Organic photoconductors and C60

We report experimental results on photoelectron spectroscopy (XPS, UPS) and X-ray absorption near edge spectroscopy (XANES) from poly(3-octylthiophene) (P3OT) and Cu-phthalocyanine (Cu-Pc) in contact with C60. The interaction between these organic photoconductors and the C60 is rather weak. At room temperature an inter-diffusion between C60 and P3OT is observed, whereas Cu-Pc and C60 build a stable interface. The spectra reveal the relative positions of the electronic levels close to the optical gap. From this we conclude that an electron transfer to C60 via some excitonic states of the photoconductor is energetically possible. Cu-Pc exhibits a band-bending induced by C60 as deduced from the observed shifts in the XPS and UPS spectra and the missing shifts in the XANES spectra.