Photoalignment of Liquid Crystalline Materials Physics and Applications

by Chigrinov, Vladimir G.; Kozenkov, Vladimir M.; Kwok, Hoi-Sing

• ISBN13: 9780470065396
• ISBN10: 0470065397
• Edition: 1st
• Format: Hardcover
• Copyright: 2008-07-14
• Publisher: Wiley

Summary

This book systematically examines current research into photoalignment technology, presenting the physical principles and the potential application of photoaligning materials for the efficient working of liquid crystal devices. As well as covering state-of-the-art techniques and key applications, the authors present their own diffusion model for photoalignment. The book begins with a full examination of the mechanisms of photoalignment, going on to look at the properties of liquid crystals during photoalignment, including its effect on their chemical structure and stability. The following chapter sets out several methods for photoalignment of liquid crystals, leading to potential applications, such as novel liquid crystal display (LCD) devices.

Author Biography

Vladimir G. Chigrinov obtained his PhD degree in solid-state physics from the Shubnikov Institute of Crystallography, USSR Academy of Sciences, in 1978. In 1988, he defended his doctoral degree and became a professor at the Shubnikov Institute of Crystallography, where he was a leading researcher from 1996. He joined HKUST in 1999 and is currently an associate professor. Since 1974 Professor Chigrinov has published 2 books. 15 reviews and book chapters, about 150 journal papers, more than 300 conference presentations, and holds more than 50 patents and patent applications in the field of liquid crystals. He is a Senior SID Member, SID Fellow and an Associate Editor of the Journal of the Society for Information Display.

Vladimir M. Kozenkov graduated from the Moscow Energetic Institute as a scientist in applied physical optics (laser department). For 30 years he worked at the Organic Intermediates and Dyes Institute (NIOPIK) in Moscow. He pioneered research and development of various organic photosensitive materials for holography, waveguide, integral and polarization optics, stereolithography, optical memory, imaging processing, and security applications. He was the first to discover the phenomenon of photoinduced birefringence in polyvinyl-cinnamate films in 1977. He has published more than 100 refereed papers and holds more than 50 patents.

Hoi-Sing Kwok obtained his PhD degree in applied physics from Harvard University in 1978. He joined the State University of New York at Buffalo in 1980 and became a full professor in 1985. He joined HKUST in 1992 an is currently Director of the Center for Display Research (www.cdr.ust.hk). Professor Kwok has written over 500 refereed publications and holds 40 patents in laser optics and LCD technologies. He is a Fellow of the OSA, the IEEE, and the SID.

Table of Contents

About the Authors	p. xi
Series Editor's Foreword	p. xiii
Introduction	p. 1
References	p. 5
Mechanisms of LC Photoalignment	p. 7
Cis-Trans Isomerization	p. 9
'Command Surface'	p. 9
Cis-Trans Transformations in Azo-Dye Side-Chain Polymers and Azo-Dye in a Polymer Matrix	p. 10
Pure Reorientation of the Azo-Dye Chromophore Molecules or Azo-Dye Molecular Solvates	p. 13
Diffusion Model	p. 13
Polarized Absorption Spectra	p. 24
Modifications: Repeated Cis-Trans Photoisomerization Reaction Resulting in the Reorientation of the Backbone Structure	p. 25
Crosslinking in Cinnamoyl Side-Chain Polymers	p. 26
Photodegradation in Polyimide Materials	p. 28
Photoinduced Order in Langmuir-Blodgett Films	p. 33
References	p. 33
LC-Surface Interaction in a Photoaligned Cell	p. 39
Pretilt Angle Generation in Photoaligning Materials	p. 39
Generation of Large Pretilt Angles	p. 45
Generation of Large Pretilt Angles by Controlled Photodegradation	p. 45
Generation of Large Pretilt Angles by Nanostructured Surfaces	p. 47
Anchoring Energy in Photoaligning Materials	p. 51
Stability of Photoaligning Materials: Sensitivity to UV Light	p. 56
Comparison of the Characteristics of Photoalignment Layers for Different Mechanisms of LC Photoalignment	p. 59
Various Methods for the Experimental Characterization of Photoalignment Layers	p. 59
References	p. 64
Photoalignment of LCs	p. 69
Vertical LC Alignment	p. 69
Twisted LC Photoalignment	p. 72
Photoalignment of Ferroelectric LC	p. 74
Optical Rewritable LC Alignment	p. 78
Photoalignment with Asymmetric Surface Anchoring	p. 82
LC Photoalignment on Plastic Substrates	p. 83
Photoalignment on Grating Surface	p. 85
Photoalignment of Lyotropic and Discotic LCs	p. 90
Other Types of LC Photoalignment	p. 93
References	p. 96
Application of Photoalignment Materials in Optical Elements	p. 101
Polarizers	p. 101
Dichroism	p. 101
Direct Photoalignment	p. 104
Indirect Photoalignment	p. 107
Patterned Polarizers	p. 108
Retardation Films	p. 109
Types of Films	p. 109
Direct and Indirect Photoalignment	p. 111
Examples of Photoaligned Retardation Films	p. 113
Photo-patterned Phase Retarders and Color Filters	p. 118
Transflective LCD with Photo-patterned Polarizers and Phase Retarders	p. 123
Security Applications of Photoaligning and Photo-patterning	p. 129
Optical Elements Based on Photoaligning Technology	p. 131
References	p. 133
Novel LCDs Based on Photoalignment	p. 137
Bistable Nematic Displays	p. 137
Photoaligned Liquid-Crystal-on-Silicon Microdisplays	p. 140
Photoaligned Ferroelectric LCDs	p. 143
New Optical Rewritable Electronic Paper	p. 148
Application of Photoalignment in Photonic LC Devices	p. 151
References	p. 154
US Patents Related to Photoalignment of Liquid Crystals	p. 157
Introductory Remarks	p. 157
List of Patents: Patent Classification	p. 167
Analysis and Comments on the Patents	p. 218
Index	p. 221
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