Achieving red room temperature afterglow carbon dots in composite matrices through chromophore conjugation degree controlling

Abstract Carbon dots (CDs), as new purely organic afterglow materials, show great potential applications in many fields, but efficient red room temperature afterglow (RTA) CDs are very scarce due to lack of effective synthetic method and blur RTA mechanism. Herein, an easy, high-output synthesis strategy for in-situ preparation of red RTA CD-based composites is developed through one-step microwave radiating large conjugated structure precursor. The systematic research shows that N, O-doped large conjugated structures on CD surfaces are responsible for the red RTA emission in view of their effectively reducing the band gap between the excited and ground state as well as creating afterglow center. Meanwhile the in-situ synthetic method makes CDs to be tightly embedded into the matrices by robust chemical covalent and multiple hydrogen bonding interactions, thus, greatly suppressing non-radiative transitions. Based on the above theoretical guidance, multi-color (green, yellow-green and red) RTA CDs-based materials were successfully prepared by controlled the conjugation degree of chromophore. In addition, the CD-based composites have potential applications in light-emitting diode and anti-counterfeiting. This work could provide an effective strategy to prepare red RTP materials.