Solution-processable pi-conjugated dendrimers with hole-transporting, electroluminescent and fluorescent pattern properties

In this paper, four new p-conjugated dendrimers G1 and G2-1-G2-3, constructed by triphenylamine and carbazole moieties, have been successfully prepared via a simple synthetic route. This molecular design imparts the materials with good solution-processability, high thermal and morphological stabilities, and low oxidation potential, all of which are promising properties for optoelectronic materials. The double-layer OLEDs fabricated using these materials through solution processing demonstrate that they can exhibit dual functions, hole-transporting and light-emitting. Devices using G1 or G2-1 as the hole-transporting layer present good stability during the passage of current, with a maximum efficiency of 1.70 and 1.59 cd A(-1), respectively. Moreover, devices using these dendrimers as the emitting layer show moderate performance, and the device of G2-2 gives a maximum luminance and efficiency of 1190 cd m(-2) and 1.67 cd A(-1), respectively, thanks to three-dimensional building of the dendritic system, which might suppress the inherent reductive or aggregation-caused quenching that usually happens for triphenylamine/carbazole derivatives to some degree. Also, the photo-cross-linking property of triple bonds enables ready fabrication of highly fluorescent photoresist patterns of these dendrimers.