Physicochemical and Optoelectronic Properties of Polyaniline Thin Films

The present article mentions about the physicochemical and optoelectronic properties of polyaniline (PANI) thin films synthesized by using solution polymerization techniques over the glass substrate at room temperature with the intension to study its physicochemical and optoelectronic properties specially as gas sensing materials. These as deposited thin films have been synthesized by varying the deposition time (substrate dipping) intervals of 40 min. The Fourier transform infra-red spectroscopy (FTIR) revealed the characteristics peaks at 1582 cm⁻¹ related to C = C stretching deformation of quinoid (Q) ring, 1492 cm⁻¹ corresponds for C = C stretching of benzenoid (B) ring, while 1109 cm⁻¹ shows B–NH⁺= Q stretching. The surface morphology represented the porous nature granular distribution of grains over the substrate surface. The optical band gap energy calculated from the absorbance spectrum shows decreases in energy band gap from 2.57 eV to 2.51 eV with the increase in deposition time which can be attributed to variation in the structural morphology with increase in thickness of the materials. The ammonia gas sensing when studies revealed that the films deposited for 240 min reponed to ammonia gas of 90% which can be inferred to increase in charge carrier’s concentrations upon increasing the films deposition time and thickness.