Droplet configuration control with orange azo dichroic dye in polymer dispersed liquid crystal for advanced electro-optic characteristics

Orange azo dichroic dye dependent droplet configuration and electro-optic (EO) characteristics of polymer dispersed liquid crystals (PDLCs) were studied. PDLCs were prepared using a nematic liquid crystal (LC) and UV-curable liquid photopolymer in equal ratio by polymerization induced phase separation (PIPS) technique. Orange azo dichroic dye was taken in different concentrations (wt./wt. ratio) particularly 0.0625, 0.125, 0.25, 0.5 and 1% of the LC mixture to prepare different PDLC samples. In OFF state, bipolar configuration of LC droplets in polymer matrix was observed predominantly for each concentration of dye. In ON state, LC molecules align along the direction of applied electric field and LC droplets configuration shifted to vertical radial configuration in orange azo dichroic dye doped PDLCs at electric field (~ 3 V/μm). Experimental results showed radically improved transmission value (~ 25.4 a. u.) and contrast (~ 1058) at relatively lower operating electric field (3.13 V/μm) with consistent average droplet size ~ 4.0 μm, at lowest (0.0625%) orange azo dichroic dye concentration among all.