Manipulating the Switching of Liquid Crystals by Interfacial Nanotips Penetrating Polyimide Hybrid Alignment Layers

Abstract

Liquid crystals (LCs) are an active area of interest for electro-optical devices, and the alignment of LCs has emerged as an extremely essential issue for LC devices. Evidence suggests that the surface topology of alignment layers plays a key role in both tuning the tilt angles and modulating the switching of LCs. Herein, nanotips are constructed by self-assembly of two different two-dimensional (2D) nanoflakes in PI hybrid alignment layers to modulate the switching of LCs. Both MoS2 nanotips and Ti3C2Tx MXene nanotips were observed on hybrid thin layers, but MoS2 nanotips are much thinner and taller. The hybrid thin layers are highly transparent, and the nanotips penetrating the hybrid layers roughened the surface but moderately declined the surface energy. LCs are strongly anchored on hybrid alignment layers, and the nanotips were found to topologically hinder the in-plane switching of LCs and hence accelerate the rewriting speed of optical data. Besides the accelerated optical rewriting speed, the surface plasmon–polariton (SPP) of nanoflakes also substantially boosted the external electric field to switch LCs and hence remarkably diminished the operating voltage and likewise sufficiently shortened the response time. In particular, the optical rewriting time of LCs that homogeneously aligned on hybrid alignment layers with 0.5% MoS2 nanoflakes doping has been deduced to as short as 43.36 s, which is a decrease of 37.81% compared to that of PI alignment layers cell; LCs can be electrically driven to switch optical data at 2.51 V and return to their original alignment state within 24.142 ms. These results signify the promising applications of hybrid thin layers for both traditional LC devices and optical rewritable LC devices.