Efficient non-doped blue-light-emitting diodes incorporating an anthracene derivative end-capped with fluorene groups

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Abstract
We have synthesized and characterized a novel blue-emitting material, 2-tert-butyl-9,10-bis[4′-(9-p-tolyl-fluoren-9-yl)biphenyl-4-yl]anthracene (BFAn), containing an anthracene core end-capped with 9-phenyl-9-fluorenyl groups. The presence of the sterically congested fluorene groups imparts BFAn with a high thermal decomposition temperature (Td = 510 °C) and results in its forming a stable glass (Tg = 227 °C). Atomic force microscopy measurements revealed that BFAn forms high-quality amorphous films and possesses good morphological stability after annealing. Organic light-emitting diodes (OLEDs) featuring BFAn as the emitter exhibited an excellent external quantum efficiency of 5.1% (5.6 cd A−1) with Commission Internationale de L'Eclairage coordinates of (0.15, 0.12) that are very close to the National Television Standards Committee's blue standard. The power efficiency of our BFAn-based devices reached as high as 5.7 lm W−1, making them superior to other reported non-doped deep-blue OLEDs.