Molecular model for the charge carrier density dependence of conductivity of polyaniline as chemical sensing materials

We presented a molecular model to investigate the relationship between macroscopic conductivity and charge carrier density in polyaniline (PANI) as chemical sensing materials. It was demonstrated that the conductivity in polyaniline depends on the charge carrier density. The charge carrier density dependence behavior of the conductivity was described as an exponential function ¿ = (An)a. The predicted relationship was verified by the previous study on the charge carrier density dependence of the mobility from the other research group. Using the computing relationship of conductivity/charge carrier density, the sensitivity of emeraldine base polyaniline (EB-PANI) and its derivative, potassium sulfonated polyaniline (K-SPANI) for the detection of HCl was evaluated. It was clearly seen that the sensitivity of K-SPANI was greatly improved about 2 orders of magnitude compared to EB-PANI. This simulation result was verified by the literature reported experimental results. The computational methodology used in this research can be used for determining the sensing properties in design and evaluation of chemical sensing materials.