New Organic Donors for High Efficiency Solar Energy Harvesting

Guodan Wei, Department of Materials Science and Engineering, University of Michigan

Tuesday, April 26, 2011, 4:15pm

Cummings 200

This seminar is part of the Jones Seminars on Science, Technology, and Society series

Organic photovoltaics (OPV) have been considered as a potential low-cost solar energy conversion solution for a clean, safe, affordable and sustainable energy future. They have attracted tremendous academic and industrial interests in recent years, which stems from the deposition flexibility of lightweight organic thin films on a variety of very-low-cost substrates such as glass, plastic or metal foils. Currently, there are three main ongoing avenues to improve the power conversion efficiency of OPVs: the development of new organic materials, improved process control and novel device architecture design. Through molecular design with chemical modification of functional organic molecules, a family of new highly absorptive squaraine (SQ) materials has been systematically synthesized and explored to improve the sunlight harvesting and charge transport. The spin-cast SQ donors are then coated with fullerene acceptors to form a unique nanocrystalline OPV device. This combination of a novel and efficient family of SQ donors, a unique device architecture and optimized fabrication processes leads to high efficiency solar cells. For example, solar cells with efficiencies of ~6.0 % and a fill factor ~0.74 are achieved, which to our knowledge both are the highest numbers reported to date for small molecule OPVs. These results suggest that SQs have promise for achieving further increases in solar cell efficiency in a more ordered nanocrystalline OPV, as will provide an ideal material system and device architecture for low-cost large-area OPVs using roll-to-roll printing techniques.

About the Speaker

Guodan Wei received her B.S. from Zhejiang University (China) in 2001, M.S. in materials science and engineering from Tsinghua University (China) in 2004, respectively. She also received M.S in mechanical engineering and aerospace from Princeton University in 2005. Then she experienced a lab move to University of Michigan, where she is currently pursuing her Ph.D. degree. She performs research in the area of high efficiency organic thin film solar cells, with a focus on new organic material synthesis, new device design and growth for low-cost renewable solar energy applications. Ms. Wei received the DSDF scholarship in 2004, for outstanding research work, and the best master thesis award in Tsinghua University. In 2004, she received a freshman fellowship in Princeton University. In 2007, she received a first-to-publish award for the first student from her class of 2006 in the MSE department to publish in a refereed archival journal as a lead author in University of Michigan. Since 2001, she has authored or co-authored 25 peer-reviewed journal papers and 12 conference papers. She has also been granted 7 U.S. patents associated with Type II quantum-dot solar cells and organic thin film solar cells.