Hot exciton transport in WSe2 monolayers

TL;DR

This paper demonstrates hot exciton transport in WSe2 monolayers at room temperature, revealing density-dependent expansion dynamics influenced by energy relaxation and Auger processes, advancing understanding of exciton behavior in 2D materials.

Contribution

It provides the first experimental observation of hot exciton transport in WSe2 monolayers with detailed analysis of expansion dynamics and underlying relaxation mechanisms.

Findings

Hot exciton transport observed at room temperature.

Density-dependent exciton expansion dynamics.

Saturation of expansion rate at high excitation densities.

Abstract

We experimentally demonstrate hot exciton transport in h-BN encapsulated WSe2 monolayers via spatially and temporally resolved photoluminescence measurements at room temperature. We show that the nonlinear evolution of the mean squared displacement of the non-resonantly excited hot exciton gas is primarily due to the relaxation of its excess kinetic energy and is characterized by a density-dependent fast expansion that converges to a slower, constant rate expansion. We also observe saturation of the hot exciton gas' expansion rate at high excitation densities due to the balance between Auger-assisted hot exciton generation and the phonon-assisted hot exciton relaxation processes.