Alignment Relation between a Nematic Liquid Crystal and ReS2 Nanosheets: Implications for Anisotropic Optoelectronic Applications

Abstract

Rhenium disulfide (ReS₂), a two-dimensional (2D) semiconductor, exhibits unique anisotropic properties rarely found in other 2D materials. This study investigates the alignment characteristics of nematic liquid crystals on ReS₂ nanosheet using optical texture analysis, transmission measurements, and Raman scattering techniques. For the $\overrightarrow{b}\text{and}\overrightarrow{c}$, crystal basis vectors of ReS₂, the director (${\hat{n}}_0$) aligned along the easy axis satisfies equations, ${\hat{n}}_0·(\overrightarrow{c}\times \overrightarrow{b})>0$ and ${\hat{n}}_0·\overrightarrow{b}=\left|\overrightarrow{b}\right|\cos \left(\theta \right)$ > 0 with θ = 15°. Both polar and azimuthal anchoring strengths were found to be very weak, with extrapolation lengths on the order of several micrometers. Additionally, the orientation of the ReS₂ nanosheets suspended in the nematic liquid crystal is effectively controlled through electric field application and director manipulation. The ability to control the orientation of ReS₂ nanosheets through several methods suggests that the anisotropic properties of ReS₂ can be effectively tuned to different values for switching applications. This capability opens up possibilities for leveraging the unique directional characteristics of ReS₂ in devices that require precise orientation-dependent control.