Control of polythiophene film microstructure and charge carrier dynamics through crystallization temperature
AuthorsMarsh, Hilary S.
Reid, Obadiah G.
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AbstractThe microstructure of neat conjugated polymers is crucial in determining the ultimate morphology and photovoltaic performance of polymer/fullerene blends, yet until recently, little work has focused on controlling the former. Here, we demonstrate that both the long-range order along the (100)-direction and the lamellar crystal thickness along the (001)-direction in neat poly(3-hexylthiophene) (P3HT) and poly[(3,3″-didecyl[2,2′:5′, 2″-terthiophene]-5,5″-diyl)] (PTTT-10) thin films can be manipulated by varying crystallization temperature. Changes in crystalline domain size impact the yield and dynamics of photogenerated charge carriers. Time-resolved microwave conductivity measurements show that neat polymer films composed of larger crystalline domains have longer photoconductance lifetimes and charge carrier yield decreases with increasing crystallite size for P3HT. Our results suggest that the classical polymer science description of temperature-dependent crystallization of polymers from solution can be used to understand thin-film formation in neat conjugated polymers, and hence, should be considered when discussing the structural evolution of organic bulk heterojunctions. © 2014 Wiley Periodicals, Inc.
CitationMarsh HS, Reid OG, Barnes G, Heeney M, Stingelin N, et al. (2014) Control of polythiophene film microstructure and charge carrier dynamics through crystallization temperature. J Polym Sci Part B: Polym Phys 52: 700–707. Available: http://dx.doi.org/10.1002/polb.23471.
SponsorsThe TRMC system described here was funded by the Solar Photochemistry Program, Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences, U.S. Department of Energy. The experimental development for controlling polymer crystalline domain size was supported by the Laboratory Directed Research and Development (LDRD) Program at the National Renewable Energy Laboratory under task number 06RF1201. This work was supported by the U.S. Department of Energy under Contract No. DE-AC36-08-GO28308 with the National Renewable Energy Laboratory. The authors also acknowledge Nikos Kopidakis from the National Renewable Energy Laboratory, Neil Treat from Imperial College, London, and Alex Ayzner and Mike Toney from the Stanford Synchrotron Radiation Lightsource (SSRL) for helpful discussions. Alan Sellinger's group at Colorado School of Mines is acknowledged for the use of the TA Q Series DSC 2000 instrument. This work was also supported by a KAUST Global Collaborative Research Academic Excellence Alliance (AEA) grant. NS is in addition supported by a European Research Council (ERC) Starting Independent Research Fellowship under the grant agreement No. 279587. The authors acknowledge EPRSC grant EP/G037515/1 for funding the polymer synthesis portion of this work.