Issue 46, 2017

Stabilized electrically induced Helfrich deformation and enhanced color tuning in cholesteric liquid crystals

Abstract

When subjected to an AC electric field perpendicular to its layers, the cholesteric planar state may undergo a periodic layer undulation, known as the Helfrich deformation, which generates a color change of the reflected light. The Helfrich deformation of regular cholesteric liquid crystals is, however, unstable and easily taken over by the focal conic state, and thus the color tuning range is narrow. We demonstrated that the Helfrich deformation can be stabilized in a large electric field region by doping a bent dimer with an anomalously small bend elastic constant and dispersing a small amount of polymer network. By varying the dimer concentration, we were able to systematically change the bend elastic constant and thus verify the theoretical prediction of the undulation threshold electric field and periodicity. We also achieved reflectance tuning with electric field less than 2 V μm−1 and color tuning covering the entire visible light region with electric field as low as 4 V μm−1.

Graphical abstract: Stabilized electrically induced Helfrich deformation and enhanced color tuning in cholesteric liquid crystals

Article information

Article type
Paper
Submitted
07 Oct 2017
Accepted
07 Nov 2017
First published
07 Nov 2017

Soft Matter, 2017,13, 8728-8735

Stabilized electrically induced Helfrich deformation and enhanced color tuning in cholesteric liquid crystals

M. Yu, H. Yang and D. Yang, Soft Matter, 2017, 13, 8728 DOI: 10.1039/C7SM01997A

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