We developed polymer-dispersed liquid crystals (PDLCs) that effectively scatter light both in the visible and near-infrared ranges simultaneously. Such PDLCs are characterized by an optimal size distribution of nematic liquid crystal droplets within 0.4 − 3 µm, which is achieved due to the specially selected copolymer, the elaborated liquid crystal material as well as the proper cooling mode from the isotropic phase. These PDLC films provide electrically controlled light scattering modulation in the spectral range 300 − 2300 nm with the response time around 10 ms.

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.

We propose an approach for development of ferroelectric liquid crystals (FLC) with low birefringence Δn. Two basic principles have been used to get lowering of Δn: selection of molecules with short chains of conjugation as components for achiral matrix and averaging of local refractive indices by FLC helical structure. FLC mixtures with low birefringence (0.07 < Δn < 0.10 at wavelength 589.3 nm of sodium line) were elaborated and investigated. They consist of an achiral matrix including both nematic and smectic liquid crystal components and of phenylpyrimidine derivatives as chiral dopants. The materials developed can be used for all basic electro-optical FLC modes such as surface stabilised FLC (SSFLC), deformed helix ferroelectrics (DHF) and electrically suppressed helix (ESH). The mixtures developed allow to reduce the FLC cells chromatic retardance variation due to the weaker birefringence dispersion as compared with the known FLC materials to date.

Extraction of spectral information using liquid crystal (LC) retarders has recently become a topic of great interest because of its importance for creating hyper- and multispectral images in a compact and inexpensive way. However, this method of hyperspectral imaging requires thick LC-layer retarders (50 µm–100 µm and above) to obtain spectral modulation signals for reliable signal reconstruction. This makes the device extremely slow in the case of nematic LCs (NLCs), since the response time of NLCs increases proportionally to the square of the LC-layer thickness, which excludes fast dynamic processes monitoring. In this paper, we explore two approaches for solving the speed problem: the first is based on the use of faster nanospiral ferroelectric liquid crystals as an alternative to NLCs, and the second is based on using a passive multiband filter and focuses on multispectral extraction rather than hyperspectral. A detailed comparative study of nematic and ferroelectric devices is presented. The study is carried out using a 9-spectral bands passive spectral filter, covering the visible and near-infrared ranges. We propose the concept of multispectral rather than hyperspectral extraction, where a small number of wavelengths are sufficient for specific applications.

We report on a ferroelectric chiral smectic C (C*) phase obtained in a mixture of a nematic liquid crystal (NLC) and a chiral nonmesogenic dopant. The existence of C* phase was proven by calorimetric, dielectric and optical measurements, and also by X-rays analysis. The smectic C* which is obtained in such a way can flow, allowing to restore the ferroelectric liquid crystal layer structure in the electro-optical cells after action of the mechanical stress, as it happens with the cells filled with NLC. The proposed method of obtaining smectic C* material allows us to create innovative electro-optical cell combining the advantages of NLC (mechanical resilience) and smectic C* (high switching speed).