A novel self-host blue-emitting iridium dendrimer, namely, B-CzPO, has been designed and synthesized via a postdendronization route, where a bipolar carbazole/triphenylphosphine oxide hybrid is selected as the peripheral dendron instead of the p-type oligocarbazole used in unipolar analogue B-CzG2. This structural modification can render B-CzPO with more balanced charge transportation relative to that of B-CzG2. As a result of the significantly reduced efficiency roll-off, the nondoped phosphorescent organic light-emitting diodes (PhOLEDs) of B-CzPO show a superior high-brightness performance, revealing a luminous efficiency of 21.2, 16.1, and 10.5 cd/A at 1000, 5000, and 10 000 cd/m, respectively. Compared with that of B-CzG2 (i.e., 7.8 cd/A @5000 cd/m), more than doubled high-brightness performance is achieved for B-CzPO. The results indicate that the design of self-host phosphorescent dendrimers with a bipolar feature will be a promising strategy to develop efficient nondoped PhOLEDs suitable for high-brightness applications including general illumination and micro displays.

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.

Solvent-driven C(sp3)–H thiocarbonylation under catalyst-free and environmentally friendly conditions.