Dynamics of Electrically Driven Cholesteric Liquid Crystals by Triboelectrification and Their Application in Self-Powered Information Securing and Vision Correcting

Abstract

Smart glass technology is rapidly evolving and finding significant application in light selectivity devices. However, a major disadvantage of such devices is their high energy requirement which hinders the commercialization progress. In this work, a self-powered optical switch is developed based on the electrochromic effect induced by a vertical contact-separation triboelectric nanogenerator (VCS-TENG) in a cholesteric liquid crystal (CLC) display. The voltage produced by the VCS-TENG causes the CLC display to transition across different physical states, viz., planar, focal conic, and homeotropic, which correspond to varying opacities and applications. Light penetration testing showed that the proposed CLC achieved a shading rate as high as 80%. Moreover, our device demonstrated high durability of up to 500 cycles. Most of all, the novel device successfully implemented reliable performance in important applications that have been demonstrated in this work, including webcam and cellphone security, and occlusion therapy devices in ophthalmology.

High-Performance and Low-Cost Overhead Projector Sheet-Based Triboelectric Nanogenerator for Self-Powered Cholesteric Liquid Crystal, Electroluminescence, and Portable Electronic Devices

“…Recently, the research group of Wang et al reported TENG-driven cholesteric liquid crystal devices and their application in information security, smart windows, optical switches, e-paper displays, and wireless sensors. − To the best of the authors’ knowledge, these are the only four reports available in the literature on TENG-driven cholesteric liquid crystals. The present manuscript also reports a similar application using TENG-driven cholesteric liquid crystal devices but with additional advantages.…”

Recent Progress in Liquid Crystal‐Based Smart Windows: Materials, Structures, and Design

“…Chen et al combined an optimized vertical contact-separation triboelectric nanogenerator (VCS-TENG) with the unique optical characteristics of the Ch-LCs to develop smart glasses (Figure 23d). [201] The VCS-TENG, which was fabricated by using a pair of triboelectric materials (polytetrafluoroethylene and chitosan/glycerol film), converted mechanical energy into an electrical signal to induce the rearrangement of Ch-LC molecules. The Ch-LCs were initially in the planar (P) state, leading to a partially transparent state.…”

“…[204] Copyright 2020, Wiley-VCH. Charging by RFS-TENG Wang et al [ 188] Energy-harvesting/conversion technologies and texture change of Ch-LCs VCS-TENG + Ch-LCs Transmittance ∼78% to ∼20% Charging by VCS-TENG Chen et al [ 201] Energy-harvesting/conversion technologies and texture change of Ch-LCs VCS-TENG + Ch-LC optical modulator…”

Particle Size Controlled Chiral Structural Color of Monodisperse Cholesteric Liquid Crystals Particles

“…Cholesteric DOI: 10.1002/adom.202300296 liquid crystals (CLCs) exhibit structural colors due to their property of selectively reflecting light by means of a helical self-assembled structure in which the dielectric constant and refractive index are periodically arranged. These properties make them highly useful for dynamic display, [1][2][3] information storage, [4][5][6] and optical security applications. [7][8][9] Spherical CLCs particles are favored by researchers due to their angle-independent structural coloration.…”