Abstract This work reports the effect of annealing treatment (550, 650, and 750 °C) and europium concentration (1-7 at.%) on the structural, morphological, and optical properties of ZnS:Eu 3 + thin films synthesized by the polyol method and dip-coating technique. The films were indexed to the zinc-blende phase of ZnS with crystallite size ranging from 2-7 nm and exhibited preferential orientation at the (111) plane according to the XRD analyses. The SEM and AFM images indicate homogeneous, flat, crack-free, compacted films, with pyramidal grain shape and particle size distribution about ∼ 25 nm. High transmittance in the visible region (above 80 %) and band gap (3.75-3.9 eV) computed by the Tauc model were obtained by UV–VIS spectroscopy. The PL spectra show the emission bands related to radiative recombination involving defect states, particularly, zinc and sulfur vacancies. The PL spectra also indicate that the higher the europium concentration, the higher the emission light intensity in the blue–green regions. At the same time, the typical 5 D 0 → 7 F 2 transition from Eu 3 + is barely noticeable due to a poor energy transfer from the ZnS host to the Eu ions. On the other hand, by increasing the annealing temperature from 550 to 750 °C, a 2.5-fold decrease in the emission intensity is recorded.

中文翻译：

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铕对多元醇和浸涂技术ZnS薄膜蓝绿光发射的影响

摘要 这项工作报告了退火处理（550、650 和 750 °C）和铕浓度（1-7 at.%）对 ZnS:Eu 3 + 薄膜的结构、形态和光学性能的影响多元醇法和浸涂技术。根据 XRD 分析，这些薄膜被索引为 ZnS 的闪锌矿相，微晶尺寸范围为 2-7 nm，并在 (111) 平面上显示出优先取向。SEM 和 AFM 图像显示均匀、平坦、无裂纹、压实的薄膜，具有金字塔形颗粒形状和约 25 nm 的粒度分布。可见光区的高透射率（超过 80%）和带隙（3.75-3.9 eV）由 Tauc 模型计算得到，通过 UV-VIS 光谱获得。PL 光谱显示了与涉及缺陷态的辐射复合相关的发射带，特别是锌和硫空位。PL 光谱还表明铕浓度越高，蓝绿色区域的发射光强度越高。同时，由于从 ZnS 主体到 Eu 离子的能量转移很差，因此从 Eu 3 + 典型的 5 D 0 → 7 F 2 跃迁几乎不明显。另一方面，通过将退火温度从 550°C 提高到 750°C，发射强度降低了 2.5 倍。