SKM 2023 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 19: Organic Electronics and Photovoltaics I (joint session CPP/HL)
HL 19.10: Talk
Tuesday, March 28, 2023, 12:00–12:15, GÖR 226
improvement of electrical transport in organic semiconductor thin films by charge transfer doping — •Hongwon Kim1, Andreas Opitz2, Florian Fenzl1, and Wolfgang Brütting1 — 1Experimentalphysik IV, Institut für Physik, Universität Augsburg — 2Institut für Physik, Supramolekulare Systeme, HU zu Berlin
Charge carrier transport in organic semiconductor is based on the hopping mechanism. We have used in-situ charge transfer doping during film-growth to improve the electrical conductivity by simultaneously increasing the carrier density and reducing their thermal activation energy. By doping planar organic semiconductors, such as DBTTF, a-6T, and DIP, with strong acceptors (F6-TCNNQ & HATCN), hybridization of pi-orbitals occurs while generating new interphases (charge transfer complex, CTC). On the other hand, DBP, a non-planar molecule, forms an amorphous thin film without any CTC generation. To measure the characteristics of CTC, we used near-infrared transmission spectroscopy, which can detect the absorption peaks of CTCs and the energy gap. In addition, the activation energy is obtained from temperature-dependent conductivity measurements. We observe a correlation between the magnitude of the electrical conductivity and its activation energy, which can be ascribed to the binding energy of CTCs. Depending on the specific system, conductivity maxima are observed between 10 and 30% molar doping ratios.