MoS$_{2}$ pixel arrays for real-time photoluminescence imaging of redox molecules

TL;DR

This paper demonstrates that MoS₂ pixel arrays can perform real-time, high-sensitivity imaging of redox molecule concentration changes, offering a fast, non-invasive optical method for chemical and biological analysis.

Contribution

The study introduces a novel use of MoS₂ monolayer pixel arrays for real-time, high-sensitivity photoluminescence imaging of redox-active molecules, surpassing traditional optical detection speeds.

Findings

Achieved 0.9 mV/√Hz sensitivity on 5 μm pixels.

Enabled nanomolar concentration detection at 100 ms frame rate.

Demonstrated real-time visualization of electrochemical potential changes.

Abstract

Measuring the behavior of redox-active molecules in space and time is crucial for better understanding of chemical and biological systems and for the development of new technologies. Optical schemes are non-invasive, scalable and can be applied to many different systems, but usually have a slow response compared to electrical detection methods. Furthermore, many fluorescent molecules for redox detection degrade in brightness over long exposure times. Here we show that the photoluminescence of pixel arrays of an atomically thin two-dimensional (2D) material, a monolayer of MoS$_{2}$, can image spatial and temporal changes in redox molecule concentration in real time. Because of the strong dependence of MoS$_{2}$ photoluminescence on doping and sensitivity to surface changes characteristic of 2D materials, changes in the local chemical potential significantly modulate the photoluminescence of MoS$_{2}$, with a sensitivity of 0.9 mV/$\sqrt{Hz}$ on a 5 $\mu$m by 5 $\mu$m pixel, corresponding to better than parts-per-hundred changes in redox molecule concentration down to nanomolar concentrations at 100 ms frame rates. The real-time imaging of electrochemical potentials with a fast response time provides a new strategy for visualizing chemical reactions and biomolecules with a 2D material screen.