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Next-Generation Photovoltaic Technologies Print
Monday, 06 February 2012 15:48

Organic solar cells based on the polymer/fullerene bulk heterojunction (BHJ) model represent one of the most promising technologies for next-generation solar energy conversion due to their low cost and scalability. Traditional organic photovoltaics (OPVs) are thought to have interpenetrating networks of pure polymer and fullerene layers with discrete interfaces. Researchers at Argonne National Laboratory, working with collaborators from the University of Chicago, LBNL, and NIST, used ALS Beamline to perform resonant soft x-ray scattering (RSoXS) on PTB7/fullerene BHJ solar cells to probe performance-related structures at different length scales. These solar cells set a historic record of conversion efficiency (7.4%). The RSoXS demonstrated that the superior performance of PTB7/fullerene solar cells is attributed to surprising hierarchical nanomorphologies ranging from several nanometers of crystallites to tens of nanometers of nanocrystallite aggregates in intermixed PTB7-rich and fullerene-rich domains, themselves hundreds of nanometers in size. This work will lead the research community to rethink ideal OPV morphologies, reconsider which structures should be targeted in OPVs, and enable the rational design of even higher-performance organic solar cells.



Correlating efficiency and morphology in polymer:fullerene solar cells: hierarchical nanomorphologies promote exciton dissociation and diagrammatic hypothesis of the refined BHJ model for polymer:fullerene devices.



Work perfomed on ALS Beamline 11.0.1.

Citation: W. Chen, T. Xu, F. He, W. Wang, C. Wang, J. Strzalka, Y. Liu, , J. Wen, D. J. Miller, J. Chen, K. Hong, L. Yu, and S. B. Darling, "Hierarchical Nanomorphologies Promote Exciton Dissociation in Polymer/Fullerene Bulk Heterojunction Solar Cells," Nano Letters, 11(9), 3707–3713 (2011). doi:10.1021/nl201715q