Novel orange red phosphor BaLaGaO4: Sm3+ with high quantum efficiency and good thermal stability for indoor illumination and anti-counterfeiting inks applications

This study achieved the synthesis of a novel phosphor, BaLaGaO4: xSm3+ (BLGO: xSm3+), via a high-temperature solid-state reaction. Comprehensive investigations were conducted on the microstructure and optical properties of the phosphor using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), absorption (Abs) spectrum, First principles calculation, photoluminescence (PL) spectroscopy, fluorescence lifetime, and quantum efficiency measurements. The XRD patterns and refinement results demonstrate that Sm3+ ions are effectively incorporated into the BaLaGaO4 lattice. The SEM images illustrate the uniform distribution of elements in the BLGO: 0.02Sm3+ phosphor. PL spectral analysis indicates that, when excited at 405 nm, the BLGO: xSm3+ phosphor exhibits a distinct emission peak at 600 nm, which corresponds to the 6G5/2→6H7/2 energy level transition of Sm3+ ions. At a doping concentration of x = 0.02, the luminance intensity reaches its peak. The phosphor demonstrates good thermal stability, maintaining 71.4% of its luminance intensity at 423 K compared to 298 K. The measured quantum efficiency is 40.51%. By incorporating BLGO: 0.02Sm3+ phosphor into a 405 nm light-emitting diode chip, we investigated the electroluminescence (EL) characteristics of the phosphor. The experimental results demonstrate that the white light-emitting diode (WLED) device doped with BLGO: 0.02Sm3+ phosphor exhibits a high color rendering index (CRI, Ra = 91.9) and a suitable correlated color temperature (CCT = 4648K). Furthermore, it has been observed that the BaLaGaO4: 0.02Sm3+ phosphor can be effectively dispersed in a polyvinyl alcohol solution, emitting bright orange-red light. These test results demonstrate that the novel BaLaGaO4: Sm3+ phosphor exhibits excellent luminescent properties and significant potential for use in indoor lighting and anti-counterfeiting inks.