Abstract Cu2-xS nanocrystals have great potential to enhance the up-conversion luminescence of rare earth materials. In this work, monodispersed Cu2-xS (Cu8S5 and Cu9S5) nanocrystals and Cu2-xS@SiO2 composited nanoparticles were synthesized by the hot-injection method and reverse micro-emulsion method, respectively. A more efficient semiconductor based plasmonic hybrid structure that Er(OH)CO3 was embedded with multiple Cu2-xS@SiO2 nanoparticles was prepared. Hotspots between Cu2-xS@SiO2 composited nanoparticles were constructed and employed to enhance the excitation photon absorption in Er(OH)CO3. Under the excitation of 980 nm light, due to the localized surface plasmon resonance (LSPR) characters of Cu2-xS nanoparticles, the UC luminescence of the multiple Cu2-xS@SiO2-embedded Er(OH)CO3 composites was obviously enhanced in both the green and red emission bands compared with that of the SiO2@Er(OH)CO3 particles. The UC fluorescence intensity of Cu8S5@SiO2 and Cu9S5@SiO2-embedded Er(OH)CO3 was increased by 45.0 and 15.2 times, compared with that of SiO2@Er(OH)CO3, respectively. We provide a clear experimental evidence that proves that the UC luminescence properties of rare earth doped phosphors are significantly reinforced by engineering localized surface plasmon resonances of Cu2-xS based plasmonic semiconductors. Finite-difference time-domain (FDTD) calculations were carried out and confirmed the effect of the reinforcement of the excitation light field. The UC enhancement mechanisms based on Cu2-xS based plasmonic semiconductor structures were discussed.

中文翻译：

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多种Cu2-S@SiO2嵌入Er(OH)CO3复合材料中的等离子体增强上转换发光

摘要 Cu2-xS纳米晶在增强稀土材料的上转换发光方面具有巨大潜力。在这项工作中，分别通过热注射法和反微乳液法合成了单分散的 Cu2-xS（Cu8S5 和 Cu9S5）纳米晶体和 Cu2-xS@SiO2 复合纳米颗粒。制备了一种更有效的基于半导体的等离子体混合结构，其中 Er(OH)CO3 嵌入了多个 Cu2-xS@SiO2 纳米粒子。构建了 Cu2-xS@SiO2 复合纳米粒子之间的热点，并用于增强 Er(OH)CO3 中的激发光子吸收。在 980 nm 光的激发下，由于 Cu2-xS 纳米粒子的局域表面等离子体共振 (LSPR) 特性，与 SiO2@Er(OH)CO3 颗粒相比，多个 Cu2-xS@SiO2 嵌入的 Er(OH)CO3 复合材料的 UC 发光在绿色和红色发射带均明显增强。Cu8S5@SiO2和Cu9S5@SiO2嵌入Er(OH)CO3的UC荧光强度分别比SiO2@Er(OH)CO3提高了45.0倍和15.2倍。我们提供了明确的实验证据，证明通过工程化基于 Cu2-xS 的等离子体半导体的局部表面等离子体共振，稀土掺杂磷光体的 UC 发光特性得到显着增强。进行了时域有限差分 (FDTD) 计算并确认了增强激发光场的效果。讨论了基于 Cu2-xS 等离子体半导体结构的 UC 增强机制。