Significantly enhanced upconversion luminescence intensity and tailorable chromaticity of Sn4+-doped NaYF4:Yb3+/Er3+

The internal modification with rare earth ion doping proved to be a very effective strategy for improving the luminescent properties of NaYF 4 -based upconversion materials. However, greatly enhancing the luminescence efficiency of NaYF 4 :Yb 3+ /Er 3+ remains a major challenge. Herein, the effects of Sn 4+ doping on the structure and luminescent performance of such material were explored. The hydrothermal molten-salt method was applied to synthesize the Sn 4+ -doped NaYF 4 :Yb 3+ /Er 3+ upconversion materials, and their crystal structures, morphologies, surface chemical composition and element states, and luminescence performance were characterized. It was found that Sn 4+ doping can significantly enhance the luminescence intensity and tailor the chromaticity of NaYF 4 :Yb 3+ /Er 3+ . In particular, the green (G) and red (R) luminescence intensity levels of the 30 mol% Sn 4+ doped material were increased by factors of 26.97 and 38.91, respectively. The R/G ratio was incremented from 0.34 for the undoped material to 0.83 for the 40 mol% Sn 4+ doped counterpart. The Sn 4+ doping led to the change of lattice distortion and crystal growth pattern of NaYF 4 :Yb 3+ /Er 3+ . The mechanism for Sn 4+ doping to affect the luminescence properties of the prepared upconversion material was also explored. The changes in luminescence intensity levels and R/G ratios could be attributed to the highly asymmetric distorted lattice and crystal field resulting from Sn 4+ doping.