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 7F6 → 5D3 excitation (∼374 nm) is more effective than 7F6 → 5D4 excitation (∼483 nm). Through the lifetime measurement, the maximum of QC efficiency (ηQE) under 7F6 → 5D4 and 7F6 → 5D3 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.