Exploring dual-emission properties in Mn4+ distinctively activated BaTaF7 red emitting phosphor

Abstract

Mn⁴⁺-activated fluoride phosphors, which exhibit narrow-band red light emission, have been extensively employed in white LED applications. However, the majority of existing research has predominantly focused on single-site emission phenomena of Mn⁴⁺ in fluoride matrices. The exploration of systems with multi-site Mn⁴⁺ luminescence is of significant importance, as it may promote the broader application of such materials. In this study, a dual-emission fluoride phosphor, BaTaF₇:Mn⁴⁺ (BTF), was successfully synthesized, which exhibits two strong zero-photon line (ZPL) emissions at 627 and 630 nm. Density functional theory (DFT) calculations were employed to investigate the electronic structure and luminescence properties of the phosphor. The results suggest that Mn⁴⁺ ions tend to substitute for Ba²⁺ and Ta⁵⁺ in the BaTaF₇ host lattice, leading to significant distortion of the Mn⁴⁺ local environment. This distortion gives rise to the dual-emission and short fluorescence lifetime of the synthesized phosphor. The white LED with BTF phosphor encapsulation shows high potential for display backlighting sources with its 113.4% NTSC color gamut achieved through RGB primary color spectral filtering. The synthesis and investigation of phosphor present a promising approach for designing and developing multi-emission Mn⁴⁺-activated fluoride phosphors with unique luminescent properties. This study provides new insights for optimizing the performance and expanding the applications of luminescent materials.