Abstract This paper presents an original two-step technology for water synthesis of Ag2S/SiO2 core/shell quantum dots (QDs) based on Ag2S QDs, passivated with thioglycolic acid with luminescence in the near IR region (800–1400 nm). The formation of Ag2S QDs with an average size of 2.5 nm, SiO2 coated with thickness of 1.3–4 nm has been established using transmission electron microscopy and energy dispersive X-ray analysis. The possibility to control the formation of Ag2S/SiO2 core/shell QDs using FTIR spectroscopy data is shown. The results show a change in the luminescence properties of Ag2S QDs with an increase in the thickness of SiO2 shell. They are i) an increase in the intensity and quantum yield of QD luminescence by 7 times during ligand exchange and up to 35 times as a result of a further increase in the thickness of SiO2 shell; ii) an increase in the average luminescence lifetime from 3.5 ns to 17.7 ns during the formation of SiO2 shell. These studies demonstrate a way to control the quantum yield of NIR recombination luminescence of colloidal Ag2S QDs and expand the ways of their application.

中文翻译：

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Ag2S/SiO2核/壳量子点的结构和光学性质

摘要 本文提出了基于 Ag2S QD 的 Ag2S/SiO2 核/壳量子点 (QD) 水合成的原始两步技术，用巯基乙酸钝化，在近红外区域 (800-1400 nm) 发光。使用透射电子显微镜和能量色散 X 射线分析确定了平均尺寸为 2.5 nm、SiO2 涂层厚度为 1.3-4 nm 的 Ag2S QD 的形成。显示了使用 FTIR 光谱数据控制 Ag2S/SiO2 核/壳 QD 形成的可能性。结果表明，随着 SiO2 壳层厚度的增加，Ag2S QD 的发光特性发生了变化。它们是 i) 在配体交换期间 QD 发光的强度和量子产率增加了 7 倍，并且由于 SiO2 壳层的厚度进一步增加而增加了 35 倍；ii) 在 SiO2 壳形成期间平均发光寿命从 3.5 ns 增加到 17.7 ns。这些研究证明了一种控制胶体 Ag2S QD 的 NIR 复合发光的量子产率并扩展其应用途径的方法。