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Korath Shivan S, Maier A, Scheele M. Emergent properties in supercrystals of atomically precise nanoclusters and colloidal nanocrystals. Chem Commun (Camb) 2022; 58:6998-7017. [DOI: 10.1039/d2cc00778a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We provide a comprehensive account of the optical, electrical and mechanical properties that result from the self-assembly of colloidal nanocrystals or atomically precise nanoclusters into crystalline arrays with long-range order....
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2
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Biondi M, Choi MJ, Wang Z, Wei M, Lee S, Choubisa H, Sagar LK, Sun B, Baek SW, Chen B, Todorović P, Najarian AM, Sedighian Rasouli A, Nam DH, Vafaie M, Li YC, Bertens K, Hoogland S, Voznyy O, García de Arquer FP, Sargent EH. Facet-Oriented Coupling Enables Fast and Sensitive Colloidal Quantum Dot Photodetectors. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2101056. [PMID: 34245178 DOI: 10.1002/adma.202101056] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 04/14/2021] [Indexed: 06/13/2023]
Abstract
Charge carrier transport in colloidal quantum dot (CQD) solids is strongly influenced by coupling among CQDs. The shape of as-synthesized CQDs results in random orientational relationships among facets in CQD solids, and this limits the CQD coupling strength and the resultant performance of optoelectronic devices. Here, colloidal-phase reconstruction of CQD surfaces, which improves facet alignment in CQD solids, is reported. This strategy enables control over CQD faceting and allows demonstration of enhanced coupling in CQD solids. The approach utilizes post-synthetic resurfacing and unites surface passivation and colloidal stability with a propensity for dots to couple via (100):(100) facets, enabling increased hole mobility. Experimentally, the CQD solids exhibit a 10× increase in measured hole mobility compared to control CQD solids, and enable photodiodes (PDs) exhibiting 70% external quantum efficiency (vs 45% for control devices) and specific detectivity, D* > 1012 Jones, each at 1550 nm. The photodetectors feature a 7 ns response time for a 0.01 mm2 area-the fastest reported for solution-processed short-wavelength infrared PDs.
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Affiliation(s)
- Margherita Biondi
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Min-Jae Choi
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Zhibo Wang
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, Scarborough, Ontario, M1C 1A4, Canada
| | - Mingyang Wei
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Seungjin Lee
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Hitarth Choubisa
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Laxmi Kishore Sagar
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Bin Sun
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Se-Woong Baek
- Department of Chemical and Biological Engineering, Korea University, Seoul, 02841, Republic of Korea
| | - Bin Chen
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Petar Todorović
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Amin Morteza Najarian
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Armin Sedighian Rasouli
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Dae-Hyun Nam
- Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, Republic of Korea
| | - Maral Vafaie
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Yuguang C Li
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Koen Bertens
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Sjoerd Hoogland
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Oleksandr Voznyy
- Department of Physical and Environmental Sciences, University of Toronto Scarborough, Scarborough, Ontario, M1C 1A4, Canada
| | - F Pelayo García de Arquer
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
| | - Edward H Sargent
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, Ontario, M5S 3G4, Canada
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Maier A, Lapkin D, Mukharamova N, Frech P, Assalauova D, Ignatenko A, Khubbutdinov R, Lazarev S, Sprung M, Laible F, Löffler R, Previdi N, Bräuer A, Günkel T, Fleischer M, Schreiber F, Vartanyants IA, Scheele M. Structure-Transport Correlation Reveals Anisotropic Charge Transport in Coupled PbS Nanocrystal Superlattices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2002254. [PMID: 32725688 DOI: 10.1002/adma.202002254] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/17/2020] [Indexed: 06/11/2023]
Abstract
The assembly of colloidal semiconductive nanocrystals into highly ordered superlattices predicts novel structure-related properties by design. However, those structure-property relationships, such as charge transport depending on the structure or even directions of the superlattice, have remained unrevealed so far. Here, electric transport measurements and X-ray nanodiffraction are performed on self-assembled lead sulfide nanocrystal superlattices to investigate direction-dependent charge carrier transport in microscopic domains of these materials. By angular X-ray cross-correlation analysis, the structure and orientation of individual superlattices is determined, which are directly correlated with the electronic properties of the same microdomains. By that, strong evidence for the effect of superlattice crystallinity on the electric conductivity is found. Further, anisotropic charge transport in highly ordered monocrystalline domains is revealed, which is attributed to the dominant effect of shortest interparticle distance. This implies that transport anisotropy should be a general feature of weakly coupled nanocrystal superlattices.
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Affiliation(s)
- Andre Maier
- Institute of Physical and Theoretical Chemistry, University of Tuebingen, Auf der Morgenstelle 18, Tuebingen, 72076, Germany
- Center for Light-Matter Interaction, Sensors & Analytics LISA+, University of Tuebingen, Auf der Morgenstelle 15, Tuebingen, 72076, Germany
| | - Dmitry Lapkin
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg, 22607, Germany
| | | | - Philipp Frech
- Institute of Physical and Theoretical Chemistry, University of Tuebingen, Auf der Morgenstelle 18, Tuebingen, 72076, Germany
| | - Dameli Assalauova
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg, 22607, Germany
| | - Alexandr Ignatenko
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg, 22607, Germany
| | - Ruslan Khubbutdinov
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg, 22607, Germany
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe shosse 31, Moscow, 115409, Russia
| | - Sergey Lazarev
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg, 22607, Germany
- National Research Tomsk Polytechnic University (TPU), pr. Lenina 30, Tomsk, 634050, Russia
| | - Michael Sprung
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg, 22607, Germany
| | - Florian Laible
- Center for Light-Matter Interaction, Sensors & Analytics LISA+, University of Tuebingen, Auf der Morgenstelle 15, Tuebingen, 72076, Germany
- Institute of Applied Physics, University of Tuebingen, Auf der Morgenstelle 10, Tuebingen, 72076, Germany
| | - Ronny Löffler
- Center for Light-Matter Interaction, Sensors & Analytics LISA+, University of Tuebingen, Auf der Morgenstelle 15, Tuebingen, 72076, Germany
| | - Nicolas Previdi
- Institute of Physical and Theoretical Chemistry, University of Tuebingen, Auf der Morgenstelle 18, Tuebingen, 72076, Germany
| | - Annika Bräuer
- Center for Light-Matter Interaction, Sensors & Analytics LISA+, University of Tuebingen, Auf der Morgenstelle 15, Tuebingen, 72076, Germany
- Institute of Applied Physics, University of Tuebingen, Auf der Morgenstelle 10, Tuebingen, 72076, Germany
| | - Thomas Günkel
- Institute of Applied Physics, University of Tuebingen, Auf der Morgenstelle 10, Tuebingen, 72076, Germany
| | - Monika Fleischer
- Center for Light-Matter Interaction, Sensors & Analytics LISA+, University of Tuebingen, Auf der Morgenstelle 15, Tuebingen, 72076, Germany
- Institute of Applied Physics, University of Tuebingen, Auf der Morgenstelle 10, Tuebingen, 72076, Germany
| | - Frank Schreiber
- Center for Light-Matter Interaction, Sensors & Analytics LISA+, University of Tuebingen, Auf der Morgenstelle 15, Tuebingen, 72076, Germany
- Institute of Applied Physics, University of Tuebingen, Auf der Morgenstelle 10, Tuebingen, 72076, Germany
| | - Ivan A Vartanyants
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, Hamburg, 22607, Germany
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe shosse 31, Moscow, 115409, Russia
| | - Marcus Scheele
- Institute of Physical and Theoretical Chemistry, University of Tuebingen, Auf der Morgenstelle 18, Tuebingen, 72076, Germany
- Center for Light-Matter Interaction, Sensors & Analytics LISA+, University of Tuebingen, Auf der Morgenstelle 15, Tuebingen, 72076, Germany
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Gilmore RH, Winslow SW, Lee EMY, Ashner MN, Yager KG, Willard AP, Tisdale WA. Inverse Temperature Dependence of Charge Carrier Hopping in Quantum Dot Solids. ACS NANO 2018; 12:7741-7749. [PMID: 29927579 DOI: 10.1021/acsnano.8b01643] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
In semiconductors, increasing mobility with decreasing temperature is a signature of charge carrier transport through delocalized bands. Here, we show that this behavior can also occur in nanocrystal solids due to temperature-dependent structural transformations. Using a combination of broadband infrared transient absorption spectroscopy and numerical modeling, we investigate the temperature-dependent charge transport properties of well-ordered PbS quantum dot (QD) solids. Contrary to expectations, we observe that the QD-to-QD charge tunneling rate increases with decreasing temperature, while simultaneously exhibiting thermally activated nearest-neighbor hopping behavior. Using synchrotron grazing-incidence small-angle X-ray scattering, we show that this trend is driven by a temperature-dependent reduction in nearest-neighbor separation that is quantitatively consistent with the measured tunneling rate.
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Affiliation(s)
| | | | | | | | - Kevin G Yager
- Center for Functional Nanomaterials , Brookhaven National Laboratory , Upton , New York 11973 , United States
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5
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Haider Z, Zheng JY, Kang YS. Surfactant free fabrication and improved charge carrier separation induced enhanced photocatalytic activity of {001} facet exposed unique octagonal BiOCl nanosheets. Phys Chem Chem Phys 2018; 18:19595-604. [PMID: 27332984 DOI: 10.1039/c6cp01740a] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Unique octagonal shaped BiOCl nanosheets (NS) dominantly exposed with high energy {001} crystal facets have been fabricated via a simple hydrothermal route without using organic surfactants. The dynamics of photogenerated charge carriers have been studied by time-resolved photoluminescence spectroscopy. The fitting parameters of the decay kinetics were used to calculate both the intensity weighted average lifetime (〈τ〉int.), as well as the amplitude weighted average lifetime (〈τ〉amp.) of the photogenerated charge carriers. The 〈τ〉int. and 〈τ〉amp. values for {001} BiOCl NS, i.e., 17.23 ns and 1.94 ns, respectively, were observed to be significantly higher than the corresponding values obtained for pristine BiOCl such as 2.52 ns and 1.07 ns, respectively. Significant quenching of the PL emission intensity of {001} BiOCl NS reflected the enhanced separation of the photogenerated charge carriers. Reduced thickness and in situ iodine doping was favorable to minimize the recombination tendency. The photocatalytic activity was monitored via the photodegradation of RhB under visible light illumination (λ > 400 nm). {001} BiOCl NS exhibited superior performance when compared to pristine BiOCl in terms of the rapid degradation kinetics and higher photonic efficiency. The photocatalytic efficiency of {001} BiOCl NS was 2.8 times higher than pristine BiOCl. Iodine doping induced extended the optical absorption in the visible region and improved the separation of the photogenerated charge carriers, which played an important role to enhance the photocatalytic activity. The photodegradation mechanism was systematically studied using various radical quenchers and it was revealed that photogenerated holes (h(+)) and superoxide radicals (˙O(2-)) actively participated whereas hydroxyl (OH˙) radicals had a negligible contribution in the photodegradation of RhB. {001} BiOCl NS has shown a higher photocurrent density and lower charge transfer resistance analyzed through photoelectrochemical and electrochemical impedance measurements. This study highlights the fabrication of unique octagonal BiOCl NS with improved separation of charge carriers across high energy crystal facts to design a highly efficient photocatalyst.
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Affiliation(s)
- Zeeshan Haider
- Korea Center for Artificial Photosynthesis and Department of Chemistry, Sogang University, Seoul 121-742, Republic of Korea.
| | - Jin You Zheng
- Korea Center for Artificial Photosynthesis and Department of Chemistry, Sogang University, Seoul 121-742, Republic of Korea.
| | - Young Soo Kang
- Korea Center for Artificial Photosynthesis and Department of Chemistry, Sogang University, Seoul 121-742, Republic of Korea.
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6
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Qu L, Vörös M, Zimanyi GT. Metal-Insulator Transition in Nanoparticle Solids: Insights from Kinetic Monte Carlo Simulations. Sci Rep 2017; 7:7071. [PMID: 28765599 PMCID: PMC5539282 DOI: 10.1038/s41598-017-06497-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 06/13/2017] [Indexed: 11/09/2022] Open
Abstract
Progress has been rapid in increasing the efficiency of energy conversion in nanoparticles. However, extraction of the photo-generated charge carriers remains challenging. Encouragingly, the charge mobility has been improved recently by driving nanoparticle (NP) films across the metal-insulator transition (MIT). To simulate MIT in NP films, we developed a hierarchical Kinetic Monte Carlo transport model. Electrons transfer between neighboring NPs via activated hopping when the NP energies differ by more than an overlap energy, but transfer by a non-activated quantum delocalization, if the NP energies are closer than the overlap energy. As the overlap energy increases, emerging percolating clusters support a metallic transport across the entire film. We simulated the evolution of the temperature-dependent electron mobility. We analyzed our data in terms of two candidate models of the MIT: (a) as a Quantum Critical Transition, signaled by an effective gap going to zero; and (b) as a Quantum Percolation Transition, where a sample-spanning metallic percolation path is formed as the fraction of the hopping bonds in the transport paths is going to zero. We found that the Quantum Percolation Transition theory provides a better description of the MIT. We also observed an anomalously low gap region next to the MIT. We discuss the relevance of our results in the light of recent experimental measurements.
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Affiliation(s)
- Luman Qu
- Physics Department, University of California, Davis, USA
| | - Márton Vörös
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
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7
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Novák J, Banerjee R, Kornowski A, Jankowski M, André A, Weller H, Schreiber F, Scheele M. Site-Specific Ligand Interactions Favor the Tetragonal Distortion of PbS Nanocrystal Superlattices. ACS APPLIED MATERIALS & INTERFACES 2016; 8:22526-22533. [PMID: 27504626 DOI: 10.1021/acsami.6b06989] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We analyze the structure and morphology of mesocrystalline, body-centered tetragonal (bct) superlattices of PbS nanocrystals functionalized with oleic acid. On the basis of combined scattering and real space imaging, we derive a three-dimensional (3D) model of the superlattice and show that the bct structure benefits from a balanced combination of {100}PbS-{100}PbS and {111}PbS-{111}PbS interactions between neighboring layers of nanocrystals, which uniquely stabilizes this structure. These interactions are enabled by the coaxial alignment of the atomic lattices of PbS with the superlattice. In addition, we find that this preferential orientation is already weakly present within isolated monolayers. By adding excess oleic acid to the nanocrystal solution, tetragonal distortion is suppressed, and we observe assembly into a bilayered hexagonal lattice reminiscent of a honeycomb with grain sizes of several micrometers.
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Affiliation(s)
- Jiřı́ Novák
- Central European Institute of Technology, Masaryk University , Kamenice 5, CZ-62500 Brno, Czech Republic
- Department of Condensed Matter Physics, Masaryk University , Kotlářská 2, CZ-61137 Brno, Czech Republic
| | - Rupak Banerjee
- Department of Physics, Indian Institute of Technology Gandhinagar , Palaj, Gandhinagar 382355, India
| | - Andreas Kornowski
- Institute of Physical Chemistry and The Hamburg Centre for Ultrafast Imaging, University of Hamburg , Grindelallee 117, 20146 Hamburg, Germany
| | - Maciej Jankowski
- Beamline ID03, European Synchrotron Radiation Facility , Grenoble F-38043, France
| | - Alexander André
- Institute of Physical and Theoretical Chemistry, University of Tübingen , Auf der Morgenstelle 18, 72076 Tübingen, Germany
| | - Horst Weller
- Institute of Physical Chemistry and The Hamburg Centre for Ultrafast Imaging, University of Hamburg , Grindelallee 117, 20146 Hamburg, Germany
| | - Frank Schreiber
- Institute of Applied Physics, University of Tübingen , Auf der Morgenstelle 10, 72076 Tübingen, Germany
- Center for Light-Matter Interaction, Sensors & Analytics, University of Tübingen , Auf der Morgenstelle 15, 72076 Tübingen, Germany
| | - Marcus Scheele
- Institute of Physical and Theoretical Chemistry, University of Tübingen , Auf der Morgenstelle 18, 72076 Tübingen, Germany
- Center for Light-Matter Interaction, Sensors & Analytics, University of Tübingen , Auf der Morgenstelle 15, 72076 Tübingen, Germany
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8
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Lim SJ, Ma L, Schleife A, Smith AM. Quantum Dot Surface Engineering: Toward Inert Fluorophores with Compact Size and Bright, Stable Emission. Coord Chem Rev 2016; 320-321:216-237. [PMID: 28344357 PMCID: PMC5363762 DOI: 10.1016/j.ccr.2016.03.012] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The surfaces of colloidal nanocrystals are complex interfaces between solid crystals, coordinating ligands, and liquid solutions. For fluorescent quantum dots, the properties of the surface vastly influence the efficiency of light emission, stability, and physical interactions, and thus determine their sensitivity and specificity when they are used to detect and image biological molecules. But after more than 30 years of study, the surfaces of quantum dots remain poorly understood and continue to be an important subject of both experimental and theoretical research. In this article, we review the physics and chemistry of quantum dot surfaces and describe approaches to engineer optimal fluorescent probes for applications in biomolecular imaging and sensing. We describe the structure and electronic properties of crystalline facets, the chemistry of ligand coordination, and the impact of ligands on optical properties. We further describe recent advances in compact coatings that have significantly improved their properties by providing small hydrodynamic size, high stability and fluorescence efficiency, and minimal nonspecific interactions with cells and biological molecules. While major progress has been made in both basic and applied research, many questions remain in the chemistry and physics of quantum dot surfaces that have hindered key breakthroughs to fully optimize their properties.
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Affiliation(s)
- Sung Jun Lim
- Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Liang Ma
- Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - André Schleife
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Andrew M. Smith
- Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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9
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Scherpelz P, Govoni M, Hamada I, Galli G. Implementation and Validation of Fully Relativistic GW Calculations: Spin–Orbit Coupling in Molecules, Nanocrystals, and Solids. J Chem Theory Comput 2016; 12:3523-44. [DOI: 10.1021/acs.jctc.6b00114] [Citation(s) in RCA: 124] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Peter Scherpelz
- Institute
for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
| | - Marco Govoni
- Institute
for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
- Materials
Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Ikutaro Hamada
- International
Center for Materials Nanoarchitectonics, Global Research Center for
Environment and Energy based on Nanomaterials Science, and Center
for Materials Research by Information Integration, National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044, Japan
| | - Giulia Galli
- Institute
for Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
- Materials
Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
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10
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Lukose B, Clancy P. A feasibility study of unconventional planar ligand spacers in chalcogenide nanocrystals. Phys Chem Chem Phys 2016; 18:13781-93. [PMID: 26918246 DOI: 10.1039/c5cp07521a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The solar cell efficiency of chalcogenide nanocrystals (quantum dots) has been limited in the past by the insulation between neighboring quantum dots caused by intervening, often long-chain, aliphatic ligands. We have conducted a computationally based feasibility study to investigate the use of ultra-thin, planar, charge-conducting ligands as an alternative to traditional long passive ligands. Not only might these radically unconventional ligands decrease the mean distance between adjacent quantum dots, but, since they are charge-conducting, they have the potential to actively enhance charge migration. Our ab initio studies compare the binding energies, electronic energy gaps, and absorption characteristics for both conventional and unconventional ligands, such as phthalocyanines, porphyrins and coronene. This comparison identified these unconventional ligands with the exception of titanyl phthalocyanine, that bind to themselves more strongly than to the surface of the quantum dot, which is likely to be less desirable for enhancing charge transport. The distribution of finite energy levels of the bound system is sensitive to the ligand's binding site and the levels correspond to delocalized states. We also observed a trap state localized on a single Pb atom when a sulfur-containing phenyldithiocarbamate (PTC) ligand is attached to a slightly off-stoichiometric dot in a manner that the sulfur of the ligand completes stoichiometry of the bound system. Hence, this is indicative of the source of trap state when thio-based ligands are bound to chalcogenide nanocrystals. We also predict that titanyl phthalocyanine in a mix with chalcogenide dots of diameter ∼1.5 Å can form a donor-acceptor system.
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Affiliation(s)
- Binit Lukose
- School of Chemical and Biomolecular Engineering, Cornell University, 14853 Ithaca, NY, USA.
| | - Paulette Clancy
- School of Chemical and Biomolecular Engineering, Cornell University, 14853 Ithaca, NY, USA.
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11
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Li H, Zhitomirsky D, Dave S, Grossman JC. Toward the Ultimate Limit of Connectivity in Quantum Dots with High Mobility and Clean Gaps. ACS NANO 2016; 10:606-614. [PMID: 26743175 DOI: 10.1021/acsnano.5b05626] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Colloidal quantum dots (CQDs) are highly versatile nanoscale optoelectronic building blocks, but despite their materials engineering flexibility, there is a considerable lack of fundamental understanding of their electronic structure as they couple within thin films. By employing a joint experimental-theoretical study, we reveal the impact of connectivity in CQD assemblies, going beyond the single CQD picture. High-resolution transmission electron microscopy (HR-TEM) demonstrates connectivity motifs across different CQD sizes and length scales and provides the necessary perspective to build robust computational models to systematically study the achievable degree of connectivity in these materials. We focused on state-of-the-art surface ligand treatments, taking into account both the degree of connectivity and nanocrystal orientation, and performed ab initio simulations within the phonon-assisted hopping regime. Importantly, both the TEM studies and our simulation results revealed morphological and electronic defects that could dramatically reduce optoelectronic performance, and yet would not have been captured within a single CQD model that neglects connectivity. We calculate carrier mobility in the presence of such defect states and conclude that the best-achievable CQD assemblies for optoelectronics will require a modest degree of fusing via the {001} facet, followed by atomic ligand passivation to generate a clean band gap and unprecedentedly high charge transport.
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Affiliation(s)
- Huashan Li
- Department of Materials Science and Engineering and §Department of Mechanical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - David Zhitomirsky
- Department of Materials Science and Engineering and §Department of Mechanical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Shreya Dave
- Department of Materials Science and Engineering and §Department of Mechanical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Jeffrey C Grossman
- Department of Materials Science and Engineering and §Department of Mechanical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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12
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Gervasi CF, Kislitsyn DA, Allen TL, Hackley JD, Maruyama R, Nazin GV. Diversity of sub-bandgap states in lead-sulfide nanocrystals: real-space spectroscopy and mapping at the atomic-scale. NANOSCALE 2015; 7:19732-19742. [PMID: 26556538 DOI: 10.1039/c5nr05236j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Colloidal semiconductor nanocrystals have emerged as a promising class of technological materials with optoelectronic properties controllable through quantum-confinement effects. Despite recent successes in this field, an important factor that remains difficult to control is the impact of the nanocrystal surface structure on the photophysics and electron transport in nanocrystal-based materials. In particular, the presence of surface defects and irregularities can result in the formation of localized sub-bandgap states that can dramatically affect the dynamics of charge carriers and electronic excitations. Here we use Scanning Tunneling Spectroscopy (STS) to investigate, in real space, sub-bandgap states in individual ligand-free PbS nanocrystals. In the majority of studied PbS nanocrystals, spatial mapping of electronic density of states with STS shows atomic-scale variations attributable to the presence of surface reconstructions. STS spectra show that the presence of surface reconstructions results in formation of surface-bound sub-bandgap electronic states. The nature of the surface reconstruction varies depending on the surface stoichiometry, with lead-rich surfaces producing unoccupied sub-bandgap states, and sulfur-rich areas producing occupied sub-bandgap states. Highly off-stoichiometric areas produce both occupied and unoccupied states showing dramatically reduced bandgaps. Different reconstruction patterns associated with specific crystallographic directions are also found for different nanocrystals. This study provides insight into the mechanisms of sub-bandgap state formation that, in a modified form, are likely to be applicable to ligand-passivated nanocrystal surfaces, where steric hindrance between ligands can result in under-coordination of surface atoms.
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Affiliation(s)
- Christian F Gervasi
- Department of Chemistry and Biochemistry, Materials Science Institute, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA.
| | - Dmitry A Kislitsyn
- Department of Chemistry and Biochemistry, Materials Science Institute, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA.
| | - Thomas L Allen
- VoxtelNano, a division of Voxtel, Inc, CAMCOR/Lorry Lokey Labs, 1241 University of Oregon, Eugene, OR 97403-1241, USA
| | - Jason D Hackley
- Department of Chemistry and Biochemistry, Materials Science Institute, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA.
| | - Ryuichiro Maruyama
- Department of Chemistry and Biochemistry, Materials Science Institute, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA.
| | - George V Nazin
- Department of Chemistry and Biochemistry, Materials Science Institute, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, USA.
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13
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Scheele M, Brütting W, Schreiber F. Coupled organic–inorganic nanostructures (COIN). Phys Chem Chem Phys 2015; 17:97-111. [DOI: 10.1039/c4cp03094j] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Materials to devices: coupled organic–inorganic nanostructures provide versatile perspectives for quantum dot-based optoelectronic devices.
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Affiliation(s)
- M Scheele
- Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany.
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14
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Kislitsyn DA, Gervasi CF, Allen T, Palomaki PKB, Hackley JD, Maruyama R, Nazin GV. Spatial Mapping of Sub-Bandgap States Induced by Local Nonstoichiometry in Individual Lead Sulfide Nanocrystals. J Phys Chem Lett 2014; 5:3701-3707. [PMID: 26278739 DOI: 10.1021/jz5019465] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The properties of photovoltaic devices based on colloidal nanocrystals are strongly affected by localized sub-bandgap states associated with surface imperfections. A correlation between their properties and the atomic-scale structure of chemical imperfections responsible for their appearance must be established to understand the nature of such surface states. Scanning tunneling spectroscopy is used to visualize the manifold of electronic states in annealed ligand-free lead sulfide nanocrystals supported on the Au(111) surface. Delocalized quantum-confined states and localized sub-bandgap states are identified, for the first time, via spatial mapping. Maps of the sub-bandgap states show localization on nonstoichiometric adatoms self-assembled on the nanocrystal surfaces. The present model study sheds light onto the mechanisms of surface state formation that, in a modified form, may be relevant to the more general case of ligand-passivated nanocrystals, where under-coordinated surface atoms exist due to the steric hindrance between passivating ligands attached to the nanocrystal surface.
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Affiliation(s)
- Dmitry A Kislitsyn
- †Department of Chemistry and Biochemistry, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, United States
| | - Christian F Gervasi
- †Department of Chemistry and Biochemistry, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, United States
| | - Thomas Allen
- ‡VoxtelNano, a division of Voxtel, Inc., CAMCOR/Lorry Lokey Laboratories, 1241 University of Oregon, Eugene, Oregon 97403-1241, United States
| | - Peter K B Palomaki
- ‡VoxtelNano, a division of Voxtel, Inc., CAMCOR/Lorry Lokey Laboratories, 1241 University of Oregon, Eugene, Oregon 97403-1241, United States
| | - Jason D Hackley
- †Department of Chemistry and Biochemistry, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, United States
| | - Ryuichiro Maruyama
- †Department of Chemistry and Biochemistry, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, United States
| | - George V Nazin
- †Department of Chemistry and Biochemistry, University of Oregon, 1253 University of Oregon, Eugene, Oregon 97403, United States
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15
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Doris SE, Lynch JJ, Li C, Wills AW, Urban JJ, Helms BA. Mechanistic Insight into the Formation of Cationic Naked Nanocrystals Generated under Equilibrium Control. J Am Chem Soc 2014; 136:15702-10. [DOI: 10.1021/ja508675t] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Sean E. Doris
- The
Molecular Foundry, Lawrence Berkeley National Laboratory, One Cyclotron
Road, Berkeley, California 94720, United States
| | - Jared J. Lynch
- The
Molecular Foundry, Lawrence Berkeley National Laboratory, One Cyclotron
Road, Berkeley, California 94720, United States
| | - Changyi Li
- The
Molecular Foundry, Lawrence Berkeley National Laboratory, One Cyclotron
Road, Berkeley, California 94720, United States
| | - Andrew W. Wills
- The
Molecular Foundry, Lawrence Berkeley National Laboratory, One Cyclotron
Road, Berkeley, California 94720, United States
| | - Jeffrey J. Urban
- The
Molecular Foundry, Lawrence Berkeley National Laboratory, One Cyclotron
Road, Berkeley, California 94720, United States
| | - Brett A. Helms
- The
Molecular Foundry, Lawrence Berkeley National Laboratory, One Cyclotron
Road, Berkeley, California 94720, United States
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16
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Teunis MB, Dolai S, Sardar R. Effects of surface-passivating ligands and ultrasmall CdSe nanocrystal size on the delocalization of exciton confinement. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:7851-7858. [PMID: 24926916 DOI: 10.1021/la501533t] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Here we report an unprecedentedly large and controllable decrease in the optical band gap (up to 107 nm, 610 meV) of molecule-like ultrasmall CdSe nanocrystals (diameters ranging from 1.6 to 2.0 nm) by passivating their surfaces with conjugated ligands (phenyldithiocarbamates, PDTCs) containing a series of electron-donating and -withdrawing functional groups through a ligand-exchange reaction on dodecylamine (DDA)-coated nanocrystals. This band-edge absorption shift is due to the delocalization of the strongly confined excitonic hole from nanocrystals to the ligand molecular orbitals and not from nanocrystal growth or dielectric constant effects. (1)H NMR analysis confirmed that the nanocrystal surface contained a mixed ligation of DDA and PDTC. The effects of the nanocrystal size on the extent of exciton delocalization were also studied and found to be smaller for larger nanocrystals. Modulating the energy level of ligand-passivated ultrasmall nanocrystals and controlling the electronic interaction at the nanocrystal-passivating ligand interface are very important to the fabrication of solid-state devices.
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Affiliation(s)
- Meghan B Teunis
- Department of Chemistry and Chemical Biology and ‡Integrated Nanosystems Development Institute, Indiana University-Purdue University Indianapolis , Indianapolis, Indiana 46202, United States
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