Acknowledgment

First and foremost, I would like to thank my advisor, Prof. Hans Kosina for his support, understanding and patience during the past three years over this project. Without his guidance as a great mentor, this work would not have been possible, and I certainly would not be here. I would also like to thank Prof. Siegfried Selberherr and Prof. Tibor Grasser for valuable time and providing great guidance for this work.

Secondly, my special gratitude goes to my fellow lab mates, Dr. Alireza Sheikholeslami and Dr. Christian Hollauer for their friendship and help in the working and living. Special thanks to M.Sc. Gregor Meller for his friendship and many detailed and enlightening discussions in pursuing deeper understanding of organic semiconductors. I also thank Dipl.-Ing. Rene Heinzl and Dipl.-Ing. Philipp Schwaha, who introduced me to the Linux system. Finally, my deep gratitude goes to Dipl.-Ing. Thomas Windbacher, Dipl.-Ing. Otmar Ertl, Dipl.-Ing. Alexander Nentschev and others who in one way or another further made by my time at TU-Wien worthwhile.

Without the love and support of my family, this would have been a very hard journey. I thank my father for teaching me good values such as hard work and appreciation for the gift of life and my mother without whom I would not be the person that I am today. My love for them is eternal.

Finally, I am grateful to the financial support from the Austrian Science Fund (FWF) through contract P16862-N02.