Photo-driven effects in twist-bend nematic phases: Dynamic and memory response of liquid crystalline dimers

Light-responsive bent-core liquid crystals as candidates for energy conversion and storage

“…We believe that the presence of cis -isomers may enhance the alignment of the layer(s) adjacent to the cells surfaces, facilitating long-range conductivity. 31 We cannot rule out, however, that continuous trans -to- cis -to- trans photoisomerisation, or the occurrence of iso-mesophase micro transitions, may also favour such alignment. As expected, similar irradiation doses have neglectable effects on the conductivity of NG75, see Fig.…”

“…[42] On the other hand, at high temperatures the thermally activated cis-to-trans back-relaxation is favoured, displacing the equilibrium towards the formation of trans azobenzene isomers. [31] It is worth noting that the maxima of the absorption peak in Fig. 7(c) appears at larger wavelengths after irradiation.…”

“…The choice of composition was based on some of our previous results obtained for liquid crystal dimers, which showed that 5% molar was the minimum concentration of azobenzene molecules required to promote photoinduced effects in the corresponding mixtures. 31…”

“…The choice of composition was based on some of our previous results obtained for liquid crystal dimers, which showed that 5% molar was the minimum concentration of azobenzene molecules required to promote photoinduced effects in the corresponding mixtures. [31] Figure 1. Chemical structure and notation used to refer to the pristine bent-core compounds (NG75, IP33 and IP33) and mixtures containing 5% molar % of azobenzene molecules (5%-IP33 and 5%-IP31)…”

Dependency of the twist-bend nematic phase formation on the molecular shape of liquid crystal dimers: A view through the lens of DFT

“…Because of the bent shape of prevailing molecular conformations, the local director in this phase is believed to follow a twist-bend geometry forming a heliconical structure with an extremely short pitch [8], thus, commonly identified as the twist-bend (Ntb) phase. The materials forming the Ntb phase are interesting not just owing to the unique structure of this phase and its properties but also potential exploitation of such materials in many new applications, i.e., in tuning selective reflection of light [9], memory devices [10], [11], LC gels [12], photoalignment technology [13], sensors [14], faster switching displays [15], etc. Despite the most vigorously researched topic in liquid crystal science, the Ntb phase remains extensively debated over its structure and properties, resulting in a disparity between experimental results and theoretical modeling [16], [17], [18].…”