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Photoalignment of Liquid Crystalline Materials: Physics and Applications



Photoalignment of Liquid Crystalline Materials: Physics and Applications

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

ISBN: 978-0-470-06539-6 July 2008 248 Pages


Photoalignment possesses significant advantages in comparison with the usual ‘rubbing’ treatment of the substrates of liquid crystal display (LCD) cells as it is a non-contact method with a high resolution. A new technique recently pioneered by the authors of this book, namely the photo-induced diffusion reorientation of azodyes, does not involve any photochemical or structural transformations of the molecules. This results in photoaligning films which are robust and possess good aligning properties making them particularly suitable for the new generation of liquid crystal devices.

Photoalignment of Liquid Crystalline Materials covers state-of-the-art techniques and key applications, as well as the authors’ own diffusion model for photoalignment.   The book aims to stimulate new research and development in the field of liquid crystalline photoalignment and in so doing, enable the technology to be used in large scale LCD production.

Key features:

  • Provides a full examination of the mechanisms of photoalignment.
  • Examines the properties of liquid crystals during photoalignment, with particular reference made to the effect on their chemical structure and stability.
  • Considers the most useful photosensitive materials and preparation procedures suitable for liquid crystalline photoalignment.
  • Presents several methods for photoalignment of liquid crystals.
  • Compares various applications of photoalignment technology for in-cell patterned polarizers and phase retarders, transflective and micro displays, security and other liquid crystal devices.

Through its interdisciplinary approach, this book is aimed at a wide range of practising electrical engineers, optical engineers, display technologists, materials scientists, physicists and chemists working on the development of liquid crystal devices. It will also appeal to researchers and graduate students taking courses on liquid crystals or display technologies.

The Society for Information Display (SID) is an international society, which has the aim of encouraging the development of all aspects of the field of information display. Complementary to the aims of the society, the Wiley-SID series is intended to explain the latest developments in information display technology at a professional level. The broad scope of the series addresses all facets of information displays from technical aspects through systems and prototypes to standards and ergonomics

About the Authors.

Series Editor's Foreword.

1. Introduction.


2. Mechanisms of LC Photoalignment.

2.1 Cis-Trans Isomerization.

2.2  Pure Reorientation of the Azo-Dye Chromophore Molecules or Azo-Dye Molecular Solvates.

2.3 Crosslinking in Cinnamoyl Side-Chain Polymers.

2.4 Photodegradation in Polymide Materials.

2.5 Photoinduced Order in Langmuir–Blodgett Films.


3. LC-Surface Interaction in a Photoaligned Cell.

3.1 Pretilt Angle Generation in Photoaligning Materials.

3.2 Generation of Large Pretilt Angles.

3.3 Anchoring Energy in Photoaligning Materials.

3.4 Stability of Photoaligning Materials Sensitivity to UV Light.

3.5 Comparison of the Characteristics of Photoalignment Layers for Different Mechanisms of LC Photoalignment.

3.6 Various Methods for the Experimental Characterization of Photoalignment Layers.


4. Photoalignment of LCs.

4.1 Vertical LC Alignment.

4.2 Twisted LC Photoalignment.

4.3 Photoalignment of Ferroelectric LC.

4.4 Optical Rewritable LC Alignment.

4.5 Photoalignment with Asymmetric Surface Anchoring.

4.6 LC Photoalignment on Plastic Substrates.

4.7 Photoalignment on Grating Surface.

4.8 Photoalignment of Lyotropic and Discotic LCs.

4.9 Other Types of LC Photoalignment.


5. Application of Photoalignment Materials in Optical Elements.

5.1 Polarizers.

5.2 Retardation Films.

5.3 Transflective LCD with Photo-Patterned Polarizers and Phase Retarders.

5.4 Security Applications of Photoaligning and Photo-Patterning.

5.5 Optical Elements Based on Photoaligning Technology.


6. Novel LCDs Based on Photoalignment.

6.1 Bistable Nematic Displays.

6.2 Photoaligned Liquid-Crystal-on-Silicon Microdisplays.

6.3 Photoaligned Ferroelectric LCDs.

6.4 New Optical Rewritable Electronic Paper.

6.5 Application of Photoalignment in Photonic LC Devices.


7. US Patents Related to Photoalignment of Liquid Crystals.

7.1 Introductory Remarks.

7.2 List of Patents Patent Classification.

7.3 Analysis and Comments on the Patents.


"I believe that the reader will obtain beneficial information on the various aspects of the physics and applications of the photoalignment of LCs and the techniques involved." (Liquid Crystals Today, June 2010)