Long-term ambient stability of MoS2via ionic liquid encapsulation

Abstract

Transition metal dichalcogenides (TMDs), such as MoS₂, have attracted considerable attention due to their potential in electronic and optoelectronic applications. However, their susceptibility to degradation under ambient conditions can limit their practical use. In this study, we investigate the impact of ionic liquid (IL) dispersion on the surface of MoS₂, with a particular focus on its electronic properties. Using a relatively simple approach, the IL (1-butyl-3 methylimidazolium hexafluorophosphate ([BMIm·PF₆]; C₈H₁₅F₆N₂P)) was effectively dispersed across the sample surface, inducing n-type doping in MoS₂, as confirmed by multiple characterization techniques. The ambient stability of the material was also evaluated, revealing no apparent degradation of the MoS₂ crystals for periods exceeding one year. The results suggest that the IL acts as a protective barrier, significantly limiting the diffusion of oxygen containing species to the underlying crystals, modulating the surface electronic environment of MoS₂, and contributing to its long-term structural stability. These findings underscore the importance of surface protective strategies in preserving the structural and electronic integrity of TMDs, thereby broadening their potential for long term applications.