Highly efficient inverted top-emitting green phosphorescent organic light-emitting diodes on glass and flexible substrates

Green phosphorescent inverted top-emitting organic light-emitting diodes with high current efficacy and luminance are demonstrated on glass and polyethersulfone (PES) substrates coated with polyethylene dioxythiophene-polystyrene sulfonate (PEDOT:PSS). The bottom cathode is an aluminum/lithium fluoride bilayer that injects electrons efficiently into an electron transport layer of 1,3,5-tri(m-pyrid-3-yl-phenyl) benzene (TpPyPB). The cathode is found to be highly sensitive to the exposure of trace amounts of O-2 and H2O. A high current efficacy of 96.3 cd/A is achieved at a luminance of 1387 cd/m(2) when an optical outcoupling layer of N,N'-Di-[(1-naphthyl)-N,N'-diphenyl]-(1,1'-biphenyl)-4,4'-diamine(alpha-NPD) is deposited on the anode. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4736573]