Observation of quantum-confined exciton states in monolayer WS2quantum dots by ultrafast spectroscopy

doi:10.1039/d1nr04868f

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	Observation of quantum-confined exciton states in monolayer WS2quantum dots by ultrafast spectroscopy
	S.-W. Zheng; L. Wang; H.-Y. Wang; C.-Y. Xu; Y. Luo and H.-B. Sun
	2021
发表期刊	Nanoscale
ISSN	20403364
卷号	13 期号:40 页码:17093-17100
摘要	Monolayer transition metal dichalcogenide quantum dots (TMDC QDs) could exhibit unique photophysical properties, because of both lateral quantum confinement effect and edge effect. However, there is little fundamental study on the quantum-confined exciton dynamics in monolayer TMDC QDs, to date. Here, by selective excitations of monolayer WS2 QDs in broadband transient absorption (TA) spectroscopy experiments, the excitation-wavelength-dependent ground state bleaching signals corresponding to the quantum-confined exciton states are directly observed. Compared to the time-resolved photophysical properties of WS2 nanosheets, the selected monolayer WS2 QDs only show one ground state bleaching peak with larger initial values for the linear polarization anisotropy of band-edge excitons, probably due to the expired spin-orbit coupling. This suggests a complete change of the band structure for monolayer WS2 QDs. In the femtosecond time-resolved circular polarization anisotropy experiments, a valley depolarization time of 100 fs is observed for WS2 nanosheets at room temperature, which is not observed for monolayer WS2 QDs. Our findings suggest a strong state-mixing of band-edge valley excitons responsible for the large linear polarization in monolayer WS2 QDs, which could be helpful for understanding the exciton relaxation mechanisms in colloidal monolayer TMDC QDs. 2021 The Royal Society of Chemistry.
DOI	10.1039/d1nr04868f
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收录类别	SCI ; EI
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文献类型	期刊论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/65475
专题	中国科学院长春光学精密机械与物理研究所
推荐引用方式 GB/T 7714	S.-W. Zheng,L. Wang,H.-Y. Wang,et al. Observation of quantum-confined exciton states in monolayer WS2quantum dots by ultrafast spectroscopy[J]. Nanoscale,2021,13(40):17093-17100.
APA	S.-W. Zheng,L. Wang,H.-Y. Wang,C.-Y. Xu,&Y. Luo and H.-B. Sun.(2021).Observation of quantum-confined exciton states in monolayer WS2quantum dots by ultrafast spectroscopy.Nanoscale,13(40),17093-17100.
MLA	S.-W. Zheng,et al."Observation of quantum-confined exciton states in monolayer WS2quantum dots by ultrafast spectroscopy".Nanoscale 13.40(2021):17093-17100.

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