Highly efficient green phosphorescent organic light-emitting diodes with simplified device geometry

© 2008 American Institute of Physics. The electronic version of this article is the complete one and can be found at: http://dx.doi.org/10.1063/1.2952452DOI: 10.1063/1.2952452We report on the performance of green phosphorescent organic light-emitting diodes based on the well-known host 4,4′-di(carbazol-9-yl)-biphenyl and the green phosphor emitter fac tris(2-phenylpyridinato-N,C²′) iridium. Using a spin-coated hole-injection/transport layer of poly(N-vinyl-carbazole) and a hole-blocking/electron-transport layer of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, devices with efficiencies of 21.2% and 72 cd/A at 100 cd/m² were obtained in a simplified device geometry that requires the deposition of only two organic layers from the vapor phase.(c) 2008 American Institute of Physics.DOI: 10.1063/1.295245