Films of pure polyaniline and polyaniline-tetracyanoquinodinodimethane have been prepared. The optical absorption spectra of both the samples in the emeraldine base forms are explained in light of the three-dimensional exciton model. A temperature dependence study of the electrical conductivity of the samples shows an interesting crossover phenomenon (T-c=143 K) which may be considered as competition of the two opposingly directed factors, namely, charge transfer interaction and the disorderness parameter (r). While charge transfer interaction is evident from optical absorption spectroscopy, the extent of disorderness is reflected by the results of CHN microanalysis and temperature dependent electrical conductivity measurement.