Inclusion of the cation iodonium (I3+) into the structure of poly(N-vinylcarbazole)

Iodine is an usual doping agent used in order to improve the conductivity of insulator polymers with either aromatic and conjugated double bonds in their structure. This paper evidences the action of the cation iodonium on the conductivity of poly(N-vinylcarbazole) (PVK) and nitrosilated-PVK (PVK-NO). The cation is introduced via bis-pyridine-iodonium tetrafluoroborate salt (IPYBF4) in both polymers yielding PVK–IPY-P and PVK-NO–IPY-P complexes, respectively, with a 1:1 ratio (carbazolyl/iodonium) in each. The complex extends the absorption band in the UV–Visible region and its IR spectrum shows characteristic bands. Both inter- and intra-molecular distances were modified in the polymer by the presence of iodonium as it is manifested by WAXS experiments. The thermal behaviour of the complex was studied by simultaneous thermogravimetry and differential thermal analysis being quite different from that of PVK. The polymer–IPY complex is stable till 200°C at which point the pyridine ligands loss takes place and results in a new structure of PVK-I+ which is stable till 380°C and then is suddenly degraded. Elecrical conductivity of the complex improves with respect to that of PVK, but it does not overcome the semiconducting level achieved with other dopants.