Iodine doping of poly(N-vinylcarbazole) thin films : Thermal degradation

After thermal evaporation, poly(N-vinylcarbazole) (PVK) thin films were iodine doped at different temperatures between 300 and 570 K. It is shown that, while thermal evaporation shortened the chain length, there is a polymerization effect of the layer induced by iodine and annealing. The d.c. conductivity measurements show that, while the iodine doping increases the conductivity, it is still quite poor because the chain of the polymer is saturated. However, after annealing at 570 K, all the experimental studies (IR absorption, photoelectron spectroscopy (XPS), scanning electron microscopy) have shown that there is PVK degradation, with NH 4 I precipitation in an amorphous polymer matrix. The electron spin resonance (ESR) and the conductivity studies are in good accordance with this polymer degradation. After annealing the carrier density increases, with the formation ofconjugated chains, which justifies the increase in the conductivity.