTU International Joint Research Unit, UMI 3654 Singapore.|NOVITAS, Nanoelectronics Center of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, 639798 Singapore.
authors.forename: Qihua
authors.initials: Q
authors.lastname: Xiong