Textural, electro-optical, dielectric and fluorescence studies of citrate buffer stabilized gold nanoparticles doped in polymer-dispersed liquid crystals composites

This work demonstrates the effect of citrate buffer stabilised gold nanoparticles (AuNPs) on the morphological, optical and dielectric properties of polymer-dispersed liquid crystal (PDLC) composites prepared by polymerisation-induced phase separation method. The effect of voltage and temperature on liquid crystal (LC) droplet configurations, transmission, permittivity, conductivity and transition temperatures are studied. The relative transmission and contrast were improved by 22% and 54%, respectively, after the dispersion of AuNPs in PDLC composites as compared to undoped PDLC. The threshold voltage (V-th) of the doped composite was reduced by 13.34% as compared to the undoped composite. The increasing concentration of AuNPs has a minor effect on the (V-th) and transmission as well. Moreover, the low concentration of AuNPs also has better optical responses. The size of LC droplets was found in the range of 35-53 mu m and almost independent of voltage and temperature. Beyond threshold voltage, maltese type LC droplet occurred. The photoluminescence spectra reveal that the intensity of AuNPs (1.5 mu l) doped sample is higher and a blue shift is seen at 3.0 mu l AuNPs-doped sample than others. With increasing AuNPs concentration, the energy bandgap also increases and is reported in the range of 3.4 eV at a higher concentration of AuNPs.

Automated summary

This study demonstrates the influence of citrate buffer stabilised gold nanoparticles (AuNPs) on the morphological, optical, and dielectric properties of polymer-dispersed liquid crystal (PDLC) composites. The dispersion of AuNPs improved the relative transmission and contrast, while lowering the threshold voltage of the doped composite. AuNPs concentration had a minor effect on the threshold voltage and transmission. Moreover, low AuNPs concentration showed better optical responses.