Interlayer exciton dynamics in van der Waals heterostructures

TL;DR

This paper investigates the microscopic processes of interlayer excitons in van der Waals heterostructures, focusing on their formation, dynamics, and contribution to photoluminescence, with detailed analysis on MoSe2-WSe2 systems.

Contribution

It provides new insights into the binding energies, wave functions, and dynamics of interlayer excitons in TMD heterostructures, advancing understanding of their optoelectronic properties.

Findings

Interlayer excitons have high binding energies and specific wave functions.

The dynamics of exciton formation, thermalization, and decay are characterized.

Interlayer excitons significantly contribute to photoluminescence in TMD heterostructures.

Abstract

Exciton binding energies of hundreds of meV and strong light absorption in the optical frequency range make transition metal dichalcogenides (TMDs) promising for novel optoelectronic nanodevices. In particular, atomically thin TMDs can be stacked to heterostructures enabling the design of new materials with tailored properties. The strong Coulomb interaction gives rise to interlayer excitons, where electrons and holes are spatially separated in different layers. In this work, we reveal the microscopic processes behind the formation, thermalization and decay of these fundamentally interesting and technologically relevant interlayer excitonic states. In particular, we present for the exemplary MoSe$_2$-WSe$_2$ heterostructure the interlayer exciton binding energies and wave functions as well as their time- and energy-resolved dynamics. Finally, we predict the dominant contribution of interlayer excitons to the photoluminescence of these materials.