Impact of Stoichiometry on the Electronic Structure of PbS Quantum Dots
Although the stoichiometry of bulk lead sulfide (PbS) is exactly 1∶1, that of quantum dots (QDs) can be considerably different from this crystalline limit. Employing first-principles calculations, we show that the impact of PbS QD stoichiometry on the electronic structure can be enormous, suggesting...
| Main Authors: | , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
American Physical Society
2013
|
| Online Access: | http://hdl.handle.net/1721.1/81326 https://orcid.org/0000-0003-1281-2359 https://orcid.org/0000-0002-6419-4129 |
| _version_ | 1826200466659213312 |
|---|---|
| author | Kim, Donghun Kim, Dong-Ho Lee, Joo-Hyoung 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 Kim, Donghun Kim, Dong-Ho Lee, Joo-Hyoung Grossman, Jeffrey C. |
| author_sort | Kim, Donghun |
| collection | MIT |
| description | Although the stoichiometry of bulk lead sulfide (PbS) is exactly 1∶1, that of quantum dots (QDs) can be considerably different from this crystalline limit. Employing first-principles calculations, we show that the impact of PbS QD stoichiometry on the electronic structure can be enormous, suggesting that control over the overall stoichiometry in the QD will play a critical role for improving the efficiency of optoelectronic devices made with PbS QDs. In particular, for bare PbS QDs, we find that: (i) stoichiometric PbS QDs are free from midgap states even without ligand passivation and independent of shape, (ii) off stoichiometry in PbS QDs introduces new states in the gap that are highly localized on certain surface atoms, and (iii) further deviations in stoichiometry lead to QDs with “metallic” behavior, with a dense number of energy states near the Fermi level. We further demonstrate that this framework holds for the case of passivated QDs by considering the attachment of ligand molecules as stoichiometry variations. Our calculations show that an optimal number of ligands makes the QD stoichiometric and heals unfavorable electronic structure, whereas too few or too many ligands cause effective off stoichiometry, resulting in QDs with defect states in the gap. |
| first_indexed | 2024-09-23T11:36:56Z |
| format | Article |
| id | mit-1721.1/81326 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T11:36:56Z |
| publishDate | 2013 |
| publisher | American Physical Society |
| record_format | dspace |
| spelling | mit-1721.1/813262022-09-27T20:45:10Z Impact of Stoichiometry on the Electronic Structure of PbS Quantum Dots Kim, Donghun Kim, Dong-Ho Lee, Joo-Hyoung Grossman, Jeffrey C. Massachusetts Institute of Technology. Department of Materials Science and Engineering Kim, Donghun Grossman, Jeffrey C. Although the stoichiometry of bulk lead sulfide (PbS) is exactly 1∶1, that of quantum dots (QDs) can be considerably different from this crystalline limit. Employing first-principles calculations, we show that the impact of PbS QD stoichiometry on the electronic structure can be enormous, suggesting that control over the overall stoichiometry in the QD will play a critical role for improving the efficiency of optoelectronic devices made with PbS QDs. In particular, for bare PbS QDs, we find that: (i) stoichiometric PbS QDs are free from midgap states even without ligand passivation and independent of shape, (ii) off stoichiometry in PbS QDs introduces new states in the gap that are highly localized on certain surface atoms, and (iii) further deviations in stoichiometry lead to QDs with “metallic” behavior, with a dense number of energy states near the Fermi level. We further demonstrate that this framework holds for the case of passivated QDs by considering the attachment of ligand molecules as stoichiometry variations. Our calculations show that an optimal number of ligands makes the QD stoichiometric and heals unfavorable electronic structure, whereas too few or too many ligands cause effective off stoichiometry, resulting in QDs with defect states in the gap. Samsung Electronics Co. (Scholarship foundation) 2013-10-04T17:15:12Z 2013-10-04T17:15:12Z 2013-05 2012-12 Article http://purl.org/eprint/type/JournalArticle 0031-9007 1079-7114 http://hdl.handle.net/1721.1/81326 Kim, Donghun, Dong-Ho Kim, Joo-Hyoung Lee, and Jeffrey C. Grossman. Impact of Stoichiometry on the Electronic Structure of PbS Quantum Dots. Physical Review Letters 110, no. 19 (May 2013). © 2013 American Physical Society. https://orcid.org/0000-0003-1281-2359 https://orcid.org/0000-0002-6419-4129 en_US http://dx.doi.org/10.1103/PhysRevLett.110.196802 Physical Review Letters 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 Physical Society APS |
| spellingShingle | Kim, Donghun Kim, Dong-Ho Lee, Joo-Hyoung Grossman, Jeffrey C. Impact of Stoichiometry on the Electronic Structure of PbS Quantum Dots |
| title | Impact of Stoichiometry on the Electronic Structure of PbS Quantum Dots |
| title_full | Impact of Stoichiometry on the Electronic Structure of PbS Quantum Dots |
| title_fullStr | Impact of Stoichiometry on the Electronic Structure of PbS Quantum Dots |
| title_full_unstemmed | Impact of Stoichiometry on the Electronic Structure of PbS Quantum Dots |
| title_short | Impact of Stoichiometry on the Electronic Structure of PbS Quantum Dots |
| title_sort | impact of stoichiometry on the electronic structure of pbs quantum dots |
| url | http://hdl.handle.net/1721.1/81326 https://orcid.org/0000-0003-1281-2359 https://orcid.org/0000-0002-6419-4129 |
| work_keys_str_mv | AT kimdonghun impactofstoichiometryontheelectronicstructureofpbsquantumdots AT kimdongho impactofstoichiometryontheelectronicstructureofpbsquantumdots AT leejoohyoung impactofstoichiometryontheelectronicstructureofpbsquantumdots AT grossmanjeffreyc impactofstoichiometryontheelectronicstructureofpbsquantumdots |