1
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Homer MK, Larson HC, Dixon GJ, Miura-Stempel E, Armstrong NR, Cossairt BM. Extremely Long-Lived Charge Donor States Formed by Visible Irradiation of Quantum Dots. ACS NANO 2024; 18:24591-24602. [PMID: 39161977 DOI: 10.1021/acsnano.4c10526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/21/2024]
Abstract
Using cyclic voltammetry under illumination, we recently demonstrated that CdS quantum dots (QDs) form charge donor states that live for at least several minutes after illumination ends, ∼12 orders of magnitude longer than expected for free carriers. This time scale suggests that the conventionally accepted mechanism of charge transfer, wherein charges directly transfer to an acceptor following exciton dissociation, cannot be complete. Because of these long time scales, this unconventional pathway is not readily observed using time-resolved spectroscopy to probe charge transfer dynamics. Here, we investigated the chemical nature of these charge donor states using cyclic voltammetry under illumination coupled with NMR spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and optical spectroscopy. Our data reveal that charges are stored locally rather than as free carriers, and the number of charges stored is dependent on the QD surface ligation and stoichiometry. Altogether, our results confirm that electrons are stored at ligated surface Cd, these sites are competent charge donors, and this storage is charge balanced by X-type ligand desorption. We found that charge storage occurs in every QD system studied, including CdS, CdSe, and InP capped with carboxylate and phosphonate ligands.
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Affiliation(s)
- Micaela K Homer
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Helen C Larson
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Grant J Dixon
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Emily Miura-Stempel
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Neal R Armstrong
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arkansas 85721, United States
| | - Brandi M Cossairt
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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2
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Pun AB, Lyons AJ, Norris DJ. Silver-doped CdSe magic-sized nanocrystals. J Chem Phys 2024; 160:154711. [PMID: 38634492 DOI: 10.1063/5.0201417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 03/29/2024] [Indexed: 04/19/2024] Open
Abstract
Magic-sized nanocrystals (MSNCs) grow via jumps between very specific sizes. This discrete growth is a possible avenue toward monodisperse nanomaterials that are completely identical in size and shape. In spite of this potential, MSNCs have seen limited study and application due to their poor optical properties. Specifically, MSNCs are limited in their range of emission wavelengths and commonly exhibit poor photoluminescence quantum yields (PLQYs). Here, we report silver doping of CdSe MSNCs as a strategy to improve the optical properties of MSNCs. Silver doping leads to controllable shifts in emission wavelength and significant increases in MSNC PLQYs. These results suggest that doped MSNCs are interesting candidates for displays or luminescent solar concentrators. Finally, we demonstrate that the doping process does not affect the magic size of our MSNCs, allowing further photophysical study of this class of nanomaterial.
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Affiliation(s)
- Andrew B Pun
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Alexandra J Lyons
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - David J Norris
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
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3
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Fabrizio K, Gormley EL, Davenport AM, Hendon CH, Brozek CK. Gram-scale synthesis of MIL-125 nanoparticles and their solution processability. Chem Sci 2023; 14:8946-8955. [PMID: 37621428 PMCID: PMC10445466 DOI: 10.1039/d3sc02257a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 07/30/2023] [Indexed: 08/26/2023] Open
Abstract
Although metal-organic framework (MOF) photocatalysts have become ubiquitous, basic aspects of their photoredox mechanisms remain elusive. Nanosizing MOFs enables solution-state techniques to probe size-dependent properties and molecular reactivity, but few MOFs have been prepared as nanoparticles (nanoMOFs) with sufficiently small sizes. Here, we report a rapid reflux-based synthesis of the photoredox-active MOF Ti8O8(OH)4(terephthalate)6 (MIL-125) to achieve diameters below 30 nm in less than 2 hours. Whereas MOFs generally require ex situ analysis by solid-state techniques, sub-30 nm diameters ensure colloidal stability for weeks and minimal light scattering, permitting in situ analysis by solution-state methods. Optical absorption and photoluminescence spectra of free-standing colloids provide direct evidence that the photoredox chemistry of MIL-125 involves Ti3+ trapping and charge accumulation onto the Ti-oxo clusters. Solution-state potentiometry collected during the photochemical process also allows simultaneous measurement of MOF Fermi-level energies in situ. Finally, by leveraging the solution-processability of these nanoparticles, we demonstrate facile preparation of mixed-matrix membranes with high MOF loadings that retain the reversible photochromism. Taken together, these results demonstrate the feasibility of a rapid nanoMOF synthesis and fabrication of a photoactive membrane, and the fundamental insights they offer into heterogeneous photoredox chemistry.
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Affiliation(s)
- Kevin Fabrizio
- Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon Eugene OR 97403 USA
| | - Eoghan L Gormley
- Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon Eugene OR 97403 USA
| | - Audrey M Davenport
- Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon Eugene OR 97403 USA
| | - Christopher H Hendon
- Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon Eugene OR 97403 USA
| | - Carl K Brozek
- Department of Chemistry and Biochemistry, Material Science Institute, University of Oregon Eugene OR 97403 USA
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4
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Abstract
Lasers and optical amplifiers based on solution-processable materials have been long-desired devices for their compatibility with virtually any substrate, scalability, and ease of integration with on-chip photonics and electronics. These devices have been pursued across a wide range of materials including polymers, small molecules, perovskites, and chemically prepared colloidal semiconductor nanocrystals, also commonly referred to as colloidal quantum dots. The latter materials are especially attractive for implementing optical-gain media as in addition to being compatible with inexpensive and easily scalable chemical techniques, they offer multiple advantages derived from a zero-dimensional character of their electronic states. These include a size-tunable emission wavelength, low optical gain thresholds, and weak sensitivity of lasing characteristics to variations in temperature. Here we review the status of colloidal nanocrystal lasing devices, most recent advances in this field, outstanding challenges, and the ongoing progress toward technological viable devices including colloidal quantum dot laser diodes.
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Affiliation(s)
- Namyoung Ahn
- Nanotechnology and Advanced Spectroscopy Team, C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Clément Livache
- Nanotechnology and Advanced Spectroscopy Team, C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Valerio Pinchetti
- Nanotechnology and Advanced Spectroscopy Team, C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Victor I Klimov
- Nanotechnology and Advanced Spectroscopy Team, C-PCS, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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5
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Septianto RD, Miranti R, Kikitsu T, Hikima T, Hashizume D, Matsushita N, Iwasa Y, Bisri SZ. Enabling metallic behaviour in two-dimensional superlattice of semiconductor colloidal quantum dots. Nat Commun 2023; 14:2670. [PMID: 37236922 DOI: 10.1038/s41467-023-38216-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 04/21/2023] [Indexed: 05/28/2023] Open
Abstract
Semiconducting colloidal quantum dots and their assemblies exhibit superior optical properties owing to the quantum confinement effect. Thus, they are attracting tremendous interest from fundamental research to commercial applications. However, the electrical conducting properties remain detrimental predominantly due to the orientational disorder of quantum dots in the assembly. Here we report high conductivity and the consequent metallic behaviour of semiconducting colloidal quantum dots of lead sulphide. Precise facet orientation control to forming highly-ordered quasi-2-dimensional epitaxially-connected quantum dot superlattices is vital for high conductivity. The intrinsically high mobility over 10 cm2 V-1 s-1 and temperature-independent behaviour proved the high potential of semiconductor quantum dots for electrical conducting properties. Furthermore, the continuously tunable subband filling will enable quantum dot superlattices to be a future platform for emerging physical properties investigations, such as strongly correlated and topological states, as demonstrated in the moiré superlattices of twisted bilayer graphene.
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Affiliation(s)
- Ricky Dwi Septianto
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
- Department of Materials Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo, 152-8550, Japan
| | - Retno Miranti
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Tomoka Kikitsu
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Takaaki Hikima
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo, 679-5198, Japan
| | - Daisuke Hashizume
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Nobuhiro Matsushita
- Department of Materials Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo, 152-8550, Japan
| | - Yoshihiro Iwasa
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
- Quantum Phase Electronic Center (QPEC) and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Satria Zulkarnaen Bisri
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.
- Department of Materials Science and Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo, 152-8550, Japan.
- Department of Applied Physics and Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo, 184-8588, Japan.
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6
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Homer MK, Kuo DY, Dou FY, Cossairt BM. Photoinduced Charge Transfer from Quantum Dots Measured by Cyclic Voltammetry. J Am Chem Soc 2022; 144:14226-14234. [PMID: 35897128 DOI: 10.1021/jacs.2c04991] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Measuring and modulating charge-transfer processes at quantum dot interfaces are crucial steps in developing quantum dots as photocatalysts. In this work, cyclic voltammetry under illumination is demonstrated to measure the rate of photoinduced charge transfer from CdS quantum dots by directly probing the changing oxidation states of a library of molecular charge acceptors, including both hole and electron acceptors. The voltammetry data demonstrate the presence of long-lived charge donor states generated by native photodoping of the quantum dots as well as a positive correlation between driving force and rate of charge transfer. Changes to the voltammograms under illumination follow mechanistic predictions from the ErCi' zone diagram, and electrochemical modeling allows for measurement of the rate of productive electron transfer. Observed rates for photoinduced charge transfer are on the order of 0.1 s-1, which are distinct from the picosecond dynamics measured by conventional transient optical spectroscopy methods and are more closely connected to the quantum yield of light-mediated chemical transformations.
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Affiliation(s)
- Micaela K Homer
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
| | - Ding-Yuan Kuo
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
| | - Florence Y Dou
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
| | - Brandi M Cossairt
- Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States
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7
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Eren H, Bednarz RJR, Alimoradi Jazi M, Donk L, Gudjonsdottir S, Bohländer P, Eelkema R, Houtepen AJ. Permanent Electrochemical Doping of Quantum Dot Films through Photopolymerization of Electrolyte Ions. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2022; 34:4019-4028. [PMID: 35573106 PMCID: PMC9097154 DOI: 10.1021/acs.chemmater.2c00199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 04/14/2022] [Indexed: 06/15/2023]
Abstract
Quantum dots (QDs) are considered for devices like light-emitting diodes (LEDs) and photodetectors as a result of their tunable optoelectronic properties. To utilize the full potential of QDs for optoelectronic applications, control over the charge carrier density is vital. However, controlled electronic doping of these materials has remained a long-standing challenge, thus slowing their integration into optoelectronic devices. Electrochemical doping offers a way to precisely and controllably tune the charge carrier concentration as a function of applied potential and thus the doping levels in QDs. However, the injected charges are typically not stable after disconnecting the external voltage source because of electrochemical side reactions with impurities or with the surfaces of the QDs. Here, we use photopolymerization to covalently bind polymerizable electrolyte ions to polymerizable solvent molecules after electrochemical charge injection. We discuss the importance of using polymerizable dopant ions as compared to nonpolymerizable conventional electrolyte ions such as LiClO4 when used in electrochemical doping. The results show that the stability of charge carriers in QD films can be enhanced by many orders of magnitude, from minutes to several weeks, after photochemical ion fixation. We anticipate that this novel way of stable doping of QDs will pave the way for new opportunities and potential uses in future QD electronic devices.
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8
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Wang L, Xiang D, Gao K, Wang J, Wu K. Colloidal n-Doped CdSe and CdSe/ZnS Nanoplatelets. J Phys Chem Lett 2021; 12:11259-11266. [PMID: 34766755 DOI: 10.1021/acs.jpclett.1c02856] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Colloidal semiconductor nanoplatelets (NPLs) are chemical versions of well-studied quantum wells (QWs). For QWs, gating and carrier doping are standard tools to manipulate their optical, electric, or magnetic properties. It would be highly desirable to use pure chemical methods to dope extra charge carriers into free-standing colloidal NPLs to achieve a similar level of manipulation. Here we report colloidal n-doped CdSe and CdSe/ZnS NPLs achieved through a photochemical doping method. The extra electrons doped into the conduction band edges are evidenced by exciton absorption bleaches recoverable through dedoping and the appearance of new intersub-band transitions in the near-infrared. A high surface ligand coverage is the key to successful doping; otherwise, the doped electrons can be depleted likely by unpassivated surface cations. Large trion binding energies of 20-30 meV are found for the n-doped CdSe NPLs, which, in contrast, are reduced by 1 order of magnitude in CdSe/ZnS core/shell NPLs due to dielectric screening. Furthermore, we identify a long-lived negative trion with a lifetime of 1.5-1.6 ns that is likely dominated by radiative recombination.
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Affiliation(s)
- Lifeng Wang
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Dongmei Xiang
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
| | - Kaimin Gao
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Junhui Wang
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kaifeng Wu
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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9
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Araujo JJ, Brozek CK, Liu H, Merkulova A, Li X, Gamelin DR. Tunable Band-Edge Potentials and Charge Storage in Colloidal Tin-Doped Indium Oxide (ITO) Nanocrystals. ACS NANO 2021; 15:14116-14124. [PMID: 34387483 DOI: 10.1021/acsnano.1c04660] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Degenerately doped metal-oxide nanocrystals (NCs) show localized surface plasmon resonances (LSPRs) that are tunable via their tunable excess charge-carrier densities. Modulation of excess charge carriers has also been used to control magnetism in colloidal doped metal-oxide NCs. The addition of excess delocalized conduction-band (CB) electrons can be achieved through aliovalent doping or by postsynthetic techniques such as electrochemistry or photodoping. Here, we examine the influence of charge-compensating aliovalent dopants on the potentials of excess CB electrons in free-standing colloidal degenerately doped oxide NCs, both experimentally and through modeling. Taking Sn4+:In2O3 (ITO) NCs as a model system, we use spectroelectrochemical techniques to examine differences between aliovalent doping and photodoping. We demonstrate that whereas photodoping introduces excess CB electrons by raising the Fermi level relative to the CB edge, aliovalent impurity substitution introduces excess CB electrons by stabilizing the CB edge relative to an externally defined Fermi level. Significant differences are thus observed electrochemically between spectroscopically similar delocalized CB electrons compensated by aliovalent dopants and those compensated by surface cations (e.g., protons) during photodoping. Theoretical modeling illustrates the very different potentials that arise from charge compensation via aliovalent substitution and surface charge compensation. Spectroelectrochemical titrations allow the ITO NC band-edge stabilization as a function of Sn4+ doping to be quantified. Extremely large capacitances are observed in both In2O3 and ITO NCs, making these NCs attractive for reversible charge-storage applications.
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Affiliation(s)
- Jose J Araujo
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Carl K Brozek
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Hongbin Liu
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Anna Merkulova
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Xiaosong Li
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
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10
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Salzmann BV, van der Sluijs MM, Soligno G, Vanmaekelbergh D. Oriented Attachment: From Natural Crystal Growth to a Materials Engineering Tool. Acc Chem Res 2021; 54:787-797. [PMID: 33502844 PMCID: PMC7893701 DOI: 10.1021/acs.accounts.0c00739] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Indexed: 12/18/2022]
Abstract
ConspectusIntuitively, chemists see crystals grow atom-by-atom or molecule-by-molecule, very much like a mason builds a wall, brick by brick. It is much more difficult to grasp that small crystals can meet each other in a liquid or at an interface, start to align their crystal lattices and then grow together to form one single crystal. In analogy, that looks more like prefab building. Yet, this is what happens in many occasions and can, with reason, be considered as an alternative mechanism of crystal growth. Oriented attachment is the process in which crystalline colloidal particles align their atomic lattices and grow together into a single crystal. Hence, two aligned crystals become one larger crystal by epitaxy of two specific facets, one of each crystal. If we simply consider the system of two crystals, the unifying attachment reduces the surface energy and results in an overall lower (free) energy of the system. Oriented attachment often occurs with massive numbers of crystals dispersed in a liquid phase, a sol or crystal suspension. In that case, oriented attachment lowers the total free energy of the crystal suspension, predominantly by removal of the nanocrystal/liquid interface area. Accordingly, we should start by considering colloidal suspensions with crystals as the dispersed phase, i.e., "sols", and discuss the reasons for their thermodynamic (meta)stability and how this stability can be lowered such that oriented attachment can occur as a spontaneous thermodynamic process. Oriented attachment is a process observed both for charge-stabilized crystals in polar solvents and for ligand capped nanocrystal suspensions in nonpolar solvents. In this last system different facets can develop a very different reactivity for oriented attachment. Due to this facet selectivity, crystalline structures with very specific geometries can be grown in one, two, or three dimensions; controlled oriented attachment suddenly becomes a tool for material scientists to grow architectures that cannot be reached by any other means. We will review the work performed with PbSe and CdSe nanocrystals. The entire process, i.e., the assembly of nanocrystals, atomic alignment, and unification by attachment, is a very complex and intriguing process. Researchers have succeeded in monitoring these different steps with in situ wave scattering methods and real-space (S)TEM studies. At the same time coarse-grained molecular dynamics simulations have been used to further study the forces involved in self-assembly and attachment at an interface. We will briefly come back to some of these results in the last sections of this review.
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Affiliation(s)
| | | | - Giuseppe Soligno
- Condensed Matter and Interfaces,
Debye Institute for Nanomaterials Science, Utrecht University, P. O. Box 80000, 3508 TA Utrecht, The Netherlands
| | - Daniel Vanmaekelbergh
- Condensed Matter and Interfaces,
Debye Institute for Nanomaterials Science, Utrecht University, P. O. Box 80000, 3508 TA Utrecht, The Netherlands
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11
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Christodoulou S, Ramiro I, Othonos A, Figueroba A, Dalmases M, Özdemir O, Pradhan S, Itskos G, Konstantatos G. Single-Exciton Gain and Stimulated Emission Across the Infrared Telecom Band from Robust Heavily Doped PbS Colloidal Quantum Dots. NANO LETTERS 2020; 20:5909-5915. [PMID: 32662655 DOI: 10.1021/acs.nanolett.0c01859] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Materials with optical gain in the infrared are of paramount importance for optical communications, medical diagnostics, and silicon photonics. The current technology is based either on costly III-V semiconductors that are not monolithic to silicon CMOS technology or Er-doped fiber technology that does not make use of the full fiber transparency window. Colloidal quantum dots (CQDs) offer a unique opportunity as an optical gain medium in view of their tunable bandgap, solution processability, and CMOS compatibility. The 8-fold degeneracy of infrared CQDs based on Pb-chalcogenides has hindered the demonstration of low-threshold optical gain and lasing, at room temperature. We demonstrate room-temperature, infrared, size-tunable, band-edge stimulated emission with a line width of ∼14 meV. Leveraging robust electronic doping and charge-exciton interactions in PbS CQD thin films, we reach a gain threshold at the single exciton regime representing a 4-fold reduction from the theoretical limit of an 8-fold degenerate system, with a net modal gain in excess of 100 cm-1.
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Affiliation(s)
- Sotirios Christodoulou
- ICFO, Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - Iñigo Ramiro
- ICFO, Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - Andreas Othonos
- Laboratory of Ultrafast Science, Department of Physics, University of Cyprus, Nicosia 1678, Cyprus
| | - Alberto Figueroba
- ICFO, Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - Mariona Dalmases
- ICFO, Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - Onur Özdemir
- ICFO, Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - Santanu Pradhan
- ICFO, Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - Grigorios Itskos
- Experimental Condensed Matter Physics Laboratory, Department of Physics, University of Cyprus, Nicosia 1678, Cyprus
| | - Gerasimos Konstantatos
- ICFO, Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
- ICREA, Institució Catalana de Recerça i Estudis Avançats, Lluis Companys 23, 08010 Barcelona, Spain
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12
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Ramiro I, Özdemir O, Christodoulou S, Gupta S, Dalmases M, Torre I, Konstantatos G. Mid- and Long-Wave Infrared Optoelectronics via Intraband Transitions in PbS Colloidal Quantum Dots. NANO LETTERS 2020; 20:1003-1008. [PMID: 31934762 PMCID: PMC7020105 DOI: 10.1021/acs.nanolett.9b04130] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 01/06/2020] [Indexed: 05/10/2023]
Abstract
Optical sensing in the mid- and long-wave infrared (MWIR, LWIR) is of paramount importance for a large spectrum of applications including environmental monitoring, gas sensing, hazard detection, food and product manufacturing inspection, and so forth. Yet, such applications to date are served by costly and complex epitaxially grown HgCdTe quantum-well and quantum-dot infrared photodetectors. The possibility of exploiting low-energy intraband transitions make colloidal quantum dots (CQD) an attractive low-cost alternative to expensive low bandgap materials for infrared applications. Unfortunately, fabrication of quantum dots exhibiting intraband absorption is technologically constrained by the requirement of controlled heavy doping, which has limited, so far, MWIR and LWIR CQD detectors to mercury-based materials. Here, we demonstrate intraband absorption and photodetection in heavily doped PbS colloidal quantum dots in the 5-9 μm range, beyond the PbS bulk band gap, with responsivities on the order of 10-4 A/W at 80 K. We have further developed a model based on quantum transport equations to understand the impact of electron population of the conduction band in the performance of intraband photodetectors and offer guidelines toward further performance improvement.
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Affiliation(s)
- Iñigo Ramiro
- The
Barcelona Institute of Science and Technology, ICFO−Institut de Ciències Fotòniques, Av. Carl Friedrich Gauss, 3, 08860 Castelldefels, Barcelona, Spain
| | - Onur Özdemir
- The
Barcelona Institute of Science and Technology, ICFO−Institut de Ciències Fotòniques, Av. Carl Friedrich Gauss, 3, 08860 Castelldefels, Barcelona, Spain
| | - Sotirios Christodoulou
- The
Barcelona Institute of Science and Technology, ICFO−Institut de Ciències Fotòniques, Av. Carl Friedrich Gauss, 3, 08860 Castelldefels, Barcelona, Spain
| | - Shuchi Gupta
- The
Barcelona Institute of Science and Technology, ICFO−Institut de Ciències Fotòniques, Av. Carl Friedrich Gauss, 3, 08860 Castelldefels, Barcelona, Spain
| | - Mariona Dalmases
- The
Barcelona Institute of Science and Technology, ICFO−Institut de Ciències Fotòniques, Av. Carl Friedrich Gauss, 3, 08860 Castelldefels, Barcelona, Spain
| | - Iacopo Torre
- The
Barcelona Institute of Science and Technology, ICFO−Institut de Ciències Fotòniques, Av. Carl Friedrich Gauss, 3, 08860 Castelldefels, Barcelona, Spain
| | - Gerasimos Konstantatos
- The
Barcelona Institute of Science and Technology, ICFO−Institut de Ciències Fotòniques, Av. Carl Friedrich Gauss, 3, 08860 Castelldefels, Barcelona, Spain
- ICREA—Institució
Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010 Barcelona, Spain
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13
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Abelson A, Qian C, Salk T, Luan Z, Fu K, Zheng JG, Wardini JL, Law M. Collective topo-epitaxy in the self-assembly of a 3D quantum dot superlattice. NATURE MATERIALS 2020; 19:49-55. [PMID: 31611669 DOI: 10.1038/s41563-019-0485-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Accepted: 08/15/2019] [Indexed: 05/25/2023]
Abstract
Epitaxially fused colloidal quantum dot (QD) superlattices (epi-SLs) may enable a new class of semiconductors that combine the size-tunable photophysics of QDs with bulk-like electronic performance, but progress is hindered by a poor understanding of epi-SL formation and surface chemistry. Here we use X-ray scattering and correlative electron imaging and diffraction of individual SL grains to determine the formation mechanism of three-dimensional PbSe QD epi-SL films. We show that the epi-SL forms from a rhombohedrally distorted body centred cubic parent SL via a phase transition in which the QDs translate with minimal rotation (~10°) and epitaxially fuse across their {100} facets in three dimensions. This collective epitaxial transformation is atomically topotactic across the 103-105 QDs in each SL grain. Infilling the epi-SLs with alumina by atomic layer deposition greatly changes their electrical properties without affecting the superlattice structure. Our work establishes the formation mechanism of three-dimensional QD epi-SLs and illustrates the critical importance of surface chemistry to charge transport in these materials.
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Affiliation(s)
- Alex Abelson
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, CA, USA
| | - Caroline Qian
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, CA, USA
| | - Trenton Salk
- Department of Physics and Astronomy, University of California, Irvine, Irvine, CA, USA
| | - Zhongyue Luan
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, CA, USA
| | - Kan Fu
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, CA, USA
| | - Jian-Guo Zheng
- Irvine Materials Research Institute, University of California, Irvine, Irvine, CA, USA
| | - Jenna L Wardini
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, CA, USA
| | - Matt Law
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, CA, USA.
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, CA, USA.
- Department of Chemistry, University of California, Irvine, Irvine, CA, USA.
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14
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Alimoradi Jazi M, Kulkarni A, Sinai SB, Peters JL, Geschiere E, Failla M, Delerue C, Houtepen AJ, Siebbeles LDA, Vanmaekelbergh D. Room-Temperature Electron Transport in Self-Assembled Sheets of PbSe Nanocrystals with a Honeycomb Nanogeometry. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2019; 123:14058-14066. [PMID: 31205579 PMCID: PMC6559210 DOI: 10.1021/acs.jpcc.9b03549] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Indexed: 06/09/2023]
Abstract
It has been shown recently that atomically coherent superstructures of a nanocrystal monolayer in thickness can be prepared by self-assembly of monodisperse PbSe nanocrystals, followed by oriented attachment. Superstructures with a honeycomb nanogeometry are of special interest, as theory has shown that they are regular 2-D semiconductors, but with the highest valence and lowest conduction bands being Dirac-type, that is, with a linear energy-momentum relation around the K-points in the zone. Experimental validation will require cryogenic measurements on single sheets of these nanocrystal monolayer superstructures. Here, we show that we can incorporate these fragile superstructures into a transistor device with electrolyte gating, control the electron density, and measure the electron transport characteristics at room temperature. The electron mobility is 1.5 ± 0.5 cm2 V-1 s-1, similar to the mobility observed with terahertz spectroscopy on freestanding superstructures. The terahertz spectroscopic data point to pronounced carrier scattering on crystallographic imperfections in the superstructure, explaining the limited mobility.
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Affiliation(s)
- Maryam Alimoradi Jazi
- Debye Institute
for Nanomaterials Science, University of
Utrecht, Princetonplein 1, 3584 CC, Utrecht, The Netherlands
| | - Aditya Kulkarni
- Optoelectronic Materials Section, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | - Sophia Buhbut Sinai
- Debye Institute
for Nanomaterials Science, University of
Utrecht, Princetonplein 1, 3584 CC, Utrecht, The Netherlands
| | - Joep L. Peters
- Debye Institute
for Nanomaterials Science, University of
Utrecht, Princetonplein 1, 3584 CC, Utrecht, The Netherlands
| | - Eva Geschiere
- Optoelectronic Materials Section, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | - Michele Failla
- Optoelectronic Materials Section, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | | | - Arjan J. Houtepen
- Optoelectronic Materials Section, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | - Laurens D. A. Siebbeles
- Optoelectronic Materials Section, Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | - Daniel Vanmaekelbergh
- Debye Institute
for Nanomaterials Science, University of
Utrecht, Princetonplein 1, 3584 CC, Utrecht, The Netherlands
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15
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Hartley CL, Dempsey JL. Electron-Promoted X-Type Ligand Displacement at CdSe Quantum Dot Surfaces. NANO LETTERS 2019; 19:1151-1157. [PMID: 30640472 DOI: 10.1021/acs.nanolett.8b04544] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Quantum dot surfaces are redox active and are known to influence the electronic properties of nanocrystals, yet the molecular-level changes in surface chemistry that occur upon addition of charge are not well understood. In this paper, we report a systematic study monitoring changes in surface coordination chemistry in 3.4 nm CdSe quantum dots upon remote chemical doping by the radical anion reductant sodium naphthalenide (Na[C10H8]). These studies reveal a new mechanism for charge-balancing the added electrons that localize on surface states through loss of up to ca. 5% of the native anionic carboxylate ligands, as quantified through a combination of UV-vis absorption, 1H NMR, and FTIR spectroscopies. A new method for distinguishing between reduction of surface metal and chalcogenide ions by monitoring ligand loss and optical changes upon doping is introduced. This work emphasizes the importance of studying changes in surface chemistry with remote chemical doping and is more broadly contextualized within the redox reactivity of the QD surface.
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Affiliation(s)
- Carolyn L Hartley
- Department of Chemistry , University of North Carolina , Chapel Hill , North Carolina 27599-3290 , United States
| | - Jillian L Dempsey
- Department of Chemistry , University of North Carolina , Chapel Hill , North Carolina 27599-3290 , United States
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16
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Lu H, Carroll GM, Chen X, Amarasinghe DK, Neale NR, Miller EM, Sercel PC, Rabuffetti FA, Efros AL, Beard MC. n-Type PbSe Quantum Dots via Post-Synthetic Indium Doping. J Am Chem Soc 2018; 140:13753-13763. [DOI: 10.1021/jacs.8b07910] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Haipeng Lu
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Gerard M. Carroll
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Xihan Chen
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Dinesh K. Amarasinghe
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - Nathan R. Neale
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Elisa M. Miller
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Peter C. Sercel
- T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, California 91125, United States
| | | | - Alexander L. Efros
- Center for Computational Materials Science, Naval Research Laboratory, Washington, District of Columbia 20375, United States
| | - Matthew C. Beard
- Chemistry & Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, United States
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