Ferroelectric Smectic Liquid Crystalline Materials with Different Degree of Chirality

Ferroelectric liquid crystals (FLCs) are key materials for high-speed electro-optical applications, yet achieving optimal properties over a broad temperature range down below room temperature remains a challenge. This study presents a novel series of systematically designed FLC mixtures, incorporating achiral, monochiral, and bichiral components to optimize the mesomorphic stability, electro-optical response, and physicochemical properties. The strategic doping by chiral components up to a 0.2 weight fraction extends the temperature range of the ferroelectric phase while lowering the melting temperature. Notably, mixtures containing two chiral centers exhibit shorter helical pitches, while increasing chirality enhances the tilt angle of the director and spontaneous polarization. However, in the complex chiral mixture (CchM), spontaneous polarization decreases due to opposing vector contributions. Switching time analysis reveals that achiral–bichiral systems exhibit the fastest response, while CchM demonstrates only intermediary behaviour, caused by its high rotational viscosity. Among all formulations, mixtures containing bichiral compounds display the most favorable balance of functional properties for deformed helix ferroelectric liquid crystal (DHFLC) applications. One such composition achieves the lowest melting temperature reported for DHFLC-compatible FLCs, enabling operation at sub-zero temperatures. These findings pave the way for next-generation electro-optical devices with enhanced performance and appropriate environmental stability.