Effect of solvent annealing on the morphology, optical and electrical properties of in-situ deposited polyaniline thin films.

Abstract

Sulfuric acid doped polyaniline thin films were grown on glass substrates by in -situ polymerization of Aniline with Ammonium peroxydisulfate as oxidant. The effect of solvent annealing on the electrical, mechanical and optical property as well as the morphology of the films were studied by profilometry, four- point probe, nano indentation and UV-visible spectroscopy respectively. It was found by profilometry that the films had an average thickness of 300nm with a roughness of 98nm. N ano indentation put the Elastic modulus at 12.77 GPa. Moreover, UV - visible spectroscopy at 328 and 636 nm indicates conformational changes due to extension of the conjugated polymer chains caused by the solvent annealing. Four points - probe resistivity measurements gave sheet resistance of 1.5 x 10 3, 3.6 x 10 3, 8.3 x 10 4 and 8.0 x 10 6 Ωsq. for the films annealed in diethyl Ether, chloroform and propanol respectively. The film annealed in diethyl ether had the best performance of 1.5 x 10 3 Ωsq. which is over 62% improvement over the 2.4 x 10 3Ωsq obtained for the pristine polyaniline.