A new spiro[fluorene-9,9′-xanthene]-based host material possessing no conventional hole- and electron-transporting units for efficient and low voltage blue PHOLED via simple two-step synthesis

A new spiro[fluorene-9,9′-xanthene]-based host material SFX-PF without possessing conventional hole- and electron-transporting units has been developed, via very simple two-step synthesis, for efficient and low voltage blue phosphorescent organic light-emitting device (PHOLED). The blue device exhibited a low turn-on voltage of 2.8 V, and high maximum current efficiency, power efficiency, and external quantum efficiency up to 29.3 cd/A, 28.9 lm/W, and 14.7%, respectively. At the luminance level of 1000 cd/m², the driving voltages are still lower than 4.0 V with 12.9% roll-off of the external quantum efficiency. Based on our previous studies, these investigations provide the clues that SFX could be a new building block for designing blue phosphorescent host materials.