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

Abstract

In this study, a luminescent material of wood-based carbon quantum dots (CQDs)/Ce0.7Zr0.3O2 with a regular, uniform shape, and a high color purity was synthesized by a facile method. CexZr1−xO2 solid-solution oxides (x = 0.7) were prepared by a hydrothermal method, and CQDs were adsorbed on the as-obtained Ce0.7Zr0.3O2 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 Ce0.7Zr0.3O2 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 Ce0.7Zr0.3O2 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 Ce0.7Zr0.3O2, thereby effectively decreasing the nonradiative transition processes and suppressing fluorescence quenching. Hence, CQDs/Ce0.7Zr0.3O2 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/Ce0.7Zr0.3O2, 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/Ce0.7Zr0.3O2 exhibits potential for practical applications.