Current–voltage characteristics of PTSA/I2 doped poly(4 vinyl pyridine)

Current–voltage characteristics of high molecular weight poly(4 vinyl pyridine) (P4VP) doped with P-toluene sulphonic acid (PTSA) and I2 is carried out in the voltage range 0–100 V and temperature range 300–440 K. It is found that for pure P4VP and PTSA doped P4VP, the current shows a linear variation with voltage following omhic characteristics with slope 0.77∼1 in the initial 0–45 V and then with slope 1.02∼1.72 leading to a partial SCLC type conduction. When the P4VP+PTSA complex is further doped with I2 the current increases drastically due to a large number of low energy carriers released by the charge transfer complex (CTC) formed. The transition voltage also shifted to the higher voltage side (75–80 V) indicating omhic conduction for a wide range of applied field. The variation is found to be nonomhic after 75 V and the SCLC mechanism along with thermally activated omhic conduction dominates. The suitability of different mechanisms are justified by considering Poole–Frenkel (PF)/Richardson–Schottky (RS) and SCLC approaches.