Impact of morphology on polaron delocalization in a semicrystalline conjugated polymer
Cherniawski, Benjamin P.
Briseno, Alejandro L.
KAUST DepartmentKAUST Solar Center (KSC)
Physical Sciences and Engineering (PSE) Division
Chemical Science Program
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AbstractWe investigate the delocalization of holes in the semicrystalline conjugated polymer poly(2,5-bis(3-alkylthiophene-2-yl)thieno[3,2-b]thiophene) (PBTTT) by directly measuring the hyperfine coupling between photogenerated polarons and bound nuclear spins using electron nuclear double resonance spectroscopy. An extrapolation of the corresponding oligomer spectra reveals that charges tend to delocalize over 4.0-4.8 nm with delocalization strongly dependent on molecular order and crystallinity of the PBTTT polymer thin films. Density functional theory calculations of hyperfine couplings confirm that long-range corrected functionals appropriately describe the change in coupling strength with increasing oligomer size and agree well with the experimentally measured polymer limit. Our discussion presents general guidelines illustrating the various pitfalls and opportunities when deducing polaron localization lengths from hyperfine coupling spectra of conjugated polymers.
CitationSteyrleuthner R, Zhang Y, Zhang L, Kraffert F, Cherniawski BP, et al. (2017) Impact of morphology on polaron delocalization in a semicrystalline conjugated polymer. Phys Chem Chem Phys. Available: http://dx.doi.org/10.1039/c6cp07485e.
SponsorsThe authors like to thank for financial support from the DFG (SPP 1601) and the Helmholtz Association (Energie-Allianz Hybrid-Photovoltaik). This work has been partly supported by King Abdullah University of Science and Technology (KAUST). We acknowledge the KAUST IT Research Computing Team for providing computational and storage resources and thank Dr Cheng Zhong, Dr Haitao Sun, and Dr Bradley D. Rose for stimulating discussions. A. L. B. acknowledges the National Science Foundation (DMR-1508627).
PublisherRoyal Society of Chemistry (RSC)
JournalPhys. Chem. Chem. Phys.