Regensburg 2016 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 49: Organic Electronics and Photovoltaics II (joint session CPP/DS/HL/O, organized by CPP)
CPP 49.4: Talk
Thursday, March 10, 2016, 10:30–10:45, H40
Investigation of the hybrid charge transfer state at ZnO/organic interfaces — •Fortunato Piersimoni1, Stefan Zeiske1, Johannes Benduhn2, Raphael Schlesinger3, Norbert Koch3, Koen Vandewal2, and Dieter Neher1 — 1Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany — 2Institut für Angewandte Photophysik, Technische Universität Dresden, Dresden, Germany — 3Institut für Physik & IRIS, Adlershof Humboldt-Universität zu Berlin, Berlin, Germany
This contribution aims to study the Charge Transfer States (CTS) in hybrid systems based upon organic small molecules and ZnO. Those systems were investigated by means of spectrally resolved electroluminescence (EL) and external quantum efficiency (EQE). The presence of Hybrid CTSs is proven by the appearance of a distinct peak in the EL and EQE spectra located below the energy gap of the molecules or ZnO. The energy gap (Egap) between the ZnO conduction band and the donor HOMO was tuned either by varying the ZnO work function through self-assembled monolayers of polar molecules, or by employing organic donors with different HOMO energy. The correspondence between the EL peak position and the Egap attributes this emission to radiative recombination between an electron on the ZnO and a hole on the organic material. Notably all samples displayed a linear relation between the maximum of the EL spectrum and the 2/3 power of the electric field F, in accordance to the confinement of the HCTS in a rectangular electrostatic potential well, implying a certain degree of delocalization perpendicularly to the donor/acceptor interface.