Band filling and depletion through the doping of polyaniline thin films

The position of the molecular orbitals of polyaniline, relative to the Fermi level, shifts with the doping of polyaniline by both charge donor and charge acceptor species. Sodium as an electron donor, when added to the polyaniline system, results in an increase in electron population in the polyaniline bands but a decrease in density of states near EF . This is evident from the consistent shifts toward the greater binding energy of the occupied as well as unoccupied molecular orbitals, the valence bands and conduction band edges and characteristic core levels. In the case of iodine doping, an electron acceptor, all the states were shifted toward smaller binding energy. These results provide compelling evidence that the molecular orbitals of vapor deposited polyaniline thin films are delocalized. © 2002 American Institute of Physics. [DOI: 10.1063/1.1484247