Dresden 2017 – scientific programme

Parts | Days | Selection | Search | Updates | Downloads | Help

CPP: Fachverband Chemische Physik und Polymerphysik

CPP 9: Organic Electronics and Photovoltaics II: Doping (joint session CPP/DS/HL, organized by CPP)

CPP 9.7: Talk

Monday, March 20, 2017, 17:00–17:15, ZEU 260

Redox-Potentials Outperform Ionization Energy / Electron Affinity for Predicting Ion Pair Formation in Molecular Electrical Doping — •Berthold Wegner¹, Lutz Grubert², Dennis Chercka³, Andreas Opitz⁴, Stefan Hecht², Klaus Müllen³, and Norbert Koch^1,4 — ¹Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin, Germany — ²Institut für Chemie, Humboldt-Universität zu Berlin, Berlin, Germany — ³Max-Planck-Institut für Polymerforschung, Mainz, Germany — ⁴Institut für Physik & IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin, Germany

Electrical doping with strong molecular donors and acceptors is a key technological component to control the charge carrier density and Fermi level of organic semiconductors. While commonly ionization energy / electron affinity values (measured on thin films via ultraviolet / inverse photoelectron spectroscopy) are employed to guide the selection of molecular dopants for organic hosts, we find strong indications that redox-potentials (measured in solution via cyclic voltammetry) are indeed better suited. A set of donor-acceptor systems, both in solution and in thin films, is studied using structurally similar molecules. Our results show that redox-potentials provide a useful basis to predict ion pair formation in the studied systems, while ionization energies / electron affinities fail to provide such a basis. This is ascribed to the molecular length scale dopant-host interaction well described by local redox events at the molecule-electrode interface, whereas thin film ionization and affinity level measurements include collective and long-range solid state properties.