Study on the effects of 5d energy locations of Ce^3+ ions on NIR quantum cutting process in Y_2SiO_5: Ce^3+, Yb^3+

The effects of the 5d energy locations of Ce³⁺ centers on the NIR quantum cutting process were studied in Y₂SiO₅ with two different substitutional Y³⁺ lattice sites for Ce³⁺ and Yb³⁺. Powder XRD and Rietveld refinement were used to characterize phase purity, crystal structure, lattice parameters and occupation fractions of Y₂₋x-yCexYbySiO₅ (x = 0.002 and 0.3, y = 0-0.2). PLE and PL spectra show that both kinds of Ce³⁺ centers in Y₂x-yCexYbySiO₅ can cooperatively transfer energy to Yb³⁺-Yb³⁺ ions pair. The dependence of the integrated emission intensities of Ce³⁺ and Yb³⁺, decay lifetime (τ) of Ce³⁺, nonradiative energy transfer rate (KCe→Yb), cooperative energy transfer efficiency (ηCET) and quantum efficiency (ηQE) on the concentration of Yb³⁺ ions were studied in details. More importantly, these results demonstrate that the 5d energy locations of Ce³⁺ ions have a great influence on NIR quantum cutting process in Ce³⁺-Yb³⁺ system: the closer they are to twice the absorption energy (~20000 cm⁻¹) of Yb³⁺, the higher the cooperative energy transfer efficiency from the lowest 5d excited state of Ce³⁺ to the Yb³⁺-Yb³⁺ ions pair.