A fringe-field switching (FFS) liquid crystal (LC) mode used with a negative dielectric LC (n-LC) that is operable at an extremely low-frequency signal voltage regime, without image flickering, is proposed. By doping charge-trapping fullerenes (doping concentration: 0.2 wt%) into a low-resistivity polyimide LC alignment layer of the FFS n-LC mode, the mobile ionic-charge density within the n-LC layer can be drastically decreased. Thus, excellent voltage-holding ratios of 98.24% and 87.91% are achievable in the proposed FFS n-LC mode at low operation frequencies of 0.5 Hz and 0.2 Hz, respectively, corresponding to the improvement rates of 155.69% and 1127.05% at each operation frequency, compared with the FFS n-LC mode without the fullerene doping case. The evaluation results by the modulation flicker level reveal that the operation frequency of the proposed device scheme can be decreased significantly (≈0.2 Hz) without inducing the perceptible image-flickering problems.
- fringe-field switching liquid crystal mode
- low-frequency driving
- power saving