Unprecedented dual alignment mode and Freedericksz transition in planar nematic liquid crystal cells doped with gold nanoclusters

We demonstrate that alkylthiol-capped gold nanoclusters doped into nematic liquid crystals (N-LCs) with positive dielectric an-isotropy 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.