Electro-optic liquid crystal device employing two-dimensional WSe2 as the planar-alignment layers

Abstract

Two-dimensional (2D) tungsten diselenide (WSe2) nanosheets were transferred onto indium tin oxide (ITO) coated glass slides. Two such 2D WSe2-covered ITO glass slides were placed together to fabricate an electro-optic liquid crystal (LC) cell. A nematic LC inside this WSe2-based device obtains uniform planar-alignment. The coherent overlay of the LC molecules along the armchair direction on the WSe2 lattice leads to this planar-alignment at the molecular scale. This WSe2-based LC device exhibits the typical electro-optical effect on the application of an electric field. A sharp Fréedericksz transition of the nematic director from this electro-optical effect confirms that the 2D WSe2 provides sufficient planar anchoring energy in the device. Finally, the WSe2/ITO slide exhibits more optical transparency than a standard polyimide alignment layer/ITO slide.