Liquid crystals for charge transport, luminescence, and photonics

Ordered molecular materials are increasingly used in active electronic and photonic organic devices. In this progress report we discuss whether the self-assembling properties and supramolecular structures of liquid crystals can be tailored to improve such devices. Recent developments in charge-transporting and luminescent liquid crystals are discussed in the context of material requirements for organic light-emitting devices, photovoltaics, and thin film transistors. We identify high carrier mobility, polarized emission, and enhanced output-coupling as the key advantages of nematic and smectic liquid crystals for electroluminescence. The formation of anisotropic polymer networks gives the added benefits of multilayer capability and photopatternability. The anisotropic transport and high carrier mobilities of columnar liquid crystals make them promising candidates for photovoltaics and transistors. We also outline some of the issues in material design and processing that these applications demand. The photonic properties of chiral liquid crystals and their use as mirror-less lasers are also directed.