Investigation of orientational order in a nematic liquid crystal with semiconductor CdSe/Zns QDs by IR spectroscopy

The dichroic ratio and orientational-order parameter of fundamental bands have been studied in the IR spectrum for a nematic liquid crystal based on alkylcyanobiphenyls and its suspensions with semiconductor CdSe/ZnS QDs with a core size of 5 nm. Analyses have been performed by the method of multiple frustrated total internal reflection. It is shown that an increase in the nanoparticle concentration from 0.5 to 1.3 wt % improves the orientation uniformity of the liquid crystal near the interface with the orienting surface. The orientational order parameter in a suspension with 1.3 wt % QDs has increased in comparison with the initial liquid crystal by more than 10% for the fundamental bands in alkylcyanobiphenyl molecules, the stretching vibrations of which correspond to the direction of their long axes.