Issue 15, 2023

Hot carrier relaxation dynamics in non-stoichiometric CdSe quantum dots: computational insights

Abstract

Spatial confinement of charge carriers in nanosize semiconductor quantum dots (QDs) results in highly tunable, size-dependent optoelectronic properties that can be utilized in various commercial applications. Although in such nanostructures, non-stoichiometry is frequently encountered using conventional synthesis techniques, it is not often addressed or considered. Here, we perform ab initio molecular dynamics simulations on non-stoichiometric CdSe clusters to study the phonon-mediated charge carrier relaxation dynamics. We model cation-rich and anion-rich QDs passivated with monocharged neutralizing ligands of different sizes. Our studies confirm the presence of localized trap states at the valence band edge in only anion-rich QDs due to the presence of undercoordinated exposed surface Se atoms. Noteworthily, these localized states disappear when using bulkier ligands. Calculations reveal that the size of the ligands controls the crystal vibrations and electron–phonon coupling, while ligand coordination number affects the electronic structure. For a particular non-stoichiometric CdSe QD, a change of a ligand can either increase or decrease the total electron relaxation time compared to that of stoichiometric QDs. Our results emphasize the importance of ligand engineering in non-stoichiometric QDs for photoinduced dynamics and guide future work for the implementation of improved materials for optoelectronic devices.

Graphical abstract: Hot carrier relaxation dynamics in non-stoichiometric CdSe quantum dots: computational insights

  • This article is part of the themed collection: #MyFirstJMCA

Supplementary files

Article information

Article type
Paper
Submitted
09 Jan 2023
Accepted
15 Mar 2023
First published
15 Mar 2023
This article is Open Access
Creative Commons BY license

J. Mater. Chem. A, 2023,11, 8256-8264

Hot carrier relaxation dynamics in non-stoichiometric CdSe quantum dots: computational insights

S. Gumber, O. Eniodunmo, S. A. Ivanov, S. Kilina, O. V. Prezhdo, D. Ghosh and S. Tretiak, J. Mater. Chem. A, 2023, 11, 8256 DOI: 10.1039/D3TA00149K

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements