Utilizing 2D materials in liquid crystal–based electro-optic devices: A perspective

Abstract

The alignment agent plays a crucial role in the electro-optical characteristics of an electro-optic liquid crystal (LC) device. Conventionally, rubbed polyimide (PI) layers have been utilized as alignment agents in LC devices. However, these organic PI layers are sensitive to UV rays and high temperatures. The rubbing procedure involved in preparing PI layers also introduces drawbacks, including non-uniform brightness due to uneven rubbing mechanisms and the presence of residual fiber dust. In our recent research, we demonstrated that various hexagonal 2D (inorganic) materials, such as monolayer graphene, monolayer tungsten diselenide (WSe2), and monolayer hexagonal boron nitride (h-BN) nanosheets, can effectively serve as planar-alignment agents in electro-optic LC devices. In this Perspective, we review the rubbing-free LC alignment process, which relies on the coherent overlay of the benzene rings of LC molecules on the hexagonal lattice structure of 2D materials. We review our recent results on LC devices utilizing 2D materials as alignment agents, highlighting their potential advantages. Furthermore, we discuss the challenges associated with this research field. Finally, we provide our perspectives on the future directions and opportunities for advancing this area of study, aiming to overcome challenges and extend the benefits of employing 2D materials as planar-alignment agents in electro-optic LC devices.