Large-area ReS₂ monolayer films on flexible substrate for SERS based molecular sensing with strong fluorescence quenching

Two-dimensional (2D) transition metal dichalcogenides materials have recently been explored as possible substrates for surface-enhanced Raman spectroscopy (SERS). However, in comparison to the conventional noble-metal-based counterpart, most of the 2D materials have very small area for SERS measurement, which is a big limitation toward practical applications. Herein, we presented our study of SERS using substrate-scale continuous ReS₂ monolayer films on flexible mica substrate. We demonstrated that the charge transfer between the target molecules and the atomically thin ReS₂ can be modulated by the underlying substrate of ReS₂, resulting in greatly different suppressing level of FL background. Kelvin probe force microscopy revealed a large difference of surface potential between ReS₂/SiO₂ and ReS₂/mica, suggesting that the strong FL quenching of molecular on ReS₂/mica might be attributed to the inert surface of layered mica. The large-area ReS₂ monolayer films on mica show a detection limit of R6G molecule around 10⁻⁷ M and a robust SERS performance after an exposure in air for one month and repeated bending for 1000 times. Our work explores the practical application of 2D ReS₂ for molecular detection via SERS technique.