Charge transfer in intercalated C60 peapods

We report on the charge transfer in intercalated C-60 peapods as a function of doping. A competition between a charge transfer to the SWCNT pods and one to the C60 peas is observed. At low intercalation levels the charge transfer is predominantly to the SWCNT pods. This leads to. a shift of the Fermi level beyond the third van Hove singularity of the semiconducting tubes for potassium intercalation (n-doping) and beyond the first singularity of the metallic tubes for FeCl3 intercalation (p-doping), respectively. In addition at high levels of potassium intercalation the C-60 pods are charged up to C-60(6-) and form a metallic one dimensional polymer.