AC impedance studies on the molecular semiconductors based on aromatic diamines-iodine charge-transfer complexes

Abstract

Molecular semiconductors based on charge-transfer complexes of benzidine, <i style="">o</i>-olidine and <i style="">N</i>, <i style="">N</i>'-diphenylbenzidine with iodine having different mole ratios have been prepared and characterized by thermal, spectral and electrical methods. The thermal decomposition behaviour of these materials indicate that they are thermally stable up to 130°C and then proceed to stoichiometric weight loss corresponding to iodine and aromatic diamines respectively. The electrical conductivity has its highest value for <i style="">N</i>, <i style="">N</i>'-diphenylbenzidine-iodine complexes and lowest for benzidine-iodine complexes which may be due to more extensive conjugation of radical cation in the former than in the later. Impedance studies show (RC)(RC), R (RC) and (RC) equivalent circuit for benzidine, <i style="">o</i>-tolidine and <i style="">N</i>, <i style="">N</i>'-diphenylbenzidine-iodine complexes respectively. The electrical data have been discussed in light of dynamic bond percolation model in which the distribution, density and availability of potential hopping sites change as a result of electronic and structural changes in the material.