A novel near-infrared LiGaW2O8:Yb3+, Cr3+ up-conversion phosphor with enhanced luminescence intensity based on Ho3+/Er3+ bridges
The development of new luminescent materials with up-conversion (UC) emission falling within the first biological window (650–1000 nm) has drawn extensive attention in biological and medical fields. In this work, LiGaW2O8:Yb3+, Cr3+ UC phosphors were prepared for the first time, and the near-infrared (NIR) emission assigned to the 4T2–4A2 transition of Cr3+ was found to derive from the cooperative sensitization mechanism from Yb3+ to Cr3+. Moreover, the NIR emission of Cr3+ in the range of 700–900 nm can be greatly enhanced by the energy transfer (ET) process from Yb3+ sensitizers to Ho3+/Er3+ bridging centers and finally to Cr3+ emitting centers. Such success in LiGaW2O8:Yb3+, Ho3+/Er3+, Cr3+ provides a new perspective for designing superior UC phosphors with appropriate NIR emission, which could be used in biomedical fields.
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