January 2013

Absorbing More of the Rainbow with Polymer-Based Organic Photovoltaics

Using newly synthesized polymers results in enhanced light harvesting capabilities and an unprecedented generation of photocurrent.

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Image courtesy of University of Southern California

New conjugated polymers absorb the rainbow of sunlight.

The Science

A simplified synthetic method was developed to produce semiconducting organic polymers that allow increased light absorption across the visible and into the near-infrared.

The Impact

Enhancing the light harvesting and photoconversion capabilities of these types of polymers could result in a robust and straightforward polymerization technique that is essential for more effective commercialization of organic photovoltaics.

Summary

A critical goal for organic photovoltaics is the development of a low cost and highly efficient design platform based on simple materials and processing methods. Progress towards this goal is evident in research at the Center for Energy Nanoscience where a novel class of polymers was recently introduced into organic solar cells to improve and extend their light harvesting ability and to attain new highs in production of photocurrent. Semi-random polymers were designed as an analogue of a well-known optical polymer, polythiophene [poly(3-hexylthiophene or P3HT], absorbing more of the light spectrum while retaining properties that have made P3HT attractive for solar cells. Different subunits were used to generate multiple light absorbing molecules, i.e. chromophores, in the polymer molecular backbone, allowing light to be more effectively harvested over a broader range.  Controlling reactive functional groups on the single subunits of the polymer led to a linkage pattern that enables one or two accepting groups to increase overall light absorption. Two-acceptor polymers demonstrated unprecedented light harvesting properties and photocurrents among the highest ever reported for polymer-C60-fullerene blend-based solar cells.

Contact

Barry C. Thompson
University of Southern California
barrycth@usc.edu

P. Daniel Dapkus
Director, Center for Energy Nanoscience (CEN) EFRC
dapkus@usc.edu

Funding

DOE Office of Science, Basic Energy Sciences program, Energy Frontier Research Centers (EFRC) program.

Publications

Burkhart, B., Khlyabich, P. P., Thompson, B. C., "Influence of the Acceptor Composition on Physical Properties and Solar Cell Performance in Semi-Random Two-Acceptor Copolymers." ACS Macro Lett. 1, 660 (2012). [DOI: 10.1021/mz300197cExternal link]

Khlyabich, P. P., Burkhart, B., Ng, C. F., Thompson, B. C., "Efficient Solar Cells from Semi-Random P3HT Analogues Incorporating Diketopyrrolopyrrole." Macromolecules. 44, 5079 (2011). [DOI: 10.1021/ma2009386External link]

Burkhart, B., Khlyabich, P. P., Cakir Canak, T., LaJoie, T. W., Thompson, B. C., “Semi-Random Multichromophoric rr-P3HT Analogues for Solar Photon Harvesting,” Macromolecules. 44, 1242 (2011). [DOI: 10.1021/ma102747eExternal link]

Related Links

Center for Energy Nanoscience EFRC

Highlight Categories

Program: BES, EFRCs

Performer/Facility: University

Additional: Technology Impact

Last modified: 12/6/2013 1:26:23 PM