Cholesteric liquid crystal devices with nanoparticle aggregation

• DOI: 10.1364/oe.18.022572
• Publication Date: 2010-10-08T21:29:10Z
• Authors: Shie-Chang Jeng; Shug-June Hwang; Yu-Hsiang Hung; Sheng-Chieh Chen
• Keywords: Optics and Photonics; Polymers; Surface Properties; Temperature; Esters; Equipment Design; 02 engineering and technology; Liquid Crystals; Kinetics; Models, Chemical; Materials Testing; Methacrylates; Nanoparticles; Nanotechnology; Organosilicon Compounds; 0210 nano-technology; Algorithms; Hydrogen

A broadband cholesteric liquid crystal (CLC) device with a multi-domain structure is demonstrated by using an aggregation of polyhedral oligomeric silsesquioxane (POSS) nanoparticles in the CLC layer. The aggregation pattern of the self-assembled POSS nanoparticles depends on the concentration of POSS doped in the mixture of POSS/CLC and the cooling rate of the mixture from a temperature higher than the clear point. POSS-induced changes in the bulk and surface properties of the cholesteric cells, such as a promotion of homeotropic alignment, help to form a cholesteric structure with a broadband reflection of light; the latter can be used for improvement of bistable CLC devices. A higher POSS concentration and a higher cooling rate both improve the appearance of the black-white CLC device.