Quantum cutting properties in KYF₄:Tb³⁺, Yb³⁺ phosphors: Judd-Ofelt analysis, rate equation models and dynamic processes

Highlights

• QC luminescent materials KYF₄:Tb³⁺,Yb³⁺ phosphors were synthesized.

• The J-O parameters were derived from emission spectra and decay curves.

• The rate equation models of QC luminescence were established.

• The time-dependent population densities of Tb³⁺ and Yb³⁺ were simulated.

• The upper limit theoretical quantum efficiencies were evaluated.

Abstract

Spectroscopic properties play a significant role during the design and development of novel luminescent materials. In this work, quantum cutting (QC) luminescent materials KYF₄:Tb³⁺,Yb³⁺ phosphors were successfully synthesized by sol–gel method. The crystal structure, morphology, fluorescence spectra, and decay curves were investigated by X-ray diffractometer (XRD), scanning electron microscope (SEM) and spectrofluorometer. The Judd-Ofelt (J-O) parameters, Ω_λ (λ = 2, 4, 6), were directly derived from the emission spectra and decay curves, attributed to the transition intensities of Tb³⁺ ions were dependent on the J-O parameters. Then, the radiative and nonradiative transition rates, fluorescent branching ratios, cross-relaxation rates and lifetimes of QC luminescence were calculated based on the obtained J-O parameters. Moreover, the rate equation models of QC luminescence were established and the time-dependent population densities in excited levels of Tb³⁺ ions and Yb³⁺ ions were simulated. Finally, the dynamic processes of QC luminescence were discussed carefully and the corresponding theoretical quantum efficiency was estimated. Our studies would provide an insight into the QC luminescence and give theoretical guidance for developing novel luminescent materials.