Glassy Liquid Crystals as Self-Organized Films for Robust Optoelectronic Devices

Abstract

This chapter will review recent advances in glassy liquid crystals (GLCs) as self-organized nano- to microstructured organic solids and their potential for optoelectronic device applications. Conformational multiplicity serves as the kinetic and thermodynamic foundation for glass formation and stability against crystallization from the glassy state as well as solubility in common solvents to facilitate material synthesis, purification, and spin-casting into films. From the molecular perspective, conformational multiplicity has been bestowed by chemically bonding mesogenic groups to volume-excluding cores via flexible linkages, and alternatively by functionalizing conjugated oligomers with aliphatic side groups. Two distinct material classes have emerged for the realization of defect-free GLC films across a large area while assuring long-term morphological stability. Solvent-vapor annealing of spin-cast films on photoalignment layers at room temperature managed to achieve the same extent of orientational order as thermal annealing on rubbed polyimide alignment layers. Varied device concepts have been demonstrated, including circular polarizers, optical notch filters and reflectors; photonic switching and optical memory; polarized fluorescence and electroluminescence; and robust organic solid-state lasers including spatial resolution for multiple lasing wavelengths on demand within a single film.