Low-toxic quantum dots with modulated light emission in the near infrared region

目的：1)研制尺寸、组成和形状可调的低毒性胶体硫系铜基量子点（QDs），其光致发光（PL）覆盖整个近红外（NIR）光谱区（700 ~ 2500 nm），高量子产率可达80%；2)设计基于这些量子点和具有可控激子动力学的等离子体硫系铜纳米晶体（NCs）的混合pl局域表面等离子体共振（LSPR）系统。动机：虽然可见光范围完全被各种具有相当高效的光吸收和荧光特性的量子点覆盖，但近红外活性材料受PbA (A = S, Se, Te), InAs, Cd3P2， CdHgTe和HgTe的限制。由于所有这些化合物都含有有毒元素，其潜在的技术应用面临严重限制。一种有价值的替代方案是基于铜硫族化合物的三元和四元量子点，如CuIn(Zn)S（Se）。然而，这些量子点的光吸收/发射范围仅限于约1200nm，即目前新兴的CuInS（Se）量子点，在近红外波段的荧光还没有开发出来。这正是本项目旨在带来重大贡献的地方。此外，这些低毒量子点表现出复杂的激子动力学，可以作为调节其光物理性质的额外手柄。这种调谐的手段之一是量子点中形成的激子与表现出强LSPR的材料产生的电磁场的相互作用。这种耦合已被证明会导致PL猝灭或增强。虽然这种相互作用已经在可见区域进行了研究，但在近红外光谱范围内仍未被探索。这种对近红外发光量子点和适当的近红外等离子体纳米材料耦合的研究构成了该项目的第二个主要部分。目的：建立基于阳离子交换反应的CuIn(Zn)Se（Te）量子点合成新方法；通过ZnS或ZnSe壳化提高其稳定性和光学性能；设计近红外PL量子点与近红外等离子体铜硫系量子点之间距离可控的杂化结构；研究近红外区激子与等离激子之间的相互作用，旨在增强和加速激子的重组。实施：项目工作方案相对于每个目标分为四个工作包。每一个都包括精确分配给两位博士研究人员的详细任务。潜在影响：具有可调光物理特性的创新光电材料和开放结构，将被开发出来，在生物成像、多光子成像、荧光寿命成像显微镜、光伏、纳米光子学、太阳能聚光器和传感等领域具有非常有前途的应用。

Aim: 1) to develop low-toxic colloidal copper chalcogenide based quantum dots (QDs) with tunable size, composition and shape, and exhibiting photoluminescence (PL) extended over the whole near infrared (NIR) spectral region (700-2500 nm) with high quantum yields reaching 80%; 2) to design hybrid PL-localized surface plasmon resonance (LSPR) systems based on these QDs and plasmonic copper chalcogenide nanocrystals (NCs) with controllable exciton dynamics. Motivation: whilst the visible range is completely covered by various QDs possessing quite efficient light absorption and fluorescence characteristics, the NIR active materials are limited by PbA (A = S, Se, Te), InAs, Cd3P2, CdHgTe, and HgTe. As all these compounds contain toxic elements, their potential technological applications face serious restrictions. A valuable alternative is copper chalcogenide-based ternary and quaternary QDs, such as CuIn(Zn)S(Se). However, the range of light absorption/emission of these QDs is limited to ca. 1200 nm, i.e. the currently emerging CuInS(Se) QDs, fluorescing farther in the NIR are not developed yet. This is exactly where the present project aims to bring a major contribution. Furthermore, these low-toxic QDs exhibit complex exciton dynamics which can be used as an additional handle to tune their photophysical properties. One of the means for this tuning is the interaction of excitons formed in QDs with electromagnetic field generated by materials exhibiting a strong LSPR. This coupling has been demonstrated to result either in the PL quenching or enhancement. Although this interaction has already been investigated in the visible region, it remains still unexplored for the NIR spectral range. Such investigation of the coupling of NIR luminescing QDs and appropriate NIR plasmonic nanomaterials constitutes the second major part of the project. Objectives: to develop new synthetic approaches to CuIn(Zn)Se(Te) QDs, based on cation exchange reactions; to enhance their stability and improve their optical properties via ZnS or ZnSe shelling; to design hybrid structures combining the NIR PL QDs with NIR plasmonic copper chalcogenide NCs with well controlled distance between them; to study the interactions between excitons and plasmons in the NIR region aiming at a PL enhancement and acceleration of the exciton recombination. Implementation: work program of the project is divided into four work packages relative to each objective. Each of them includes detailed tasks precisely assigned to two doctoral researchers. Potential Impact: innovative optoelectronic materials and opestructures with tunable photophysical properties, which will be developed, are very promising candidates for applications in bio-imaging, multiphoton imaging, fluorescence-lifetime imaging microscopy, photovoltaics, nanophotonics, solar concentrators, and sensing.