Simulations of energy and switching in AFLCDs with different boundary conditions

Abstract

Using standard expressions for the various terms in the Gibbs free energy, the switching in antiferroelectric liquid crystal (AFLC) displays is simulated and the time evolution of various energy terms and of the liquid crystal director distributions are calculated. It is shown that when returning from a strong positive voltage to zero, one can reach two types of antiferroelectric state: the normal alternating state with the two bulk polarizations perpendicular to the electrodes and opposite to each other, and the alternative splayed symmetric state with two bulk polarizations parallel to the electrodes and again opposite to each other. The former case gives rise to tri-state switching characteristics, the latter to V-shaped switching. In general strong polar interaction with the alignment layer favours V-shaped switching while weak or no polar interaction give rise to tri-state switching characteristics. Since the V-shaped characteristic has so far only been demonstrated experimentally in ferroelectric liquid crystals (or antiferroelectric liquid crystals being in the ferroelectric state), the difference in AFLCs is discussed and the conditions for continuous switching are modelled. The simulations show that the switching characteristics of the antiferroelectric display can be controlled by the surface parameters.

Molecular Structure and Ordering in Biphenyl Molecules with Strong Polar Group: A Comparative Computational Analysis Between a Mesogen and Non-Mesogens

“…Liquid crystal research has an interdisciplinary and international pursuit. Recent research on these molecular devices explores new innovations with much attention to the molecular interactions, suitable aromatic groups and functional groups that causes/vanishes liquid crystallinity 1,2 . Such focus can bring a deeper knowledge to ascertain the correlation between structure and properties of liquid crystals.…”

Alignment and switching of AFLC materials using various boundary conditions

“…However, the AFLC state, to which the cell relaxes, cannot give rise to thresholdless/V-shaped switching [17][18][19]. The fact that the slopes overlap is caused by the interaction of surfaces with the continuous director reorientation between two F-states, giving the illusion of a V-shaped-like characteristic.…”