Advanced Functional Materials

Cover image for Vol. 26 Issue 17

18_02b/2008Inside Front Cover: Unprecedented Dual Alignment Mode and Freedericksz Transition in Planar Nematic Liquid Crystal Cells Doped with Gold Nanoclusters (Adv. Funct. Mater. 2/2008)

On p. 212, Torsten Hegmann and co-workers describe nematic liquid crystals (N-LCs) confined in planar liquid crystal cells after doping with small quantities of gold nanoclusters. These give rise to a dual alignment mode and electro-optic response (Freedericksz transition). By fine-tuning of experimental conditions, N-LCs doped with gold nanoclusters can be electrically reoriented and aligned either like N-LCs with a positive dielectric anisotropy (used in twisted nematic displays) in a planar cell or alternatively as N-LCs with a negative dielectric anisotropy (used in large LCD TVs based on the vertical alignment mode).

We demonstrate that alkylthiol-capped gold nanoclusters doped into nematic liquid crystals (N-LCs) with positive dielectric anisotropy give rise to an unprecedented dual alignment mode and electro-optical response, which has a potential impact on current liquid crystal (LC) display technologies and N-LC optical-biosensor design. By fine-tuning experimental conditions (temperature, electric field, and alignment), N-LCs doped with gold nanoclusters can be aligned and electrically reoriented either like N-LCs with a positive dielectric anisotropy in a planar cell or, alternatively, as N-LCs with a negative dielectric anisotropy in a homeotropic cell, both at lower threshold voltages than the pure N-LC.

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