Synthesis and photoelectric properties of new Pr-bonded polymers by coordination of isopropyloxide and bipyridine unit

A series of novel praseodymium (Pr)-bonded polymers were successfully synthesized via the coordination reaction and palladium-catalyzed Suzuki coupling reaction of 2,7-dibromo-9,9′-dioctylfluorene and different amounts of 5,5′-dibromo-2,2′-bipyridine. The resulting polymers were characterized by 1H-NMR and GPC. The photoluminescence (PL) and electroluminescence (EL) properties of the resulting polymers were studied to explore the effects of the Pr triisopropyloxide. The results showed that the incorporation of Pr into the polymers caused better coplanarity and effective intermolecular or intramolecular interaction, leading to the higher emission intensity at long-wavelength. Further, it was also found that the emission light color could be tuned from blue to green by introduction of a small amount of Pr into the polymer main chain. A single-layer green emitting EL device based on PF(BipyPr)6 with 6 mol% Pr content was fabricated. The device had a low turn-on voltage of 6 V, a brightness of 705.3 cd·m−2, the maximum luminous efficiency of 1.53 cd·A−1 and the maximum power efficiency of 0.69 lm·W−1.