Near-infrared quantum cutting in Ho3+ Yb3+-codoped BaGdF5 nanoparticles via first- and second-order energy transfers

摘要

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.