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Title: Sequential Processing for Organic Photovoltaics: Design Rules for Morphology Control by Tailored Semi-Orthogonal Solvent Blends

Abstract

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.

Authors:
 [1];  [2];  [1];  [1];  [3];  [3];  [4];  [5]
  1. Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles CA 90095-1569 USA
  2. Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles CA 90095-1569 USA
  3. Departments of Chemical Engineering and Chemistry, University of Washington, Seattle WA 98195-1750 USA
  4. 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
  5. 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
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Molecularly Engineered Energy Materials (MEEM)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1386001
DOE Contract Number:  
SC0001342
Resource Type:
Journal Article
Journal Name:
Advanced Energy Materials
Additional Journal Information:
Journal Volume: 5; Journal Issue: 11; Related Information: MEEM partners with University of California, Los Angeles (lead); University of California, Berkeley; Eastern Washington University; University of Kansas; National Renewable Energy Laboratory; Journal ID: ISSN 1614-6832
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; solar (photovoltaic), energy storage (including batteries and capacitors), charge transport, membrane, materials and chemistry by design, synthesis (novel materials), synthesis (self-assembly), synthesis (scalable processing)

Citation Formats

Aguirre, Jordan C., Hawks, Steven A., Ferreira, Amy S., Yee, Patrick, Subramaniyan, Selvam, Jenekhe, Samson A., Tolbert, Sarah H., and Schwartz, Benjamin J.. Sequential Processing for Organic Photovoltaics: Design Rules for Morphology Control by Tailored Semi-Orthogonal Solvent Blends. United States: N. p., 2015. Web. doi: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.. Sequential Processing for Organic Photovoltaics: Design Rules for Morphology Control by Tailored Semi-Orthogonal Solvent Blends. United States. 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., and Schwartz, Benjamin J.. Wed . "Sequential Processing for Organic Photovoltaics: Design Rules for Morphology Control by Tailored Semi-Orthogonal Solvent Blends". United States. https://doi.org/10.1002/aenm.201402020.
@article{osti_1386001,
title = {Sequential Processing for Organic Photovoltaics: Design Rules for Morphology Control by Tailored Semi-Orthogonal Solvent Blends},
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.},
abstractNote = {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 = {1614-6832},
number = 11,
volume = 5,
place = {United States},
year = {2015},
month = {3}
}

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