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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 53: Organic Electronics and Photovoltaics B (original: DS, joined by CPP, HL, O)
CPP 53.4: Talk
Thursday, April 3, 2014, 18:30–18:45, CHE 91
UPS studies on different air-stable molecular n-dopants — •Martin Schwarze1, Max L. Tietze1, Paul Pahner1, Ben Naab2, Zhenan Bao2, Björn Lüssen1, Daniel Kasemann1, and Karl Leo1 — 1Institut für Angewandte Photophysik, Technische Universität Dresden, 01062 Dresden, Germany — 2Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
Understanding the working mechanism of electrical doping in organic semiconductors is essential for the optimization of organic semiconductor devices. A defined doping level allows for the control of the Fermi level position and the conductivity of transport layers. In comparison to molecular p-doping of organic semiconductors, n-doping has the additional problem of air instability. To successfully transfer an electron to the lowest unoccupied molecular orbital (LUMO) of the matrix material, dopants exhibiting shallow highest molecular orbitals (HOMO) are necessary, rendering them prone to reactions with e.g. oxygen. In this study, three different types of n-dopants are compared, an air stable cationic DMBI and DMBI dimer with the air sensitive W2(hpp)4. Doping efficiency, Fermi-level shift, air stability, and conductivity at different doping concentrations are investigated by ultraviolet photoelectron spectroscopy (UPS) and electrical measurements.