Abstract

Full-spectrum lighting is benefit to human eyes’ healthy and attracts increasing attention. Therefore, phosphor-converted 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 Eu2+ 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 pc-wLEDs based on these two types of phosphors suggests their potential as green-emitting component to achieve full-spectrum illumination.

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