A reddish La2O2S-based long-afterglow phosphor with effective absorption in the visible light region

Sm3+-activated La2O2S phosphors with good crystallinity were prepared by solid-state reaction. The formation mechanism of La2O2S formation was assumed and the phase change with different temperatures was discussed. The luminescence properties of phosphors with different sintering temperatures and different doping concentrations of Sm3+were investigated. The emission peak at 605 nm showed a well intensity can be attributed to the 4G5/2 → 6H7/2 transition of Sm3+. The optical absorption of La2O2S phosphors showed a stronger intensity in UV–vis region comparing with the Y2O2S phosphors. The long afterglow properties were investigated after the phosphors were excited with a fluorescent lamp. Phosphorescence lasted for about 3 min in the limit of light perception of the dark-adapted human eye (0.32 mcdm−2).

► Y2−xSmxO2S long afterglow phosphors were synthesized via a solid-state method.
► The phosphors have a mixture of four emissions (569, 605, 645 and 656 nm).
► Comparing to Y2O2S:Eu3+, the vis-absorbance properties of La2O2S:Sm3+ phosphors are stronger.