15 research outputs found
Conjugated organic polymers: Effect of morphology and defects on the emission of DL-alkyl polyfluorenes.
Direct fabrication of nanoscale light emitting diode on silicon probe tip for scanning microscopy
Effect of film morphology on the energy transfer to emissive green defects in dialkyl polyfluorenes
Near-field scanning optical microscopy with monolithic silicon light emitting diode on probe tip
Direct fabrication of nanoscale light emitting diode on silicon probe tip for scanning microscopy
Near-field scanning optical microscopy with monolithic silicon light emitting diode on probe tip
Effect of film morphology on the energy transfer to emissive green defects in dialkyl polyfluorenes
Correlated fluorescence blinking in two-dimensional semiconductor heterostructures
‘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.NRF (Natl Research Foundation, S’pore)MOE (Min. of Education, S’pore