Enhancement of near-infrared quantum-cutting luminescence in NaBaPO4: Er3+ phosphors by Bi3+

Abstract NaBaPO4:Bi3+, Er3+ phosphors were prepared by the solid-state reaction. The fluorescence spectra and decay curves demonstrate that four-photon near-infrared (NIR) quantum-cutting (QC) with 1534 nm emission (4I13/2 → 4I15/2) occurs under the excitation of 377 nm (4I15/2 → 4G11/2) in NaBaPO4: Er3+ phosphors. The intensity of four-photon NIR QC luminescence emission is enhanced when NaBaPO4:Er3+ is co-doped with Bi3+. The maximum enhancement factor is up to 10.65 times while the Bi3+ doping concentration is 4%. The fluorescence spectra and the XRD patterns of NaBaPO4:Bi3+, Er3+ samples demonstrate that the great enhancement of NIR emission does not mainly come from energy transfer from Bi3+ to Er3+, but from the distortion of crystal field. Eu3+ is introduced into host as probes to further demonstrate the distortion of crystal field induced by Bi3+. Our study has potential application in Ge solar cells and optical waveguide amplifier.