Single-band near-infrared quantum cutting of Ho3+-Yb3+ codoped KLu2F7 phosphors by energy clustering

A single-band near-infrared (NIR) quantum cutting (QC) is efficiently achieved for 1190 nm fluorescence by structuring Ho3+-Yb3+ couple as energy clustering in KLu2F7 host under excitation of ultraviolet-to-green photons. In comparison with Ho3+ singly doping, the intensity of NIR emission was enhanced by at least 5 times as 75%Yb3+ is codoped into KLu2F7: Ho3+. On the basis of experimental data and theoretical analysis, the formation of Yb3+ (fractional Ho3+) energy clustering at sub-lattice level is demonstrated to account for resonant energy transfer (ET) of Ho3+-> Yb3+, back ET of Yb3+: F-2(5/2) -> Ho3+: I-5(6), and the crucial energy preserving by confining Yb3+ 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(Lu0.24Ho0.01Yb0.75) F-2(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. (C) 2016 Elsevier B.V. All rights reserved.