Luminescent materials comprised of wood-based carbon quantum dots adsorbed on a Ce0.7Zr0.3O2 solid solution: synthesis, photoluminescence properties, and applications in light-emitting diode devices

In this study, a luminescent material of wood-based carbon quantum dots (CQDs)/Ce 0.7 Zr 0.3 O 2 with a regular, uniform shape, and a high color purity was synthesized by a facile method. Ce x Zr 1− x O 2 solid-solution oxides ( x = 0.7) were prepared by a hydrothermal method, and CQDs were adsorbed on the as-obtained Ce 0.7 Zr 0.3 O 2 nanoparticles. The crystal structure was identified by powder X-ray diffraction and Rietveld refinement. In addition, the effect of adsorbed CQDs on the luminescence properties of Ce 0.7 Zr 0.3 O 2 was systematically investigated by Raman spectroscopy, elemental analysis, electron spin resonance spectroscopy, and photoluminescence spectroscopy, as well as decay curve and quantum yield (QY) measurements. Herein, a promising strategy of surface engineering, that is, reduction of the surface defect concentration in Ce 0.7 Zr 0.3 O 2 by the adsorption of CQDs to decrease the nonradiative transition processes at defect sites was described. As expected, the adsorption of CQDs decreased the Ce–O bond length and the surface defect concentration of Ce 0.7 Zr 0.3 O 2 , thereby effectively decreasing the nonradiative transition processes and suppressing fluorescence quenching. Hence, CQDs/Ce 0.7 Zr 0.3 O 2 with a perfect cubic structure exhibits a performance improvement in terms of the luminescence and QY value. Furthermore, a light-emitting diode device was fabricated using as-synthesized CQDs/Ce 0.7 Zr 0.3 O 2 , emitting apparent yellow light with a high color purity (93.3%), with International Commission on Illumination coordinates of (0.5239, 0.4531), and a low correlated color temperature (2271 K) under a driven current of 60 mA, suggesting that CQDs/Ce 0.7 Zr 0.3 O 2 exhibits potential for practical applications.