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Spectral shift, electronic coupling and exciton delocalization in nanocrystal dimers: insights from all-atom electronic structure computations.
Nanoscale ( IF 5.8 ) Pub Date : 2020-08-18 , DOI: 10.1039/d0nr05601d
Maurizio Coden 1 , Pietro De Checchi 1 , Barbara Fresch 1
Affiliation  

Delocalization of excitons promoted by electronic coupling between clusters or quantum dots (QD) changes the dynamical processes in nanostructured aggregates enhancing energy transport. A spectroscopic shift of the absorption spectrum upon QD aggregation is commonly observed and ascribed to quantum mechanical coupling between neighbouring dots but also to exciton delocalization over the sulphur-based ligand shell or to other mechanisms as a change in the dielectric constant of the surrounding medium. We address the question of electronic coupling and exciton delocalization in nanocrystal aggregates by performing all-atom electronic structure calculations in models of colloidal QD dimers. The relation between spectral shift, interdot coupling and exciton delocalization is investigated in atomistic detail in models of dimers formed by CdSe clusters kept together by bridging organic ligands. Our results support the possibility of obtaining exciton delocalization over the dimer and point out the crucial role of the bridging ligand in enhancing interdot electronic coupling.

中文翻译:

纳米晶体二聚体中的光谱位移,电子耦合和激子离域:从全原子电子结构计算中获得的见解。

由团簇或量子点(QD)之间的电子耦合促进的激子的离域改变改变了纳米结构聚集体中的动力学过程,从而增强了能量传输。通常观察到QD聚集时吸收光谱的光谱移动,这归因于相邻点之间的量子机械耦合,也归因于基于硫的配体壳上的激子离域,或归因于周围介质介电常数的变化的其他机理。我们通过在胶体QD二聚体模型中执行全原子电子结构计算,解决了纳米晶聚集体中电子耦合和激子离域的问题。光谱偏移之间的关系 在CdSe簇通过桥接有机配体而保持在一起的二聚体模型中,对原子间耦合和激子离域进行了原子详细的研究。我们的结果支持在二聚体上获得激子离域的可能性,并指出桥接配体在增强点间电子耦合中的关键作用。
更新日期:2020-09-18
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