Dark-exciton driven energy funneling into dielectric inhomogeneities in two-dimensional semiconductors

Abstract

The optoelectronic and transport properties of two-dimensional transition metal dichalcogenide semiconductors (2D TMDs) are highly susceptible to external perturbation, enabling precise tailoring of material function through post-synthetic modifications. Here we show that nanoscale inhomogeneities known as nanobubbles can be used for both strain and, less invasively, dielectric tuning of exciton transport in bilayer tungsten disulfide (WSe2). We use ultrasensitive spatiotemporally resolved optical scattering microscopy to directly image exciton transport, revealing that dielectric nanobubbles are surprisingly efficient at funneling and trapping excitons at room temperature, even though the energies of the bright excitons are negligibly affected. Our observations suggest that exciton funneling in dielectric inhomogeneities is driven by momentum-indirect (dark) excitons whose energies are more sensitive to dielectric perturbations than bright excitons. These results reveal a new pathway to control exciton transport in 2D semiconductors with exceptional spatial and energetic precision using dielectric engineering of dark state energetic landscapes.

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Cited by in corpus (7)

• Exciton optics, dynamics and transport in atomically thin semiconductors
• Ultra Localized Optoelectronic Properties of Nanobubbles in 2D Semiconductors
• Detecting, distinguishing, and spatiotemporally tracking photogenerated charge and heat at the nanoscale
• Algorithm for Reproducible Analysis of Semiconducting 2D Nanomaterials Based on UV/VIS Spectroscopy
• Electrically Controlled Interfacial Charge Transfer Induced Excitons in MoSe2-WSe2 Lateral Heterostructure
• Curvature-enhanced localised emission from dark states in wrinkled monolayer WSe2 at room temperature
• Two dimensional semiconductors: optical and electronic properties