金属超宽表面等离子体共振薄膜增强稀土上转换发光研究

Rare earth doped upconversion luminescence (UCL) nanocrystals (NCs) have the disadvantages of narrow excitation band and low UCL efficiency, which severely restrict its photon conversion and application under the excitation of broad band sunlight. The project is proposed the use of ultra-broad metal surface plasmon resonance combined with suitable rare earth ions doped NCs to achieve the UCL enhancement under the broad band excitation. First, exploring the ultra-broad band surface plasmon resonance absorption of metal thin film self-assembled by the different structures of metal NCs, realizing the coverage of the solar spectrum. On this basis, combining the metal film with the appropriate rare earth ions doped UCL NCs to achieve the UCL enhancement of the composite film under multi-wavelength excitation. Furthermore, introducing the multi-layer structure to overcome the low UCL intensity of the composite film, ultimately realizing the UC emission enhancement under the excitation of broad band sunlight. In addition, we can reveal the physical nature of the local optical field enhanced UCL of composite film in depth, by measuring the temperature-dependent spectra and dynamics, the internal quantum efficiency and local optical field simulation. This project will provide an efficient metal @ rare earth ions doped UCL NCs composite film under broad band excitation, and further provide theoretical guidance and experimental basis for the photon conversion application of this type of material in solar cells.

稀土掺杂上转换发光纳米材料的激发谱带窄和发光效率低，严重制约了其在宽谱带太阳光激发下的光转换和应用。本项目提出利用超宽的金属表面等离子体共振结合合适的稀土离子掺杂的纳米材料，实现宽谱带激发下的上转换增强。探索不同结构的金属纳米晶自组装的金属薄膜结构实现超宽带的表面等离子体共振吸收，达到覆盖太阳光谱的范围。在此基础上，将金属薄膜结构与适当的稀土离子掺杂的上转换发光纳米材料相结合，实现复合薄膜中多波长激发下稀土上转换发光的增强。进一步引入多层结构克服复合薄膜绝对强度低的问题，最终实现宽谱带太阳光激发下的上转换发射增强研究。另外，通过变温光谱及动力学、内量子效率的测试以及局域光场模拟，深入揭示复合结构中局域光场增强上转换发光的物理本质。本项目将提供一类高效的宽带激发的金属@稀土掺杂上转换纳米发光复合薄膜材料，并为这类材料在太阳能电池中的光转换应用提供理论指导和实验依据。

稀土上转换荧光材料，在太阳能谱转换和基于能量转换的光伏器件方面展示了诱人的应用前景，但还存在上转换效率低和激发谱带窄的瓶颈问题，无法满足太阳能谱转换的实际需要。本项目聚焦稀土掺杂纳米晶发光的局域光场调控研究，取得如下创新成果：(1) 采用合金/多孔/定向/核壳等不同结构的金属提高稀土上转换纳米晶发光强度/效率，并揭示了影响上转换增强的主要因素和物理机制；(2) 利用金属表面等离子体和光子晶体的协同效应增强局域光场，实现突破性的上转换增强，实现3个数量级的增加；(3) 在国际上率先提出利用半导体表面等离子体增强上转换荧光，发现非线性效应与表面等离子体的共同作用机制；(4) 首次实现钙钛矿量子点的稀土离子掺杂和量子剪裁发光（效率高达146%），并用于大幅度提高硅电池效率。在本项目资助下，在Advanced Materials, Advanced Functional Materials, ACS Nano, Nano Today, Nano Letters等等国际顶尖与著名学术期刊上发表SCI论文 27篇 (IF> 10.0 以上 7 篇);这些论文累计被引用550余次，ESI高引用论文2篇， 研究成果获得了国内外同行的高度瞩目。在国际国内会议上做邀请报告5次.