Optimization and luminescence studies of Sm3+ doped LiCaBO3 phosphors for high-performance white light-emitting diodes

An undoped and a series of orange-red emitting LiCaBO₃:Sm³⁺ (x = 0.5–3 mol%) phosphors have been synthesized using a highly reliable and cost-effective combustion method. The synthesized phosphors were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), photoluminescence spectroscopy (PL), and Diffuse Reflectance spectroscopy (DRS). The structural studies of the LiCaBO₃:Sm³⁺phosphor confirm the single-phase orthorhombic structure with space group Pbca and the presence of borate anionic groups. Upon near-UV excitation at 405 nm, the PL emission spectra show four emission peaks centered at 564 nm, 602 nm, 650 nm, and 708 nm corresponding to the ⁴G_5/2 → ⁶H_5/2, ⁴G_5/2 → ⁶H_7/2, ⁴G_5/2 → ⁶H_9/2 and ⁴G_5/2 → ⁶H_11/2 transitions respectively resulting in the emission of orange-red light. The optimum dopant concentration of Sm³⁺ion was 1 mol% and the main mechanism of concentration quenching was calculated using Dexter's theory. The bandgap of the undoped phosphor was found to be 5.31 eV. The CIE chromaticity coordinates are (0.56, 0.40) which confirms the orange-red emission. The obtained results indicate that the synthesized phosphor can be a potential candidate for application in solid-state lighting devices.