Matrix-free, color-tunable carbon quantum dots with solid-state emission for white LEDs

Solid-state photoluminescence quenching poses a major challenge for carbon quantum dots (CQDs) in optoelectronic applications. This work presents a facile one-step microwave synthesis of self-quenching-resistant, color-tunable CQDs from phloroglucinol and urea without requiring external matrices. By precisely controlling reactant ratios and microwave power, we achieved tunable photoluminescence from blue to yellow (395–590 nm) through an aggregation-induced redshift mechanism. The resulting CQDs exhibited exceptional solid-state quantum yields of 45.2% (blue) and 52.0% (yellow), along with remarkable photostability (> 90.5% retention after 90 min UV exposure). Leveraging these properties, we fabricated dual-color and white light-emitting diodes that demonstrated promising performance, including a maximum luminous efficacy of 55.8 lm/W, color rendering index of 72, and excellent operational stability (85% luminous flux retention after 120 min). This matrix-free approach effectively overcomes solid-state quenching and positions CQDs as promising materials for advanced solid-state lighting technologies.