Exciton-phonon coupling strength in single-layer MoSe2 at room temperature

TL;DR

This paper introduces a novel 2D micro-spectroscopy technique to measure exciton-phonon coupling strength in single-layer MoSe2 at room temperature, revealing a large Huang-Rhys factor and enabling insights for optoelectronic device design.

Contribution

The study develops a new spectroscopic method to quantify exciton-phonon interactions in 2D materials at ambient conditions, with high spatial resolution.

Findings

Detected exciton-phonon beating signals in MoSe2.

Measured a Huang-Rhys factor of approximately 1.

Provided a tool for spatially resolved exciton-phonon coupling analysis.

Abstract

Single-layer transition metal dichalcogenides are at the center of an ever increasing research effort both in terms of fundamental physics and applications. Exciton-phonon coupling plays a key role in determining the (opto)electronic properties of these materials. However, the exciton-phonon coupling strength has not been measured at room temperature. Here, we develop two-dimensional micro-spectroscopy to determine exciton-phonon coupling of single-layer MoSe2. We detect beating signals as a function of waiting time T, induced by the coupling between the A exciton and the A'1 optical phonon. Analysis of two-dimensional beating maps combined with simulations provides the exciton-phonon coupling. The Huang-Rhys factor of ~1 is larger than in most other inorganic semiconductor nanostructures. Our technique offers a unique tool to measure exciton-phonon coupling also in other heterogeneous semiconducting systems with a spatial resolution ~260 nm, and will provide design-relevant parameters for the development of optoelectronic devices.