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

目的：1）开发低毒性的基于胶体铜硫属化物的量子点（QD），其具有可调的尺寸、组成和形状，并且表现出在整个近红外（NIR）光谱区域上延伸的光致发光（PL（700-2500 nm），量子产率高达80%; 2）基于这些量子点和等离子体铜硫族化物纳米晶体（NC）设计混合PL局域表面等离子体共振（LSPR）系统具有可控的激子动力学。动机：虽然可见光范围被具有相当有效的光吸收和荧光特性的各种QD完全覆盖，但是NIR活性材料受到PbA（A = S、Se、Te）、InAs、Cd 3 P2、CdHgTe和HgTe的限制。由于所有这些化合物都含有有毒元素，它们的潜在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物的三元和四元QD，例如CuIn（Zn）S（Se）。然而，这些量子点的光吸收/发射的范围被限制到约100 nm。1200 nm，即目前出现的CuInS（Se）QD，在NIR中发荧光更远，尚未开发。这正是本项目旨在做出重大贡献的地方。此外，这些低毒性量子点表现出复杂的激子动力学，可以用作调节其物理性质的额外手柄。用于这种调谐的手段之一是在QD中形成的激子与由表现出强LSPR的材料产生的电磁场的相互作用。这种耦合已被证明导致PL猝灭或增强。虽然这种相互作用已经在可见光区域进行了研究，但在近红外光谱范围内仍然没有进行探索。这种近红外发光量子点和适当的近红外等离子体纳米材料的耦合研究构成了该项目的第二个主要部分。目的：开发基于阳离子交换反应的CuIn（Zn）Se（Te）QD的新合成方法;通过ZnS或ZnSe壳化增强其稳定性并改善其光学性质;设计将NIR PL QD与NIR等离子体铜硫属化物NC组合的混合结构，其中它们之间的距离得到良好控制;研究激子和等离子体激元之间的相互作用，在近红外区域旨在PL增强和激子复合的加速。实施：项目的工作计划分为与每个目标相关的四个工作包。每个项目都包括精确分配给两名博士研究人员的详细任务。潜在影响：将开发的具有可调光物理特性的创新光电材料和opestructures是在生物成像、多光子成像、荧光寿命成像显微术、光致发光学、纳米光子学、太阳能集中器和传感器中应用的非常有前途的候选者。

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.