The book describes experimental methods to develop and employ composite films of carbon nanotubes and conjugated polymers for application in photovoltaics and LEDs. It explains how doping of carbon nanotubes in polymer films affect/improve the native optical and electrical properties. The dependence of transport properties of the composite film on the dimensions/size of both the nanomaterials (nanotubes and polymer chains) has also been briefly described. At the end, book elucidates experimental fabrication of a polymer based LED incorporating nanotubes as electron transporting media. The findings will be helpful to researchers working in the area of organic electronics.