Tuesday, March 8, 2016

SID Student Chapter Seminar: "High-performance and fast-switching liquid crystal devices based on polymer-stabilized cholesteric blue phase III and uniform lying helix" Prof. Liang-Chy Chien 3.18.16/2:00-3:00pm/ CREOL RM A214

SID Student Chapter Seminar: "High-performance and fast-switching liquid crystal devices based on polymer-stabilized cholesteric blue phase III and uniform lying helix" Prof. Liang-Chy Chien
Friday, March 18, 2016 2:00 PM to 3:00 PM
CREOL Room A214

Prof. Liang-Chy Chien
Liquid Crystal Institute and Chemical Physics Interdisciplinary Program
Kent State University, Kent, Ohio 44242

As ultrahigh resolution UHD-TV becomes mainstream products, the demand on high dynamic range (HDR), which preserves details in the darkest and brightest areas of a picture, is high. HDTVs also suffer from motion blur. Liquid crystal displays (LCDs) in particular, tended to display distinct blurriness during very fast movements because of ghosting or the image left behind after switching. Current LCD technologies have not solved these issues completely.  Our expertise in flexoelectro-optical and blue phase devices has led to a level of innovative new approaches for flat-panel and wearable devices that could in some ways redefine how we access the HDR and video-rate response time. These and other topics will be reviewed, providing insights at both the applied and theoretical device levels.
The Novel Materials, Devices and Applications Lab at the Liquid Crystal Institute of Kent State University has continued to create high-performance and high-contrast electro-optical devices that provide leaps in capability for HDR and video-rate image response time. Most recently, we have developed a promising wide-temperature amorphous blue phase material (blue phase III) with novel physical behavior which is based on combining unique achromatic optical dark state and sub-millisecond switching behavior with hysteresis-free in voltage ramping.  The polymer-stabilized blue phase III (PSBP III) enables a wide temperature range and affords achromatic bright state and excellent dark state.  Our device now provides the first-ever approach to resolve LCDs issues of HDR and video-rate image.
The lecture will conclude with a discussion on a hot issue in LC technologies such as an in-plane-switching liquid crystal device based on uniform lying helix (ULH) alignment on polymerized surface is presented.  The surface alignment is formed by polymerizing a minute amount of a reactive monomer in a liquid crystal host to form nano-sized polymer fibers on the two substrates of the cell.  The short-pitch cholesteric comprises of a dual-frequency nematic liquid crystal, a twist-bend nematic liquid crystal and a chiral dopant.  Substantial improvements in electro-optical properties such as large field-induced tilt angle (> 45o) and fast response time (~100 ms) have been achieved.  We will also present the analytical analyses of flexoelectric behavior and morphological properties of the polymer stabilized ULH.

L.-C. Chien received his Ph.D. in Polymer Chemistry from the University of Southern Mississippi and joined Liquid Crystal Institute of Kent State in 1988.  His research interests include the studies of advanced functional materials, structures and surfaces as well as the innovative applications of such materials in displays electro-optical and photonic devices. He has published 150 articles, over 150 scientific proceedings and digest papers, edited 15 conference proceedings, three books and seven book chapters as well as 25 issued patents. He is a co-inventor of the bistable reflective cholesteric displays, polymer-stabilized liquid crystal display devices and technologies. Dr. Chien has been active in providing his services to professional society such as organizing and chair conferences as well as serve as an advisor or program committee on many international conferences.
His research in polymer and liquid crystal composites focuses on control of dimension, location and spatial distribution of phase separated polymers at the micro- and nano-scale on substrate surfaces or in the bulk.  His research in polymer dispersed, modified and stabilized liquid crystal materials have led to the development of advanced electro-optical, photonic and display devices such as reflective bistable displays, electrically switchable color filters, electrically-switchable gratings, and blue phases based devices.  The recently developed polymer dispersed and stabilized blue phases enable the fabrication of fast-switching spatial light modulators. 
His research in tailoring liquid crystal materials to provide control over structure, surface, morphology, and processing have led to the development of new electro-optical devices. For examples, research in active and stimuli-responsive low- and high-molar-mass materials have led to the development of artificial muscles, light emitting devices and organic thin film transistors; Furthermore, the active materials whose functionality are used for controlled- assembly or self-assembly of dispersed nanoparticles to ordered structures to enhance desired properties of functional devices.

For additional information:
Haiwei Chen

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