Single-Phase White Phosphor via Energy Transfer from Ce3+ to Sm3+/Tb3+ in Ca3LuAl3B4O15 for High-Quality UV LEDs

Single-phase white phosphors are highly desirable for achieving stable white light-emitting diodes (w-LEDs). In this work, a series of Ce3+-, Tb3+-, and Sm3+-doped as well as codoped Ca3LuAl3B4O15 (CLAB) phosphors were successfully synthesized, and white light was achieved by tuning relative doping concentrations. The phase structure, morphology, and optical properties were systematically investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence spectroscopy. Energy transfer from the parity-allowed Ce3+ ions to the parity-forbidden Tb3+ and Sm3+ ions was confirmed through spectral analysis and comparison. Under 342 nm excitation, the optimized CLAB:1%Ce3+,2.5%Sm3+,10%Tb3+ phosphor exhibits warm-white-light emission originating from three activators. In addition, the phosphor retains 71% and 42% of its initial emission intensity at 450 and 600 K, respectively, demonstrating the good thermal stability of the phosphor. By combining the optimized CLAB:1%Ce3+,2.5%Sm3+,10%Tb3+ phosphor with a commercial 340 nm ultraviolet (UV) chip, a warm w-LED was fabricated, exhibiting CIE chromaticity coordinates of (0.3631, 0.3625), a correlated color temperature (CCT) of 4419 K, and a color rendering index (CRI) of 93. This study offers a newly designed single-phase white phosphor for high-quality warm w-LEDs.