Tunable Command Layers for Liquid Crystal Alignment

• Published in: Journal of the American Chemical Society Vol. 127; no. 31; pp. 11047 - 11052
• Main Authors: Hoogboom, Johan, Garcia, Paula M. L, Otten, Matthijs B. J, Elemans, Johannes A. A. W, Sly, Joseph, Lazarenko, Sergiy V, Rasing, Theo, Rowan, Alan E, Nolte, Roeland J. M
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 10.08.2005; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Multidisciplinary; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Liquid crystals; Orientational order of liquid crystals; electric and magnetic field effects on order; Physical Sciences; Physics; Science & Technology; Structure of solids and liquids; crystallography; FILMS; TRANSITIONS; MECHANISM; PHTHALOCYANINE; SURFACES; Transition elements Complexes; Atomic force microscopy; Molecular orientation; Nitrogen heterocycle; Metallophthalocyanine; Organic ligand; Molecular aggregation; Experimental study; Zinc Complexes; Liquid crystals
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja051865l

A simple method for the construction of a stable, tunable, self-assembled command layer for liquid crystal display purposes is described. A pyridine-functionalized oligosiloxane spontaneously forms an anisotropic, grooved surface on indium−tin-oxide, enabling it to align liquid crystalline molecules. The pyridine functions act as seeds for the epitaxial growth of stacks of highly ordered zinc phthalocyanines, the height of which can be controlled. These stacks increase the interaction between the surface and the liquid crystalline matrix by amplifying the surface ordering into the liquid crystal bulk. By varying the height of the stacks, direct control over the properties of the liquid crystal domains is achieved. These properties can be further tuned by adding to the liquid crystal, micro- and nanomolar concentrations of nitrogen-containing compounds, which are capable of interacting with and dissolving the stacks. The procedures we describe offer possibilities to use such tunable systems in LCD-based sensor devices as well as in solar-cell applications.