Highly efficient single-layer dendrimer light-emitting diodes with balanced charge transport

High-efficiency single-layer-solution-processed green light-emitting diodes based on a phosphorescent dendrimer are demonstrated. A peak external quantum efficiency of 10.4% (35 cd/A) was measured for a first generation $fac-tris(2-phenylpyridine)$ iridium cored dendrimer when blended with $4,4′-bis(N-carbazolyl)biphenyl$ and electron transporting $1,3,5-tris(2-N-phenylbenzimidazolyl)benzene$ at 8.1 V. A maximum power efficiency of 12.8 lm/W was measured also at 8.1 V and 550 cd/m². These results indicate that, by simple blending of bipolar and electron-transporting molecules, highly efficient light-emitting diodes can be made employing a very simple device structure.