We report the enhancement in photoluminescence (PL) intensity and shift in spectral energy band of ferroelectric liquid crystal (FLC) doped with ZnS quantum dots (QDs). The emission from ZnS QDs has combined constructively with that of FLC to give enhanced PL intensity. On the other hand, the smectic phases of FLC provided strong light scattering and hence improved the PL intensity of the composite. The change in effective refractive index of FLC due to different concentrations of ZnS QDs has caused the red shift. Our observations will certainly provide a promising tool in the realization of enhanced PL-LC display devices.

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A small amount of cadmium telluride quantum dots (CdTe QDs) has been doped into various ferroelectric liquid crystals (FLCs) to observe the modifications in the alignment and dielectric anisotropy (Δɛ) of the composites. The CdTe QDs have induced a uniform homeotropic (HMT) alignment in most of the FLC mixtures. We observed an unexpected switching (from HMT to homogeneous configuration) of CdTe QDs doped FLC CS1026 (having positive Δɛ) by the application of high dc bias. This reverse switching has been attributed to the interaction between FLC molecules and CdTe QDs which caused the sign reversal of Δɛ of FLC CS1026.

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The collective dielectric relaxation studies have been carried out on the electroclinic liquid crystals ͑ELCs͒ doped with 0.1 to 0.2 wt % of graphene oxide ͑GO͒ in the frequency range of 20 Hz to 1 MHz. The GO favors for a good quality vertical alignment without any surface treatment of the substrates. The coupling of GO with indium tin oxide ͑ITO͒ substrate and ELC materials affects the molecular ordering and supports the ELC molecules to be aligned along the GO attached to the ITO surface in vertical direction. The vertical alignment can be changed to homogeneous by applying a high bias field to the sample and such converted homogeneous cell shows an additional dielectric relaxation peak in the low frequency side of Goldstone mode in SmC ‫ء‬ phase due to presence of GO whereas in the pure material no such peak was observed. The frequency separation of both peaks ͑Goldstone mode and an additional peak͒ increases with temperature and low frequency peak vanishes near transition temperature.