Light-stimulated electro-optics by azo-doped aerosil/7CB nanocomposites

Photoactive nanofilled nematic is proposed. Stable three-component photoresponsive nanocomposite was prepared from photo-insensitive nanofilled nematic by inclusion of 3?wt.% azobenzene-containing photoactive mesogen 4-(4′-ethoxyphenylazo)phenyl hexanoate (EPH). The host nanofilled nematic was produced from the room-temperature nematic liquid crystal 4-n-heptyl cyanobiphenyl (7CB) and 3?wt.% filler of Aerosil 300 hydrophilic silica nanospheres of size 7?nm. Apparent effect of stimulation with a relatively weak continuous illumination by UV light (375?nm wavelength) takes place for both the alternating-current electric field-dependent optical transmittance and the electro-optic amplitude-frequency modulation by thin films (25?µm thick) of the EPH/aerosil/7CB nanocomposite. The light-stimulated electro-optics of EPH-doped aerosil/7CB films and the corresponding reversible light control are achieved through trans-cis-trans photoisomerization of the photoactive agent EPH. As such, the initial electro-optical response of the studied photoactive nanocomposites is recovered with continuous blue-light illumination. The examined EPH/aerosil/7CB nanocomposites exhibit photo-controllable electro-optical response that is of practical interest.