Solid-State Fluorescent Carbon Dots with Hydrophobic\nModification Induced Red Emission for White Light-Emitting Diodes

Herein,\nwe developed red solid-state fluorescent carbon dots (SSF-CDs)\nthrough a one-step solvothermal method, utilizing acetone as the carbonization\nsolvent. Optical and structural characterization revealed that the\nsp<sup>2</sup> domains in the core of the R-CDs were consistently\ninterrupted and that the oxygen-containing groups on the surface were\nreplaced by alkyl groups. This substitution mitigates excessive π–π\ninteractions, thereby preventing quenching of fluorescence in the\nsolid state. Adjusting the molar ratio of citric acid (CA) and urea\nyielded solid fluorescent carbon dots (CDs) with panchromatic luminescence,\nindicating enhanced π–π interactions and more pronounced\nred shifts in the emission peaks. Furthermore, we found that this\nstrategy is applicable to other carbon sources, including phenylenediamine,\nsalicylic acid, and lignin. This research presents an innovative strategy\nfor the fabrication of solid-state luminescent CDs.