“Click” chemistry synthesis of carbazole dendrimer as host material for electrophosphorescent device

A new solution processable dendrimer, with carbazole as a hole transporting unit, was efficiently synthesized based on convergent approach by alternation of Cu-catalyzed azide/alkyne cycloaddition (CuAAC) reaction and Williamson ether synthesis. The orthogonal chemistry completely avoided protection and activation of the focal points in the process of dendrimer synthesis. The dendrimer showed wide bandgap and has good thermal stability. The carbazole dendrimer was studied as electrophosphorescent host materials. Electrophosphorescent devices with the configuration of ITO/PEDOT:PSS/carbazole dendrimer:Ir(ppy)3/TPBI/LiF/Al were fabricated. The device showed turn-on voltage of 5.74 V, a maximum current efficiency of 13.7 cd/A, a power efficiency of 6.39 lm/W and an external quantum efficiency of 5.03%.