A spiro [fluorene-9, 9′-xanthene]-based host material for efficient green and blue phosphorescent OLED

A spiro[fluorene-9,9′-xanthene]-based host material SFX-PF, without possessing conventional hole- or electron-transporting units, has been demonstrated to be host material for efficient and low voltage green phosphorescent organic light-emitting device (PHOLED). This compound showed good thermal stability with high glass transition temperatures (Tg) at 172 °C. The green device exhibited a low turn-on voltage of 3 V, and maximum current efficiency, power efficiency, and external quantum efficiency (EQE) up to 47.9 cd/A, 45.4 lm/W, and 13.2%, respectively. At the luminance level of 1000 cd/m2, the driving voltages are still lower than 4 V with 15.9% roll-off in the EQE. In addition, SFX-PF can also host Fir6 with the blue device exhibiting a low turn-on voltage of 2.8 V and maximum current efficiency, power efficiency, and EQE up to 12.8 cd/A, 11.3 lm/W, and 7.5%, respectively. Based on our present and previous studies, it can be concluded that SFX could serve as a new building block for designing blue and green phosphorescent host materials.