Efficient near-infrared downconversion and energy transfer mechanism in Tb^4+-Yb^3+ co-doped NaYF_4 nanoparticles

Abstract

Tb 4+-Yb 3+ co-doped NaYF 4 nanoparticles (NPs) are prepared by sintering the assynthesized NaYF 4 :Tb 3+ , Yb 3+ NPs at 380°C under air atmosphere. The oxidization of Tb 3+ ions to Tb 4+ ions in NaYF 4 NPs after sintering is demonstrated through X-ray photoelectron spectroscopy (XPS). The near-infrared (NIR) downconversion (DC) luminescence of Tb 4+-Yb 3+ couple is measured and investigated for the first time. The results show that DC luminescence of Tb 4+-Yb 3+ couple enhance obviously compared with Tb 3+-Yb 3+ couple in assynthesized sample. The enhancement factor is about 14 and 19 excited at 379nm and 487nm, respectively. On analyzing the exponential dependence of NIR fluorescence intensity on the pumping power, we reveal that the energy transfer (ET) mechanism from Tb 4+ to Yb 3+ in NaYF 4 NPs occurs by the single-step ET process. Our study may provide a promising DC layer on the top of silicon-based solar cells to improve the photovoltaic conversion efficiency.

Engineering of Solar Energy Harvesting Tb3+-Ion-Doped CdS Quantum Dot Glasses for Photodissociation of Hydrogen Sulfide

“… 45 The strong and broad absorption band of the Tb 4+ charge transfer transitions appear from 350 to 600 nm as reported in the literature. 46 − 48 Moreover, in Figure 6 B,C, the strong absorption of the CdS Q-dots in the UV–visible spectral range suppresses the absorption bands of Tb 3+ ions in this spectral region.…”

“…This can be attributed to the oxidized species of Tb-doped CdS Q-dots from the occupied O-orbitals to unoccupied Tb 4+ orbitals charge transfer in the glass matrix . The strong and broad absorption band of the Tb 4+ charge transfer transitions appear from 350 to 600 nm as reported in the literature. − Moreover, in Figure B,C, the strong absorption of the CdS Q-dots in the UV–visible spectral range suppresses the absorption bands of Tb 3+ ions in this spectral region.…”