Acid-Assisted Ligand Exchange Enhances Coupling in Colloidal Quantum Dot Solids

Jea Woong Jo; Jongmin Choi; F. Pelayo García De Arquer; Ali Seifitokaldani; Bin Sun; Younghoon Kim; Hyungju Ahn; James Fan; Rafael Quintero-Bermudez; Junghwan Kim; Min Jae Choi; Se Woong Baek; Andrew H. Proppe; Grant Walters; Dae Hyun Nam; Shana Kelley; Sjoerd Hoogland; Oleksandr Voznyy; Edward H. Sargent

doi:10.1021/acs.nanolett.8b01470

Acid-Assisted Ligand Exchange Enhances Coupling in Colloidal Quantum Dot Solids

Jea Woong Jo, Jongmin Choi, F. Pelayo García De Arquer, Ali Seifitokaldani, Bin Sun, Younghoon Kim, Hyungju Ahn, James Fan, Rafael Quintero-Bermudez, Junghwan Kim, Min Jae Choi, Se Woong Baek, Andrew H. Proppe, Grant Walters, Dae Hyun Nam, Shana Kelley, Sjoerd Hoogland, Oleksandr Voznyy, Edward H. Sargent^*

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

69 Scopus citations

Abstract

Colloidal quantum dots (CQDs) are promising solution-processed infrared-absorbing materials for optoelectronics. In these applications, it is crucial to replace the electrically insulating ligands used in synthesis to form strongly coupled quantum dot solids. Recently, solution-phase ligand-exchange strategies have been reported that minimize the density of defects and the polydispersity of CQDs; however, we find herein that the new ligands exhibit insufficient chemical reactivity to remove original oleic acid ligands completely. This leads to low CQD packing and correspondingly low electronic performance. Here we report an acid-assisted solution-phase ligand-exchange strategy that, by enabling efficient removal of the original ligands, enables the synthesis of densified CQD arrays. Our use of hydroiodic acid simultaneously facilitates high CQD packing via proton donation and CQD passivation through iodine. We demonstrate highly packed CQD films with a 2.5 times increased carrier mobility compared with prior exchanges. The resulting devices achieve the highest infrared photon-to-electron conversion efficiencies (>50%) reported in the spectral range of 0.8 to 1.1 eV.

Original language	English (US)
Pages (from-to)	4417-4423
Number of pages	7
Journal	Nano letters
Volume	18
Issue number	7
DOIs	https://doi.org/10.1021/acs.nanolett.8b01470
State	Published - Jul 11 2018

Funding

This work was supported by the Ontario Research Fund-Research Excellence program (ORF-RE7 ministry of Research and Innovation, Ontario Research Fund-Research Excellence Round 7) and by the Natural Sciences and Engineering Research Council (NSERC) of Canada. All DFT computations were performed on the IBM BlueGene/Q supercomputer with support from the Southern Ontario Smart Computing Innovation Platform (SOSCIP, SOSCIP is funded by the Federal Economic Development Agency of Southern Ontario, the Province of Ontario, IBM Canada Ltd., Ontario Centres of Excellence, Mitacs and 15 Ontario academic member institutions). A.S. thanks Fonds de Recherche du Quebec - Nature et Technologies (FRQNT) for support in the form of a postdoctoral fellowship award. We thank L. Levina, R.

Keywords

Colloidal quantum dots
infrared
narrow bandgap
photovoltaics
solution-phase ligand exchange
surface passivation

ASJC Scopus subject areas

General Chemistry
Condensed Matter Physics
Mechanical Engineering
Bioengineering
General Materials Science

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1021/acs.nanolett.8b01470

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Jo, J. W., Choi, J., García De Arquer, F. P., Seifitokaldani, A., Sun, B., Kim, Y., Ahn, H., Fan, J., Quintero-Bermudez, R., Kim, J., Choi, M. J., Baek, S. W., Proppe, A. H., Walters, G., Nam, D. H., Kelley, S., Hoogland, S., Voznyy, O., & Sargent, E. H. (2018). Acid-Assisted Ligand Exchange Enhances Coupling in Colloidal Quantum Dot Solids. Nano letters, 18(7), 4417-4423. https://doi.org/10.1021/acs.nanolett.8b01470

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title = "Acid-Assisted Ligand Exchange Enhances Coupling in Colloidal Quantum Dot Solids",

abstract = "Colloidal quantum dots (CQDs) are promising solution-processed infrared-absorbing materials for optoelectronics. In these applications, it is crucial to replace the electrically insulating ligands used in synthesis to form strongly coupled quantum dot solids. Recently, solution-phase ligand-exchange strategies have been reported that minimize the density of defects and the polydispersity of CQDs; however, we find herein that the new ligands exhibit insufficient chemical reactivity to remove original oleic acid ligands completely. This leads to low CQD packing and correspondingly low electronic performance. Here we report an acid-assisted solution-phase ligand-exchange strategy that, by enabling efficient removal of the original ligands, enables the synthesis of densified CQD arrays. Our use of hydroiodic acid simultaneously facilitates high CQD packing via proton donation and CQD passivation through iodine. We demonstrate highly packed CQD films with a 2.5 times increased carrier mobility compared with prior exchanges. The resulting devices achieve the highest infrared photon-to-electron conversion efficiencies (>50%) reported in the spectral range of 0.8 to 1.1 eV.",

keywords = "Colloidal quantum dots, infrared, narrow bandgap, photovoltaics, solution-phase ligand exchange, surface passivation",

author = "Jo, {Jea Woong} and Jongmin Choi and {Garc{\'i}a De Arquer}, {F. Pelayo} and Ali Seifitokaldani and Bin Sun and Younghoon Kim and Hyungju Ahn and James Fan and Rafael Quintero-Bermudez and Junghwan Kim and Choi, {Min Jae} and Baek, {Se Woong} and Proppe, {Andrew H.} and Grant Walters and Nam, {Dae Hyun} and Shana Kelley and Sjoerd Hoogland and Oleksandr Voznyy and Sargent, {Edward H.}",

note = "Publisher Copyright: {\textcopyright} 2018 American Chemical Society.",

year = "2018",

month = jul,

day = "11",

doi = "10.1021/acs.nanolett.8b01470",

language = "English (US)",

volume = "18",

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Jo, JW, Choi, J, García De Arquer, FP, Seifitokaldani, A, Sun, B, Kim, Y, Ahn, H, Fan, J, Quintero-Bermudez, R, Kim, J, Choi, MJ, Baek, SW, Proppe, AH, Walters, G, Nam, DH, Kelley, S, Hoogland, S, Voznyy, O & Sargent, EH 2018, 'Acid-Assisted Ligand Exchange Enhances Coupling in Colloidal Quantum Dot Solids', Nano letters, vol. 18, no. 7, pp. 4417-4423. https://doi.org/10.1021/acs.nanolett.8b01470

TY - JOUR

T1 - Acid-Assisted Ligand Exchange Enhances Coupling in Colloidal Quantum Dot Solids

AU - Jo, Jea Woong

AU - Choi, Jongmin

AU - García De Arquer, F. Pelayo

AU - Seifitokaldani, Ali

AU - Sun, Bin

AU - Kim, Younghoon

AU - Ahn, Hyungju

AU - Fan, James

AU - Quintero-Bermudez, Rafael

AU - Kim, Junghwan

AU - Choi, Min Jae

AU - Baek, Se Woong

AU - Proppe, Andrew H.

AU - Walters, Grant

AU - Nam, Dae Hyun

AU - Kelley, Shana

AU - Hoogland, Sjoerd

AU - Voznyy, Oleksandr

AU - Sargent, Edward H.

PY - 2018/7/11

Y1 - 2018/7/11

N2 - Colloidal quantum dots (CQDs) are promising solution-processed infrared-absorbing materials for optoelectronics. In these applications, it is crucial to replace the electrically insulating ligands used in synthesis to form strongly coupled quantum dot solids. Recently, solution-phase ligand-exchange strategies have been reported that minimize the density of defects and the polydispersity of CQDs; however, we find herein that the new ligands exhibit insufficient chemical reactivity to remove original oleic acid ligands completely. This leads to low CQD packing and correspondingly low electronic performance. Here we report an acid-assisted solution-phase ligand-exchange strategy that, by enabling efficient removal of the original ligands, enables the synthesis of densified CQD arrays. Our use of hydroiodic acid simultaneously facilitates high CQD packing via proton donation and CQD passivation through iodine. We demonstrate highly packed CQD films with a 2.5 times increased carrier mobility compared with prior exchanges. The resulting devices achieve the highest infrared photon-to-electron conversion efficiencies (>50%) reported in the spectral range of 0.8 to 1.1 eV.

AB - Colloidal quantum dots (CQDs) are promising solution-processed infrared-absorbing materials for optoelectronics. In these applications, it is crucial to replace the electrically insulating ligands used in synthesis to form strongly coupled quantum dot solids. Recently, solution-phase ligand-exchange strategies have been reported that minimize the density of defects and the polydispersity of CQDs; however, we find herein that the new ligands exhibit insufficient chemical reactivity to remove original oleic acid ligands completely. This leads to low CQD packing and correspondingly low electronic performance. Here we report an acid-assisted solution-phase ligand-exchange strategy that, by enabling efficient removal of the original ligands, enables the synthesis of densified CQD arrays. Our use of hydroiodic acid simultaneously facilitates high CQD packing via proton donation and CQD passivation through iodine. We demonstrate highly packed CQD films with a 2.5 times increased carrier mobility compared with prior exchanges. The resulting devices achieve the highest infrared photon-to-electron conversion efficiencies (>50%) reported in the spectral range of 0.8 to 1.1 eV.

KW - Colloidal quantum dots

KW - infrared

KW - narrow bandgap

KW - photovoltaics

KW - solution-phase ligand exchange

KW - surface passivation

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AN - SCOPUS:85048888751

SN - 1530-6984

VL - 18

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EP - 4423

JO - Nano letters

JF - Nano letters

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ER -

Acid-Assisted Ligand Exchange Enhances Coupling in Colloidal Quantum Dot Solids

Abstract

Funding

Keywords

ASJC Scopus subject areas

UN SDGs

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