Correlated fluorescence blinking in two-dimensional semiconductor heterostructures

• Main Authors: Xu, Weigao, Liu, Weiwei, Schmidt, Jan F., Zhao, Weijie, Lu, Xin, Raab, Timo, Diederichs, Carole, Gao, Weibo, Seletskiy, Denis V., Xiong, Qihua
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2017
• Subjects: Quantum effects; Single photons
• Online Access: https://hdl.handle.net/10356/86302; http://hdl.handle.net/10220/43979
• Institution: Nanyang Technological University

‘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.