Berlin 2008 – wissenschaftliches Programm
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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications
SYSA 5: Poster Session SYSA
SYSA 5.20: Poster
Dienstag, 26. Februar 2008, 14:30–20:00, Poster A
NTCDA as transparent electron transport material in organic p-i-n solar cells — •Christiane Falkenberg1, Christian Uhrich1, Selina Olthof1, Bert Männig1,2, Moritz Riede1, and Karl Leo1 — 1Institut für Angewandte Photophysik, Technische Universität Dresden, 01069 Dresden, Germany, http://www.iapp.de — 2Now at Heliatek GmbH, Liebigstr. 26, 01187 Dresden, Germany
In organic p-i-n-solar cells, the active layer where light is absorbed and free charge carries are generated is sandwiched between two doped charge carrier transport layers which are preferentially electron or hole conducting. In order to increase the efficiency of organic photovoltaic devices, the properties of those doped layers play a crucial role: high conductivities and charge carrier mobilities, thermal and morphological stability, and a good energy level alignment relative to the neighboring active layers are required. We investigate here the electron transport materials and successfully substitute the standard system consisting of n-C60 by the wide-gap material NTCDA (naphthalenetetracarboxylic dianhydride). Unlike C60, it does not absorb in the visible range and therefore blocks the excitons which were created in the active layer. Combined photoelectron spectroscopy (PES) and absorption determine HOMO and LUMO energies of -8.01eV and approximately -4.5...-4.0eV, respectively. Furthermore, the electronic structure of the aluminum/NTCDA-contact and the morphology of thin evaporated layers are analyzed via PES and AFM, respectively. The power conversion efficiency of simple p-i-n-cell structures is improved by 10% upon substitution of C60 in electron transport layers by NTCDA.