Spirophenylacridine‐2,7‐(diphenylphosphineoxide)‐fluorene: A Bipolar Host for High‐Efficiency Single‐Layer Blue Phosphorescent Organic Light‐Emitting Diodes

Herein, a high-efficiency host material for single-layer phosphorescent organic light-emitting diodes (SL-PhOLEDs) is reported. This host material is synthesized via an efficient approach and is constructed on the association of an electron-rich phenylacridine unit connected by a spiro carbon atom to an electron-deficient 2,7-bis(diphenylphosphineoxide)-fluorene. In addition to a high ET value and adequate highest occupied molecular orbital/lowest unoccupied molecular orbital energy levels, the key point in this molecular design is the suitable balance between hole and electron mobilities, which leads to a high-performance blue SL-PhOLED with an external quantum efficiency of 17.6% (current efficiency = 37.8 cd A−1 and power efficiency = 37.1 lm W−1) and a low Von of 2.5 V. This performance shows that the molecular design of the present host fulfills the criteria required for high-efficiency SL-PhOLEDs. The present performance is one of the highest reported to date for blue SL-PhOLEDs and more importantly shows the potential of such a molecular design to reach very high-performance single-layer devices.