Regensburg 2019 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 37: Poster Session III

CPP 37.37: Poster

Mittwoch, 3. April 2019, 11:00–13:00, Poster B1

Comparison of sequential and solution-mixed doping of poly(3-hexylthiophene) in thin films using the Lewis acid BCF — •Dominique Lungwitz¹, Ahmed E. Mansour¹, Andreas Opitz¹, and Norbert Koch^1,2 — ¹Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin — ²Helmholtz-Zentrum Berlin für Materialien und Energie GmbH

Molecular doping of organic semiconductors is a commonly used technique to increase the conductivity and tune the electronic structure. Sequential doping method allows for an improved film morphology with controlled dopant load by avoiding agglomeration of polymer and dopant before deposition as observed partially for solution-mixed doping [1]. Herein, we investigate the changes in the electronic structure by photoemission spectroscopy and dopant distribution for sequentially and solution-mixed doping of poly(3-hexylthiophene) (P3HT) in regiorandom (RRa) and regioregular (RRe) forms. The Lewis acid dopant tris(pentafluorophenyl)borane (BCF) is applied for p-doping. We find that the solution-mixed process results in homogeneous bulk doping with an increase in the ionization energy for both P3HT regularities. However, for sequential doping by vapour exposure of thin RRa-P3HT films, a saturation for the BCF load is found at the surface and Fermi-level pinning is observed due to interfacial doping of the top polymer surface. Furthermore our results demonstrate that dopant molecules tend to diffuse more in RRe-P3HT than in RRa-P3HT films once they are sequentially doped and result in intermixed doped P3HT similar to solution mixed doping.