Studies on the optical properties and stability in dc: Conductivity of PTSA-I2 doped poly-4-vinyl pyridine

The optical and electrical properties of high molecular weight (M̄v=14.8×105) poly(4vinylpyridine) (P4VP) doped with PTSA/I2 have been studied. The polymer has been synthesized by bulk polymerization technique and characterized by viscometry, IR spectra and DSC studies. P-toluene sulfonic acid (PTSA) is used as counter ion with strong electron acceptor iodine(I2) dopant. It acts as a good stabilizer and a plasticizer. The formation of charge transfer complex between P4VP/PTSA/I2 has been confirmed by UV–VIS absorption spectra in the wavelength range 190–700 nm. The absorption coefficient, Energy band gap and activation energy are calculated. The charge transfer complex (CTC) formed between P4VP and iodine shows good stability by the addition of PTSA. dc conductivity of these films has been studied as a function of temperature and conduction mechanisms have been discussed by motts approach. The stability in dc conductivity of the complex at high temperature is mainly due to the reabsorption of I2 by PTSA.