Effect of ionic space charge polarization on the charge injection of molecularly doped polymer light emitting diodes

In this study, we report the effect of lithium perchlorate (LiClO/sub 4/) doping with only about 1 wt% on the electrical properties and luminance of heat-treated polymer-based LED obtained by molecular dispersion of tris (8-hydroxyquinoline) aluminium (Alq/sub 3/) [or 2-(4-Biphenyl)-5-(4tert-butyl-phenyl)-1, 3, 4-oxadiazole (BuBPD)] and Coumarin6 (C6) in poly (N-vinylcarbazole) (PVCz). We compare the current-voltage (I-V) and the luminance-voltage (L-V) characteristics of the devices with or without LiClO/sub 4/. We also investigate the effect of prebiasing on the electrical conduction of the molecularly doped polymer films.