Out of the dark and into the light: towards dark-state based chemical sensors

TL;DR

This paper introduces a novel sensing mechanism using dark excitons in atomically thin transition metal dichalcogenides, enabling highly sensitive and unambiguous optical detection of molecules through bright exciton formation.

Contribution

It presents a new sensor concept based on dark-to-bright exciton transformation in 2D materials, offering a clear optical fingerprint for molecule detection.

Findings

Dark excitons can be transformed into bright excitons by molecules with dipole moments.

This transformation results in a distinct optical peak, enabling unambiguous sensing.

The method shows high sensitivity and specificity for molecular detection.

Abstract

The rapidly increasing use of sensors throughout different research disciplines and the demand for more efficient devices with less power consumption depends critically on the emergence of new sensor materials and novel sensor concepts. Atomically thin transition metal dichalcogenides have a huge potential for sensor development within a wide range of applications. Their optimal surface-to-volume ratio combined with strong light-matter interaction results in a high sensitivity to changes in their surrounding. Here, we present a novel, highly efficient sensing mechanism to detect molecules based on dark excitons in these materials. We show that the presence of molecules with a dipole moment transforms dark states into bright excitons resulting in an additional pronounced peak in easy accessible optical spectra. This effect exhibits a huge potential for sensor applications, since it offers an unambiguous optical finger print for the detection of molecules - in contrast to common sensing schemes relying on small peak shifts and intensity changes.