Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 27: Organic Electronics and Photovoltaics II (jointly with CPP, DS, HL)
O 27.8: Vortrag
Dienstag, 12. März 2013, 11:30–11:45, H32
Doping of organic semiconductors in case of dopant precipitation: the internal interface charge transfer doping model — •Thomas Mayer1,2, Eric Mankel1,2, Corinna Hein1, and Wolfram Jaegermann1,2 — 1Technische Universität Darmstadt, Institute of Materials Science, Surface Science Division — 2Innovation Lab Heidelberg
Doping of organic semiconductors is of paramount interest for device optimization as in addition to improved conductivity, engineering of space charge regions at interfaces e.g. of donor acceptor hetero-junction solar cells is achieved. Photoemission data taken at the synchrotron BESSY on co-sublimed and bilayer films of prototypical organic semiconductors as CuPc and spiro-MeoTAD and prototypical p-type organic and inorganic dopants as TCNQ and WO3 show similar electronic trends, which can be explained assuming phase separation of the dopants within the matrix material. For metal oxides the precipitation is directly observed using TEM. For the doping induced variations of the matrix Fermi level in such semiconductor-dopant composites we propose the internal interface charge transfer doping model. According to this model the doping limit can be predicted from pristine matrix and pristine dopant electronic band diagrams. The model also admits of deriving measures that can be taken to improve doping efficiency.