金属表面等离子体共振对碳量子点的荧光增强作用机理研究

Localized surface plasmon resonance (LSPR) is one of the unique properties of metal nanoparticles. The aim of this project is to enhance the luminescence efficiency of carbon quantum dot by using the LSPR of Au, Ag, Cu metal nanoparticles or their alloy nanoparticles, solve the problem of low quantum yield of carbon-based luminescence materials, and promote its applications in white light emitting diode (LED), display and biomedicine. The metal/alloy nanoparticles and carbon quantum dots will be prepared by liquid phase method and microwave method, respectively. The property of LSPR will be modulated by controlling the size, morphology, alloy constitution, type of coating layer and its thickness. The luminescence spectra of carbon quantum dots will be modulated by changing the raw materials and preparation conditions. The emission enhancement and electron transport regulation of carbon quantum dots will be achieved via the modulation of coupling mode and electromagnetic field enhancement between LSPR of metal and carbon quantum dots, which will be applied to white light emitting diode (LED) and ions/organics detection. To clarify the mechanism of metal enhanced emission for carbon quantum dots, the energy transfer and coupling mechanism between LSPR of metal/alloy nanoparticles and carbon quantum dots will be investigated, and the electrons transition rules will also be studied by combining experiments and theoretical calculations. In addition, the influence of energy band structures for carbon quantum dots will be investigated and the mechanism of fluorescence enhancement via LSPR will be clarified, which will provide a theoretical and technical support for the application of carbon-based luminescence nanomaterials in white LED, biomedicine and other related areas.

金属颗粒具有局域表面等离子体共振(LSPR)特性，本项目拟利用Au、Ag、Cu金属及其合金的LSPR增强碳量子点的发光效率，解决当前碳基材料发光效率较低的难题，促进其在白光LED照明、显示和生物医学等领域的应用。分别采用液相法和微波法合成金属/合金纳米颗粒和碳量子点，通过控制金属的尺寸、形貌、合金组分、包覆介质种类和厚度调节其LSPR吸收特性，通过原料种类和微波工艺参数调节碳量子点的发光特性。通过调控金属的LSPR与碳量子点间的耦合方式和电磁场增强作用，实现碳量子点的荧光增强和电子调控，并将其应用于白光LED和离子/有机物检测。通过实验研究和理论计算相结合，系统研究金属LSPR与碳量子点的能量传递和耦合机制，分析电子在金属和碳量子点间的跃迁规律，确定金属的LSPR对碳量子点的能带结构的影响，阐明金属LSPR对碳量子点的荧光增强作用机理，为碳基纳米发光材料的应用提供理论和技术支撑。

金属具有表面等离子体共振特性，它能够与其附近的光子产生耦合和能量传递，从而实现对其附近材料的光电特性调控。当金属表面等离子体限域在纳米粒子表面时，当入射光子频率与金属纳米颗粒的整体振荡频率相匹配，纳米颗粒对光子能量产生强吸收，从而发生局域表面等离子体共振 (LSPR: Localized Surface Plasmon Resonance)。LSPR在荧光增强、拉曼增强、光/电催化和生物医学等方面具有重要的应用价值。碳量子点具有工艺简单、节能环保、光谱可调、生物相容性好等优点，在荧光标记、生物成像、离子检测、催化及光电器件等领域具有广阔的应用前景。但是，碳量子点也存在固态发光强度不高、红光量子效率较低、自身电子传输性能较弱等问题，利用金属LSPR效应有望解决碳量子点的上述问题。如何调控金属的LSPR场及其和碳量子点间的电子传输和能量传递过程，阐明金属LSPR对碳量子点的荧光增强和能量转移机理，促进它们在能源、离子检测和环境领域的应用具有重要的研究意义和价值。.本项目利用化学法合成了不同发射波长的碳量子点发光材料，通过改变原料种类和工艺参数、元素掺杂种类和含量、表面官能团种类和含量实现了碳量子点的光谱调控；采用液相还原法合成了IB族金/银/铜及其合金纳米颗粒，通过改变表面活性剂和工艺条件实现了金属纳米颗粒的尺寸、形貌和LSPR调控；通过表面修饰和光谱调控实现金属和碳量子点的有效耦合，利用金属的LSPR实现了碳量子点的荧光增强，并确定了它们之间的能量传递和LSPR作用机理；此外，将金属的LSPR用于白光LED、离子检测、荧光分子的拉曼增强。本项目的研究对于实现碳量子点和金属纳米颗粒的可控制备和LSPR调控，揭示LSPR效应对于碳量子点的荧光增强作用机理，促进金属的LSPR效应在能源、化学传感、生物医学和环境领域的应用具有重要意义。