Opto-electronic properties of liquid crystals are controlled by their orientation with respect to a light source and/or an electrode surface. The best known examples are liquid crystal displays. Their performance depends crucially on the surface induced alignment of the mesophase. Such challenges have to be overcome also when columnar LC phases are used as molecular cables in plastic electronics, such as field effect transistors (FET), light-emitting diodes (LED) or photovoltaic cells (PV).

This lecture presents how mesogens (liquid crystal forming molecules) orient in thin films and how this orientation can be controlled by surfaces, by dopants and mechanical alignment techniques. Examples are given for discotic nematic liquid crystals used for compensation films and columnar assemblies which are promising for their application in plastic electronics.