Quantum-cutting of KYF4:Tb3+,Yb3+ under multiple excitations with high Tb3+ concentration

A new kind of quantum-cutting (QC) phosphor KYF4:Tb3+,Yb3+ was prepared by the sol-gel method by using trifluoroacetic acid as a fluorine source. Tb3+-doped samples represent high quenching concentration as 15%. The near-infrared fluorescence spectra of Tb3+&Yb3+ co-doped samples with high Tb3+ concentration (15%) indicate that QC can occur under different excitations of Tb3+, and the F-7(6) -> D-5(3) excitation (similar to 374 nm) is more effective than F-7(6) -> D-5(4) excitation (similar to 483 nm). Through the lifetime measurement, the maximum of QC efficiency (eta(QE)) under F-7(6) -> D-5(4) and F-7(6) -> D-5(3) excitations are calculated as 161% and 150%, respectively. The results all above infer that this phosphor can make use of high-energy photons of several wavelengths and may raise the conversion efficiency of solar cells greatly. (C) 2014 Elsevier B.V. All rights reserved.