title: Near-infrared quantum cutting in Ho3+, Yb3+-codoped BaGdF5 nanoparticles via first-  and second-order energy transfers.
abstract: Infrared quantum cutting involving Yb3+ 950-1,000 nm (2 F5/2 → 2 F7/2) and Ho3+ 1,007 nm (5S2,5F4 → 5I6) as well as 1,180 nm (5I6 → 5I8) emissions is achieved in BaGdF5: Ho3+, Yb3+ nanoparticles which are synthesized by a facile hydrothermal route. The mechanisms through first- and second-order energy transfers were analyzed by the dependence of Yb3+ doping concentration on the visible and infrared emissions, decay lifetime curves of the 5 F5 → 5I8, 5S2/5F4 → 5I8, and 5 F3 → 5I8 of Ho3+, in which a back energy transfer from Yb3+ to Ho3+ is first proposed to interpret the spectral characteristics. A modified calculation equation for quantum efficiency of Yb3+-Ho3+ couple by exciting at 450 nm was presented according to the quantum cutting mechanism. Overall, the excellent luminescence properties of BaGdF5: Ho3+, Yb3+ near-infrared quantum cutting nanoparticles could explore an interesting approach to maximize the performance of solar cells.
authors.affiliation: Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000, People's Republic of China. wyh@lzu.edu.cn.
authors.forename: Linna
authors.initials: L
authors.lastname: Guo
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Wang
authors.forename: Jia
authors.initials: J
authors.lastname: Zhang
authors.forename: Yanzhao
authors.initials: Y
authors.lastname: Wang
authors.forename: Pengyu
authors.initials: P
authors.lastname: Dong