Defect-free half-V-mode ferroelectric liquid-crystal device

Abstract

The horizontal chevron defect found in a half-V-mode ferroelectric-liquid-crystal (HV-FLC) device can be suppressed by lowering the FLC's total free energy. The energy levels between spontaneous polarization (P(S)) up and down domains were degenerated by asymmetrical-alignment treatments. The difference in the polar surface coefficient (gamma(2)) was the key to suppressing the alignment defect. Alignment layers with opposite surface polarities and different anchoring energies were applied to control the sign and value of gamma(2). The asymmetric cells of PI(rub) - PI(plasma) (rubbed polyimide and plasma-treated polyimide surfaces), PVA(rub) - PI(plasma) (rubbed polyvinyl alcohol and plasma-treated polyimide surfaces), and PVA(rub) - PI(rub) (both rubbed PI and PVA) alignment conditions presented defect-free alignment textures under a slow-cooling process. Among these different alignment treatments, the PVA(rub) - PI(rub) treated cell demonstrated the best alignment result, benefited by the largest difference in polar surface coefficient.