Synthesis and characterization of novel red-emitting copolymers containing fluorene,diketopyrrolopyrrole,and phenothiazine units

摘要

A novel three-component copolymer (PFDP),derived from 9,9-dihexylfluorene,diketopyrrolopyrrole(DPP),and 10-octylphenothiazine,was synthesized through palladium-catalyzed Suzuki polycondensation in good yields. PFDP possessed moderate molecular weight and polydispersity,well-defined structure,and excellent thermal properties with an onset decomposition temperature at 357℃. PFDP in thin film exhibited red photoluminescence from DPP chromophore exclusively,with a peak at 602 nm. Electron-rich phenothiazine units sighificantly improved the injection and transport of holes by incorporating into polymer backbone. Light-emitting device was fabricated in the ITO/PEDOT:PSS/PVK/ polymer/Ba/Al configuration using PFDP as the emitting layer. The device based on PFDP showed red emission [CIE coordinate value (0.62,0.38)] that was close to the standard red (0.66,0.34). The results on electroluminescent performance revealed that PFDP may be a promising candidate for the red emitter with a maximum brightness of 259 cd/m2 and a maximum external quantum efficiency of 0.25%.