Controllable synthesis highly efficient red, yellow and blue carbon nanodots for photo-luminescent light-emitting devices

According to mastery of solvent and reaction temperature, red, yellow, and blue emissive carbon nanodots (CNDs) with high quantum yield are successfully achieved using neutral red carbon source by solvothermal methods. The differences on the emission color of CNDs are evidently ascribed to conjugated absorption bands from n-π* transition confirmed by structural and optical characterizations. The results of quantum yield, transmission electron microscopy images, high magnification fluorescent micrographs of CNDs ethanol solution and solid-state CNDs & polyvinylpyrrolidone (CNDs&PVP) powders reveal that the obtained CNDs possess ultrahigh luminescence, favorable solubility, uniform dispersibility and well material compatibility. The bright fluorescent films were fabricated by mixing the CNDs &PVP composite powders with the epoxy. By taking advantage of these remarkable properties, the red, yellow, blue light-emitting diode was realized by combining CNDs&PVP film with a UV-LED chip. This work provides a new perspective for the explanation of the PL mechanism and the exploration of stable, high-performance, and environment-friendly multicolored CNDs-based LEDs.