Absorption spectra of thin film of polyaniline

The absorption spectra of thin film of polyaniline (PANI) on slide glass coated by a spin coater were measured as a function of the protonation state of PANI, the concentration of solution of PANI in NMP, drying temperature, and atmosphere. The absorbance value of the 950 nm peak and the ratio of the absorbance value at 950 nm to that of the 630 nm peak increases with increasing the protonation state of PANI. This is consistent with the observation of varying the conductivity with the protonation state. A modified molecular structure of PANI is proposed: magnified image where y and x are defined as the oxidation and the protonation states of PANI, respectively.