Controlled electro-alignment molecular dynamics in a high tilt angle ferroelectric liquid crystal cell

In a high tilt angle ferroelectric liquid crystal (HTAFLC), spontaneous polarization (Ps) minimization leads to the stripe domain formation with respect to the rubbing direction, arising from the smectic layer bending, limiting uniform alignment and hence practicality. A strategy to suppress the stripe domain and achieve defect-free alignment is presented in this study. A dc bias treatment near Tc controls molecular dynamics and reorients the smectic layer, and later at room temperature, polarization-driven relaxation holds molecules unidirectionally in the reoriented state. It is found that the application of unidirectional and unbalanced bias with one electrode grounded produces robust and uniform alignment, whereas traditional balanced biasing does not. Under specific combinations of amplitude and frequency of the triangular electric field, the uniformly aligned structure induces the ribbon-like domain fluctuation, which exhibits the dynamical precursors for stable and uniform alignment. The polarization reversal method confirms the asymmetry in polarization switching, which arises from smectic layer reorientation, whereas dielectric spectroscopy is used for the analysis of relaxation dynamics. These results illustrate the interplay between electric boundary conditions, smectic elasticity, and polarization memory in HTAFLCs, providing a physically grounded route toward defect-free alignment in high-tilt and polarization ferroelectric liquid-crystal systems.