Dichroic Dyes for Liquid Crystal Displays

Selective Bragg reflection of visible light from coaxial electrospun fiber mats

“…DSC was used to locate the vicinity of any transitions in the pure liquid crystal, the core-filled fibers, and the PVP fibers. CB15 forms a single blue phase at~−28 C [45] while the nematic liquid crystal E9 forms an isotropic phase at~84 C. [40] Owing to this large difference in transition temperatures (~112 C), small variations in composition of blends can significantly alter which blue phases exist and the phase transitions within them. A 50-50 CB15/E9 mixture forms BPII and BPI and strongly reflects blue light.…”

“…E9 (Merck) is a trade name for a nematic mixture of 4-n-alkyl cyano-biphenyls, 4-nalkoxy cyano-biphenyls, and 4-n-cyano-terphenyls, which was specifically designed for display applications. [40,41] PVP was obtained from Sigma-Aldrich and has an average molecular weight of 360,000 g/mol. PVP was chosen because it solidifies to states with very low birefringence and this leads to nearly transparent outer sheaths.…”

Parameter Space Design of a Guest-Host Liquid Crystal Device for Transmittance Control

“…For a dye concentration of over 4 wt%, the measured transmittance difference was higher than the calculated value because the dye molecules were not dissolved completely in the LC, as shown in Figure 4a. These insoluble dye molecules may crystallize in the cell and can cause stability issues [24]. We plotted the constant transmittance-difference contour maps of each LC mode on the parameter space of the cell gap and dye concentration, as shown in Figure 5.…”

“…By increasing the cell gap or dye concentration, the transmittance in the opaque state can be lowered, but that in the transparent state is also lowered. Moreover, the response time and the driving voltage of a GHLC cell are dependent on the cell gap and dye concentration, and the solubility of the dye molecule can be an issue [22][23][24]. Therefore, it is necessary Crystals 2019, 9, to find the condition that gives the maximum transmittance difference between the transparent and opaque states while satisfying the desired performance, such as the response time and driving voltage, and without the solubility issue.…”

Photo-responsive dye-doped liquid crystals for smart windows

“…Guest-host liquid crystal (LC) devices [1][2][3][4], developed in late 1960s, have found renewed interest as dimmer for see-through displays [5], diffractive photonic devices [6], portable information system [7], and smart windows for energy-saving buildings [8]. Its unique features are electrically controllable transmittance, no need for polarizer, wide viewing angle, low manufacturing cost, and possible usage of flexible plastic substrates [9,10].…”