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

A series of twisted fluorenyl anthracenes linked by a rigid sp3-hybridized carbon atom, containing an end-capping aryl substituent at either the C2-position of fluorene or at the C10-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/cm2 and a maximum brightness of 3013 cd/m2 at 11 V. It was found that the introduction of the aryl substituents to the C2 position of fluorene could improve the performance of OLEDs based on C9-fluorenyl anthracenes.

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► Six new C9-fluorenyl anthracenes were prepared.
► All have high glass transition temperatures above 100 °C.
► Better performance of OLEDs based on C9-fluorenyl anthracenes with C2-substituents.
► An efficiency (1.47 cd/A) and an external quantum efficiency (1.84%) at 20 mA/cm2.