Antiferroelectric liquid crystal model with ions diffusion

TL;DR

This paper models the behavior of ions in antiferroelectric liquid crystals under electric fields, highlighting how ion diffusion and electrostatic interactions influence electrooptical responses and switching dynamics in display applications.

Contribution

It introduces a combined model of ion diffusion and electrostatic effects in antiferroelectric liquid crystals, considering various voltage pulse waveforms for improved display performance.

Findings

Ions tend to delocalize from alignment layers under high-frequency AC pulses.

Ion distribution evolves over time with different electric field applications.

The model predicts ionic behavior affecting electrooptical response in displays.

Abstract

Antiferroelectric liquid crystals can be considered as a promising alternative to nematic mixtures in the area of microdisplays. Switching behaviour of the molecules has been modelled as two adjacent smectic layers. However, some studies made so far reveal that electrooptical response can be seriously affected by ion content of the test cells, specially in the area of asymmetric cells. Regarding such influence, both molecules and ions have been studied in the present work under the influence of an external electric field. The mechanisms governing ionic behaviour considered so far in the simulations have been diffusion, which was dealt through the Nerst-Planck equation, and electrostatic interaction, which mixes ionic and antiferroelectric liquid crystal effects by means of Gauss equation. In addition, voltage pulses applied to the simulated antiferroelectric liquid crystal cell, have been considered under different waveforms for possible driving schemes in display applications. Results show time evolution of ions within the cell, under different external applied electric fields and their delocalization from alignment layers when high frequency AC pulses are included in the structure of the switching waveform.