Ligand-Induced Size-Dependent Circular Dichroism in Quantum Dots,The Journal of Physical Chemistry Letters

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Ligand-Induced Size-Dependent Circular Dichroism in Quantum Dots
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2024-07-25 , DOI: 10.1021/acs.jpclett.4c01682
Daniel Chabeda ₁ , Stephen Gee ₂ , Eran Rabani _{1,

3,

4}

Affiliation

Recent experiments have probed the chiral properties of semiconductor nanocrystal (NC) quantum dots (QDs), but understanding the circular dichroism line shape, excitonic features, and chirality induction mechanism remains a challenge. We propose an atomistic pseudopotential method to model chiral ligand passivated QDs, computing circular dichroism (CD) spectra for CdSe QDs (2.6–3.8 nm). We find strong agreement between calculated and measured line shapes, predicting consistent bisignate line shapes with decreasing CD magnitude as size increases. Our analysis reveals the origin of bisignate line shapes, arising from nondegenerate excitons with opposing angular momenta. We also explore the impact of chiral ligand orientation on QD surfaces, observing changes in the optical activity magnitude and sign. This orientation sensitivity offers the means to distinguish ordered from disordered ligand configurations, facilitating the study of order–disorder transitions at ligand–QD interfaces.

中文翻译：

量子点中配体诱导的尺寸依赖性圆二色性

最近的实验探索了半导体纳米晶体（NC）量子点（QD）的手性特性，但了解圆二色性线形状、激子特征和手性感应机制仍然是一个挑战。我们提出了一种原子赝势方法来模拟手性配体钝化量子点，计算 CdSe 量子点（2.6-3.8 nm）的圆二色性（CD）光谱。我们发现计算的线形状和测量的线形状之间有很强的一致性，预测一致的双符号线形状随着尺寸的增加 CD 幅度减小。我们的分析揭示了双符号线形状的起源，它是由具有相反角动量的非简并激子产生的。我们还探索了手性配体方向对量子点表面的影响，观察光学活性大小和符号的变化。这种方向敏感性提供了区分有序和无序配体构型的方法，有助于研究配体-QD界面的有序-无序转变。

更新日期：2024-07-25

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