Date of Award

Fall 2013

Degree Type


Degree Name

Doctor of Philosophy (PhD)


Electrical and Computer Engineering

First Advisor

Muhammad A. Alam

Committee Chair

Muhammad A. Alam

Committee Member 1

Mark A. Ratner

Committee Member 2

Mark S. Lundstrom

Committee Member 3

Rakesh Agrawal


Organic photovoltaic (OPV) technology is currently a topic of great interest for potentially low cost solar energy conversion and possibility of many novel PV applications (e.g., building-integrated PV, portable solar cells). Successful commercialization of this technology, however, will require significant improvement in efficiency and lifetime. In the last few years, innovation in novel polymer synthesis has raised the efficiency of OPV above 10%, at par with a-Si and earth-abundant solar cells. Further improvement in performance relies on breakthroughs in device design, which requires profound understanding of the physics of device operation. A major challenge in the design of the state of the art OPV cells is that it requires randomly mixed two different organic semiconductors for its absorbing layer. Even though such complex morphology reduces charge loss by separating electrons and holes in respective channels, it introduces many technological problems such as reliability, variability and yield which may preclude the large scale adoption of this technology.

In this work, we develop a theoretical and conceptual framework to facilitate fundamental understanding of the device physics of organic solar cells. In addition, this work has inspired several new design concepts, which can potentially improve the efficiency and lifetime of OPV cells. One crucial contribution of this thesis work is the proposal of single material based OPV design, which provides a paradigm shift in the design of organic solar cells. In general, the thesis work provides several new insights on the role of active layer morphology and defect states in organic semiconducting devices, which will broaden the field of organic electronics.