Design, preparation and characterization of mixed semiconductor nanocrystal-salt crystals as extremely photostable and highly efficient light emitting materials for optical applications

极高的光致发光量子产率（PL QY）和在应用相关条件下尽可能高的光稳定性是使用半导体（SC）纳米晶体（nc）作为光学器件中荧光标记和有源元件的先决条件。实现和保持高PL QY的典型方法是将scnc封装到鲁棒和透明的矩阵中。为此，我们建议采用不同晶格和折射率的无机盐（如NaCl、KCl、KJ、NH4J等）晶体作为基质，包埋不同材料组成和表面化学性质的胶体SCNCs，并在可见光和红外光谱区发射这些盐晶体，并将这些盐晶体整合成聚合物。我们初步研究了无机盐晶体对scnc光稳定性的保护和增强作用。提出的项目的目的是系统地研究我们新开发的结晶方法与不同类型的scnc的兼容性。这些将在水和有机溶液中制备，然后对表面化学性质进行表征。我们将应用复杂的光学表征方法，从而比较scnc在分散、盐基质以及盐基质-聚合物复合材料中的光学性质和光化学稳定性。待研究的纳米材料将包括含cd材料，如碲化镉；CdSe， CdHgTe或PbS以及潜在毒性较小的材料，如InP和CuInS（Se）。特别强调将致力于推导高发射和光稳定的scnc -盐晶体复合结构设计的结构-性能关系，该结构可能适用于固态照明，发光太阳能聚光器以及强大的近红外和红外发射源。为此，我们还将开发这些不同散射的scnc -盐晶体系统的PL - QY绝对测量方法。

Extremely high photoluminescence quantum yields (PL QY) and as high as possible photostability under application-relevant conditions are prerequisites for the use of semiconductor (SC) nanocrystals (NCs) as fluorescent labels and active components in optical devices. A typical approach to achieve and maintain a high PL QY is the encapsulation of SCNCs into robust and transparent matrices. For this purpose, we propose to use inorganic salt (e.g. NaCl, KCl, KJ, NH4J, etc.) crystals varying in crystal lattice and refractive index as matrices for embedding colloidal SCNCs of varying material composition and surface chemistry with emission in the visible and the infrared spectral region and the integration of these salt crystals into polymers. The protective and enhancing influence of inorganic salt crystals on the PL QY of SCNCs and their photostability was shown in first preliminary studies by us. The aim of the proposed project is the systematic study of the compatibility of our newly developed crystallization approaches with different types of SCNCs. Those will be prepared in aqueous and in organic solutions followed by characterization of the surface chemistries. We will apply sophisticated optical characterization methods, thereby comparing the optical properties and photochemical stability of the SCNCs in dispersion, in the salt matrix and, for selected systems, also as salt matrix-polymer composite materials. The NCs to be studied will include Cd-containing materials like CdTe; CdSe, CdHgTe or PbS and potentially less toxic materials like InP and CuInS(Se). Special emphasis will be dedicated to derive structure-property relations for the design of highly emissive and photostable SCNC-salt crystal composite structures potentially applicable for solid state lighting, luminescent solar concentrators as well as robust NIR and IR emission sources. For this purpose, we will also develop methods for the absolute measurement of PL QY of these differently scattering SCNC-salt crystal systems.