Nonconventional near-infrared room-temperature phosphorescent materials based on spiropolymer alloy.

Near-infrared room-temperature phosphorescent (NIR-RTP) materials feature the advantages of large Stokes shift, long emission lifetime, and high penetration ability, and have been broadly applied in bio-medical imaging, fiber optic telecommunication, and night vision-readable display. Developing organic NIR-RTP materials heavily relies on the long-conjugated chemical structures. The large conjugation could result in aggregation caused quenching, complex synthesis, poor processability, and high biological toxicity. Herein, by solution blending poly(iminofuran-spiro-pyrrolone) (PISP) with polystyrene (PS), we construct a nonconventional NIR-RTP polymer alloy without significantly extensive conjugation. The PISP was synthesized via a catalyst-free multicomponent polymerization in air with high molecular weights (up to 41000 g/mol) and decent yields (up to 84%). Although lacking classical luminescent segments and largely extended conjugation, PISPs exhibit the clusterization-triggered cryogenic phosphorescence. More importantly, upon solution blending PISP with PS, the resultant polymer alloy shows a NIR-RTP emission up to 715 nm with a Stokes shift of 375 nm. This work will be of interest for developing luminescent materials for the optoelectronic devices, in vivo imaging, and flexible electronics.