Controlled synthesis, photoluminescence, and the quantum cutting mechanism of Eu3+ doped NaYbF4 nanotubes
Abstract
Quantum cutting down-conversion has been the subject of intense research activity due to its wide application in optoelectronic devices. However, the energy transfer mechanism behind this down-conversion process is not fully understood. In this work, monodispersed Eu3+ doped NaYbF4 nanotubes were synthesized by a hydrothermal route. Simultaneous phase transition from cubic to hexagonal and size modification are controlled by changing the Eu3+ doping concentration. Excited by 393 nm ultraviolet monochromatic light, Eu3+ doped NaYbF4 nanotubes show quantum cutting down-conversion involving visible and broadband near-infrared emissions through an energy migration process 5D2 (Eu3+) → 2F5/2 (Yb3+) + 2F5/2 (Yb3+). Based on the emission spectra of Eu3+ ions, an improved method is proposed to calculate Judd–Ofelt intensity parameters and radiative transition probability. A comprehensive seven-level rate-equation model is developed to study the energy transfer mechanism. This work offers a method to calculate Judd–Ofelt parameters of opaque powder phosphors and to evaluate the population dynamics of excited states.