Novel blue luminescent materials for organic light-emitting diodes based on C9-fluorenyl anthracenes

摘要

A series of twisted fluorenyl anthracenes linked by a rigid sp~3-hybridized carbon atom, containing an end-capping aryl substituent at either the C2-position of fiuorene or at the ClO-position of anthracene, have been synthesized and characterized. These materials exhibited good thermal stabilities and amorphous properties. Theoretical calculations and X-ray diffraction studies revealed that the six blue emitters possess non-coplanar structures to suppress intermolecular interactions. The relationship between the chemical structures with different end-capping groups and the electroluminescent properties has been investigated. Organic light-emitting diodes utilizing 9-(2-phenyl-9H-fluoren-9-yl) anthracene as the emitter exhibited deep-blue emissions CIE x, y (0.166, 0.153) with a current efficiency of 1.47 cd/A, external quantum efficiency of 1.84% at 20 mA/cm~2 and a maximum brightness of 3013 cd/ m~2 at 11 V. It was found that the introduction of the aryl substituents to the C2 position of fiuorene could improve the performance of OLEDs based on C9-fluorenyl anthracenes.