TY - JOUR
T1 - Aggregation control in natural brush-printed conjugated polymer films and implications for enhancing charge transport
AU - Wang, Gang
AU - Huang, Wei
AU - Eastham, Nicholas D.
AU - Fabiano, Simone
AU - Manley, Eric F.
AU - Zeng, Li
AU - Wang, Binghao
AU - Zhang, Xinan
AU - Chen, Zhihua
AU - Li, Ran
AU - Chang, Robert P.H.
AU - Chen, Lin X.
AU - Bedzyk, Michael J.
AU - Melkonyan, Ferdinand S.
AU - Facchetti, Antonio
AU - Marks, Tobin J.
N1 - Funding Information:
ACKNOWLEDGMENTS. This research was supported, in part, by the Argonne– Northwestern Solar Energy Research Center, an Energy Frontier Research Center funded by US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences Award DE-SC0001059 and Air Force Office of Scientific Research Grant FA9550-15-1-0044. Use of the Advanced Photon Source, an Office of Science User Facility operated for the US DOE Office of Science by Argonne National Laboratory, was supported by US DOE Contract DE-AC02-06CH11357. S.F. acknowledges support from Swedish Governmental Agency for Innovation Systems Grant 2015-04859 and Swedish Research Council Grant 2016-03979. E.F.M. was supported by Qatar National Priorities Research Program Grant 7-286-1-046. F.S.M. was supported by US Department of Commerce, National Institute of Standards and Technology Award 70NANB14H012 as part of the Center for Hierarchical Materials Design. This work made use of The Electron Probe Instrumentation Center, Keck-II, and/or Scanned Probe Imaging and Development facilities of Northwestern University’s Northwestern University Atomic and Nanoscale Characterization Experimental Center, which has received support from Soft and Hybrid Nanotechnology Experimental Resource Grant NSF ECCS-1542205, Materials Research Science and Engineering Center Program NSF DMR-1121262 at the Materials Research Center, the International Institute for Nanotechnology (IIN), the Keck Foundation, and the State of Illinois through the IIN.
PY - 2017/11/21
Y1 - 2017/11/21
N2 - Shear-printing is a promising processing technique in organic electronics for microstructure/charge transport modification and large-area film fabrication. Nevertheless, the mechanism by which shear-printing can enhance charge transport is not well-understood. In this study, a printing method using natural brushes is adopted as an informative tool to realize direct aggregation control of conjugated polymers and to investigate the interplay between printing parameters, macromolecule backbone alignment and aggregation, and charge transport anisotropy in a conjugated polymer series differing in architecture and electronic structure. This series includes (i) semicrystalline hole-transporting P3HT, (ii) semicrystalline electron-transporting N2200, (iii) low-crystallinity hole-transporting PBDTT-FTTE, and (iv) low-crystallinity conducting PEDOT:PSS. The (semi-)conducting films are characterized by a battery of morphology and microstructure analysis techniques and by charge transport measurements. We report that remarkably enhanced mobilities/conductivities, as high as 5.7×/3.9×, are achieved by controlled growth of nanofibril aggregates and by backbone alignment, with the adjusted R2 (R2adj) correlation between aggregation and charge transport as high as 95%. However, while shear-induced aggregation is important for enhancing charge transport, backbone alignment alone does not guarantee charge transport anisotropy. The correlations between efficient charge transport and aggregation are clearly shown, while mobility and degree of orientation are not always well-correlated. These observations provide insights into macroscopic charge transport mechanisms in conjugated polymers and suggest guidelines for optimization.
AB - Shear-printing is a promising processing technique in organic electronics for microstructure/charge transport modification and large-area film fabrication. Nevertheless, the mechanism by which shear-printing can enhance charge transport is not well-understood. In this study, a printing method using natural brushes is adopted as an informative tool to realize direct aggregation control of conjugated polymers and to investigate the interplay between printing parameters, macromolecule backbone alignment and aggregation, and charge transport anisotropy in a conjugated polymer series differing in architecture and electronic structure. This series includes (i) semicrystalline hole-transporting P3HT, (ii) semicrystalline electron-transporting N2200, (iii) low-crystallinity hole-transporting PBDTT-FTTE, and (iv) low-crystallinity conducting PEDOT:PSS. The (semi-)conducting films are characterized by a battery of morphology and microstructure analysis techniques and by charge transport measurements. We report that remarkably enhanced mobilities/conductivities, as high as 5.7×/3.9×, are achieved by controlled growth of nanofibril aggregates and by backbone alignment, with the adjusted R2 (R2adj) correlation between aggregation and charge transport as high as 95%. However, while shear-induced aggregation is important for enhancing charge transport, backbone alignment alone does not guarantee charge transport anisotropy. The correlations between efficient charge transport and aggregation are clearly shown, while mobility and degree of orientation are not always well-correlated. These observations provide insights into macroscopic charge transport mechanisms in conjugated polymers and suggest guidelines for optimization.
KW - Natural brush-printing
KW - Polymer aggregation
KW - Polymer alignment
KW - Polymer charge transport
KW - Shear effects
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U2 - 10.1073/pnas.1713634114
DO - 10.1073/pnas.1713634114
M3 - Article
C2 - 29109282
AN - SCOPUS:85034602819
VL - 114
SP - E10066-E10073
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 47
ER -