Ultrashort helix pitch antiferroelectric liquid crystals based on chiral esters of terphenyldicarboxylic acid†
Antiferroelectric liquid crystals (AFLCs) with a nanoscale helix pitch (<100 nm) were revealed in a composition containing achiral smectic-C biphenylpyrimidines and two non-mesogenic chiral dopants: p-terphenyldicarboxylates of chiral (2S)-1,1,1-trifluorooctane-2-ol and (S,S)-1,1,1-trifluorooctan-2-yl 2-hydroxypropanoate. The prepared multicomponent AFLCs exhibit two electro-optical effects, which are interrelated with the chemical structures of the mixture’s components. The first effect is hysteresis free under special voltage waveform U-shaped switching, which exhibits an electro-optical response similar to that of nematic liquid crystals (NLCs) but around 1–2 orders of magnitude faster. Secondly, the deformed helix antiferroelectric liquid crystal (DHAFLC) effect has been investigated. The observed temperature independence of the electro-optical parameters, in a certain temperature range, combined with a fast U-shape response or with DHAFLC, adds a great value for applications.