Atomically Thin Boron Nitride as an Ideal Spacer for Metal-Enhanced Fluorescence

TL;DR

This paper demonstrates that atomically thin hexagonal boron nitride serves as an ideal dielectric spacer for metal-enhanced fluorescence, significantly improving enhancement, sensitivity, and reusability in fluorescence applications.

Contribution

It introduces atomically thin BN as a defect-free, thermally stable spacer with atomic-level thickness control, outperforming traditional dielectric films in MEF.

Findings

Enhancement factor up to ~95+-5

Reusability of ~90% after heating cycles

Improved sensitivity down to 10^-8 M

Abstract

The metal-enhanced fluorescence (MEF) considerably enhances the luminescence for various applications, but its performance largely depends on the dielectric spacer between the fluorophore and plasmonic system. It is still challenging to produce a defect-free spacer having an optimized thickness with a subnanometer accuracy that enables reusability without affecting the enhancement. In this study, we demonstrate the use of atomically thin hexagonal boron nitride (BN) as an ideal MEF spacer owing to its multifold advantages over the traditional dielectric thin films. With rhodamine 6G as a representative fluorophore, it largely improves the enhancement factor (up to ~95+-5), sensitivity (10^-8 M), reproducibility, and reusability (~90% of the plasmonic activity is retained after 30 cycles of heating at 350 {\deg}C in air) of MEF. This can be attributed to its two-dimensional structure, thickness control at the atomic level, defect-free quality, high affinities to aromatic fluorophores, good thermal stability, and excellent impermeability. The atomically thin BN spacers could increase the use of MEF in different fields and industries.