Abstract: This work successfully synthesized a five-membered cyclic carbonate compound, tris(hydroxymethyl)propyl pentacyclic carbonate (TPTE), using CO₂ and trihydroxymethylpropane triglycidyl ether as starting materials via cycloaddition reaction. Subsequently, red-emissive carbon dots (R-CDs) with a quantum yield of 38% were prepared through a solvothermal method using TPTE and o-phenylenediamine as precursors and ethanol as the solvent. Structural characterization revealed that the obtained R-CDs exhibited an average particle size of 9.41 nm, with a highly graphitized carbon core and surface-rich hydroxyl and amino functional groups. Optical performance testing demonstrated that the R-CDs in ethanol solution displayed distinct excitation-independent characteristics, showing three-fingered emission peaks at 599, 648, and 702 nm under excitation at 535 nm, accompanied by a fluorescence lifetime of 6.46 ns. Theoretical calculations and spectroscopic analyses confirmed that these luminescent properties originated from extended π-conjugated systems within the carbon core inducing (π, π*) transitions. Notably, when combined with polyvinylpyrrolidone (PVP), the ultraviolet-visible absorption and fluorescence emission characteristics of R-CDs remained essentially unchanged, indicating negligible electronic interactions between PVP matrices and R-CDs. Leveraging their excellent optical properties, R-CDs/PVP composites were employed as phosphors integrated with a 360 nm ultraviolet LED chip to fabricate red-emitting devices. The prepared LED exhibited CIE chromaticity coordinates of (0.42, 0.21), precisely falling within the red light region with high monochromaticity. Significantly, this research achieved efficient indirect fixation of CO₂ by converting it into functionalized cyclic carbonate precursors, providing an innovative approach for greenhouse gas valorization. This integrated strategy combining high-quantum-yield fluorescent material development with carbon reduction technology holds substantial application potential in optoelectronic devices and green chemistry.

Key words: Carbon dots, Carbon dioxide, Red-emissive, Light-emitting diodes