Influence of the deposition temperature on the structure and performance of tris(8-hydroxyquinoline) aluminum based flexible organic light-emitting devices

Based on indium tin oxide (ITO)/N,N0diphenyl-N-N0-di(m-tdyl) benzidine (TPD)/Alq3/Al structure, flexible OLEDs on polyethylene terephthalate (PET) substrates were fabricated by physical vapor deposition (PVD) method. Tris(8-hydroxyquinoline)aluminum (Alq3) films were deposited at 90, 120 and 150 8C to examine the influence of the deposition temperature on the structure and performance of OLEDs. Electroluminescence (EL) spectra and current–voltage–luminance (I–V–L) characteristics of the OLEDs were examined. It was found that the device fabricated at a high temperature had a higher external efficiency and longer lifetime. Atomic force microscope (AFM) was adopted to characterize the surface morphology of ITO/TPD/Alq3. The higher uniform morphology of the Alq3 formed at high temperature might contribute to the performance improvement of the OLEDs