科研之友
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摘要
Lanthanide ions generally have abundant metastable excited states enabling lanthanide-doped nanocrystals (NCs) to display multipeak emission profiles. We address this issue by presenting a series of novel fluoride-based nanophosphors exhibiting spectrally pure upconversion (UC) red fluorescence upon near-infrared (980 nm) excitation. Single-band deep-red UC luminescence was achieved when a Yb3+-Er3+ ion-pair was incorporated into K3MF7 (M = Zr, Hf). This UC luminescence feature of K3MF7:Yb3+,Er3+ (M = Zr, Hf) NCs is independent of the doping levels of Yb3+-Er3+ and the pump power of incident light. High-energy vibrational oscillators on the NCs surfaces are likely to result in a striking increase in the population of the F-4(9/2) level of Er3+, accounting for the spectrally pure luminescence. The composition-optimized nanophosphor presents relatively perfect red monochromaticity.
