Broadband near-ultraviolet excited La₂Mo₂O₉:Eu³⁺ red-emitting phosphors with high color purity for solid-state lighting

A series of different Eu³⁺ ions incorporated La₂Mo₂O₉ phosphors exhibiting photoluminescence (PL) peaks in the red region (613 nm; ⁵D₀→⁷F₂) were successfully synthesized by a citrate sol-gel method. Under the 351 nm excitation, the optimal doping concentration of Eu³⁺ ions was identified to be 25 mol% with higher PL emission intensity and further the concentration quenching mechanism was governed by electric diploe-diploe interaction. More importantly, the optimized phosphor was demonstrated high color purity while the Commission Internationale de I'Eclairage chromaticity coordinates were (0.661, 0.339). The intrinsic radiative transition lifetime for the optimized red phosphor was calculated to be 530.7 μs and the local structure environment of Eu³⁺ ions in the La₂Mo₂O₉ host matrix was also analyzed by the Judd-Ofelt theory. Moreover, a red-emitting light-emitting diode (LED) device was fabricated by combing a near-ultraviolet LED chip with the optimized red phosphor, which exhibits a dazzling red light. Based on the obtained results, the Eu³⁺ ions activated La₂Mo₂O₉ phosphors are expected to be as a promising red-emitting phosphor for solid-state lighting.