Curvature-induced structural transition of nematic liquid crystals in coaxial cylinder π cell: From bulk to surface order reconstruction

The structural transition of asymmetric pi cell under a certain voltage was investigated to understand the display mode and performance of flexible substrates. Nematic liquid crystals show a splay texture at ground state (off state) and bend texture at on state induced by electric field in planar pi and coaxial cylinder pi cells. Changes in the topological discontinuous transformation of liquid crystal directors can appear between on and off states, and the symmetric splay state can be directly transited to the bend state by order reconstruction under high voltage. This phenomenon cannot be explained by Frank theory. Thus, we used Landau-de Gennes theory to study the effects of curvature on order reconstruction and the splay-bend transition through the detailed process of time dynamics. Results show that bulk-order reconstruction appears in planar pi cell, whereas surface-order reconstruction appears in coaxial cylinder pi cell because of the existence of a finite curvature radius. Moreover, the results will not change when we exchange the inner and outer boundary conditions under coaxial cylinder pi cell. By changing the setting of pretilt angle and comparing the results in planar pi and coaxial cylinder pi cells, we found that the position of order reconstruction is close to the boundary when the curvature is large. (C) 2019 Elsevier B.V. All rights reserved.