Metastable Fingerprint States in a Frustrated Cholesteric Liquid Crystal

Abstract

We demonstrate a metastable fingerprint (mFP) state in a homeotropically aligned cholesteric liquid crystal (CLC) with negative dielectric anisotropy. The mFP forms upon gradual removal of a high-voltage, low-frequency electric field and persists for several hours at zero field. Factors influencing the stability of this state include the confinement ratio—the ratio of the cell thickness to the cholesteric pitch, ρ = d/p—the alignment layer rubbing strength, and material composition. Electro-optical characterization of the dichroic dye-doped CLC in a single-layer cell reveals four distinct optical states: a clear state, two tinted states, and a hazy state. Furthermore, CTAB-doping enables controlled erasure of the mFP and access to bubble domains, a distinct, weakly scattering, tinted state. In the optimized configuration (ρ ≈ 1, five-times rubbed alignment layer), driving at 80 mV s^–1, the induced mFP persists for 400–500 min when the voltage is removed. These findings establish mFP textures as a promising route for developing bistable cholesteric optical devices such as liquid crystal windows.