Fabrication of Vertically Aligned Liquid Crystals Devices Using Nanoscale Self-Assembled Alignment Layers of Photoluminescent Pyrene Derivatives.

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Nanoscale self-assembled molecular layers of 1-pyrene carboxylic acid, 1-pyrene butylic acid, and 1-amino pyrene were employed as photoluminescent alignment agents to form vertical arrays of liquid crystals (LCs). The LC device using alignment agent of 1-amino pyrene appeared to have a stable vertical alignment based on crossed polarization analysis. The electro-optical properties of the LCs fabricated using this self-assembled layer exhibited better performance than those of general LC cells containing a conventional polyimide layer. The proposed self-assembled alignment method is sufficient as a replacement for more commonly used polyimide layers, which require complex film forming processing and high production costs; conversely, the proposed technique allows for simple mixing using low concentrations of alignment agents (0.05 wt%). Moreover, as LCs were mixed with the pyrene derivatives, photoluminescence (PL) under ultraviolet (UV) light was exhibited. This proposed method has excellent LC alignment and PL property, both of which can be utilized in advanced display technologies for next-generation LC devices, such as polyimide-free alignment or color-filter-free color expression.