Green-Emitting Perovskite BaTiO₃:Ho³⁺ Phosphors for Solid-State Lighting

This study investigates the potential of Ho³⁺ doped BaTiO₃ perovskite phosphor, synthesized via the sol–gel method. X-ray diffraction (XRD) analysis confirmed a hexagonal crystallographic structure (P63/mmc), consistent with JCPDS card no. 82-1175. The shifts in the XRD pattern suggest that the concentration of Ho³⁺ ions influence the structure. Fourier transform infrared (FT-IR) spectroscopy is used to study the vibrational behavior of the synthesized perovskite phosphor. The diffuse reflectance spectra (DRS) presented several bands in the UV–Vis regions due to Ho³⁺ ions. The bandgap for Ho³⁺-doped BaTiO₃ was calculated as 2.8 eV, which aligns with the literature values. This value was derived from fitting the Tauc equation to the absorption coefficient data. Extensive photoluminescence (PL) spectroscopy revealed sharp excitation and emission spectra. The PL spectrum, corresponding to an excitation wavelength of 456 nm, exhibited a dominant green emission at 540 nm that corresponds to the ⁵F₄/⁵S₂ → ⁵I₈ transition, suggesting its suitability for a green-emitting phosphor. Concentration quenching optimization occurred beyond 0.015 mol Ho³⁺ ions. The CIE color coordinates and color purity analysis confirmed the phosphor’s suitability for green-emitting applications. Preliminary results suggest that this research highlights the potential of the phosphor for green light generation and advancing solid-state lighting technology.