Novel near-infrared luminescent linear copolymer based on tris(8-hydroxyquinoline)erbium

A novel near-infrared (NIR) luminescent linear copolymer based on tris(8-hydroxyquinoline)erbium (ErQ3), PCzErQ3, was synthesized and characterized. The copolymer had appropriate molecular weight as well as good solubility in common organic solvents. The glass transition temperature (Tg) and the temperature of 5% weight loss (Td) for the copolymer were 200 °C and 368 °C respectively, indicating that the copolymer had excellent thermal stability. Absorption and photoluminescence (PL) spectra of the copolymer were recorded and PL decay analysis was measured. Excited at the absorption band of carbazole (235, 265 and 295 nm) and metalloquinolate (390 nm), the copolymer emitted the characteristic NIR-luminescence of ErIII ion. The result indicates that the energy absorbed by carbazole (light-harvesting group) was transferred to 8-hydroxyquinoline (coordination group), where it is finally transferred to ErIII ion. In addition, the full width at half maximum (FWHM) centered at 1525 nm in the PL emission spectrum of the copolymer was 92 nm, which enabled a wide gain bandwidth for optical amplification.