NSF Award
0078722
This Small Business Innovation Research Phase II project's goal is a commercial<br/>quality liquid crystal exhibiting V-shaped switching with no hysteresis. This LC will be<br/>used in gray-scale displays and telecommunications optical switches.<br/>Ferroelectric liquid crystals (FLCs), due to their fast switching speed and wide<br/>viewing angle, have inherent advantages over the more commonly used nematic liquid<br/>crystals. However, when used in displays, they have a disadvantage - they generally can<br/>be driven to only two states, on and off. Since displays require intermediate gray states,<br/>FLCs currently attain gray scale by rapidly switching on and off. This project uses a new<br/>type of FLC which, in addition to its speed and viewing angle advantage, also shows<br/>analog switching. This type of material, previously known as a "thresholdless<br/>antiferroelectric", is now known to be an FLC with a linear optical response to applied<br/>field (also known as "V-shaped switching").<br/><br/>This project's objective is to make new liquid crystal compounds and mixtures that<br/>exhibit V-shaped switching. Towards that end, a variety of cores, chiral tails, and achiral<br/>tails, all of which are either known or suspected to promote a de Vries-type smectic A,<br/>have been proposed. About 50 - 100 liquid crystals will be synthesized by combining<br/>these various components. These new LCs will be combined with LCs made in the Phase<br/>I or earlier, giving mixtures that ideally will have not only a de Vries smectic A phase,<br/>but also a wide room-temperature smectic C phase, good low-voltage analog electrooptic<br/>response, good alignability, and fast hysteresis-free switching. An optimal alignment<br/>layer configuration will be determined. The newly formulated mixtures will be placed in<br/>cells containing this alignment layer to give V-shaped switching displays.<br/>This project could be instrumental in advancing our knowledge of the root causes of<br/>V-shaped switching in FLC and, by extension, add insight into the responses of self-assembling molecules to applied forces. In addition, since the interaction of the alignment<br/>layer with the liquid crystal is crucial for V-shaped switching, much more so than for<br/>typical FLCs, this project will provide a better understanding of the alignment layer-LC<br/>interactions.
