Photoluminescence properties and energy transfer of novel orange–red emitting phosphors: Ba₃Bi₂(PO₄)₄: Sm³⁺, Eu³⁺ for white light-emitting diodes

Sm³⁺, Eu³⁺ co-coped Ba₃Bi₂(PO₄)₄ phosphors, as potential phosphors for white light-emitting diode applications, were synthesized through the solid-state reaction method for the first time. The crystal structure, absorption spectra, photoluminescence properties, decay time, energy transfer mechanism, temperature-dependent properties, and Commission International De L’Eclairage (CIE) chromaticity coordinates were investigated systematically. The pure eulytite-type Ba₃Bi₂(PO₄)₄ phase was obtained after heating at 980 °C for 5 h. A notably enhanced absorption efficiency at 393 nm was observed when Sm³⁺, as a sensitizer, was doped into Ba₃Bi_1.82(PO₄)₄: 0.18Eu³⁺ and the band gap of the Ba₃Bi₂(PO₄)₄ host was estimated to be 4.19 eV. The emission intensity of Ba₃Bi_1.82(PO₄)₄: 0.18Eu³⁺ was significantly enhanced when Sm³⁺ was co-doped. The existence and mechanism of energy transfer from Sm³⁺ to Eu³⁺ were evaluated by photoluminescence spectra and decay time measurements. The CIE chromaticity coordinate of Ba₃Bi_1.75(PO₄)₄: 0.07Sm³⁺, 0.18Eu³⁺ phosphor was calculated to be (0.5746, 0.4197), respectively.