Resolving the Triexciton Recombination Pathway in CdSe/CdS Nanocrystals through State-Specific Correlation Measurements,Nano Letters

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Resolving the Triexciton Recombination Pathway in CdSe/CdS Nanocrystals through State-Specific Correlation Measurements
Nano Letters ( IF 9.6 ) Pub Date : 2021-09-13 , DOI: 10.1021/acs.nanolett.0c05109
Katherine E Shulenberger ₁ , Sophie C Coppieters 't Wallant ₁ , Megan D Klein ₁ , Alexandra R McIsaac ₁ , Tamar Goldzak ₁ , David B Berkinsky ₁ , Hendrik Utzat ₁ , Ulugbek Barotov ₁ , Troy Van Voorhis ₁ , Moungi G Bawendi ₁

Affiliation

As luminescence applications of colloidal semiconductor nanocrystals push toward higher excitation flux conditions, there is an increased need to both understand and potentially control emission from multiexciton states. We develop a spectrally resolved correlation method to study the triply excited state that enables direct measurements of the recombination pathway for the triexciton, rather than relying on indirect extraction of rates. We demonstrate that, for core–shell CdSe–CdS nanocrystals, triexciton emission arises exclusively from the band-edge S-like state. Time-dependent density functional theory and extended particle-in-a-sphere calculations demonstrate that reduced carrier overlap induced by the core–shell heterostructure can account for the lack of emission observed from the P-like state. These results provide a potential avenue for the control of nanocrystal luminescence, where core–shell heterostructures can be leveraged to control carrier separation and therefore maintain emission color purity over a broader range of excitation fluxes.

中文翻译：

通过状态特异性相关测量解析 CdSe/CdS 纳米晶体中的三激子复合途径

随着胶体半导体纳米晶体的发光应用朝着更高的激发通量条件发展，越来越需要了解和潜在地控制多激子态的发射。我们开发了一种光谱解析相关方法来研究三重激发态，该方法能够直接测量三激子的重组途径，而不是依赖于速率的间接提取。我们证明，对于核-壳 CdSe-CdS 纳米晶体，三激子发射完全来自带边 S 状状态。时间相关的密度泛函理论和扩展的球中粒子计算表明，核壳异质结构引起的载流子重叠减少可以解释从 P 状态观察到的发射缺乏。

更新日期：2021-09-22

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