Electric-field symmetrization for ultra-low flicker in low-frequency FFS LCDs with commercial negative liquid crystals

Low-frequency driving reduces the power consumption of fringe-field switching liquid crystal displays (FFS-LCDs), yet severe image flicker caused by the flexoelectric effect remains a critical bottleneck for industrial applications. In this paper, we propose an electric-field symmetrisation strategy to suppress flicker by eliminating the frame-to-frame asymmetry in vertical electric-field components. The flexoelectric coefficients of commercially available negative LCs are precisely calibrated using a joint fitting method involving multiple physical quantities. A coupling-field dimension-separation framework is derived from the Oseen-Frank free-energy variational principle, demonstrating that the flexoelectric torques on the molecular tilt and azimuthal angles are governed by distinct field–gradient combinations, revealing that the frame-to-frame asymmetry of the vertical electric-field component constitutes the dominant origin of low-frequency flicker. Through concurrent optimisation of the insulation layer thickness and the electrode gap-to-width ratio, a universal design rule is established for all structural parameters examined in this study. The optimised structure (S6) achieves an ultra-low flicker of 0.01%, substantially below the human flicker perception threshold (<0.01%), with a saturation voltage of 8.0 V and a peak transmittance of 0.389. This strategy requires no material modification and demonstrates good tolerance against batch-to-batch variations of flexoelectric coefficients, offering a potential industrial route towards flicker-free low-power FFS-LCDs.