Characterization of optical and mechanical modification of surface alignment layers for liquid crystal devices

摘要

Reliable performance of liquid crystal (LC) materials in display applications is critically dependent on the behavior of surface treatments that induce molecular alignment parallel to the cell widows. While general understanding of the nature of this effect has been available for some time, the detailed characteristics of the LC-surface interaction are not sufficiently well understood to enable reliable interface engineering. This is particularly true for new materials that might otherwise possess favorable qualities but cannot be reproducibly oriented in a device. Our work is concentrated on understanding optical and mechanical modification of organic monolayers that have been self-assembled on dielectric surfaces. We use vibrationally resonant sum-frequency generation and ellipsometry as well as non-optical techniques, such as contact angle testing, to evaluate the influence of these perturbations. We have been able to follow subtle conformation changes as well as more dramatic photochemical effects. The results help reveal the anchoring mechanisms and provide insight into ways of tailoring interfaces for new materials.