Design, synthesis and properties of triple-color hyperbranched polymers derived from poly(9,9-dioctylfluorene) with phosphorescent core tris(1-phenylisoquinoline)iridium(Ⅲ)

A series of triple-color hyperbranched polymers based on poly(9,9-dioctylfluorene) (PF) were designed and synthesized, in which phosphorescent tris(1-phenylisoquinoline)iridium(Ш) (Ir(piq)3) acts as red core and poly[(9,9-dioctylfluorene-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,7-diyl)] (PFBT) is inserted as green-emission segment. The synthesized polymers have good thermostability, film forming ability and high fluorescence quantum yield. By tuning the contents of red core and green-emission segment, the optimized triple-color hyperbranched polymer is acquired, named PF-BT250-Ir(piq)325. Furthermore, the PF-BT250-Ir(piq)325 is utilized as single emission layer in white polymer light emitting diode with the configuration of ITO/PEDOT:PSS (50 nm)/PF-BT250-Ir(piq)325 (80 nm)/TPBI (40 nm)/LiF (1 nm)/Al (100 nm). The diode exhibits a maximum luminous efficiency of 1.60 cd/A, a maximum luminance of 3267 cd/m2 and the Commission Internationale de l’Eclairage coordinate of (0.32, 0.34) very close to the pure white point of (0.33, 0.33).