| AVS 55th International Symposium & Exhibition | |
| Applied Surface Science | Wednesday Sessions |
| Session AS-WeA |
| Session: | Frontiers of Analysis and Combined Materials |
| Presenter: | F. Bebensee, Universitaet Erlangen, Germany |
| Authors: | F. Bebensee, Universitaet Erlangen, Germany J.F. Zhu, University of Science and Technology of China J.H. Baricuatro, University of Washington J.A. Farmer, University of Washington W. Lew, University of Washington H.-P. Steinrueck, Universitaet Erlangen, Germany J.M. Gottfried, Universitaet Erlangen, Germany C.T. Campbell, University of Washington |
| Correspondent: | Click to Email |
Regioregular poly(3-hexylthiophene) (rr-P3HT), a semiconducting polymer, is widely used in organic electronics (OLED, OFET). Both the interface structure and the interaction strength between the polymer and the electrode (e.g. Ca) are very important for the performance of such devices. The heat of adsorption, which directly reflects the bonding energy between the metal and the polymer, was probed using adsorption microcalorimetry. We find high initial heats of adsorption indicating a strong interaction between Ca and rr-P3HT. In high-resolution X-ray photoelectron spectroscopy (XPS) experiments, a substantial shift of the S 2p signal suggests electron transfer from Ca to S in the polymer. We therefore conclude that the high initial heat of adsorption is due to the interaction of Ca atoms with S in the sample. Furthermore, shifts of the C 1s signal imply a band bending of about 0.5 eV, while no hints for structural degradation of the polymer can be found. Ion scattering spectroscopy (ISS) measurements suggests that the initial Ca reacts below the surface, followed by 3D Ca island growth. Both of these observations are corroborated by the XPS measurements. We also investigated the effects of electron irradiation of the polymer surface prior to Ca evaporation. Financial support by the DAAD and the NSF is gratefully acknowledged.