Near-Infrared Down-Conversion and Energy Transfer Mechanism of Ce³⁺-Yb³⁺Co-Doped Ba₂Y(BO₃)₂Cl Phosphors

Abstract

Ce3+ and Yb3+ co-doped Ba2Y(BO3)2Cl phosphors are synthesized via a conventional high-temperature solid-state method in CO atmosphere. The structure and luminescent properties of sample are characterized by X-ray diffraction (XRD) and photoluminescence excitation (PLE) and emission (PL) spectra. The phosphor has strong broad band absorption and strong near infrared (NIR) emission, which matches well with the Si-based solar response curve. As a function of Yb3+ concentration, the decay time curves of Ce3+ emission in Ba2Y(BO3)2Cl: Ce3+, Yb3+ are measured to prove the occurrence of energy transfer (ET) from Ce3+ to Yb3+ and the energy transfer efficiency is also calculated. The energy transfer processes are also discussed, and possible transfer models are proposed. Results demonstrate that Ba2Y(BO3)2Cl: Ce3+, Yb3+ phosphors might act as a promising down-conversion (DC) solar spectral convertor to enhance the efficiency of the silicon solar cell by utilizing the broadband absorption for solar spectrum.

Synthesis Attempt and Structural Studies of Novel A2CeWO6 Double Perovskites (A2+ = Ba, Ca) in and outside of Ambient Conditions

“…The best excitation wavelengths to observe such phenomena are ∼275 (Ce 3+ + WO x ) or 360 nm (WO x + oxygen-related defect absorption bands) according to Figure b,c. The suggested physicochemical origins of those bands were discussed in a few sources. ,− However, the deeper the excitation the faster our emission disappeared. Even after moving back to optimal wavelengths (from, i.e., 212 nm) the registered emission was hard to trace.…”

“…NUV and magnetically active Ce 3+ /W 5+ pairs unrecoverably turn into inactive Ce 4+ /W 4+ couples mitigating all energy conversion efforts. But, this could be useful regarding other technical (sensory) applications. , Regarding CCWO, which contains mainly Ce 3+ and W 6+ ions, it seems that this material does not exhibit such behavior despite: showing the same, weak luminescence also influenced by oxygen vacancies (Figure a) and hosting similar, broad EPR Ce 3+ signals characteristic for the predominant phase. ,− Here, we can also see a visible weak W 5+ signal persisting to 298 K (Figure b) with a g -factor around 1.973. CCWO also emits stable but weak light, unaffected by NUV illumination within a respective time frame.…”

Temperature Dependent Energy Transfer in Ce3+-Yb3+Co-Doped YAG Phosphors

“…Recently, Ce 3+ -Yb 3+ co-doped phosphors have attracted many attentions because they have a broad absorption band (300-500 nm) due to 4f-5d transitions of Ce 3+ ions and the NIR emission of Yb 3+ at 1030 nm (Yb 3+ : 2 F 5/2 → 2 F 7/2 ) which perfectly matches the spectral response of the c-Si solar cells. [10][11][12][13][14][15][16][17][18][19] To improve the quantum efficiency of Ce 3+ -Yb 3+ co-doped phosphors, it is important to understand the mechanism of the energy transfer from Ce 3+ to Yb 3+ . However, due to the complexity inside the phosphors, the mechanism is still not clear.…”

“…Some earlier studies suggested that the energy of Ce 3+ at the 5d level was transferred to two nearby Yb 3+ via a cooperative energy transfer (CET) process, [10][11][12] while other studies suggested that the energy was transferred from Ce 3+ to Yb 3+ through an intermediate Ce 4+ -Yb 2+ charge transfer state (CTS). [13][14][15][16][17][18][19] In this paper, in order to investigate the energy transfer process, Ce 3+ -Yb 3+ co-doped YAG phosphors were prepared. Their Photoluminescence (PL), photoluminescence excitation (PLE) and fluorescence decay curves were measured at different temperatures (8-300 K).…”