Colorless molecular dopants for low voltage operation of nematic liquid crystals

摘要

Molecules designed to possess large dipole moments have been synthesized and doped into liquid crystals for the purpose of reducing the threshold voltage associated with the Freedericksz transition in nematics. These molecules were tested in the commercial nematic mixture E7 at varying concentrations and the resultant mixtures were evaluated to determine their nematic-isotropic transition temperature, threshold voltage, dielectric anisotropy, and visco-elastic constant as a function of dopant concentration. We have shown that these materials reduce the threshold voltage by up to 25 % at the 10 wt.% doping level but do so via a reduction of the splay elastic constant, not by the increase of the dielectric anisotropy as was expected. As a consequence of this result these dopants have also shown to increase the response time of the dopant/liquid crystal mixture.