Abstract
Cation exchange has become a major postsynthetic tool to obtain nanocrystals with a combination of stoichiometry, size, and shape that is challenging to achieve by direct wet-chemical synthesis. Here, we report on the transformation of highly anisotropic, ultrathin, and planar PbS nanosheets into CdS nanosheets of the same dimensions. We monitor the evolution of the Cd-for-Pb exchange by ex-situ TEM, HAADF-STEM, and EDX. We observe that in the early stages of the exchange the sheets show large in-sheet voids that repair spontaneously upon further exchange and annealing, resulting in ultrathin, planar, and crystalline CdS nanosheets. After cation exchange, the nanosheets show broad sub-band gap luminescence, as often observed in CdS nanocrystals. The photoluminescence excitation spectrum reveals the heavy- and light-hole exciton features, with very strong quantum confinement and large electron–hole Coulomb energy, typical for 2D ultrathin Cd-chalcogenide nanosheets.
Original language | English |
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Pages (from-to) | 8301-8308 |
Number of pages | 8 |
Journal | Chemistry of Materials |
Volume | 35 |
Issue number | 19 |
DOIs | |
Publication status | Published - 10 Oct 2023 |
Bibliographical note
Publisher Copyright:© 2023 The Authors. Published by American Chemical Society.
Funding
M.M.S. and D.V. acknowledge financial support from the European ERC Council, ERC Advanced grant 692691 “First Step”. D.V. acknowledges the research program “Materials for the Quantum Age” (QuMat) for financial support, which is part of the Gravitation program financed by the Dutch Ministry of Education, Culture and Science (OCW, registration number 024.005.006).
Funders | Funder number |
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European ERC Council | |
European Research Council | 692691 |
Ministerie van onderwijs, cultuur en wetenschap | 024.005.006 |
Keywords
- Ligand-exchange
- Nanocrystals
- Nanoplatelets
- Quantum dots