Reorienting Liquid Crystals Will Improve LCD Displays

A group of physicists from Russia, France and Germany have proposed a new method for orienting liquid crystals, which in the future will help increase the viewing angle of LCD displays. The article was published in ACS Macro Letters.

Physicists applied poly (dialkylsiloxanes) polymers to a Teflon substrate, which have two symmetrical hydrocarbon side chains that are “stitched” to each silicon atom of the main chain. These chains fit into large supramolecular structures – lamellas. Each subsequent polymer in the experiment was one methyl group longer than the previous one.

The scientists monitored whether the polymers were oriented along the longitudinal grooves of the Teflon substrate and found that even a small change in the polymer structure could completely change the orientation of the liquid crystal.

Two possible orientations of LC phases on an oriented Teflon surface, in which the polymer chains of the liquid crystal are either perpendicular (left) or parallel (right) to the Teflon grooves

The first representative of these LC polymers, polydiethylsiloxane (which has only two methyl groups), oriented its lamellas along the surface relief, and the chains – perpendicular to it. With an increase in the side chain by one methyl group, the lamellas are oriented perpendicular to the surface relief, and the chains are located parallel. The effect persisted when one more methyl group was added to the polymer chain. But with a further increase in the chain (five or six methyl groups), the polymer lamellae again lined up along the Teflon surface relief.

Scientists hope to apply the discovered effect to create simpler and cheaper LCD screens with an increased viewing angle. For this, the authors of the work propose to use a multi-domain technology, where subpixels of the same colors will be oriented in different ways. Then, when viewed from different angles, they will compensate for each other, improving the image quality

. Source: indicator.ru