Anthracene-cored dendrimer for solution-processible blue emitter: Syntheses, characterizations, photoluminescence, and electroluminescence

A second-generation blue fluorescent anthracene-cored dendrimer EH-G2AN was readily synthesized via a convergent method. Its monodispersity was confirmed by H-1 NMR and MALDI-TOF mass measurement. The peak emission of EH-G2AN in a dilute CH2Cl2 solution was observed at 416 nm with a shoulder at 434 nm and moved to 418 nm in the solid film with the shoulder at 433 nm. The nearly "perfect" overlap of solution and solid emission spectra revealed the absence of molecular aggregations in the solid film, which was apparently suppressed by the presence of rigid and bulky 1,3,5-phenylene-based dendrons and 2-ethylhexyloxy solubilizing peripheral groups. EH-G2AN appeared strikingly stable with the onset decomposition temperature above 350 degrees C and remained at the high temperature of 428 degrees C where 5% weight loss occurred. The electroluminescent device [ITO/PEDOT:PSS/EH-G2AN/Ba/Al] showed a peak emission at 442 nm and maximal external device efficiency of 0.82%@170cd . m(-2). After inserting a PVK layer between the hole injection layer and emitting layer, a maximal external device efficiency of 1.05%@184 cd . m(-2) was obtained with a narrow FWHI of merely ca. 42 nm in the device configuration [ITO/PEDOT:PSS/PVK/EH-G2AN/Ba/Al].