Self-Host Blue-Emitting Iridium Dendrimer with Carbazole Dendrons: Nondoped Phosphorescent Organic Light-Emitting Diodes

A blue‐emitting iridium dendrimer, namely B‐G2, has been successfully designed and synthesized with a second‐generation oligocarbazole as the dendron, which is covalently attached to the emissive tris[2‐(2,4‐difluorophenyl)‐pyridyl]iridium(III) core through a nonconjugated link to form an efficient self‐host system in one dendrimer. Unlike small molecular phosphors and other phosphorescent dendrimers, B‐G2 shows a continuous enhancement in the device efficiency with increasing doping concentration. When using neat B‐G2 as the emitting layer, the nondoped device is achieved without loss in efficiency, thus giving a state‐of‐art EQE as high as 15.3 % (31.3 cd A−1, 28.9 lm W−1) along with CIE coordinates of (0.16, 0.29). Out of the blue: The title dendrimer has been developed by covalently attaching a second‐generation carbazole dendron to an emissive tris[2‐(2,4‐difluorophenyl)‐pyridyl]iridium(III) core through a nonconjugated linker to form an efficient self‐host system (see figure). Unlike small molecular phosphors and other phosphorescent dendrimers known to date, the nondoped phosphorescent organic light‐emitting diodes herein are realized without a loss in efficiency.