Synthesis and photophysics properties of novel bipolar copolymers containing quinoline aluminum moieties and carbazole segments

Novel bipolar copolymers containing Alq3 and carbazole were prepared and characterized. The bipolar copolymer exhibited excellent thermal properties. Particularly, due to energy transfer from carbazole to Alq3 moieties, the bipolar copolymer had good photoluminescence properties. A novel polymerizable 8-hydroxyquinoline aluminum (Alq3) complex monomer and its copolymers (Alq3/N-vinylcarbazole (NVK)) with different mole fractions of Alq3 in feed were designed and synthesized. The structure of the Alq3-complex monomer was characterized by 1H NMR, FT-IR and elemental analysis, and the bipolar copolymers with various desired Alq3 loading were characterized by 1H NMR, FT-IR, elemental analysis, and gel permeation chromatography (GPC). The results indicate that these copolymers have moderate molecular weight as well as good solubility in common organic solvent. Thermal properties measurement and analysis show that these copolymers possess excellent thermal stability and high glass transition temperature (Tg). The photophysics properties of the copolymers were studied by UV–vis and fluorescence spectra. Nearly monochromatic yellow–green emission from Alq3 was observed in high concentration solution and solid state, showing effective energy transfer characteristic. The results demonstrate that introduction of carbazole as hole-transporting and energy transfer group is a potential method to improve the luminescent performance of the Alq3-based polymers.