The new azo-dye photoaligning films are robust and possess very good aligning properties for liquid crystal (LC) cells such as anchoring energies and voltage holding ratios as well as a high thermo and UV stability both in glass and plastic substrates with very high resolution on submicron level. The most important characteristics of azo-dye photoaligning films will be compared with those of rubbed polyimide films usually used for LC alignment. In this chapter, we will also describe the new applications of azo-dye photoalignment: (i) LC display devices, such as ferroelectric LCD for IPS, field sequential color and microdisplay applications; (ii) LC photonics devices, such as LC lenses; (iii) LC E-paper devices, such as electrically and optically rewritable LC E-paper; (iv) nanoscopic optically engineered polymeric thin film polarizers.

Chapter Contents:

• 3.1 Introduction
• 3.2 LC surface interaction in azo-dye photoaligned cell
• 3.2.1 Pretilt angle generation in azo-dye photoaligning materials
• 3.2.2 Anchoring energy in azo-dye photoalignment materials
• 3.2.3 Characteristics of azo-dye photoalignment materials: voltage holding ratio (VHR) and residual DC voltage (RDC): image sticking
• 3.2.4 Super high resolution of azo-dye photoaligning materials
• 3.2.5 LC photoalignment on plastic substrates
• 3.2.6 Effect of humidity on the azo-dye photoalignment
• 3.2.7 Stability of photo-aligning materials: sensitivity to UV light: strengthening of liquid crystal photoalignment on azo-dye films: passivation by reactive mesogens
• 3.3 Application of azo-dye photoalignment
• 3.3.1 Optically-rewritable LCD
• 3.3.2 Low-voltage driving-tunable LC lens using photoalignment method
• 3.3.3 Nanoscopic optically engineered polymeric thin film polarizer
• 3.3.4 Fast ferroelectric LCD
• 3.3.5 In plane switching (IPS) azo-dye photoalignment
• 3.4 Summary
• References

Inspec keywords: liquid crystal displays; optical films; dyes; optical polarisers; liquid crystal polymers; ferroelectric displays; colour displays; lenses; polymer films; microdisplays; optical polymers

Other keywords: LC E-paper devices; electrically rewritable LC E-paper; LC alignment; voltage holding ratios; azo-dye photoaligning films; field sequential color display; LC lenses; ferroelectric LCD; LC display devices; LC photonics devices; microdisplay applications; optically rewritable LC E-paper; azo-dye photoalignment materials; high thermostability; liquid crystal cells; aligning properties; nanoscopic optically engineered polymeric thin film polarizers

Subjects: Other optical system components; Liquid crystal devices; Optical polymers and other organic optical materials; Liquid crystals (optical materials); Ferroelectric devices; Spatial filters, zone plates, and polarizers; Optical materials; Display equipment and systems; Display materials; Optical lenses and mirrors