Luping Yu Discusses Organic Photovoltaic Research
Fast Breaking Papers Commentary, February 2011
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Article: For the Bright Future-Bulk Heterojunction Polymer Solar Cells with Power Conversion Efficiency of 7.4%
Authors: LLiang, YY;Xu, Z;Xia, JB;Tsai, ST;Wu, Y;Li, G;Ray,
C;Yu, LP |
Luping Yu talks with ScienceWatch.com and answers a few questions about this month's Fast Breaking Paper paper in the field of Materials Science.
Why do you think your paper is highly
cited?
The organic photovoltaic (OPV) research is a very active and important area nowadays as OPV devices are promising candidates for solar energy harvesting with low cost, simple processing, and environmental friendliness. Many groups around the world devoted their efforts in developing new materials that can solve the problems associated with current OPV solar cells for practical application, such as low power conversion efficiency. Our work represented a significant progress in improving the efficiency of OPV solar cells and shows the promise of OPV, which attracts people's attention.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
The paper described development of a new class of polymer material that exhibits high power conversion efficiency in OPV solar cell. It's a new discovery of a polymer system with the potential to be useful in real solar cells.
Would you summarize the significance of your paper
in layman's terms?
This is the first polymer system that breaks the 7% efficiency barrier for OPV solar cells. It's a significant efficiency boost, which makes OPV solar cells very close to some of the inorganic solar cells. It gave impetus to the field that organic materials exhibit great potential to be competitive with inorganic counterparts.
For the Bright Future—Bulk Heterojunction
Polymer Solar Cells with Power Conversion Efficiency of 7.4%
The external quantum efficiency spectra of polymer
solar cells prepared in different solvents, (CB, chlorobenzene, DCB,
Dichlorobenzene, DIO, Di-iodooctane); and the structure of polymer PBT7 and
PCBM. Yongye Liang, et
al., Adv.
Mater., Vol 22, 2010, E135–E138, May 25,
2010. Copyright Wiley-VCH Verlag GmbH & Co. KGaA. Reproduced with
permission.
How did you become involved in this research, and
how would you describe the particular challenges, setbacks, and
successes that you've encountered along the way?
Our involvement started in our research project in p-n junction molecules. We studied the photophysics in single molecular diodes and discovered their photovoltaic effect. We decided to pursue conjugated diblock copolymers containing donor-acceptor blocks for solar cell application. It did not work, most likely due to fast charge recombination process in these materials that converts photons into heat.
Then we turned our attention to bulk heterojunctions polymer solar cells. By that time, the area had been developed for some time, many groups were ahead of us, but there were still very few polymer systems that worked efficiently. Combing our group's long-term experience on designing conjugated systems with lessons learned from other groups working in OPV area, we decided to synthesize a novel polymer system using quinoidal structure to lower bandgap.
We pursued the research and continuously optimized the structures with new ideas. Thanks to the students' efforts and our collaboration from Solarmer Energy Inc. in device characterization, we finally succeeded.
Where do you see your research leading in the
future?
We are not chasing the power conversion efficiency per se; rather, we are trying to understand why these polymers are good and what we can learn from these systems so that we can design better materials. In this aspect, we have made important progress. Recently we have studied structure/property relationship and had important discoveries. Of course, we also continue to design new materials. Similar challenges, setbacks, and successes follow.
Do you foresee any social or political
implications for your research?
I believe our work will have a positive impact to society and the
environment. We have made significant improvement for OPV materials. The
further development will lead to promising alternative materials for solar
energy harvesting with low cost and possible flexible
structures.
Luping Yu, Ph.D.
Professor
Department of Chemistry
University of Chicago
Chicago, IL, USA
KEYWORDS: PHOTOVOLTAIC CELLS; ORGANIC PHOTOVOLTAICS; POLY(3-HEXYLTHIOPHENE); MORPHOLOGY; NETWORK; BLENDS.