Influence of thickness and conductivity of alignment layers on the bistability of ferroelectric liquid-crystal devices

The bistability conditions on both the thickness and conductivity of the alignment layers as a function of spontaneous polarization and other cell parameters for ferroelectric liquid-crystal devices have been obtained analytically based on a uniform switching model. It is found that there exists a practical threshold conductivity of the alignment layers, above which good bistability can be obtained. Below this threshold conductivity, there exists a critical total alignment-layer thickness, below which bistability can be achieved. For the latter case, the two quantities depend linearly on each other, with a coefficient increasing monotonically with cell thickness, the difference between the ratio of the square of the spontaneous polarization to the rotational viscosity, and the conductivity of the liquid crystal.