Investigation of the Energy-Transfer Mechanism in Ho3+- and Yb3+-Codoped Lu2O3 Phosphor with Efficient Near-Infrared Downconversion

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• 作者：Guotao XiangYan Ma ; Xianju Zhou ; Sha Jiang ; Li Li ; Xiaobing Luo ; Zhendong Hao ; Xia Zhang ; Guo-Hui Pan ; Yongshi Luo ; Jiahua Zhang
• 刊名：Inorganic Chemistry
• 出版年：2017
• 出版时间：February 6, 2017
• 年：2017
• 卷：56
• 期：3
• 页码：1498-1503
• 全文大小：454K
• ISSN：1520-510X

文摘

A high-temperature solid-state method was used to synthesize the Ho³⁺- and Yb³⁺-codoped cubic Lu₂O₃ powders. The crystal structures of the as-prepared powders were characterized by X-ray diffraction. The energy-transfer (ET) phenomenon between Ho³⁺ ions and Yb³⁺ ions was verified by the steady-state spectra including visible and near-infrared (NIR) regions. Beyond that, the decay curves were also measured to certify the existence of the ET process. The downconversion phenomena appeared when the samples were excited by 446 nm wavelength corresponding to the transition of Ho³⁺: ⁵I₈→⁵G₆/⁵F₁. On the basis of the analysis of the relationship between the initial transfer rate of Ho³⁺: ⁵F₃ level and the Yb³⁺ doping concentration, it indicates that the ET from ⁵F₃ state of Ho³⁺ ions to ²F_5/2 state of Yb³⁺ ions is mainly through a two-step ET process, not the long-accepted cooperative ET process. In addition, a 62% ET efficiency can be achieved in Lu₂O₃: 1% Ho³⁺/30% Yb³⁺. Unlike the common situations in which the NIR photons are all emitted by the acceptors Yb³⁺, the sensitizers Ho³⁺ also make contributions to the NIR emission upon 446 nm wavelength excitation. Meanwhile, the ⁵I₅→⁵I₈ transition and ⁵F₄/⁵S₂→⁵I₆ transition of Ho³⁺ as well as the ²F_5/2→²F_7/2 transition of Yb³⁺ match well with the optimal spectral response of crystalline silicon solar cells. The current research indicates that Lu₂O₃: Ho³⁺/Yb³⁺ is a promising material to improve conversion efficiency of crystalline silicon solar cell.