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.