Thermal control of tunable photonic optical bandgaps in different cholesteric liquid crystals mixtures

Tunable photonic optical bandgaps materials and devices have attracted many interests since the beginning of the second millennia. The cholesteric liquid crystals and their mixtures are having the ability to tune photonic bandgaps. This research article is presenting ternary and binary cholesteric liquid crystals which are based on Cholesteryl Oleyl Carbonate COC, Cholesteryl Benzoate CB, and Cholesteryl Nonanoate CN. The six composed mixtures are suitable for tunability adaptation and have been studied by Polarizing optical microscope POM to investigating the formed textures. The differential scanning Calorimetry DSC measurements were performed to determine the thermal stability and phase transitions for both composing materials and composed mixtures. The optical properties as Maximum wavelength (λmax), full width half maximum (FWHM), and photonic bandgap energy (Ug) determination have been determined for all composed mixtures at different temperatures. Interestingly, the bandgap is tuned overall IR-Vis-UV bands with different percentages of cholesteric liquid crystalline materials and concerning to their twist power of the imposed helical structures. The optimum tuned bandgap is produced in mixtures coded AMJ3 and AMJ4.