This book deals with basic aspects of polymer electronics and optoelectronics. There is an enormous world-wide effort both in basic scientific research as well as in industrial development in the area of organic electronics. It is becoming increasingly clear that, if devices based on organic materials are ever going to have a significant relevance beyond being a cheap replacement for inorganic semiconductors, there will be a need to understand interface formation, film growth and functionality. A control of these aspects will allow the realisation of totally new device concepts exploiting the enormous flexibility inherent in organic chemistry. In this book we focus on oligomeric/molecular films as we believe that the control of molecular structures and interfaces provides highly defined systems which allow, on the one hand the study of the basic physics and on the other hand to find the important parameters necessary to improve organic devices.