Molecule signatures in photoluminescence spectra of transition metal dichalcogenides

TL;DR

This paper explores how molecule signatures can be detected in the photoluminescence spectra of monolayer transition metal dichalcogenides, enabling potential room-temperature molecule sensing.

Contribution

It investigates the influence of various molecular and experimental parameters on photoluminescence signatures, highlighting conditions for room-temperature detection.

Findings

Detection of molecules is possible under optimal conditions.

Photoluminescence spectra are sensitive to molecular dipole moment and orientation.

Room-temperature detection of molecules can be achieved.

Abstract

Monolayer transition metal dichalcogenides (TMDs) show an optimal surface-to-volume ratio and are thus promising candidates for novel molecule sensor devices. It was recently predicted that a certain class of molecules exhibiting a large dipole moment can be detected through the activation of optically inaccessible (dark) excitonic states in absorption spectra of tungsten-based TMDs. In this work, we investigate the molecule signatures in photoluminescence spectra in dependence of a number of different experimentally accessible quantities, such as excitation density, temperature as well as molecular characteristics including the dipole moment and its orientation, molecule-TMD distance, molecular coverage and distribution. We show that under certain optimal conditions, even room temperature detection of molecules can be achieved.