Synergistic effects of anionic surfactant doping on dielectric and electro-optical properties of nematic liquid crystals by cyano-ionic interactions

Modern research has long focused on controlling and optimizing the dielectric, electro-optical and optical attributes of liquid crystals (LCs) to increase their technological value. Numerous approaches have been investigated for this reason in an effort to overcome various issues such as high response time, high driving voltage requirements, low dielectric anisotropy and limited operating temperature range, etc. The strategy utilizing binary/multicomponent systems is the most investigated and seems to have the most potential out of all the other techniques. In keeping with the same subject, the influence of anionic surfactant on the dielectric, electro-optical, and optical properties of nematic LC (NLC) has been examined. Precisely, dodecane-1-sulfonic acid sodium salt (SDS) which is an anionic surfactant was dispersed in a room temperature NLC E7 at various concentrations. Our findings reveal a significant alteration in the electro-optical behavior resulting from the introduction of an anionic surfactant, extending well beyond the instance of electrode polarization, albeit with a detrimental impact on performance within the low-frequency range as a result of increased ionic contribution. The main findings of this study include a 17.5%% increase in dielectric anisotropy, an appreciable reduction of about 30%% in threshold voltage and rotational viscosity, and approximately 64% reduction in response time in the host NLC due to the addition of anionic salt in it. A significant photoluminescence quenching of about 64%% is observed after dispersion of 3.0% by weight anionic surfactant in E7. These findings offer potential pathways for the development of future technologies in various domains, including photonic devices, biological imaging, light- emitting diodes (LEDs), and luminescent markers.