A novel red-emitting phosphors K2Ba (MoO4)2: Eu, Sm and improvement of luminescent properties for light emitting diodes

The novel red-emitting phosphors K₂Ba(MoO₄)₂: Eu³⁺, Sm³⁺ were prepared by solid-state reaction and their crystal structures, photo luminescent characteristics were investigated. The results show that all samples can be excited efficiently by UV (397 nm) and blue (466 nm) light, which are coupled well with the characteristic emission from UVLED and blue LED, respectively. A small amount of Sm³⁺, acting as a sensitizer, increased the energy absorption around 400 nm. In the Eu³⁺-Sm³⁺ co-doped system, both Eu³⁺ and Sm³⁺ f-f transition absorptions are observed in the excitation spectra, the intensities of the main emission line (⁵D₀ → ⁷F₂ transition of Eu³⁺ at 616 nm) are strengthened because of the energy transition from Sm³⁺ to Eu³⁺. The doping concentration of Eu³⁺-Sm³⁺ was optimized. The approach to charge compensation was used: Ba²⁺ → Eu³⁺/Sm³⁺ + X⁻ (X = F, Cl, and Br), and the influence of charge compensation on the luminescent intensity of phosphors is investigated.