Poly- and Oligoaniline Thin Films: Charge Transport, Optical Properties and Effect of Doping

Abstract

We report a study of the electrical and optical properties of thin films of tetraanilinobenzene (TAB) and polyaniline (PANI) deposited using the Langmuir-Blodgett (LB), layer-by-layer selfassembly and vacuum-evaporation techniques. The paper will mainly concentrate on TAB LB films, but also results for other films are presented for comparison. The optical studies of undoped TAB LB films indicate H-aggregates. Upon doping new polaronic absorption bands appear and the photoluminescence of TAB becomes quenched. Doped LB and self-assembled films can reach conductivities up to about 104 S/cm for TAB and a few S/cm for PANT. The conductivity has a temperature dependence logo cc T"ý2, suggesting variable-range hopping in a quasi-gap, possibly due to the Coulomb interactions between localized carriers.