A new tricarbazole phosphine oxide bipolar host for efficient single-layer blue PhOLED

A novel tricarbazole phosphine oxide (POCz3) with high triplet energy and promising physical properties serves as a bipolar host material of blue-emitting phosphor (FIrpic) to realize highly efficient single-layer blue PhOLED which achieves a maximum external quantum efficiency up to 9% (ηp = 10.4 lm/W, ηc = 21.3 cd/A) and shows low efficiency roll-off effect. POCz3 was also utilized in a three-layer device with a double confinement effect exhibiting maximum luminance 60098 cd/m2 and maximum EQE (power efficiency) of 14.5% (31.3 lm/W).

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A new bipolar host material was synthesized in one step. ► The promising physical properties allow the new host to realize highly efficient single- and mutiple-layer PhOLEDs. ► These devices show low efficiency roll-off effect.