The improvement in hole-transporting and electroluminescent properties of diketopyrrolopyrrole pigment by grafting with carbazole dendrons.

Diketopyrrolopyrrole (DPP) pigments are essential and have been intensively exploited as building-blocks for the synthesis of organic semiconducting polymers and small molecules; however, DPP derivatives as emissive materials for electroluminescent (EL) devices have rarely been explored. In this work, a series of new DPP derivatives grafted with carbazole dendrons in a non-conjugated fashion using an amide linkage was designed to improve the performance of DPP in EL devices. Three DPP derivatives (G0DPP, G1DPP and G2DPP) bearing di(-chlorophenyl)-DPP (Pigment Red 254) as the core substituted with a hexyl chain, -hexyl carbazole and -hexyl-'-9,3':6',''-tercarbazole, respectively, were synthesized to afford improved hole-transporting properties without affecting the photophysical and electronic properties of the DPP core.