Investigation on structure and photoluminescence properties of Ho doped Ca(VO) phosphors for luminescent devices.

This study focuses on the synthesis and characterization of Ho doped Ca(VO) phosphor for potential application in solid-state lighting technology. A citrate-based sol-gel process is optimized to achieve sheet-like morphologies in the phosphor material. The investigation reveals UV absorption at 371 nm, indicating a band gap of 3.28 eV. Emission transitions at (506, 541, and 651) nm are observed when excited at 451 nm, with an optimal Ho concentration of 0.05 mol resulting in robust green emission at 541 nm. The concentration quenching in Ca(VO):Ho phosphors is discussed in detail with Blesse's and Dexter's models. The concentration quenching effect found in the studied samples is due to the dipole-dipole interactions. Judd-Ofelt intensity parameters were calculated from the excitation bands, and for , , and are (0.16, 0.17, and 0.36) × 10 cm, respectively. The emission properties for the (S + F) → I and F → I transitions are also estimated with - parameters. The higher magnitude of branching ratios (83%) and emission cross-sections (1.6 × 10 cm) suggest that the Ca(VO):0.05Ho phosphor materials may be suitable for efficient green-emitting device applications. The CIE coordinates confirm the potential of Ho-doped phosphors for green emissions, making them suitable for solid-state lighting and display technology.