Tunable luminescence and structural modifications in Eu³⁺/Li⁺ Co-doped YBa₃(BO₃)₃ phosphors for LEDs

Abstract

Eu³⁺-doped and Eu³⁺/Li⁺ co-doped YBa₃(BO₃)₃ (YBBO) phosphors were synthesized via a microwave-assisted sol-gel combustion method for warm white LED applications. Li⁺ co-doping improved crystallinity and luminescence efficiency. XRD with Rietveld refinement confirmed single-phase YBBO with lattice modifications due to doping. SEM-EDS analysis revealed improved particle densification and uniformity, while FTIR and Raman spectra confirmed alterations in the borate network. Photoluminescence studies showed a dominant red emission at 611 nm. The intensity corresponding to 0.05 mol Eu³⁺ doping was approximately 8.38-fold higher than that of the 0.005 mol Eu³⁺ sample, indicating enhanced luminescence efficiency before the onset of concentration quenching. The phosphor exhibited high color purity (88.3 %) based on CIE coordinates, making it suitable for color evaluation over CCT. Time-resolved PL measurements showed prolonged lifetimes and decreased non-radiative decay. These results demonstrate the potential of YBBO:Eu³⁺/Li⁺ as a highly efficient red-emitting phosphor for next-generation optoelectronic and solid-state lighting applications.