Dresden 2011 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 8: Poster: Organic Semiconductors
CPP 8.47: Poster
Montag, 14. März 2011, 17:30–19:30, P2
Investigating the effect of molecular doping on the energy levels using Seebeck measurements — •Torben Menke1, Peng Wei2, Zhenan Bao2, Karl Leo1, and Moritz Riede1 — 1Institut für Angewandte Photophysik (IAPP), TU Dresden, 01062 Dresden, Germany — 2Stanford University, CA 94305, USA
Molecular doping plays an essential role in small molecule based organic devices like solar cells or light-emitting diodes, because it allows to control the Fermi level in the doped layers with the corresponding advantages. However the exact mechanisms of molecular doping are still far from being fully understood.
We investigate the influence of doping in different material combinations of dopants and host materials. Seebeck measurements are used to study the energetic distance between Fermi energy and transport level of doped charge transport materials, e.g. fullerene C60 or N,N,N',N'-Tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD). For n-doping of C60 a novel airstable dopant is presented.
For MeO-TPD and C60 a shift of the energetic distances from 180 meV down to 30 meV and from 120 meV down to 25 meV, respectively, is observed when increasing the doping concentration. Furthermore the influence of the temperature on conductivity and Seebeck measurements is shown. For MeO-TPD and C60 the activation energies of the conductivity are found to shift from 310 meV down to 210 meV and from 240 meV down to 60 meV, respectively, with increased doping concentration.