Excellent luminescence films of excitation-independent carbon quantum dots toward non-rare-earth phosphor-based white light-emitting diodes

Currently, fluorescent carbon quantum dots have been extensively studied for their promising application in solid-state lighting. However, most of the reported carbon quantum dots exhibit short-wavelength blue-green emissions and the obtained carbon solid powders usually show weak luminescence due to aggregation-induced emissive quenching. In this work, carbon quantum dots with excitation wavelength independent yellow emission were synthesized by a facile and green hydrothermal route using water as solvent and o-phenylenediamine as carbon source. Structural and spectroscopic characterizations evidenced that N-related defect state was responsible for yellow luminescence. Importantly, the carbon quantum dots embedded solid films were successfully prepared, which exhibited strong blue light absorption and retained intense yellow emission. As a proof-of-concept experiment, carbon polymer monolith was demonstrated to be an alternative to traditional Ce: Y3Al5O12 phosphors as color converter for constructing white light-emitting diode device with improved color rendering index and correlated color temperature. © 2018 Elsevier B.V.