CHARACTERIZATION OF 6PV PHENYLENE VINYLENE OLIGOMER THIN-FILMS

Investigations of phenylene vinylene oligomer thin films with 7 phenyl , 6 vinyl units (6PV) have been performed by optical and electrical me asurements, The optical characterizations including infrared, Raman an d UV-VIS spectroscopies were discussed by comparing the results with t hose obtained in poly(p-phenylene vinylene) (PPV). The electrical prop erties of oligomer based diodes were studied by measuring the current- voltage-temperature characteristics and the thermally stimulated curre nts (TSC). At high fields, tunneling of carriers through the interfaci al barrier would occur while at lower fields, two distinct temperature ranges were observed. In the high temperature range (> 250 K), a fiel d assisted mechanism occurs involving localized states in the oligomer bulk whereas in the low temperature range, hopping conduction is prob able. The TSC spectrum shows two relaxation peaks at 219 and 261 K whi ch correspond to trap depths of 0.4 and 0.55 eV. The deep traps appear ed as a characteristic of phenylenevinylene oligomers. (C) 1998 Elsevi er Science B.V.