Photoelectron spectroscopy of hybrid interfaces for light emitting diodes: Influence of the substrate work function

Photoelectron spectroscopy results of studies of a conjugated polymer poly(9, 9-dioctylfluorene) thin films embedded between two contacts with different work functions are reported in this work. It is demonstrated that, depending on the work function of contact material involved, the binding energy of the C(1s) core level of the polymer, changes according to the resulting built-in potential in the polymer layer. The deposition of the same metal onto a polymer surface can lead to binding energy shifts of the core-level spectra in either direction, determined by the work function of the underlying substrate. (C) 2001 American Institute of Physics.