Fabrication of coloured liquid crystal device using photoluminescent biomolecular chlorophyll

Abstract

ABSTRACTWe fabricated a coloured liquid crystal (LC) device using photoluminescent biomolecular chlorophyll. The chlorophyll molecule, which is inexpensive because of its abundance in nature, was doped in the LCs for manufacturing the coloured LC device. We confirmed the green colour property of the LC doped with chlorophyll dye using UV-vis spectroscopy. Although the LC cell filled with 0.5 wt% chlorophyll showed good vertical alignment and fast response time, the doping of LC medium with 1.5 wt% chlorophyll resulted in imperfect vertical alignment and slowed response time due to the aggregation of chlorophyll molecules at high concentration. Furthermore, the photoluminescence (PL) characteristics of the LC doped with chlorophyll were investigated using PL spectroscopy. The coloured LC cell doped with chlorophyll dye showed emission in the red wave number region under UV light. As the LC doped with chlorophyll exhibited good colour performance, conventional colour filter layers could be avoided with the employment of the proposed coloured LC device. By controlling the light source, it is possible to apply the advanced LC device for colour switching. Moreover, a full-colour-switching LC device can be realised using various biomolecular dyes that can emit other colours.