Colorless Molecular Dopants for Low-Operating-Voltage Nematic Liquid Crystals

ABSTRACT

In this paper we present a study of two similar, colorless molecular dopants designed to decrease the operating voltages of nematic liquid crystals by increasing the dielectric anisotropy. Experimental analysis shows that these materials reduced the threshold voltage (voltage associated with the Freedericksz transition) by up to 20%, but via a reduction in the liquid crystal order parameter. To gain insight into the decrease of the order parameter, we used density-functional and single-point MP2 theory to investigate the conformational preferences of our dopants; the calculations suggest that, because of steric interactions, the conformations adopted are rather rigid.

Keywords:

• colorless dopants
• dielectric anisotropy
• nematic liquid crystal
• order parameter
• steric hindrance
• threshold voltage

ACKNOWLEDGMENTS

This work was supported in part by the National Science Foundation (through the Science and Technology Center, (STC) Program under Award Number DMR-0120967 and a CAREER Award to B. Kippelen) and the IBM Shared University Research Program.