Styrenic polymers P1(G0-CZ) and P2(G2-CZ) with carbazoles and carbazole containing dendrons as side chains were efficiently synthesized via "graft-to" approach by using copper-catalyzed azide/alkyne cycloaddition (CuAAC) reaction. The new polymers showed wide band gaps and had good thermal stabilities. Two new polymers were studied as electrophosphorescent host materials in OLED devices. Electrophosphorescent devices with the configuration of ITO/PEDOT:PSS/polymers:Ir(ppy)(3)/TPBI/LiF/Al were fabricated. The polymer P1(G0-CZ) based device showed a maximum current efficiency of 21.4 cd/A, a power efficiency of 12.7 lm/W and an external quantum efficiency of 6.02%. The effect of host polymer structures on the aggregation of transition metal complexes Ir(ppy)(3) in active layer was also investigated. (C) 2011 Elsevier Ltd. All rights reserved.