Dresden 2006 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HL: Halbleiterphysik
HL 31: Organic semiconductors
HL 31.12: Vortrag
Mittwoch, 29. März 2006, 17:30–17:45, POT 51
Relation between chain length, disorder and conductivity in Polypyrrole films — •Thomas Heinzel1, Cesar Bof Bufon1, Pamela Espindola2, and Jürgen Heinze2 — 1Heinrich-Heine-Universität Düsseldorf — 2Albert-Ludwigs-Universität Freiburg
The effects of polymerization temperature, electrosynthesis current density and voltammetric cycling on the transport properties of polypyrrole (PPy) films are investigated. PPy films are prepared by galvanostatic electropolymerization at a variety of experimental conditions. The films are investigated by UV-VIS spectroscopy, cyclic voltammetry and temperature-dependent transport measurements. It is observed that as the current density is reduced or the growth temperature is increased, the formation of short oligomers (PPy II) is favored, at the expense of the formation of long polymer chains (PPy I). Surprisingly, we observe a higher conductivity in films with a higher fraction of PPY II. In samples containing predominantly PPY II, quais-metallic behavior is found. Furthermore, PPY II can be transferred in PPY I by voltammetric cycling, which goes along with a decrease of the conductivity and a localization of the states at the Fermi level. We interpret these results in terms of a disorder-dominated conductivity.