Single-phased emission-tunable Mg and Ce co-doped ZnO quantum dots for white LEDs

In this study, a simple low-temperature route is presented for the synthesis of Mg and Ce co-doped ZnO quantum dots (QDs). X-ray diffraction, transmission electron microscopy, electron paramagnetic resonance, X-ray photoelectron spectroscopy, UV-vis absorption spectra, and fluorescence measurements were used to characterize the synthesized QDs. The results indicate that the oxygen vacancy concentration could be tuned via Mg and Ce ions doping, which leads to the regulation of luminescence. The visible emission was directly associated with oxygen vacancies, and a blue shift of the visible emission with increasing Ce doping concentration was due to the quantum confinement effect. Finally, we explored the application of Mg and Ce co-doped ZnO QDs by fabricating a white LED device. Notably, the white LED device presents good luminescence properties under a voltage of 3 V and a driven current of 200 mA. The Commission International de l'Eclairage chromaticity, the correlated color temperature, and the color rendering index were determined to be (x = 0.32, y = 0.30), 5733 K, and 81, respectively, which make them potential candidates as single-phased QDs for white light-emitting diodes.