Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles CA 90095-1569 USA
Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles CA 90095-1569 USA
Departments of Chemical Engineering and Chemistry, University of Washington, Seattle WA 98195-1750 USA
Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles CA 90095-1569 USA; Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles CA 90095-1569 USA; California NanoSystems Institute, University of California, Los Angeles, Los Angeles CA 90095 USA
Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles CA 90095-1569 USA; California NanoSystems Institute, University of California, Los Angeles, Los Angeles CA 90095 USA
Design rules are presented for significantly expanding sequential processing (SqP) into previously inaccessible polymer:fullerene systems by tailoring binary solvent blends for fullerene deposition. Starting with a base solvent that has high fullerene solubility, 2-chlorophenol (2-CP), ellipsometry-based swelling experiments are used to investigate different co-solvents for the fullerene-casting solution. By tuning the Flory-Huggins χ parameter of the 2-CP/co-solvent blend, it is possible to optimally swell the polymer of interest for fullerene interdiffusion without dissolution of the polymer underlayer. In this way solar cell power conversion efficiencies are obtained for the PTB7 (poly[(4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)(3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl)]) and PC61BM (phenyl-C61-butyric acid methyl ester) materials combination that match those of blend-cast films. Both semicrystalline (e.g., P3HT (poly(3-hexylthiophene-2,5-diyl)) and entirely amorphous (e.g., PSDTTT (poly[(4,8-di(2-butyloxy)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)-alt-(2,5-bis(4,4'-bis(2-octyl)dithieno[3,2-b:2'3'-d]silole-2,6-diyl)thiazolo[5,4-d]thiazole)]) conjugated polymers can be processed into highly efficient photovoltaic devices using the solvent-blend SqP design rules. Grazing-incidence wide-angle x-ray diffraction experiments confirm that proper choice of the fullerene casting co-solvent yields well-ordered interdispersed bulk heterojunction (BHJ) morphologies without the need for subsequent thermal annealing or the use of trace solvent additives (e.g., diiodooctane). The results open SqP to polymer/fullerene systems that are currently incompatible with traditional methods of device fabrication, and make BHJ morphology control a more tractable problem.
Aguirre, Jordan C., et al. "Sequential Processing for Organic Photovoltaics: Design Rules for Morphology Control by Tailored Semi-Orthogonal Solvent Blends." Advanced Energy Materials, vol. 5, no. 11, Mar. 2015. https://doi.org/10.1002/aenm.201402020
Aguirre, Jordan C., Hawks, Steven A., Ferreira, Amy S., Yee, Patrick, Subramaniyan, Selvam, Jenekhe, Samson A., Tolbert, Sarah H., & Schwartz, Benjamin J. (2015). Sequential Processing for Organic Photovoltaics: Design Rules for Morphology Control by Tailored Semi-Orthogonal Solvent Blends. Advanced Energy Materials, 5(11). https://doi.org/10.1002/aenm.201402020
Aguirre, Jordan C., Hawks, Steven A., Ferreira, Amy S., et al., "Sequential Processing for Organic Photovoltaics: Design Rules for Morphology Control by Tailored Semi-Orthogonal Solvent Blends," Advanced Energy Materials 5, no. 11 (2015), https://doi.org/10.1002/aenm.201402020
@article{osti_1386001,
author = {Aguirre, Jordan C. and Hawks, Steven A. and Ferreira, Amy S. and Yee, Patrick and Subramaniyan, Selvam and Jenekhe, Samson A. and Tolbert, Sarah H. and Schwartz, Benjamin J.},
title = {Sequential Processing for Organic Photovoltaics: Design Rules for Morphology Control by Tailored Semi-Orthogonal Solvent Blends},
annote = {Design rules are presented for significantly expanding sequential processing (SqP) into previously inaccessible polymer:fullerene systems by tailoring binary solvent blends for fullerene deposition. Starting with a base solvent that has high fullerene solubility, 2-chlorophenol (2-CP), ellipsometry-based swelling experiments are used to investigate different co-solvents for the fullerene-casting solution. By tuning the Flory-Huggins χ parameter of the 2-CP/co-solvent blend, it is possible to optimally swell the polymer of interest for fullerene interdiffusion without dissolution of the polymer underlayer. In this way solar cell power conversion efficiencies are obtained for the PTB7 (poly[(4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)(3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl)]) and PC61BM (phenyl-C61-butyric acid methyl ester) materials combination that match those of blend-cast films. Both semicrystalline (e.g., P3HT (poly(3-hexylthiophene-2,5-diyl)) and entirely amorphous (e.g., PSDTTT (poly[(4,8-di(2-butyloxy)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)-alt-(2,5-bis(4,4'-bis(2-octyl)dithieno[3,2-b:2'3'-d]silole-2,6-diyl)thiazolo[5,4-d]thiazole)]) conjugated polymers can be processed into highly efficient photovoltaic devices using the solvent-blend SqP design rules. Grazing-incidence wide-angle x-ray diffraction experiments confirm that proper choice of the fullerene casting co-solvent yields well-ordered interdispersed bulk heterojunction (BHJ) morphologies without the need for subsequent thermal annealing or the use of trace solvent additives (e.g., diiodooctane). The results open SqP to polymer/fullerene systems that are currently incompatible with traditional methods of device fabrication, and make BHJ morphology control a more tractable problem.},
doi = {10.1002/aenm.201402020},
url = {https://www.osti.gov/biblio/1386001},
journal = {Advanced Energy Materials},
issn = {ISSN 1614-6832},
number = {11},
volume = {5},
place = {United States},
publisher = {Wiley},
year = {2015},
month = {03}}