Image courtesy of UMass PHaSE
The composition of solvents, such as chloroform and toluene, during nanoparticle fabrication can alter the internal aggregate structure of polymer P3HT (poly(3-hexylthiophene)), a well-studied electronic semiconductor polymer that serves as a benchmark for comparisons with new materials. Changing the internal structure could enable control of the polymer’s optical and electronic properties.
Researchers organized organic polymers into well-defined nanoscale particles and fibers to create pre-assembled building blocks. The solvent mixture controlled the polymer chain-packing within the nanoparticles, which differed from the kind of structural order seen in thin films.
Optimizing an organic solar cell’s light-to-power capability requires measurements on real-world-sized test devices, as well as sophisticated control and characterization of polymer organization in a nanoscale device. Studies of these arranged polymer chains provide an opportunity to understand how changes in structure at the nanoscale level affect charge movement in prototype solar cells.
Understanding the fundamental science behind conversion of light to electricity can provide important insights regarding their activity and behavior. However, to create commercially successful solar technology, the new materials require performance optimization. To address this issue, members of the Polymer-Based Materials for Harvesting Solar Energy (PHaSE) EFRC at University of Massachusetts, Amherst are pursuing all major areas of polymer solar-cell research – from basic design strategies to prototype testing. Recently, the PHaSE team began research on a well-studied electronic semiconductor polymer that serves as a benchmark for comparisons with new materials. Researchers developed ways to pre-organize polymers into specific-sized nano-spheres and to make larger polymer nano-fibers with individual structures that varied in length and in small-scale structure. Analysis of the structural and electronic behavior of various polymer samples indicated that electronic properties depended strongly on how polymers were assembled. Using larger samples, researchers found that disordered regions of the films negatively impact polymer performance. By investigating all size ranges, from nano-scale to real-world-sized prototypes, PHaSE researchers are learning important lessons about the impact of polymer assembly and organization on the design of next generation of solar cell materials.
Thomas P. Russell
Director, Polymer-Based Materials for Harvesting Solar Energy (PHaSE) EFRC
D. Venkataraman and Michael D. Barnes
University of Massachusetts, Amherst MA
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DOE Office of Science, Basic Energy Sciences, Energy Frontier Research Centers (EFRC) Program. Work by J. Labastide in Baghgar et al. was provided through the UMass Amherst National Science Foundation-supported Materials Research Science and Engineering Center. Measurement facilities for the time resolved photoluminescence was supported by the Department of Energy Office of Basic Energy Sciences.
M. Baghgar, J. A. Labastide, F. A. Bokel, I. Dujovne, K. P. McKenna, A. M. Barnes, E. Pentzer, T. Emrick, R. Hayward, M. D. Barnes, "Probing Inter- and Intrachain Exciton Coupling in Isolated Poly(3-hexylthiophene) Nanofibers: Effect of Solvation and Regioregularity”. J. Phys. Chem. Lett., 3, 1674-1679 (2012). [DOI: 10.1021/jz3005909]
G. Nagarajuna, M. Baghgar, J. A. Labastide, D. D. Algaier, M. D. Barnes, D. Venkataraman, "Tuning Aggregation of Poly-(3-hexylthiophene) within Nanoparticles". ACS Nano, 6, 10750-10758 (2012). [DOI: 10.1021/nn305207b]
X. Shen, V. V. Duzhko, T. P. Russell, "A Study on the Correlation Between Structure and Hole Transport in Semi-Crystalline Regioregular P3HT”. Advanced Energy Materials, 3, 263–270 (2013). [DOI: 10.1002/aenm.201200509]
Polymer-Based Materials for Harvesting Solar Energy (PHaSE) EFRC
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