Voltage reduction in twisted nematic liquid crystals by reverse (negative) doping

Abstract

The concept of reverse or negative doping of a liquid crystal is introduced, in which the sense of the twist of the helix induced by a chiral dopant in the unconstrained liquid crystal material is opposite to that induced by the alignment layers. Some considerations of the extent to which the liquid crystal may be negatively doped before reverse twist domains appear, and the effect of the threshold voltage, are presented. The concept is applied to a reflective liquid crystal display (LCD) and it is demonstrated how the data voltage and power consumption of twisted nematic reflective LCDs may be reduced.