AVS 49th International Symposium
    Organic Films and Devices Tuesday Sessions
       Session OF+SS+EL+SC-TuA

Paper OF+SS+EL+SC-TuA7
Interfaces with Evaporated Short Chain Polyaniline

Tuesday, November 5, 2002, 4:00 pm, Room C-102

Session: Organic Molecular Films
Presenter: B. Xu, University of Nebraska-Lincoln
Authors: B. Xu, University of Nebraska-Lincoln
A.N. Caruso, University of Nebraska-Lincoln
M. Bai, University of Nebraska-Lincoln
Y. Ovchenkov, University of Nebraska-Lincoln
S. Ducharme, University of Nebraska-Lincoln
B. Doudin, University of Nebraska-Lincoln
P.A. Dowben, University of Nebraska-Lincoln
Correspondent: Click to Email
The interface properties of evaporated short chain polyaniline (PANI) were investigated by X-ray photoemission spectroscopy (XPS), inverse photoemission spectroscopy (IPES), as well as angle integrated photoemission spectroscopy (UPS). With sodium doping, the valence bands, conduction bands as well as the characteristic core levels show consistent shifts to the higher binding energy. Sodium, as an electron donor, when added to the polyaniline system, results in increased electron populations in the polyaniline bands --- effectively filling the almost completely filled band. In the case of iodine doping, all the states shifted to lower binding energy. Iodine, as an electron acceptor, effectively depletes the electron population in the occupied bands polyaniline. There is no abrupt interface formed between sodium or iodine and polyaniline, as demonstrated by the angle-resolved XPS. By comparison, the interface between polyaniline and another polymer poly(vinylidene fluoride with trifluoroethylene) copolymer (PVDF-TrFE) is quite abrupt. A P-N diode was made by evaporating PANI (p type) on the top of PVDF-TrFE (n type). The results presented here should apply to the problems associated with improving heterojunction polymer devices.