High Efficiency and Small Roll-Off Electrophosphorescence from a New Iridium Complex with Well-Matched Energy Levels


  • This work was supported by a Hong Kong Baptist University Faculty research grant (FRG/05-06/I-48), a Hong Kong Innovation and Technology Commission Guangzhou-Hong Kong Industrial Support Grant (ITC/05-06/02), and financial support from Nanjing University of Posts and Telecommunications (NY207013).


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Phenylpyridazine ligands coordinating to the iridium(III) atom yield a thermally stable (5 % weight loss at 439 °C) homoleptic iridium complex with a high phosphorescent quantum yield (0.32 at room temperature). This material has well-matched energy levels with the host, and highly efficient electrophosphorescence (52 cd A–1; see figure) with a small roll-off (23 % at 70 mA cm–2) in device efficiency is achieved.