Comparison of luminescence between Eu2+-activated Na2CaPO4F and NaCaPO4 green-emitting phosphors for pc-wLEDs

Full-spectrum lighting is benefit to human eyes' healthy and attracts increasing attention. Therefore, phosphorconverted white light-emitting diodes (pc-wLEDs) for illumination need phosphors with broadband emission, especially those covering the cyan-emitting region. This work compares the structure and luminescent properties of NaCaPO4:Eu2+ and Na2CaPO4F:Eu2+ phosphors. Although both phosphors exhibit a broad emission band peaking at 505 nm, Na2CaPO4F:Eu2+ has a broader band than NaCaPO4:Eu2+. This is because Na2CaPO4F has more crystallographic sites for Eu(2+ )ion. Furthermore, the phosphors with NaCaPO4 phase have better thermal stability and higher internal quantum efficiency than those with Na2CaPO4F phase. A smaller Stokes shift and a larger band gap are responsible for the better thermal stability of NaCaPO4:Eu2+. The performance of the pcwLEDs based on these two types of phosphors suggests their potential as green-emitting component to achieve full-spectrum illumination.

Automated summary

Full-spectrum lighting is important for human eyes' health and has gained increasing attention. Phosphor-converted white light-emitting diodes (pc-wLEDs) for illumination require phosphors with broadband emission, especially in the cyan-emitting region. This study compares the structure and luminescent properties of NaCaPO4:Eu2+ and Na2CaPO4F:Eu2+ phosphors. Na2CaPO4F:Eu2+ exhibits a broader emission band than NaCaPO4:Eu2+ due to more crystallographic sites for Eu(2+) ion. The NaCaPO4:Eu2+ phosphors have better thermal stability and higher internal quantum efficiency. The pcwLEDs based on these phosphors show potential as green-emitting components for achieving full-spectrum illumination.