Pluta Denis, Graf Rebecca T, Dorfs Dirk, Bigall Nadja C
Institute of Physical Chemistry and Electrochemistry, Leibniz University Hannover, Callinstraße 3A, Hannover 30167, Germany.
Laboratory of Nano and Quantum Engineering, Leibniz University Hannover, Schneiderberg 39, Hannover 30167, Germany.
Phys Chem Chem Phys. 2024 Oct 17;26(40):25828-25836. doi: 10.1039/d4cp02427c.
Nanocrystal (NC) assemblies, such as films or NC-based three-dimensional networks, provide insight into the nanoscopic properties of their building blocks, and are macroscopic materials. In NC assemblies in general, interactions between the building blocks have to be considered, since a decrease of the distance between the NCs allows phenomena such as energy transfer to occur. Novel quantum dot-based aerogels with optical properties in the near-infrared (NIR) region are not characterized in terms of these important properties in the literature, while the structural complexity of these networks raises questions about the interactions within. Since knowledge about the physical phenomena is vital for applications, we here investigate the photoluminescence (PL) of PbS/CdS QD-based assemblies, namely drop-cast films and aerogels with steady-state measurements at cryogenic temperatures and time-resolved measurements at room temperature. We find multiple emissive in-gap states (IGS), and a correlation between the number of nearest QD neighbors, the distance between the QDs in the assemblies and the non-radiative recombination rate by linking the observations to different energy transfer phenomena.
纳米晶体（NC）组件，如薄膜或基于NC的三维网络，能让人们深入了解其组成单元的纳米特性，并且它们是宏观材料。一般来说，在NC组件中，必须考虑组成单元之间的相互作用，因为NC之间距离的减小会使诸如能量转移等现象发生。具有近红外（NIR）区域光学特性的新型量子点基气凝胶在文献中尚未根据这些重要特性进行表征，而这些网络的结构复杂性引发了关于其内部相互作用的问题。由于对物理现象的了解对于应用至关重要，我们在此研究基于PbS/CdS量子点的组件的光致发光（PL），即通过低温下的稳态测量和室温下的时间分辨测量，研究滴铸薄膜和气凝胶。我们发现了多个发射性带隙内态（IGS），并通过将观察结果与不同的能量转移现象联系起来，发现了最近量子点邻居数量、组件中量子点之间的距离与非辐射复合率之间的相关性。
