Exciton Manipulation and Transport in 2D Semiconductor Heterostructures

Long-lived interlayer excitons in van der Waals heterostructures based on TMDCs have recently emerged as a promising platform for controlling exciton transport on the mesoscopic length scales, allowing control over exciton diffusion length, energy and polarization. One of the driving forces for exciton transport is the interaction between out-of-plane dipoles in the exciton bosonic gas. By using spatial and time-resolved photoluminescence imaging, we can observe the dynamics of exciton transport, enabling a direct estimation of the exciton mobility [1]. The presence of interactions significantly modifies the diffusive transport of excitons, effectively acting as a source of drift force and enhancing the diffusion coefficient by one order of magnitude. In certain types of vdW heterostructures, the layer hybridization and exciton-exciton interaction can also be electrically tuned, allowing us to uncover dipole-dependent properties and transport of excitons with different degrees of hybridization [2]. Moreover, we find constant emission quantum yields of the transporting species as a function of excitation power with dominating radiative decay mechanisms dominating over nonradiative ones, a fundamental requirement for efficient excitonic devices.
References

[1] Z. Sun et al.: “Excitonic Transport Driven by Repulsive Dipolar Interaction in a van Der Waals Heterostructure”. Nature Photonics 16, 79–85 (2022).
[2] F. Tagarelli, E. Lopriore et al. : “Electrical Control of Hybrid Exciton Transport in a van Der Waals Heterostructure”. Nature Photonics 17 615- (2023).