Abstract The photoluminescence (PL) of yttrium oxyfluoride (YOF) samples co-doped with praseodymium (Pr3+) and ytterbium (Yb3+) was investigated for possible down-conversion (DC) applications for c-Si solar cells (SCs). The optimum infrared (IR) emission obtained through DC was recorded with a Yb3+ content of 2% and a Pr3+ content of 0.3% and this was within the effective response range for Si SCs. YOF:Pr3+, Yb3+ samples were synthesized by the pyrolysis method with trifluoroacetate as precursor. The X-ray diffraction patterns indicated a crystalline phase of stoichiometric rhombohedral YOF (space group: R 3 ‾ m (166)) after annealing at 900 °C. X-ray photoemission spectroscopy's high resolution peak fits for the high concentration YOF: 0.3 mol % Pr3+, 6 mol % Yb3+ co-doped sample revealed two Pr oxidation states, Pr3+ and Pr4+. The presence of Pr4+ was due to the annealing in ambient air. The Pr3+ visible (VIS) emission's excitation spectra showed an intense 4f-5d band of Pr3+ at 250 nm accompanied with weaker 4f-4f peaks at 456, 470 and 483 nm. The VIS green PL emission was due to the 4f-4f [3P0 → 3H4] and [3P0 → 3F2] transitions at 498 nm and 659 nm, respectively. Quenching of the Pr3+ green emission was due to the energy transfer to Yb3+ ions through the cross-relaxation mechanism with a dipole-dipole interaction. The Yb3+ IR emission's excitation spectrum revealed a new band at 225 nm that overlapped with the 4f-5d band of Pr3+. The band at 225 nm was ascribed to the charge transfer band of Yb3+ due to electrons transferred from the O2− 3p6 level to the 4f13 level of Yb3+. Excitation with 250 nm showed multi-narrow peaks in the IR range between 885 nm and 1120 nm that corresponded to the Pr3+ 3P0 → 1G4 and 1D2 → 3F3, 3F4 transitions and to the 2F7/2 → 2F5/2 transition of Yb3+. Upon excitation of 225 nm, the IR emission showed only emission of Yb3+ transitions with almost no traces of Pr3+ emission. The decay times for VIS and IR emissions were calculated to be in the microseconds range.

中文翻译：

---

YOF 的下转换：Pr3+、Yb3+ 荧光粉

摘要 研究了共掺杂镨 (Pr3+) 和镱 (Yb3+) 的氟氧化钇 (YOF) 样品的光致发光 (PL)，以用于 c-Si 太阳能电池 (SC) 可能的下转换 (DC) 应用。通过 DC 获得的最佳红外 (IR) 发射记录为 Yb3+ 含量为 2%，Pr3+ 含量为 0.3%，这在 Si SC 的有效响应范围内。YOF:Pr3+、Yb3+样品以三氟乙酸盐为前驱体通过热解法合成。X 射线衍射图表明在 900 °C 下退火后化学计量的菱形 YOF（空间群：R 3 ‾ m (166)）的结晶相。X 射线光电子能谱的高分辨率峰适合高浓度 YOF：0.3 mol% Pr3+、6 mol% Yb3+ 共掺杂样品显示两种 Pr 氧化态，Pr3+ 和 Pr4+。Pr4+ 的存在是由于在环境空气中退火。Pr3+ 可见光 (VIS) 发射的激发光谱显示 Pr3+ 在 250 nm 处有强烈的 4f-5d 带，并在 456、470 和 483 nm 处出现较弱的 4f-4f 峰。可见光绿色 PL 发射是由于分别在 498 nm 和 659 nm 处的 4f-4f [3P0 → 3H4] 和 [3P0 → 3F2] 跃迁。Pr3+ 绿色发射的猝灭是由于通过偶极-偶极相互作用的交叉弛豫机制将能量转移到 Yb3+ 离子。Yb3+ IR 发射的激发光谱揭示了 225 nm 处的一个新带，该带与 Pr3+ 的 4f-5d 带重叠。由于电子从 O2− 3p6 能级转移到 Yb3+ 的 4f13 能级，因此 225 nm 的能带归因于 Yb3+ 的电荷转移能带。250 nm 激发显示在 885 nm 和 1120 nm 之间的 IR 范围内出现多个窄峰，对应于 Pr3+ 3P0 → 1G4 和 1D2 → 3F3、3F4 跃迁以及 Yb3+ 的 2F7/2 → 2F5/2 跃迁。在 225 nm 激发下，IR 发射仅显示 Yb3+ 跃迁的发射，几乎没有 Pr3+ 发射的痕迹。计算出的 VIS 和 IR 发射的衰减时间在微秒范围内。