‘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 dots1 and molecules2, 3, and scarcely in one-dimensional systems4, 5. A generally accepted mechanism for blinking in quantum dots involves random switching between neutral and charged states6, 7 (or is accompanied by fluctuations in charge-carrier traps8), 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 heterostructures9, 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.
At a glance
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- Video 1: High speed dynamic fluorescence imaging of the WS2 component in the WS2/MoSe2 heterostructure (4.92 MB, Download)
- High speed dynamic fluorescence imaging of the WS2 component in the WS2/MoSe2 heterostructure.
- Video 2: High speed dynamic fluorescence imaging of the MoSe2 component in the WS2/MoSe2 heterostructure (8.16 MB, Download)
- High speed dynamic fluorescence imaging of the MoSe2 component in the WS2/MoSe2 heterostructure.
- Video 3: Dynamic fluorescence imaging of the WS2 component in a MoS2/WS2 heterostructure acquired with a color CCD camera (1.8 MB, Download)
- Dynamic fluorescence imaging of the WS2 component in a MoS2/WS2 heterostructure acquired with a color CCD camera.
- Supplementary Information (5.7 MB)
This file contains Supplementary Text, Supplementary Figures 1-16 and Supplementary References.