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Title: Trap Passivation in Indium-Based Quantum Dots through Surface Fluorination: Mechanism and Applications

Abstract

Treatment of InP colloidal quantum dots (QDs) with hydrofluoric acid (HF) has been an effective method to improve their photoluminescence quantum yield (PLQY) without growing a shell. Previous work has shown that this can occur through the dissolution of the fluorinated phosphorus and subsequent passivation of indium on the reconstructed surface by excess ligands. In this article, we demonstrate that very significant luminescence enhancements occur at lower HF exposure though a different mechanism. At lower exposure to HF, the main role of the fluoride ions is to directly passivate the surface indium dangling bonds in the form of atomic ligands. The PLQY enhancement in this case is accompanied by red shifts of the emission and absorption peaks rather than blue shifts caused by etching as seen at higher exposures. Density functional theory shows that the surface fluorination is thermodynamically preferred and that the observed spectral characteristics might be due to greater exciton delocalization over the outermost surface layer of the InP QDs as well as alteration of the optical oscillator strength by the highly electronegative fluoride layer. Passivation of surface indium with fluorides can be applied to other indium-based QDs. PLQY of InAs QDs could also be increased by anmore » order of magnitude via fluorination. We fabricated fluorinated InAs QD-based electrical devices exhibiting improved switching and higher mobility than those of 1,2-ethanedithiol cross-linked QD devices. The effective surface passivation eliminates persistent photoconductivity usually found in InAs QD-based solid films.« less

Authors:
 [1];  [2]; ORCiD logo [3];  [4];  [2];  [5]; ORCiD logo [6]
  1. Samsung Advanced Institute of Technology, Suwon (Korea); Univ. of California, Berkeley, CA (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Technion-Israel Inst. of Technology, Haifa (Israel)
  4. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  5. Samsung Advanced Inst. of Technology, Suwon (Korea)
  6. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kavli Energy NanoScience Inst., Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1545143
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 12; Journal Issue: 11; Journal ID: ISSN 1936-0851
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; indium phosphide; quantum dots; fluorine; etching; atomic ligand; indium arsenide

Citation Formats

Kim, Tae -Gon, Zherebetskyy, Danylo, Bekenstein, Yehonadav, Oh, Myoung Hwan, Wang, Lin -Wang, Jang, Eunjoo, and Alivisatos, A. Paul. Trap Passivation in Indium-Based Quantum Dots through Surface Fluorination: Mechanism and Applications. United States: N. p., 2018. Web. doi:10.1021/acsnano.8b06692.
Kim, Tae -Gon, Zherebetskyy, Danylo, Bekenstein, Yehonadav, Oh, Myoung Hwan, Wang, Lin -Wang, Jang, Eunjoo, & Alivisatos, A. Paul. Trap Passivation in Indium-Based Quantum Dots through Surface Fluorination: Mechanism and Applications. United States. doi:10.1021/acsnano.8b06692.
Kim, Tae -Gon, Zherebetskyy, Danylo, Bekenstein, Yehonadav, Oh, Myoung Hwan, Wang, Lin -Wang, Jang, Eunjoo, and Alivisatos, A. Paul. Tue . "Trap Passivation in Indium-Based Quantum Dots through Surface Fluorination: Mechanism and Applications". United States. doi:10.1021/acsnano.8b06692. https://www.osti.gov/servlets/purl/1545143.
@article{osti_1545143,
title = {Trap Passivation in Indium-Based Quantum Dots through Surface Fluorination: Mechanism and Applications},
author = {Kim, Tae -Gon and Zherebetskyy, Danylo and Bekenstein, Yehonadav and Oh, Myoung Hwan and Wang, Lin -Wang and Jang, Eunjoo and Alivisatos, A. Paul},
abstractNote = {Treatment of InP colloidal quantum dots (QDs) with hydrofluoric acid (HF) has been an effective method to improve their photoluminescence quantum yield (PLQY) without growing a shell. Previous work has shown that this can occur through the dissolution of the fluorinated phosphorus and subsequent passivation of indium on the reconstructed surface by excess ligands. In this article, we demonstrate that very significant luminescence enhancements occur at lower HF exposure though a different mechanism. At lower exposure to HF, the main role of the fluoride ions is to directly passivate the surface indium dangling bonds in the form of atomic ligands. The PLQY enhancement in this case is accompanied by red shifts of the emission and absorption peaks rather than blue shifts caused by etching as seen at higher exposures. Density functional theory shows that the surface fluorination is thermodynamically preferred and that the observed spectral characteristics might be due to greater exciton delocalization over the outermost surface layer of the InP QDs as well as alteration of the optical oscillator strength by the highly electronegative fluoride layer. Passivation of surface indium with fluorides can be applied to other indium-based QDs. PLQY of InAs QDs could also be increased by an order of magnitude via fluorination. We fabricated fluorinated InAs QD-based electrical devices exhibiting improved switching and higher mobility than those of 1,2-ethanedithiol cross-linked QD devices. The effective surface passivation eliminates persistent photoconductivity usually found in InAs QD-based solid films.},
doi = {10.1021/acsnano.8b06692},
journal = {ACS Nano},
number = 11,
volume = 12,
place = {United States},
year = {2018},
month = {10}
}

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Cited by: 17 works
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Figures / Tables:

Figure 1 Figure 1: (a) Optical absorption and (b) photoluminescence (PL) spectra of pristine InP QDs (black), HF-treated InP QDs (orange), and HF-treated InP QDs after 1-month aging at room temperature (red) normalized by the optical density at 450 nm as an excitation wavelength. Absorption peak positions and relative PL intensities ofmore » HF-treated InP QDs as functions of (c) distilled water concentrations (0, 0.4, 1, 2, 4, and 10 vol %) at [HF]/[QD] = 1000 and (d) [HF]/[QD] = 0, 10, 100, 1000, and 10000 without adding water. Red solid circle and vacant diamond in (c) indicate the absorption peak position and the relative PL intensity before the HF treatment, respectively.« less

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Works referencing / citing this record:

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Unraveling the role of zinc complexes on indium phosphide nanocrystal chemistry
journal, November 2019

  • McVey, B. F. P.; Swain, R. A.; Lagarde, D.
  • The Journal of Chemical Physics, Vol. 151, Issue 19
  • DOI: 10.1063/1.5128234