Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 41: Organic Electronics and Photovoltaics: Simulations and Optics II (jointly with DS, CPP, O)
HL 41.6: Vortrag
Dienstag, 27. März 2012, 12:45–13:00, H 2032
Electronic structure of prototypical organic-organic heterojunctions for photovoltaic applications — •Andreas Wilke1, Raphael Schlesinger1, Ullrich Hörmann2, Jens Niederhausen1, Johannes Frisch1, Antje Vollmer3, Julia Wagner2, Mark Gruber2, Andreas Opitz1, Wolfgang Brütting2, and Norbert Koch1,3 — 1Humboldt-Universität zu Berlin — 2Universität Augsburg — 3Helmholtz-Zentrum Berlin für Materialien und Energie GmbH
In organic photovoltaic cells (OPVCs) typically two organic materials with electron acceptor and donor character are sandwiched between anode and cathode, forming either layered planar (PHJ) or bulk heterojunctions, where charge separation occurs. We report ultraviolet photoelectron spectroscopy (UPS) measurements done for three different organic-organic PHJs, comprising the donors sexithiophene (6T) and poly(3-hexylthiophene) (P3HT), and the acceptors diindenoperylene (DIP) and C60. The respective heterojunctions were formed on poly(ethylenedioxythiophene) : poly(styrenessulfonate) (PEDT:PSS) electrodes. The energy level alignment found experimentally for these heterojunctions are discussed in relationship to the open circuit voltages achieved in corresponding PHJ OPVCs. The offset between the highest occupied molecular orbital of the donor and the lowest unoccupied molecular orbital of the acceptor, an estimate for the maximum achievable open circuit voltage, peaked at 1.75 eV for the 6T/DIP PHJ. In actual OPVCs based on 6T/DIP, an open circuit voltage of up to 1.38 V was observed.