LCD alignment layers. Controlling nematic domain properties

Abstract

From simple pocket calculators, to mobile telephones and LCD-TV, over the past few decades devices based on liquid crystal display technology have proliferated into just about all conceivable aspects of everyday life. Although used in cutting-edge technology, it is surprising that a vital part in the construction of such displays relies essentially on a process invented almost 100 years ago. This essential part, the alignment layer, dictates the macroscopic uniform alignment of liquid crystalline molecules (mesogens) near its surface. The current method for manufacturing such layers is the mechanical rubbing of spin-coated polymers with a piece of velvet cloth. This very successful method is still at the basis of the production process of even the largest displays currently manufactured in industry. Unfortunately, the construction of ever larger displays with this technique is becoming a technological nightmare for engineers. Therefore, over the past decades, many alternatives to rubbing have been explored. This review will focus on advances towards achieving one of the most important goals in LCD technology: attaining rational control over the properties of nematic liquid crystal domains.