PCJ Clark
The passivating effect of cadmium in PbS/CdS colloidal quantum dots probed by nm-scale depth profiling
Clark, PCJ; Radtke, H; Pengpad, A; Williamson, AI; Spencer, BF; Hardman, SJO; Leontiadou, M; Neo, DCJ; Fairclough, SM; Watt, AAR; Pis, I; Nappini, S; Bondino, F; Magnano, E; Handrup, K; Schulte, K; Silly, MG; Sirotti, F; Flavell, WR
Authors
H Radtke
A Pengpad
AI Williamson
BF Spencer
SJO Hardman
Dr Marina Leontiadou M.Leontiadou@salford.ac.uk
Associate Professor/Reader
DCJ Neo
SM Fairclough
AAR Watt
I Pis
S Nappini
F Bondino
E Magnano
K Handrup
K Schulte
MG Silly
F Sirotti
WR Flavell
Abstract
Achieving control of the surface chemistry of colloidal quantum dots (CQDs) is essential to fully exploit their properties in solar cells, but direct measurement of the chemistry and electronic structure in the outermost atomic layers is challenging. Here we probe the surface oxidation and passivation of cation-exchanged PbS/CdS core/shell CQDs with sub nm-scale precision using synchrotron-radiation-excited depth-profiling photoemission. We investigate the surface composition of the topmost 1–2.5 nm of the CQDs as a function of depth, for CQDs of varying CdS shell thickness, and examine how the surface changes after prolonged air exposure. We demonstrate that the Cd is localized at the surface of the CQDs. The surface-localized products of oxidation are identified, and the extent of oxidation quantified. We show that oxidised sulfur species are progressively eliminated as Cd replaces Pb at the surface. A sub-monolayer surface ‘decoration’ of Cd is found to be effective in passivating the CQDs. We show that the measured energy-level alignments at PbS/CdS colloidal quantum dot surfaces differ from those expected on the basis of bulk band offsets, and are strongly affected by the oxidation products. We develop a model for the passivating action of Cd. The optimum shell thickness (of around 0.1 nm, previously found to give maximised power conversion efficiency in PbS/CdS solar cells) is found to correspond to a trade-off between the rate of oxidation and the introduction of a surface barrier to charge transport.
Citation
Clark, P., Radtke, H., Pengpad, A., Williamson, A., Spencer, B., Hardman, S., …Flavell, W. (2017). The passivating effect of cadmium in PbS/CdS colloidal quantum dots probed by nm-scale depth profiling. Nanoscale, 9(2017), 6056-6067. https://doi.org/10.1039/c7nr00672a
Journal Article Type | Article |
---|---|
Acceptance Date | Apr 7, 2017 |
Online Publication Date | Apr 10, 2017 |
Publication Date | Apr 10, 2017 |
Deposit Date | Apr 1, 2019 |
Publicly Available Date | Apr 1, 2019 |
Journal | Nanoscale |
Print ISSN | 2040-3364 |
Publisher | Royal Society of Chemistry |
Volume | 9 |
Issue | 2017 |
Pages | 6056-6067 |
DOI | https://doi.org/10.1039/c7nr00672a |
Publisher URL | https://doi.org/10.1039/c7nr00672a |
Related Public URLs | https://pubs.rsc.org/en/journals/journalissues/nr#!recentarticles&adv |
Files
c7nr00672a.pdf
(3.5 Mb)
PDF
Licence
http://creativecommons.org/licenses/by/3.0/
Publisher Licence URL
http://creativecommons.org/licenses/by/3.0/
You might also like
Ultrafast charge dynamics in dispersions of monolayer MoS2 nanosheets
(2017)
Journal Article
Multiple exciton generation and dynamics in InP/CdS colloidal quantum dots
(2017)
Journal Article
Downloadable Citations
About USIR
Administrator e-mail: library-research@salford.ac.uk
This application uses the following open-source libraries:
SheetJS Community Edition
Apache License Version 2.0 (http://www.apache.org/licenses/)
PDF.js
Apache License Version 2.0 (http://www.apache.org/licenses/)
Font Awesome
SIL OFL 1.1 (http://scripts.sil.org/OFL)
MIT License (http://opensource.org/licenses/mit-license.html)
CC BY 3.0 ( http://creativecommons.org/licenses/by/3.0/)
Powered by Worktribe © 2024
Advanced Search