Single-band near-infrared quantum cutting of Ho~(3+)-Yb~(3+) codoped KLu_2F_7 phosphors by energy clustering

摘要

A single-band near-infrared (NIR) quantum cutting (QC) is efficiently achieved for 1190 nm fluorescence by structuring Ho~(3+)-Yb~(3+) couple as energy clustering in KLu_2F_7 host under excitation of ultraviolet-to-green photons. In comparison with Ho~(3+) singly doping, the intensity of NIR emission was enhanced by at least 5 times as 75%Yb~(3+) is codoped into KLu_2Fy:Ho~(3+). On the basis of experimental data and theoretical analysis, the formation of Yb~(3+) (fractional Ho~(3+)) energy clustering at sub-lattice level is demonstrated to account for resonant energy transfer (ET) of Ho~(3+) →Yb~(3+), back ET of Yb~(3+): ~2F_(5/2) → Ho~(3+): ~5I_6, and the crucial energy preserving by confining Yb~(3+) energy migration. By mean of steady and dynamic spectroscopies, an internal quantum yield for the single-band 1190 nm emission is appropriately evaluated to be more than 190% for K(Lu_(0.24)Ho_(0.01)Yb_(0.75))~2F_7 without any obvious concentration quenching. This nanostructured design of single-band NIR QC will open up novel available way to get efficient NIR emitters, which can boost the promising applications of solar cells, optical communication, short-wavelength infrared (SWIR) bio-imaging in vivo, etc.