Origins of the Stokes Shift in PbS Quantum Dots: Impact of Polydispersity, Ligands, and Defects
© 2018 American Chemical Society. Understanding the origins of the excessive Stokes shift in the lead chalcogenides family of colloidal quantum dots (CQDs) is of great importance at both the fundamental and applied levels; however, our current understanding is far from satisfactory. Here, utilizing...
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| Format: | Article |
| Language: | English |
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American Chemical Society (ACS)
2021
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| Online Access: | https://hdl.handle.net/1721.1/135791 |
| _version_ | 1826193881568378880 |
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| author | Liu, Yun Kim, Donghun Morris, Owen P Zhitomirsky, David Grossman, Jeffrey C |
| author2 | Massachusetts Institute of Technology. Department of Materials Science and Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Materials Science and Engineering Liu, Yun Kim, Donghun Morris, Owen P Zhitomirsky, David Grossman, Jeffrey C |
| author_sort | Liu, Yun |
| collection | MIT |
| description | © 2018 American Chemical Society. Understanding the origins of the excessive Stokes shift in the lead chalcogenides family of colloidal quantum dots (CQDs) is of great importance at both the fundamental and applied levels; however, our current understanding is far from satisfactory. Here, utilizing a combination of ab initio computations and UV-vis and photoluminescence measurements, we investigated the contributions to the Stokes shift from polydispersity, ligands, and defects in PbS CQDs. The key results are as follows: (1) The size and energetic disorder of a polydisperse CQD film increase the Stokes shift by 20 to 50 meV compared to that of an isolated CQD; (2) Franck-Condon (FC) shifts increase as the electronegativities of the ligands increase, but the variations are small (<15 meV). (3) Unlike the aforementioned two minor factors, the presence of certain intrinsic defects such as VCl+ (in Cl-passivated CQDs) can cause substantial electron density localization of the band edge states and consequent large FC shifts (100s of meV). This effect arising from defects can explain the excessive Stokes shifts in PbS CQDs and improve our understanding of the optical properties of PbS CQDs. |
| first_indexed | 2024-09-23T09:46:47Z |
| format | Article |
| id | mit-1721.1/135791 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T09:46:47Z |
| publishDate | 2021 |
| publisher | American Chemical Society (ACS) |
| record_format | dspace |
| spelling | mit-1721.1/1357912023-02-24T18:37:36Z Origins of the Stokes Shift in PbS Quantum Dots: Impact of Polydispersity, Ligands, and Defects Liu, Yun Kim, Donghun Morris, Owen P Zhitomirsky, David Grossman, Jeffrey C Massachusetts Institute of Technology. Department of Materials Science and Engineering © 2018 American Chemical Society. Understanding the origins of the excessive Stokes shift in the lead chalcogenides family of colloidal quantum dots (CQDs) is of great importance at both the fundamental and applied levels; however, our current understanding is far from satisfactory. Here, utilizing a combination of ab initio computations and UV-vis and photoluminescence measurements, we investigated the contributions to the Stokes shift from polydispersity, ligands, and defects in PbS CQDs. The key results are as follows: (1) The size and energetic disorder of a polydisperse CQD film increase the Stokes shift by 20 to 50 meV compared to that of an isolated CQD; (2) Franck-Condon (FC) shifts increase as the electronegativities of the ligands increase, but the variations are small (<15 meV). (3) Unlike the aforementioned two minor factors, the presence of certain intrinsic defects such as VCl+ (in Cl-passivated CQDs) can cause substantial electron density localization of the band edge states and consequent large FC shifts (100s of meV). This effect arising from defects can explain the excessive Stokes shifts in PbS CQDs and improve our understanding of the optical properties of PbS CQDs. 2021-10-27T20:29:19Z 2021-10-27T20:29:19Z 2018 2019-09-19T14:08:13Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/135791 en 10.1021/ACSNANO.8B00132 ACS Nano Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Chemical Society (ACS) MIT web domain |
| spellingShingle | Liu, Yun Kim, Donghun Morris, Owen P Zhitomirsky, David Grossman, Jeffrey C Origins of the Stokes Shift in PbS Quantum Dots: Impact of Polydispersity, Ligands, and Defects |
| title | Origins of the Stokes Shift in PbS Quantum Dots: Impact of Polydispersity, Ligands, and Defects |
| title_full | Origins of the Stokes Shift in PbS Quantum Dots: Impact of Polydispersity, Ligands, and Defects |
| title_fullStr | Origins of the Stokes Shift in PbS Quantum Dots: Impact of Polydispersity, Ligands, and Defects |
| title_full_unstemmed | Origins of the Stokes Shift in PbS Quantum Dots: Impact of Polydispersity, Ligands, and Defects |
| title_short | Origins of the Stokes Shift in PbS Quantum Dots: Impact of Polydispersity, Ligands, and Defects |
| title_sort | origins of the stokes shift in pbs quantum dots impact of polydispersity ligands and defects |
| url | https://hdl.handle.net/1721.1/135791 |
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