Homogeneous alignment of liquid crystals using functionalized tungsten-oxide nanostructures: a route to improved electro-optical device performance.

Alignment layers play a vital role in liquid crystal (LC) technologies as they not only control the initial orientation of LCs but also influence the key parameters like threshold voltage, response time etc., making them essential for high-quality optoelectronic applications. Conventional rubbed polyimide-based alignment layers exhibit poor ion-trapping, limited transparency and incompatibility with flexible substrates. Therefore, the quest for alternative options has become an important research field. In this study, we report the application of tungsten oxide nanostructures as an inorganic alignment layer for nematic LC devices, offering an effective alternative to conventional polyimide coatings. Precisely, chemically functionalized tungsten oxide monohydrate (WO3·H2O) nanodiscs are synthesized via the hydrothermal method. The WO3-based layers are fabricated on indium tin oxide (ITO)-coated glass substrates using a simple and versatile deposition technique. The LC molecules demonstrated uniform planar anchoring. Comprehensive dielectric and electro-optical characterization studies reveal that the LC cells with WO3 alignment layers exhibit significantly improved threshold voltage reduced by 41%, around 70% faster switching response, and enhanced dielectric anisotropy compared to their polyimide-based counterparts. The observed performance enhancement is attributed to the nanostructured surface morphology and favorable interfacial interactions between WO3 layers and LC molecules. These findings highlight the potential of tungsten oxide nanomaterials as functional alignment layers for high-performance and next-generation LC devices.