Tuning of the Emission Color of Ba_1−xGa₂S₄:xEu²⁺ Phosphors for Use in Three‐Band White LEDs

Abstract

Ba 1-x Ga 2 S 4 :xEu 2+ (x = 0.10, 0.25, 0.50, 0.75, 1.0) phosphors were prepared by performing a solid-state reaction. The PL spectra of the Ba 1−x Ga 2 S 4 :xEu 2+ phosphors were recorded. Very broad excitation bands are located in the range 300-480 nm, which suggests that the Ba 1−x Ga 2 S 4 :xEu 2+ can be used as color emission phosphors when pumped with an excitation of 465 nm, which is the wavelength of a commercial blue-emitting diode. The emission wavelength at the maximum PL intensity (λ max ) for the Ba 1−x Ga 2 S 4 : xEu 2+ phosphors increases gradually from 504 to 548 nm as the mole fraction of europium ions (x) in the phosphors increases. The variation in λ max for the Ba 1−x Ga 2 S 4 :xEu 2+ phosphors with the mole fraction of europium ions can be interpreted in terms of the crystal structures of the Ba 1−x Ga 2 S 4 :xEu 2+ phosphors. A three-band white emission was obtained by coating a mixture of Ba 0.5 Ga 2 S 4 :0.5Eu 2+ and CaS:Eu 2+ phosphors onto the surface of a blue-emitting diode.