Hot carrier relaxation dynamics in non-stoichiometric CdSe quantum dots: computational insights
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- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Dept. Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, USA, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Dept. Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, USA
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA, Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, USA
- Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi-110016, India, Department of Materials Science and Engineering (DMSE), Indian Institute of Technology, Delhi, Hauz Khas, New Delhi-110016, India
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
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, in this study, 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.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- 89233218NCA000001; AC02-439 05CH11231; SC0014429; 89233218CNA000001
- OSTI ID:
- 2007438
- Alternate ID(s):
- OSTI ID: 1963758; OSTI ID: 1972123
- Report Number(s):
- LA-UR-23-20127; JMCAET
- Journal Information:
- Journal of Materials Chemistry. A, Journal Name: Journal of Materials Chemistry. A Vol. 11 Journal Issue: 15; ISSN 2050-7488
- Publisher:
- Royal Society of Chemistry (RSC)Copyright Statement
- Country of Publication:
- United Kingdom
- Language:
- English
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