Application of impedance technique to OELD

Impedance spectroscopy was applied to investigate the stability and the eff ect of electrode on the charge injection in organic electroluminescent devi ce (OLED). Alq(3) and poly(vinyl carbazole) (PVK) were used as an emissive layer and a hole transport layer, respectively. The lower impedance of a on e-layer cell may be related to the charge carrier mobility and work functio n of cathode. The impedance spectrum of ITO/Alq(3)/MgIn was very sensitive to the atmosphere and increased by a factor of five upon 1-day exposure. Th e rubrene doped in PVK of ITO/PVK/Al resulted in much higher impedance but enhanced the environmental stability. It also resulted in lower current den sity on I-V curve of ITO/PVK/Alq(3)/Al and more smooth transition at the lo wer voltage region. (C) 2000 Elsevier Science S.A. All rights reserved.