S.Z. Chen, J.H. Jou, F.S. Tang, P.H. Chiang, C.Y. Chang
Post-annealing copper phthalocyanine (CuPc) can effectively improve the efficiency of a green organic light-emitting diode, consisting of indium tin oxide/CuPc/N,N’-bis-(1-naphthyl)- N,N’-diphenyl-1,10-biphenyl-4-4’-diamine/tris-8-hydroxy-quinoline aluminum/lithium fluoride /aluminum. By annealing the device at 120℃ for 1 hr, the power efficiency was increased from 1.7 to 2.0 lm/W, with a required driving voltage dropping from 4.7 to 4.2 V. The improvement may be correlated to the smoothening of the CuPc surface upon annealing.