Regensburg 2019 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 3: Molecular Electronics and Excited State Properties
CPP 3.11: Vortrag
Montag, 1. April 2019, 12:30–12:45, H13
Differentiation between the optical signatures of aggregates and of isolated chains in doped P3HT solutions — •Ahmed E. Mansour1, Dominique Lungwitz1, Thorsten Schultz1, Andreas Opitz1, and Norbert Koch1,2 — 1Institut für Physik & IRIS Adlershof, Humboldt Universität zu Berlin, Germany — 2Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Germany
Molecular doping of Poly(3-hexylthiophene-2,5-diyl) (P3HT) results in the formation of polarons as the main charge carriers. Charged polymer segments can be identified by optical absorption spectroscopy.[1,2] Furthermore, molecular doping typically may lead to aggregation of P3HT and the dopant already in the solution, which alters the film morphology.[3,4] Herein, we compare the optical signatures of doped aggregates and doped single chains in solution. Their relative size is compared by filtering doped suspensions for different absolute concentrations and dopant ratios. We find that doped single chains exhibit absorption features at 1.5 eV and 0.6 eV. For doped aggregates, the peak at higher absorption energy is split into two absorption features at 1.3 eV and 1.65 eV. Further, we show that the size of dopant induced aggregation increases as a function of absolute concentration and dopant ratio. Doped P3HT suspensions are shown to comprise both doped species, with the aggregates exhibiting a larger dopant loading.
[1]Bredas, J. L. et al., Acc. Chem. Res. 1985, 18, 309. [2]Heimel, G., ACS Cent. Sci. 2016, 2, 309. [3]McFarland, F. M. et al., J. Phys. Chem. C 2017, 121, 4740. [4]Jacobs, I. E. et al, J. Mater. Chem. C 2016, 4 (16), 3454.