Influence of linking units on the photo responsive studies of azobenzene liquid Crystals: Application in optical storage devices

Abstract

In this paper, we report on the photoisomerization process of three series of photosensitive bent-core liquid crystals with a lateral chlorine atom in the central resorcinol core and various linkers. The effect of linkers, such as benzoate ester, biphenyl, cinnamate, Schiff base and stilbene on the photoisomerization and thermal back relaxation have been studied using UV–Vis spectroscopy. Resorcinol with benzoate ester showed the longest thermal back relaxation of 7 h, whereas, the bent-cores with the stilbene linker rendered the shortest relaxation time of 4 h. The compiled results suggest the influence of linkers, central resorcinol core and position of the azobenzene moiety on the photoisomerization. Additionally, optical storage device fabricated using cinnamate containing bent-core LC (A3), showed the visibility of bright and dark regions in a crossed polarizers upon illumination at λ = 365 nm, indicating the changes from the ordered to disordered state. The observed properties of constructed device demonstrate the potential application of reported azobenzene derivatives in optical storage devices.