Single molecular tuning of the charge balance in blue-emitting iridium dendrimers for efficient nondoped solution-processed phosphorescent OLEDs

The single molecular tuning of charge balance has been demonstrated here by integrating a p-type dendron, an n-type dendron and a blue emissive Ir core into one dendritic platform. Compared with the commonly used physical blending, not only can the charge balance be well tailored, but also the intrinsic phase separation can be successfully eliminated in such developed single molecular systems (B-TCz2TPO1 and B-TCz1TPO2). As a consequence, their corresponding nondoped solution-processed PhOLEDs achieve more than doubled external quantum efficiencies accompanied by a negligible efficiency roll-off.