| 1 | Understanding and tuning blue-to-near-infrared photon cutting by the Tm^(3+)/Yb^(3+) couple显示文摘Lanthanide-based photon-cutting phosphors absorb high-energy photons and‘cut’them into multiple smaller excitation quanta.These quanta are subsequently emitted,resulting in photon-conversion efficiencies exceeding unity.The photon-cutting process relies on energy transfer between optically active lanthanide ions doped in the phosphor.However,it is not always easy to determine,let alone predict,which energy-transfer mechanisms are operative in a particular phosphor.This makes the identification and design of new promising photon-cutting phosphors difficult.Here we unravel the possibility of using the Tm^(3+)/Yb^(3+) lanthanide couple for photon cutting.We compare the performance of this couple in four different host materials.Cooperative energy transfer from Tm^(3+)to Yb^(3+) would enable blue-to-near-infrared conversion with 200% efficiency.However,we identify phonon-assisted cross-relaxation as the dominant Tm^(3+)-to-Yb^(3+) energy-transfer mechanism in YBO_(3),YAG,and Y_(2)O_(3).In NaYF_(4),in contrast,the low maximum phonon energy renders phonon-assisted cross-relaxation impossible,making the desired cooperative mechanism the dominant energy-transfer pathway.Our work demonstrates that previous claims of high photon-cutting efficiencies obtained with the Tm^(3+)/Yb^(3+) couple must be interpreted with care.Nevertheless,the Tm^(3+)/Yb^(3+) couple is potentially promising,but the host material-more specifically,its maximum phonon energy-has a critical effect on the energy-transfer mechanisms and thereby on the photon-cutting performance. | Dechao Yu Ting Yu Arnoldus Jvan Bunningen Qinyuan Zhang Andries Meijerink Freddy T.Rabouw | 2020 | Light(Science & Applications)2020，9，1： | 2 |
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