Enhanced luminescence and ultra-stability of WLEDs combined with urchin-like Ca_1−xSr_xWO₄:Ln³⁺ with hierarchical structure through charge self-compensation combined with 3D printing

Although rare-earth tungstates exhibit significant advantages in luminescence, the common problem of charge imbalance in traditional Ln³⁺ doping systems poses a serious challenge for further improving luminescence intensity and color purity. Based on this, a charge self-compensation strategy is proposed by optimizing the charge balance state within the crystal lattice at the atomic scale, which effectively suppresses lattice defects and significantly reduces non-radiative transition processes, thereby greatly improving the luminescence intensity and stability. Detailed calculations and analysis based on density functional theory (DFT) were conducted on the crystal structure, band structure, density of states (DOS), and charge density distribution by constructing different doping structure models. The luminescence efficiency and stability have been improved by enhancing the hybridization of material orbitals. Compared with the corresponding uncompensated samples, the integrated emission peak areas of Ca_1−xSr_xWO₄:Ln³⁺ is enhanced by up to 2.96-fold after charge compensation. In addition, the 3D-printed phosphor-resin composites exhibit robust storage stability, with their integrated emission peak areas remaining above 95% of the initial values after six months of storage. Finally, white light-emitting diodes (WLEDs) manufactured using optimized phosphors achieved better color quality with a color rendering index (CRI) of 95, highlighting their potential in high-quality solid-state lighting and indoor photovoltaic applications.