A cholesteric liquid crystal device having stable uniform lying helix structure

• Published in: Journal of molecular liquids Vol. 299; p. 112141
• Main Authors: Yip, W.C., Welch, Chris, Mehl, Georg H., Wilkinson, Timothy D.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2020
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2019.112141

A cholesteric liquid crystal device having the uniform lying helix (ULH) structure shows stable and reversible characteristics and it has been demonstrated for the analogue modulation in 10 micro-second response time at room temperature. The device comprises a polymer-free chiral nematic liquid crystal mixture and the photoalignment layer is irradiated by the UV light to cause a preferred orientation of the liquid crystal. The ULH structure is obtained by cooling the liquid crystal mixture from the isotropic phase transition temperature in the presence of electric field. On the electrical and thermal cycling, no noticeable hysteresis has been observed. In addition, the tilt angle and response time have been measured in good agreement with Meyer's theory on the flexoelectric effect in liquid crystals. •Stable uniform lying helix structure in three different electrode configurations were obtained.•Formation of aligned domains of splay and bend deformation was found.•Long standing problems of stability and hysteresis were solved.•The response time of 10 μs at room temperature was demonstrated.•Measurements of tilt angle and response time at different temp agreed.