Regensburg 2019 – wissenschaftliches Programm
CPP 14.8: Vortrag
Montag, 1. April 2019, 17:00–17:15, H31
The three optical signatures of p-doping in poly(3-hexylthiophene) — Malavika Arvind1, •Claudia Tait2, Jan Behrends2, and Dieter Neher1 — 1Universität Potsdam, Potsdam, Germany — 2Freie Universität Berlin, Berlin, Germany
Doping is an important process in the realization of electronic devices. Here we investigate the mechanism of p-doping of regioregular- and regiorandom- poly(3-hexylthiophene) (P3HT) using two dopants - F4TCNQ and tris(pentafluorophenyl)borane (BCF). Although both dopants exhibit Integer Charge Transfer (ICT) with rreP3HT in solution, the sub-band gap features in the UV-Vis-NIR spectra of F4TCNQ- and BCF-doped rraP3HT differ significantly. The concentration and nature of paramagnetic states generated in the different systems was investigated using EPR spectroscopy. The results reveal significantly reduced spin concentrations in the doped rraP3HT solutions, in particular with F4TCNQ as dopant, supporting the existence of EPR-silent bound charge pairs. Additionally, the hole delocalization was shown to be reduced in regiorandom- compared to regioregular-P3HT. We conclude that CTC and ITC formation is not specific for thiophene-based polymers and oligomers, respectively, as suggested by earlier results.  Instead, the nature of the doping-induced state correlates strongly with the ability of the conjugated backbone to planarize and to delocalize the polaron along the conjugated system.
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