Infrared spectroelectrochemical investigations on the doping of soluble poly(isothianaphthene methine) (PIM)

Abstract

Attenuated total reflection Fourier transform infrared (ATR-FTIR) investigations on the doping processes in substituted poly(isothianaphtene methine) (PIM), a new low band-gap conjugated polymer, are reported. The doping was studied in situ during chemical p-doping (oxidation) by iodine and during electrochemical p-doping (oxidation) and n-doping (reduction). During both signs of doping, infrared active vibrational (IRAV) bands due to strong coupling of the electrons to lattice vibrations are observed. The results are compared to FT-Raman spectra. Electrochemical p-doping shows two different doping regimes depending on the electrochemical potential. The narrow linewidth and low absorption intensities of the IRAV bands indicate a strong localization of the doping induced charge carriers, which is ascribed to a tilted geometry of the conjugated backbone due to steric repulsion effects. (C) 1999 American Institute of Physics. [S0021-9606(99)51924-7].