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Gallagher S, Kline J, Jahanbakhshi F, Sadighian JC, Lyons I, Shen G, Hammel BF, Yazdi S, Dukovic G, Rappe AM, Ginger DS. Ligand Equilibrium Influences Photoluminescence Blinking in CsPbBr 3: A Change Point Analysis of Widefield Imaging Data. ACS NANO 2024; 18:19208-19219. [PMID: 38982590 DOI: 10.1021/acsnano.4c04968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2024]
Abstract
Photoluminescence intermittency remains one of the biggest challenges in realizing perovskite quantum dots (QDs) as scalable single photon emitters. We compare CsPbBr3 QDs capped with different ligands, lecithin, and a combination of oleic acid and oleylamine, to elucidate the role of surface chemistry on photoluminescence intermittency. We employ widefield photoluminescence microscopy to sample the blinking behavior of hundreds of QDs. Using change point analysis, we achieve the robust classification of blinking trajectories, and we analyze representative distributions from large numbers of QDs (Nlecithin = 1308, Noleic acid/oleylamine = 1317). We find that lecithin suppresses blinking in CsPbBr3 QDs compared with oleic acid/oleylamine. Under common experimental conditions, lecithin-capped QDs are 7.5 times more likely to be nonblinking and spend 2.5 times longer in their most emissive state, despite both QDs having nearly identical solution photoluminescence quantum yields. We measure photoluminescence as a function of dilution and show that the differences between lecithin and oleic acid/oleylamine capping emerge at low concentrations during preparation for single particle experiments. From experiment and first-principles calculations, we attribute the differences in lecithin and oleic acid/oleylamine performance to differences in their ligand binding equilibria. Consistent with our experimental data, density functional theory calculations suggest a stronger binding affinity of lecithin to the QD surface compared to oleic acid/oleylamine, implying a reduced likelihood of ligand desorption during dilution. These results suggest that using more tightly binding ligands is a necessity for surface passivation and, consequently, blinking reduction in perovskite QDs used for single particle and quantum light experiments.
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Affiliation(s)
- Shaun Gallagher
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Jessica Kline
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Farzaneh Jahanbakhshi
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - James C Sadighian
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Ian Lyons
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Gillian Shen
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Benjamin F Hammel
- Materials Science and Engineering, University of Colorado Boulder, Boulder, Colorado 80309-0215, United States
| | - Sadegh Yazdi
- Materials Science and Engineering, University of Colorado Boulder, Boulder, Colorado 80309-0215, United States
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80309-0215, United States
| | - Gordana Dukovic
- Materials Science and Engineering, University of Colorado Boulder, Boulder, Colorado 80309-0215, United States
- Renewable and Sustainable Energy Institute, University of Colorado Boulder, Boulder, Colorado 80309-0215, United States
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309-0215, United States
| | - Andrew M Rappe
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - David S Ginger
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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2
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Priya S, Berchmans S. Ferrocene probe-assisted fluorescence quenching of PEI-carbon dots for NO detection and the logic gates based sensing of NO enabled by trimodal detection. Sci Rep 2024; 14:10402. [PMID: 38710731 DOI: 10.1038/s41598-024-61117-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 05/02/2024] [Indexed: 05/08/2024] Open
Abstract
Our research demonstrates the effectiveness of fluorescence quenching between polyethyleneimine functionalised carbon dots (PEI-CDs) and cyclodextrin encapsulated ferrocene for fluorogenic detection of nitric oxide (NO). We confirmed that ferrocene can be used as a NO probe by observing its ability to quench the fluorescence emitted from PEI-CDs, with NO concentrations ranging from 1 × 10-6 M to 5 × 10-4 M. The photoluminescence intensity (PL) of PEI-CDs decreased linearly, with a detection limit of 500 nM. Previous studies have shown that ferrocene is a selective probe for NO detection in biological systems by electrochemical and colorimetric methods. The addition of fluorogenic NO detection using ferrocene as a probe enables the development of a three-way sensor probe for NO. Furthermore, the triple mode NO detection (electrochemical, colorimetric, and fluorogenic) with ferrocene aids in processing sensing data in a controlled manner similar to Boolean logic operations. This work presents key findings on the mechanism of fluorescence quenching between ferrocene hyponitrite intermediate and PEI-CDs, the potential of using ferrocene for triple channel NO detection as a single molecular entity, and the application of logic gates for NO sensing.
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Affiliation(s)
- S Priya
- NSS College, Nemmara, Palakkad, India.
| | - Sheela Berchmans
- Electrodics and Electrocatalysis Division, CSIR-Central Electrochemical Research Institute, Karaikudi, Tamilnadu, 630006, India
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3
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Gutierrez IZ, Gerke C, Shen Y, Ximendes E, Silvan MM, Marin R, Jaque D, Calderón OG, Melle S, Rubio-Retama J. Boosting the Near-Infrared Emission of Ag 2S Nanoparticles by a Controllable Surface Treatment for Bioimaging Applications. ACS APPLIED MATERIALS & INTERFACES 2022; 14:4871-4881. [PMID: 35049282 PMCID: PMC8815038 DOI: 10.1021/acsami.1c19344] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Affiliation(s)
- Irene Zabala Gutierrez
- Departamento de Química en Ciencias Farmacéuticas, Universidad Complutense de Madrid, Madrid 28040, Spain
| | - Christoph Gerke
- Departamento de Química en Ciencias Farmacéuticas, Universidad Complutense de Madrid, Madrid 28040, Spain
- Nanobiology Group, Instituto Ramón y Cajal de Investigación Sanitaria, IRYCIS, Madrid 28034, Spain
| | - Yingli Shen
- NanoBIG, Facultad de Ciencias, Departamento de Física de Materiales,Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Erving Ximendes
- NanoBIG, Facultad de Ciencias, Departamento de Física de Materiales,Universidad Autónoma de Madrid, Madrid 28049, Spain
- Nanobiology Group, Instituto Ramón y Cajal de Investigación Sanitaria, IRYCIS, Madrid 28034, Spain
| | - Miguel Manso Silvan
- Facultad de Ciencias, Departamento de Física Aplicada, Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Riccardo Marin
- NanoBIG, Facultad de Ciencias, Departamento de Física de Materiales,Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Daniel Jaque
- NanoBIG, Facultad de Ciencias, Departamento de Física de Materiales,Universidad Autónoma de Madrid, Madrid 28049, Spain
- Nanobiology Group, Instituto Ramón y Cajal de Investigación Sanitaria, IRYCIS, Madrid 28034, Spain
| | - Oscar G Calderón
- Departamento de Óptica, Universidad Complutense de Madrid, Madrid 28037, Spain
| | - Sonia Melle
- Departamento de Óptica, Universidad Complutense de Madrid, Madrid 28037, Spain
| | - Jorge Rubio-Retama
- Departamento de Química en Ciencias Farmacéuticas, Universidad Complutense de Madrid, Madrid 28040, Spain
- Nanobiology Group, Instituto Ramón y Cajal de Investigación Sanitaria, IRYCIS, Madrid 28034, Spain
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4
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Greytak AB, Abiodun SL, Burrell JM, Cook EN, Jayaweera NP, Islam MM, Shaker AE. Thermodynamics of nanocrystal–ligand binding through isothermal titration calorimetry. Chem Commun (Camb) 2022; 58:13037-13058. [DOI: 10.1039/d2cc05012a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Manipulations of nanocrystal (NC) surfaces have propelled the applications of colloidal NCs across various fields such as bioimaging, catalysis, electronics, and sensing applications.
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Affiliation(s)
- Andrew B. Greytak
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Sakiru L. Abiodun
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Jennii M. Burrell
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Emily N. Cook
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Nuwanthaka P. Jayaweera
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Md Moinul Islam
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
| | - Abdulla E Shaker
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA
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5
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Quaternary Alloy Quantum Dots as Fluorescence Probes for Total Acidity Detection of Paper-Based Relics. NANOMATERIALS 2021; 11:nano11071726. [PMID: 34209119 PMCID: PMC8308194 DOI: 10.3390/nano11071726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 06/25/2021] [Accepted: 06/25/2021] [Indexed: 11/17/2022]
Abstract
Traditionally, the acidity of paper-based relics was determined by an extraction method and using a pH meter. This method could not obtain the total acidity of the paper-based relics because it only detected the concentration of free protons in the aqueous soaking solution. To overcome this defect, a new method for determining the total acidity of paper-based relics has been established by using quaternary alloy quantum dots. The quantum dots, CdZnSeS, modified by p-Aminothiophenol (pATP) were prepared, and their composition and structure were characterized. The fluorescence behavior of prepared quantum dots with acidity was investigated. The following results were obtained. The fluorescence of CdZnSeS-pATP quantum dots could decrease with increases in acidity because pATP dissociated from the surfaces of the quantum dots due to protons or undissociated weak acids. Based on this feature, a method for determining the acidity of paper-based relics was constructed, and this method was used to evaluate the acidity of actual paper-based relics. Obviously, for a given paper sample, since both free protons and bound protons can be determined by this method, the acidity measured by this method is more reasonable than that by pH meter.
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Kagan CR, Bassett LC, Murray CB, Thompson SM. Colloidal Quantum Dots as Platforms for Quantum Information Science. Chem Rev 2020; 121:3186-3233. [DOI: 10.1021/acs.chemrev.0c00831] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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7
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Lei H, Wang Y, Liu S, Zhu M, Pu C, Lin S, Qin H, Peng X. Delocalized Surface Electronic States on Polar Facets of Semiconductor Nanocrystals. ACS NANO 2020; 14:16614-16623. [PMID: 33095559 DOI: 10.1021/acsnano.0c07176] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Wurtzite CdSe@CdS dot@platelet nanocrystals with (001) and (00-1) polar facets as the basal planes and (100) family of nonpolar facets as the side planes are applied for studying surface defects on semiconductor nanocrystals. When they are terminated with cadmium ions coordinated with carboxylate ligands, a single set of absorption features and band-edge photoluminescence (PL) with near unity PL quantum yield and monoexponential PL decay dynamics (lifetime ∼28 ns) are observed. In addition to these spectral signatures, when the surface is converted to sulfur-terminated, a second set of sharp absorption features with decent extinction coefficients and a secondary band-edge PL with low PL quantum yield and long-lifetime (>78 ns) PL decay dynamics are reproducibly recorded. Photochemical analysis confirms that the secondary UV-vis and PL spectral features are quantitatively correlated with each other. Chemical analysis and X-ray photoelectron spectroscopy measurements confirm that such secondary spectral features are well correlated with the sulfide (such as -SH) and disulfide (such as -S-S-) surface sites of a basal plane, which likely form surface hole electronic states delocalized on the entire basal plane. Results suggest that, for studying surface defects on semiconductor nanocrystals, it is essential to prepare a nearly monodisperse surface structure in terms of facets and surface chemical bonding.
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Affiliation(s)
- Hairui Lei
- Center for Chemistry of Novel and High-Performance Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Yonghong Wang
- Center for Chemistry of Novel and High-Performance Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Shaojie Liu
- Center for Chemistry of Novel and High-Performance Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Meiyi Zhu
- Center for Chemistry of Novel and High-Performance Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Chaodan Pu
- Center for Chemistry of Novel and High-Performance Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Shangxin Lin
- Center for Chemistry of Novel and High-Performance Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Haiyan Qin
- Center for Chemistry of Novel and High-Performance Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Xiaogang Peng
- Center for Chemistry of Novel and High-Performance Materials, Department of Chemistry, Zhejiang University, Hangzhou 310027, China
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8
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Nicoli F, Zhang T, Hübner K, Jin B, Selbach F, Acuna G, Argyropoulos C, Liedl T, Pilo-Pais M. DNA-Mediated Self-Assembly of Plasmonic Antennas with a Single Quantum Dot in the Hot Spot. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1804418. [PMID: 30734483 DOI: 10.1002/smll.201804418] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 11/23/2018] [Indexed: 06/09/2023]
Abstract
DNA self-assembly is a powerful tool to arrange optically active components with high accuracy in a large parallel manner. A facile approach to assemble plasmonic antennas consisting of two metallic nanoparticles (40 nm) with a single colloidal quantum dot positioned at the hot spot is presented here. The design approach is based on DNA complementarity, stoichiometry, and steric hindrance principles. Since no intermediate molecules other than short DNA strands are required, the structures possess a very small gap (≈ 5 nm) which is desired to achieve high Purcell factors and plasmonic enhancement. As a proof-of-concept, the fluorescence emission from antennas assembled with both conventional and ultrasmooth spherical gold particles is measured. An increase in fluorescence is obtained, up to ≈30-fold, compared to quantum dots without antenna.
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Affiliation(s)
- Francesca Nicoli
- Faculty of Physics and Center for Nanoscience (CeNS), Ludwig-Maximilians-Universität, München (LMU), 80539, Munich, Germany
| | - Tao Zhang
- Faculty of Physics and Center for Nanoscience (CeNS), Ludwig-Maximilians-Universität, München (LMU), 80539, Munich, Germany
| | - Kristina Hübner
- Department of Chemistry and Center for Nanoscience (CeNS), Ludwig-Maximilians-Universität München (LMU), 81377, Munich, Germany
| | - Boyuan Jin
- Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Florian Selbach
- Department of Chemistry and Center for Nanoscience (CeNS), Ludwig-Maximilians-Universität München (LMU), 81377, Munich, Germany
| | - Guillermo Acuna
- Department of Physics, University of Fribourg, 1700, Fribourg, Switzerland
| | - Christos Argyropoulos
- Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Tim Liedl
- Faculty of Physics and Center for Nanoscience (CeNS), Ludwig-Maximilians-Universität, München (LMU), 80539, Munich, Germany
| | - Mauricio Pilo-Pais
- Faculty of Physics and Center for Nanoscience (CeNS), Ludwig-Maximilians-Universität, München (LMU), 80539, Munich, Germany
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9
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Mazzio KA, Prasad SKK, Okamoto K, Hodgkiss JM, Luscombe CK. End-Functionalized Semiconducting Polymers as Reagents in the Synthesis of Hybrid II-VI Nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:9692-9700. [PMID: 30056697 DOI: 10.1021/acs.langmuir.8b01307] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The functionalization of II-VI nanocrystals with semiconducting polymers is of fundamental interest for lightweight, solution-processed optoelectronics. The direct surface functionalization of nanocrystals is useful for facilitating charge transfer across the donor/acceptor interface, in addition to promoting good mixing properties and thereby helping prevent nanoparticle aggregation. In this work, we develop a new method for the direct attachment of semiconducting polymers to II-VI inorganic nanocrystals, where the polymer plays a dual role, acting as both the desired capping agent and a chalcogenide monomer during synthesis. The success of this hybridization procedure relies on the establishment of a new polymer end-functionalization scheme, where a route toward a thio-phosphonate polymer end-group is developed; this end-group resembles many chalcogenide precursor materials used in the synthesis of II-VI nanomaterials. We show the applicability of this hybrid functionalization procedure by attaching poly(3-hexylthiophene-2,5-diyl) to CdSe and CdS. We followed the progress of the reaction by NMR and used transmission electron microscopy to determine the morphology of the resulting materials, which we found to have narrow size distributions after hybridization. Polymer attachment to the nanocrystals was confirmed by examining the steady-state and time-resolved optical properties of the hybrid materials, which also provided an insight into excited-state processes occurring across the hybrid interface.
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Affiliation(s)
| | - Shyamal K K Prasad
- School of Chemical and Physical Sciences , Victoria University of Wellington , Wellington 6040 , New Zealand
- The MacDiarmid Institute for Advanced Materials and Nanotechnology , Wellington 6140 , New Zealand
| | - Ken Okamoto
- Department of Engineering for Future Innovation, Division of Chemical Engineering and Biotechnology , National Institute of Technology, Ichinoseki College , Takanashi, Hagisho, Ichinoseki , Iwate 021-8511 , Japan
| | - Justin M Hodgkiss
- School of Chemical and Physical Sciences , Victoria University of Wellington , Wellington 6040 , New Zealand
- The MacDiarmid Institute for Advanced Materials and Nanotechnology , Wellington 6140 , New Zealand
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10
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Cui Y, Cui X, Zhang L, Xie Y, Yang M. Theoretical characterization on the size-dependent electron and hole trapping activity of chloride-passivated CdSe nanoclusters. J Chem Phys 2018; 148:134308. [DOI: 10.1063/1.5023408] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Affiliation(s)
- Yingqi Cui
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, People’s Republic of China
| | - Xianhui Cui
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, People’s Republic of China
| | - Li Zhang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, People’s Republic of China
| | - Yujuan Xie
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, People’s Republic of China
| | - Mingli Yang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, People’s Republic of China
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11
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Abstract
Ozone (O3) gas is widely used as a strong oxidizing agent for many purposes, such as the decomposition/removal of organic contaminants and photoresist, and the deodorization/disinfection of air and water. However, ozone is highly toxic to the human body when the air concentration exceeds about 1 ppm. Therefore, there is increasing demand for simple, sensitive, reliable, and cost-effective techniques for sensing ozone gas. This article describes the features, advantages, and disadvantages of the available, practical techniques for sensing ozone gas in ambient air. The advantages of optical gas sensors as next-generation sensors is specifically introduced. The features of photoluminescent, semiconductor nanoparticles (quantum dots, QDs) as bright phosphors with the potential for various applications is further explored. Lastly, recent research results demonstrating the ozone sensitivity of photoluminescent CdSe-based core-shell quantum dots are presented. These results strongly suggest that optical ozone sensing using photoluminescent quantum dots is a promising technique.
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Affiliation(s)
- Masanori Ando
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST)
| | - Vasudevanpillai Biju
- Research Institute for Electronic Science and Graduate School of Environmental Science, Hokkaido University
| | - Yasushi Shigeri
- Health Research Institute, National Institute of Advanced Industrial Science and Technology (AIST)
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12
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Shen Y, Gee MY, Greytak AB. Purification technologies for colloidal nanocrystals. Chem Commun (Camb) 2018; 53:827-841. [PMID: 27942615 DOI: 10.1039/c6cc07998a] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Almost all applications of colloidal nanocrystals require some type of purification or surface modification process following nanocrystal growth. Nanocrystal purification - the separation of nanocrystals from undesired solution components - can perturb the surface chemistry and thereby the physical properties of colloidal nanocrystals due to changes in solvent, solute concentrations, and exposure of the nanocrystal surface to oxidation or hydrolysis. For example, nanocrystal quantum dots frequently exhibit decreased photoluminescence brightness after precipitation from the growth solvent and subsequent redissolution. Consequently, purification is an integral part of the synthetic chemistry of colloidal nanocrystals, and the effect of purification methods must be considered in order to accurately compare and predict the behavior of otherwise similar nanocrystal samples. In this Feature Article we examine established and emerging approaches to the purification of colloidal nanoparticles from a nanocrystal surface chemistry viewpoint. Purification is generally achieved by exploiting differences in properties between the impurities and the nanoparticles. Three distinct properties are typically manipulated: polarity (relative solubility), electrophoretic mobility, and size. We discuss precipitation, extraction, electrophoretic methods, and size-based methods including ultracentrifugation, ultrafiltration, diafiltration, and size-exclusion chromatography. The susceptibility of quantum dots to changes in surface chemistry, with changes in photoluminescence decay associated with surface chemical changes, extends even into the case of core/shell structures. Accordingly, the goal of a more complete description of quantum dot surface chemistry has been a driver of innovation in colloidal nanocrystal purification methods. We specifically examine the effect of purification on surface chemistry and photoluminescence in quantum dots as an example of the challenges associated with nanocrystal purification and how improved understanding can result from increasingly precise techniques, and associated surface-sensitive analytical methods.
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Affiliation(s)
- Yi Shen
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA.
| | - Megan Y Gee
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA.
| | - A B Greytak
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA. and USC Nanocenter, University of South Carolina, Columbia, SC 29208, USA
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Kisslinger R, Hua W, Shankar K. Bulk Heterojunction Solar Cells Based on Blends of Conjugated Polymers with II⁻VI and IV⁻VI Inorganic Semiconductor Quantum Dots. Polymers (Basel) 2017; 9:E35. [PMID: 30970717 PMCID: PMC6431844 DOI: 10.3390/polym9020035] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 01/16/2017] [Accepted: 01/18/2017] [Indexed: 01/06/2023] Open
Abstract
Bulk heterojunction solar cells based on blends of quantum dots and conjugated polymers are a promising configuration for obtaining high-efficiency, cheaply fabricated solution-processed photovoltaic devices. Such devices are of significant interest as they have the potential to leverage the advantages of both types of materials, such as the high mobility, band gap tunability and possibility of multiple exciton generation in quantum dots together with the high mechanical flexibility and large molar extinction coefficient of conjugated polymers. Despite these advantages, the power conversion efficiency (PCE) of these hybrid devices has remained relatively low at around 6%, well behind that of all-organic or all-inorganic solar cells. This is attributed to major challenges that still need to be overcome before conjugated polymer⁻quantum dot blends can be considered viable for commercial application, such as controlling the film morphology and interfacial structure to ensure efficient charge transfer and charge transport. In this work, we present our findings with respect to the recent development of bulk heterojunctions made from conjugated polymer⁻quantum dot blends, list the ongoing strategies being attempted to improve performance, and highlight the key areas of research that need to be pursued to further develop this technology.
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Affiliation(s)
- Ryan Kisslinger
- Department of Electrical and Computer Engineering, University of Alberta, 9211-116 St., Edmonton, AB T6G 1H9, Canada.
| | - Weidi Hua
- Department of Electrical and Computer Engineering, University of Alberta, 9211-116 St., Edmonton, AB T6G 1H9, Canada.
| | - Karthik Shankar
- Department of Electrical and Computer Engineering, University of Alberta, 9211-116 St., Edmonton, AB T6G 1H9, Canada.
- National Research Council Canada National Institute for Nanotechnology, 11421 Saskatchewan Drive NW, Edmonton, AB T6G 2M9, Canada.
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UEMATSU T. Improvement of Optical Properties for Semiconductor Nanoparticles by the Precise Control of Electron and Energy Transfer. ELECTROCHEMISTRY 2017. [DOI: 10.5796/electrochemistry.85.543] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Taro UEMATSU
- Frontier Research Base for Global Young Researchers, Graduate School of Engineering, Osaka University
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University
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15
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Sensing of ozone based on its quenching effect on the photoluminescence of CdSe-based core-shell quantum dots. Mikrochim Acta 2016. [DOI: 10.1007/s00604-016-1938-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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16
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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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17
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Nepomnyashchii AB, Harris RD, Weiss EA. Composition and Permeability of Oleate Adlayers of CdS Quantum Dots upon Dilution to Photoluminescence-Relevant Concentrations. Anal Chem 2016; 88:3310-6. [DOI: 10.1021/acs.analchem.5b04786] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Alexander B. Nepomnyashchii
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Rachel D. Harris
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Emily A. Weiss
- Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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18
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Zhou Y, Wang F, Buhro WE. Large Exciton Energy Shifts by Reversible Surface Exchange in 2D II–VI Nanocrystals. J Am Chem Soc 2015; 137:15198-208. [DOI: 10.1021/jacs.5b09343] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Yang Zhou
- Department of Chemistry, Washington University, Saint Louis, Missouri 63130-4899, United States
| | - Fudong Wang
- Department of Chemistry, Washington University, Saint Louis, Missouri 63130-4899, United States
| | - William E. Buhro
- Department of Chemistry, Washington University, Saint Louis, Missouri 63130-4899, United States
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19
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Lifshitz E. Evidence in Support of Exciton to Ligand Vibrational Coupling in Colloidal Quantum Dots. J Phys Chem Lett 2015; 6:4336-4347. [PMID: 26538048 DOI: 10.1021/acs.jpclett.5b01567] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The Perspective focuses on the investigation of an unresolved conflict in semiconductor colloidal quantum dots (CQDs) research, concerning the influence of the immediate surrounding on the optical properties of the materials. Today's advanced synthetic colloidal procedures offer formation of a high-quality inorganic crystallite, capped with various organic/inorganic molecular ligands. The Perspective aims to clarify whether exciton recombination processes in CQDs are influenced by the type of crystallite-ligand bonding and, moreover, whether these excitonic processes experience direct coupling to the ligands' vibrational modes. Most ligands used have redox characteristics whose functional groups are added on to the CQDs' surface via coordination, covalent or ionic bonding. The surface-ligand bonding introduces electronic states either above or below the intraband/interband energy gap, resulting in electronic passivation or in creation of trapping states that affect intraband and interband relaxation processes. Furthermore, crystalline electronic states may have a direct coupling to molecular vibrational states via direct overlap of electronic wave functions or through a long-range energy-transfer process. Also, photoejected carriers resulting from an Auger process or ionization processes may diffuse temporarily onto a ligand site. These scenarios are discussed in the current publication with supporting theoretical and experimental observations.
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Affiliation(s)
- Efrat Lifshitz
- Schulich Faculty of Chemistry, Russell Berrie Nanotechnology Institute, Solid State Institute, Technion, Israel Institute of Technology , Haifa 32000, Israel
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20
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Miller JB, Dandu N, Velizhanin KA, Anthony RJ, Kortshagen UR, Kroll DM, Kilina S, Hobbie EK. Enhanced Luminescent Stability through Particle Interactions in Silicon Nanocrystal Aggregates. ACS NANO 2015; 9:9772-9782. [PMID: 26348831 DOI: 10.1021/acsnano.5b02676] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Close-packed assemblies of ligand-passivated colloidal nanocrystals can exhibit enhanced photoluminescent stability, but the origin of this effect is unclear. Here, we use experiment, simulation, and ab initio computation to examine the influence of interparticle interactions on the photoluminescent stability of silicon nanocrystal aggregates. The time-dependent photoluminescence emitted by structures ranging in size from a single quantum dot to agglomerates of more than a thousand is compared with Monte Carlo simulations of noninteracting ensembles using measured single-particle blinking data as input. In contrast to the behavior typically exhibited by the metal chalcogenides, the measured photoluminescent stability shows an enhancement with respect to the noninteracting scenario with increasing aggregate size. We model this behavior using time-dependent density functional theory calculations of energy transfer between neighboring nanocrystals as a function of nanocrystal size, separation, and the presence of charge and/or surface-passivation defects. Our results suggest that rapid exciton transfer from "bright" nanocrystals to surface trap states in nearest-neighbors can efficiently fill such traps and enhance the stability of emission by promoting the radiative recombination of slowly diffusing excited electrons.
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Affiliation(s)
- Joseph B Miller
- North Dakota State University , Fargo, North Dakota 58108, United States
| | - Naveen Dandu
- North Dakota State University , Fargo, North Dakota 58108, United States
| | - Kirill A Velizhanin
- Theoretical Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Rebecca J Anthony
- University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Uwe R Kortshagen
- University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Daniel M Kroll
- North Dakota State University , Fargo, North Dakota 58108, United States
| | - Svetlana Kilina
- North Dakota State University , Fargo, North Dakota 58108, United States
| | - Erik K Hobbie
- North Dakota State University , Fargo, North Dakota 58108, United States
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21
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Zenkevich E, Stupak A, Göhler C, Krasselt C, von Borczyskowski C. Tuning electronic states of a CdSe/ZnS quantum dot by only one functional dye molecule. ACS NANO 2015; 9:2886-2903. [PMID: 25703788 DOI: 10.1021/nn506941c] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Self-assembly of only one functionalized porphyrin dye molecule with one CdSe/ZnS quantum dot (QD) not only modifies the photoluminescence (PL) intensity but also creates a few energetically clearly distinguishable electronic states, opening additional effective relaxation pathways. The related energy modifications are in the range of 10-30 meV and show a pronounced sensitivity to the specific nature of the respective dye. We assign the emerging energies to surface states. Time-resolved PL spectroscopy in combination with spectral deconvolution reveals that surface properties of QDs are a complex interplay of the nature of the dye molecule and the topography of the ligand layer across a temperature range from 77 to 290 K. This includes a kind of phase transition of trioctylphosphine oxide ligands, switching the nature of surface states observed below and above the phase transition temperature. Most importantly, our findings can be closely related to recent calculations of ligand-induced modifications of surface states of QDs. The identification of the optical properties emerged from a combination of spectroscopy on single QDs and QDs in an ensemble.
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Affiliation(s)
- Eduard Zenkevich
- †Department of Information Technologies and Robotics, National Technical University of Belarus, Nezavisimosti Ave., 65, 220013 Minsk, Belarus
| | - Aleksander Stupak
- ‡B.I. Stepanov Institute of Physics, National Academy of Science of Belarus, Nezavisimosti Ave., 70, 220072 Minsk, Belarus
| | - Clemens Göhler
- §Institute of Physics, Technische Universität Chemnitz, Reichenhainerstr. 70, 09107 Chemnitz, Germany
| | - Cornelius Krasselt
- §Institute of Physics, Technische Universität Chemnitz, Reichenhainerstr. 70, 09107 Chemnitz, Germany
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22
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Shen Y, Tan R, Gee MY, Greytak AB. Quantum yield regeneration: influence of neutral ligand binding on photophysical properties in colloidal core/shell quantum dots. ACS NANO 2015; 9:3345-59. [PMID: 25753127 DOI: 10.1021/acsnano.5b00671] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
This article describes an experiment designed to identify the role of specific molecular ligands in maintaining the high photoluminescence (PL) quantum yield (QY) observed in as-synthesized CdSe/CdZnS and CdSe/CdS quantum dots (QDs). Although it has been possible for many years to prepare core/shell quantum dots with near-unity quantum yield through high-temperature colloidal synthesis, purification of such colloidal particles is frequently accompanied by a reduction in quantum yield. Here, a recently established gel permeation chromatography (GPC) technique is used to remove weakly associated ligands without a change in solvent: a decrease in ensemble QY and average PL lifetime is observed. Minor components of the initial mixture that were removed by GPC are then added separately to purified QD samples to determine whether reintroduction of these components can restore the photophysical properties of the initial sample. We show that among these putative ligands trioctylphosphine and cadmium oleate can regenerate the initial high QY of all samples, but only the "L-type" ligands (trioctyphosphine and oleylamine) can restore the QY without changing the shapes of the optical spectra. On the basis of the PL decay analysis, we confirm that quenching in GPC-purified samples and regeneration in ligand-introduced samples are associated chiefly with changes in the relative population fraction of QDs with different decay rates. The reversibility of the QY regeneration process has also been studied; the introduction and removal of trioctylphosphine and oleylamine tend to be reversible, while cadmium oleate is not. Finally, isothermal titration calorimetry has been used to study the relationship between the binding strength of the neutral ligands to the surface and photophysical property changes in QD samples to which they are added.
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Affiliation(s)
- Yi Shen
- †Department of Chemistry and Biochemistry and ‡USC Nanocenter, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Rui Tan
- †Department of Chemistry and Biochemistry and ‡USC Nanocenter, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Megan Y Gee
- †Department of Chemistry and Biochemistry and ‡USC Nanocenter, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Andrew B Greytak
- †Department of Chemistry and Biochemistry and ‡USC Nanocenter, University of South Carolina, Columbia, South Carolina 29208, United States
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23
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Yalcin AO, Goris B, van Dijk-Moes RJA, Fan Z, Erdamar AK, Tichelaar FD, Vlugt TJH, Van Tendeloo G, Bals S, Vanmaekelbergh D, Zandbergen HW, van Huis MA. Heat-induced transformation of CdSe-CdS-ZnS core-multishell quantum dots by Zn diffusion into inner layers. Chem Commun (Camb) 2015; 51:3320-3. [PMID: 25431813 DOI: 10.1039/c4cc08647c] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work, we investigate the thermal evolution of CdSe-CdS-ZnS core-multishell quantum dots (QDs) in situ using transmission electron microscopy (TEM). Starting at a temperature of approximately 250 °C, Zn diffusion into inner layers takes place together with simultaneous evaporation of particularly Cd and S. As a result of this transformation, CdxZn1-xSe-CdyZn1-yS core-shell QDs are obtained.
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Affiliation(s)
- Anil O Yalcin
- Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
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24
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Ding TX, Olshansky JH, Leone SR, Alivisatos AP. Efficiency of Hole Transfer from Photoexcited Quantum Dots to Covalently Linked Molecular Species. J Am Chem Soc 2015; 137:2021-9. [DOI: 10.1021/ja512278a] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Tina X. Ding
- Kavli Energy Nanosciences Institute, Berkeley, California 94720, United States
| | - Jacob H. Olshansky
- Kavli Energy Nanosciences Institute, Berkeley, California 94720, United States
| | | | - A. Paul Alivisatos
- Kavli Energy Nanosciences Institute, Berkeley, California 94720, United States
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25
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Würth C, Geißler D, Behnke T, Kaiser M, Resch-Genger U. Critical review of the determination of photoluminescence quantum yields of luminescent reporters. Anal Bioanal Chem 2014; 407:59-78. [DOI: 10.1007/s00216-014-8130-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/15/2014] [Accepted: 08/22/2014] [Indexed: 12/13/2022]
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26
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Li X, Nichols VM, Zhou D, Lim C, Pau GSH, Bardeen CJ, Tang ML. Observation of multiple, identical binding sites in the exchange of carboxylic acid ligands with CdS nanocrystals. NANO LETTERS 2014; 14:3382-3387. [PMID: 24810426 DOI: 10.1021/nl500885t] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We study ligand exchange between the carboxylic acid group and 5.0 nm oleic-acid capped CdS nanocrystals (NCs) using fluorescence resonance energy transfer (FRET). This is the first measurement of the initial binding events between cadmium chalcogenide NCs and carboxylic acid groups. The binding behavior can be described as an interaction between a ligand with single binding group and a substrate with multiple, identical binding sites. Assuming Poissonian binding statistics, our model fits both steady-state and time-resolved photoluminescence (SSPL and TRPL, respectively) data well. A modified Langmuir isotherm reveals that a CdS nanoparticle has an average of 3.0 new carboxylic acid ligands and binding constant, Ka, of 3.4 × 10(5) M(-1).
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Affiliation(s)
- Xin Li
- Department of Chemistry, University of California, Riverside , Riverside, California 92521, United States
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27
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Hines DA, Kamat PV. Recent advances in quantum dot surface chemistry. ACS APPLIED MATERIALS & INTERFACES 2014; 6:3041-3057. [PMID: 24506801 DOI: 10.1021/am405196u] [Citation(s) in RCA: 165] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Quantum dot (QD) surface chemistry is an emerging field in semiconductor nanocrystal related research. Along with size manipulation, the careful control of QD surface chemistry allows modulation of the optical properties of a QD suspension. Even a single molecule bound to the surface can introduce new functionalities. Herein, we summarize the recent advances in QD surface chemistry and the resulting effects on optical and electronic properties. Specifically, this review addresses three main issues: (i) how surface chemistry affects the optical properties of QDs, (ii) how it influences the excited state dynamics, and (iii) how one can manipulate surface chemistry to control the interactions between QDs and metal oxides, metal nanoparticles, and in self-assembled QD monolayers.
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Affiliation(s)
- Douglas A Hines
- Notre Dame Radiation Laboratory, Department of Chemistry, Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
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28
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Peterson MD, Cass LC, Harris RD, Edme K, Sung K, Weiss EA. The role of ligands in determining the exciton relaxation dynamics in semiconductor quantum dots. Annu Rev Phys Chem 2013; 65:317-39. [PMID: 24364916 DOI: 10.1146/annurev-physchem-040513-103649] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This article reviews the mechanisms through which molecules adsorbed to the surfaces of semiconductor nanocrystals, quantum dots (QDs), influence the pathways for and dynamics of intra- and interband exciton relaxation in these nanostructures. In many cases, the surface chemistry of the QDs determines the competition between Auger relaxation and electronic-to-vibrational energy transfer in the intraband cooling of hot carriers, and between electron or hole-trapping processes and radiative recombination in relaxation of band-edge excitons. The latter competition determines the photoluminescence quantum yield of the nanocrystals, which is predictable through a set of mostly phenomenological models that link the surface coverage of ligands with specific chemical properties to the rate constants for nonradiative exciton decay.
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Affiliation(s)
- Mark D Peterson
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113;
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29
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Anderson NC, Hendricks MP, Choi JJ, Owen JS. Ligand exchange and the stoichiometry of metal chalcogenide nanocrystals: spectroscopic observation of facile metal-carboxylate displacement and binding. J Am Chem Soc 2013; 135:18536-48. [PMID: 24199846 PMCID: PMC4102385 DOI: 10.1021/ja4086758] [Citation(s) in RCA: 430] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We demonstrate that metal carboxylate complexes (L-M(O2CR)2, R = oleyl, tetradecyl, M = Cd, Pb) are readily displaced from carboxylate-terminated ME nanocrystals (ME = CdSe, CdS, PbSe, PbS) by various Lewis bases (L = tri-n-butylamine, tetrahydrofuran, tetradecanol, N,N-dimethyl-n-butylamine, tri-n-butylphosphine, N,N,N',N'-tetramethylbutylene-1,4-diamine, pyridine, N,N,N',N'-tetramethylethylene-1,2-diamine, n-octylamine). The relative displacement potency is measured by (1)H NMR spectroscopy and depends most strongly on geometric factors such as sterics and chelation, although also on the hard/soft match with the cadmium ion. The results suggest that ligands displace L-M(O2CR)2 by cooperatively complexing the displaced metal ion as well as the nanocrystal. Removal of up to 90% of surface-bound Cd(O2CR)2 from CdSe and CdS nanocrystals decreases the Cd/Se ratio from 1.1 ± 0.06 to 1.0 ± 0.05, broadens the 1S(e)-2S(3/2h) absorption, and decreases the photoluminescence quantum yield (PLQY) from 10% to <1% (CdSe) and from 20% to <1% (CdS). These changes are partially reversed upon rebinding of M(O2CR)2 at room temperature (∼60%) and fully reversed at elevated temperature. A model is proposed in which electron-accepting M(O2CR)2 complexes (Z-type ligands) reversibly bind to nanocrystals, leading to a range of stoichiometries for a given core size. The results demonstrate that nanocrystals lack a single chemical formula, but are instead dynamic structures with concentration-dependent compositions. The importance of these findings to the synthesis and purification of nanocrystals as well as ligand exchange reactions is discussed.
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Affiliation(s)
- Nicholas C. Anderson
- Department of Chemistry, Columbia University, 3000 Broadway, MC 3121, New York, NY 10027
| | - Mark P. Hendricks
- Department of Chemistry, Columbia University, 3000 Broadway, MC 3121, New York, NY 10027
| | - Joshua J. Choi
- Department of Chemistry, Columbia University, 3000 Broadway, MC 3121, New York, NY 10027
| | - Jonathan S. Owen
- Department of Chemistry, Columbia University, 3000 Broadway, MC 3121, New York, NY 10027
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30
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Weiss EA. Organic molecules as tools to control the growth, surface structure, and redox activity of colloidal quantum dots. Acc Chem Res 2013; 46:2607-15. [PMID: 23734589 DOI: 10.1021/ar400078u] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In order to achieve efficient and reliable technology that can harness solar energy, the behavior of electrons and energy at interfaces between different types or phases of materials must be understood. Conversion of light to chemical or electrical potential in condensed phase systems requires gradients in free energy that allow the movement of energy or charge carriers and facilitate redox reactions and dissociation of photoexcited states (excitons) into free charge carriers. Such free energy gradients are present at interfaces between solid and liquid phases or between inorganic and organic materials. Nanostructured materials have a higher density of these interfaces than bulk materials. Nanostructured materials, however, have a structural and chemical complexity that does not exist in bulk materials, which presents a difficult challenge: to lower or eliminate energy barriers to electron and energy flux that inevitably result from forcing different materials to meet in a spatial region of atomic dimensions. Chemical functionalization of nanostructured materials is perhaps the most versatile and powerful strategy for controlling the potential energy landscape of their interfaces and for minimizing losses in energy conversion efficiency due to interfacial structural and electronic defects. Colloidal quantum dots are semiconductor nanocrystals synthesized with wet-chemical methods and coated in organic molecules. Chemists can use these model systems to study the effects of chemical functionalization of nanoscale organic/inorganic interfaces on the optical and electronic properties of a nanostructured material, and the behavior of electrons and energy at interfaces. The optical and electronic properties of colloidal quantum dots have an intense sensitivity to their surface chemistry, and their organic adlayers make them dispersible in solvent. This allows researchers to use high signal-to-noise solution-phase spectroscopy to study processes at interfaces. In this Account, I describe the varied roles of organic molecules in controlling the structure and properties of colloidal quantum dots. Molecules serve as surfactant that determines the mechanism and rate of nucleation and growth and the final size and surface structure of a quantum dot. Anionic surfactant in the reaction mixture allows precise control over the size of the quantum dot core but also drives cation enrichment and structural disordering of the quantum dot surface. Molecules serve as chemisorbed ligands that dictate the energetic distribution of surface states. These states can then serve as thermodynamic traps for excitonic charge carriers or couple to delocalized states of the quantum dot core to change the confinement energy of excitonic carriers. Ligands, therefore, in some cases, dramatically shift the ground state absorption and photoluminescence spectra of quantum dots. Molecules also act as protective layers that determine the probability of redox processes between quantum dots and other molecules. How much the ligand shell insulates the quantum dot from electron exchange with a molecular redox partner depends less on the length or degree of conjugation of the native ligand and more on the density and packing structure of the adlayer and the size and adsorption mode of the molecular redox partner. Control of quantum dot properties in these examples demonstrates that nanoscale interfaces, while complex, can be rationally designed to enhance or specify the functionality of a nanostructured system.
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Affiliation(s)
- Emily A. Weiss
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113, United States
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31
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Cassette E, Mirkovic T, Scholes GD. Toward the Control of Nonradiative Processes in Semiconductor Nanocrystals. J Phys Chem Lett 2013; 4:2091-2093. [PMID: 26283258 DOI: 10.1021/jz4010812] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Affiliation(s)
- Elsa Cassette
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Tihana Mirkovic
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Gregory D Scholes
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
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32
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Mazzio KA, Okamoto K, Li Z, Gutmann S, Strein E, Ginger DS, Schlaf R, Luscombe CK. A one pot organic/CdSe nanoparticle hybrid material synthesis with in situ π-conjugated ligand functionalization. Chem Commun (Camb) 2013; 49:1321-3. [DOI: 10.1039/c2cc38544a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Katherine A Mazzio
- Department of Materials Science and Engineering and Molecular Engineering and Sciences Institute, University of Washington, Box 352120, Seattle, WA 98195-2120, USA
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33
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Leubner S, Hatami S, Esendemir N, Lorenz T, Joswig JO, Lesnyak V, Recknagel S, Gaponik N, Resch-Genger U, Eychmüller A. Experimental and theoretical investigations of the ligand structure of water-soluble CdTe nanocrystals. Dalton Trans 2013; 42:12733-40. [DOI: 10.1039/c3dt50802a] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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34
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Carlini L, Nadeau JL. Uptake and processing of semiconductor quantum dots in living cells studied by fluorescence lifetime imaging microscopy (FLIM). Chem Commun (Camb) 2013; 49:1714-6. [DOI: 10.1039/c3cc36326k] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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35
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Size-Dependent Non-FRET Photoluminescence Quenching in Nanocomposites Based on Semiconductor Quantum Dots CdSe/ZnS and Functionalized Porphyrin Ligands. ACTA ACUST UNITED AC 2012. [DOI: 10.1155/2012/971791] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We review recent experimental work to utilize the size dependence of the luminescence quenching of colloidal semiconductor quantum dots induced by functionalized porphyrin molecules attached to the surface to describe a photoluminescence (PL) quenching process which is different from usual models of charge transfer (CT) or Foerster resonant energy transfer (FRET). Steady-state and picosecond time-resolved measurements were carried out for nanocomposites based on colloidal CdSe/ZnS and CdSe quantum dots (QDs) of various sizes and surfacely attached tetra-mesopyridyl-substituted porphyrin molecules (“Quantum Dot-Porphyrin” nanocomposites), in toluene at 295 K. It was found that the major part of the observed strong quenching of QD PL in “QD-Porphyrin” nanocomposites can neither be assigned to FRET nor to photoinduced charge transfer between the QD and the chromophore. This PL quenching depends on QD size and shell and is stronger for smaller quantum dots: QD PL quenching rate constants scale inversely with the QD diameter. Based on the comparison of experimental data and quantum mechanical calculations, it has been concluded that QD PL quenching in “QD-Porphyrin” nanocomposites can be understood in terms of a tunneling of the electron (of the excited electron-hole pair) followed by a (self-) localization of the electron or formation of trap states. The major contribution to PL quenching is found to be proportional to the calculated quantum-confined exciton wave function at the QD surface. Our findings highlight that single functionalized molecules can be considered as one of the probes for the complex interface physics and dynamics of colloidal semiconductor QD.
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36
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Zenkevich EI, Stupak AP, Kowerko D, Borczyskowski CV. Influence of single dye molecules on temperature and time dependent optical properties of CdSe/ZnS quantum dots: Ensemble and single nanoassembly detection. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2012.02.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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37
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Aykut Y, Saquing CD, Pourdeyhimi B, Parsons GN, Khan SA. Templating quantum dot to phase-transformed electrospun TiO₂ nanofibers for enhanced photo-excited electron injection. ACS APPLIED MATERIALS & INTERFACES 2012; 4:3837-3845. [PMID: 22799496 DOI: 10.1021/am300524a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report on the microstructural crystal phase transformation of electrospun TiO(2) nanofibers generated via sol-gel electrospinning technique, and the incorporation of as-synthesized CdSe quantum dots (QDs) to different phases of TiO(2) nanofibers (NFs) via bifunctional surface modification. The effect of different phases of TiO(2) on photo-excited electron injection from CdSe QDs to TiO(2) NFs, as measured by photoluminescence spectroscopy (PL) is also discussed. Nanofiber diameter and crystal structures are dramatically affected by different calcination temperatures due to removal of polymer carrier, conversion of ceramic precursor into ceramic nanofibers, and formation of different TiO(2) phases in the fibers. At a low calcination temperature of 400 (o)C only anatase TiO(2) nanofiber are obtained; with increasing calcination temperature (up to 500 (o)C) these anatase crystals became larger. Crystal transformation from the anatase to the rutile phase is observed above 500(o)C, with most of the crystals transforming into the rutile phase at 800(o)C. Bi-functional surface modification of calcined TiO(2) nanofibers with 3-mercaptopropionic acid (3-MPA) is used to incorporate as-synthesized CdSe QD nanoparticles on to TiO(2) nanofibers. Evidence of formation of CdSe/TiO(2) composite nanofibers is obtained from elemental analysis using Energy Dispersive X-ray spectroscopy (EDS) and TEM microscopy that reveal templated quantum dots on TiO(2) nanofibers. Photoluminescence emission intensities increase considerably with the addition of QDs to all TiO(2) nanofiber samples, with fibers containing small amount of rutile crystals with anatase crystals showing the most enhanced effect.
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Affiliation(s)
- Yakup Aykut
- Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, North Carolina State University, Raleigh, North Carolina 27695-8301, United States
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38
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Chang WS, Link S. Enhancing the Sensitivity of Single-Particle Photothermal Imaging with Thermotropic Liquid Crystals. J Phys Chem Lett 2012; 3:1393-9. [PMID: 26286788 DOI: 10.1021/jz300342p] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Individual molecules and nanoparticles can be imaged based on their absorption using photothermal microscopy. This technique relies on the heating-induced changes in the refractive index of the surrounding medium. Here, we demonstrate an order of magnitude larger enhancement of the signal-to-noise ratio in photothermal imaging of 20 nm gold nanoparticles when using a thermotropic liquid crystal (5CB). We show quantitatively that this increase is due to the large change in the thermo-optical properties of 5CB mainly along the nematic director. Enhancing the sensitivity is important for the further development of absorption-based single-molecule spectroscopy techniques.
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Affiliation(s)
- Wei-Shun Chang
- †Department of Chemistry and §Department of Electrical and Computer Engineering, Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
| | - Stephan Link
- †Department of Chemistry and §Department of Electrical and Computer Engineering, Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
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Giam LR, He S, Horwitz NE, Eichelsdoerfer DJ, Chai J, Zheng Z, Kim D, Shim W, Mirkin CA. Positionally defined, binary semiconductor nanoparticles synthesized by scanning probe block copolymer lithography. NANO LETTERS 2012; 12:1022-1025. [PMID: 22250864 DOI: 10.1021/nl204233r] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We report the first method for synthesizing binary semiconductor materials by scanning probe block copolymer lithography (SPBCL) in desired locations on a surface. In this work, we utilize SPBCL to create polymer features containing a desired amount of Cd(2+), which is defined by the feature volume. When they are subsequently reacted in H(2)S in the vapor phase, a single CdS nanoparticle is formed in each block copolymer (BCP) feature. The CdS nanoparticles were shown to be both crystalline and luminescent. Importantly, the CdS nanoparticle sizes can be tuned since their diameters depend on the volume of the originally deposited BCP feature.
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Affiliation(s)
- Louise R Giam
- Department of Materials Science and Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA
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40
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Buso D, Jasieniak J, Lay MDH, Schiavuta P, Scopece P, Laird J, Amenitsch H, Hill AJ, Falcaro P. Highly luminescent metal-organic frameworks through quantum dot doping. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:80-88. [PMID: 22009888 DOI: 10.1002/smll.201100710] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 06/09/2011] [Indexed: 05/31/2023]
Abstract
The incorporation of highly luminescent core-shell quantum dots (QDs) within a metal-organic framework (MOF) is achieved through a one-pot method. Through appropriate surface functionalization, the QDs are solubilized within MOF-5 growth media. This permits the incorporation of the QDs within the evolving framework during the reaction. The resulting QD@MOF-5 composites are characterized using X-ray fluorescence, cross-sectional confocal microscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and small-angle X-ray scattering. The synergistic combination of luminescent QDs and the controlled porosity of MOF-5 in the QD@MOF-5 composites is harnessed within a prototype molecular sensor that can discriminate on the basis of molecular size.
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Affiliation(s)
- Dario Buso
- CSIRO, Materials Science and Engineering, Locked Bag 33, Clayton Sth MDC, VIC 3169, Australia
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41
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Dayal S, Kopidakis N, Rumbles G. Photoinduced electron transfer in composites of conjugated polymers and dendrimers with branched colloidal nanoparticles. Faraday Discuss 2012; 155:323-37; discussion 349-56. [DOI: 10.1039/c1fd00081k] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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42
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Greytak AB, Allen PM, Liu W, Zhao J, Young ER, Popović Z, Walker B, Nocera DG, Bawendi MG. Alternating layer addition approach to CdSe/CdS core/shell quantum dots with near-unity quantum yield and high on-time fractions. Chem Sci 2012; 3:2028-2034. [PMID: 24932403 DOI: 10.1039/c2sc00561a] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We report single-particle photoluminescence (PL) intermittency (blinking) with high on-time fractions in colloidal CdSe quantum dots (QD) with conformal CdS shells of 1.4 nm thickness, equivalent to approximately 4 CdS monolayers. All QDs observed displayed on-time fractions > 60% with the majority > 80%. The high-on-time-fraction blinking is accompanied by fluorescence quantum yields (QY) close to unity (up to 98% in an absolute QY measurement) when dispersed in organic solvents and a monoexponential ensemble photoluminescence (PL) decay lifetime. The CdS shell is formed in high synthetic yield using a modified selective ion layer adsorption and reaction (SILAR) technique that employs a silylated sulfur precursor. The CdS shell provides sufficient chemical and electronic passivation of the QD excited state to permit water solubilization with greater than 60% QY via ligand exchange with an imidazole-bearing hydrophilic polymer.
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Affiliation(s)
- Andrew B Greytak
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Peter M Allen
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Wenhao Liu
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Jing Zhao
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Elizabeth R Young
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Zoran Popović
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Brian Walker
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Daniel G Nocera
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
| | - Moungi G Bawendi
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, USA
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43
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Yan C, Deng Z, Tang F, Li L, Chen D, Ren J. Non-trioctylphosphine and chemical aerosol flow growth of high quality thiol-capped CdSe nanocrystals. CrystEngComm 2012. [DOI: 10.1039/c2ce06523a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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44
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Blaudeck T, Zenkevich EI, Abdel-Mottaleb M, Szwaykowska K, Kowerko D, Cichos F, von Borczyskowski C. Formation Principles and Ligand Dynamics of Nanoassemblies of CdSe Quantum Dots and Functionalised Dye Molecules. Chemphyschem 2011; 13:959-72. [DOI: 10.1002/cphc.201100711] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Indexed: 11/11/2022]
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45
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Durisic N, Godin AG, Walters D, Grütter P, Wiseman PW, Heyes CD. Probing the "dark" fraction of core-shell quantum dots by ensemble and single particle pH-dependent spectroscopy. ACS NANO 2011; 5:9062-73. [PMID: 22023370 PMCID: PMC3259027 DOI: 10.1021/nn203272p] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The optical properties of core-shell CdSe-ZnS quantum dots (QDs) are characterized by complex photophysics leading to difficulties in interpreting quantitative measurements based on QD emission. By comparing the pH dependence of fluorescence of single QDs to that of an ensemble, we have been able to propose a molecular scale model of how QD surface chemical and physical processes are affected by protons and oxygen. We show that the connection between the ensemble fluorescence intensity and the single QD fluorescence properties such as dark fraction, blinking, particle brightness, and a multiexponential fluorescence lifetime decay is not trivial. The ensemble fluorescence intensity is more weakly dependent on pH than the single particle fluorescence which, together with fluorescence lifetime analysis, provided evidence that the dark fraction of QDs emits photons with low quantum efficiency and long lifetime. We uncovered two surface-dependent mechanisms that affected the fluorescence emission: an immediate physical effect of charges surrounding the QD and an irreversible chemical effect from reaction of the H(+) and O(2) with the QD shell surface. These results will have important implications for those using QD-based fluorescence lifetime imaging as well as for proper implementation of these probes for quantitative cellular imaging applications.
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Affiliation(s)
- Nela Durisic
- Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec, Canada, H3A 2T8
| | - Antoine G. Godin
- Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec, Canada, H3A 2T8
| | - Derrel Walters
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701
| | - Peter Grütter
- Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec, Canada, H3A 2T8
| | - Paul W. Wiseman
- Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec, Canada, H3A 2T8
- Department of Chemistry, McGill University, 800 Rue Sherbrooke Ouest, Montreal, Quebec, Canada, H3A 2K6
| | - Colin D. Heyes
- Department of Chemistry and Biochemistry, University of Arkansas, 345 N. Campus Drive, Fayetteville, AR, 72701
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46
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Yang X, Tiam TS, Yu X, Demir HV, Sun XW. Europium (II)-doped microporous zeolite derivatives with enhanced photoluminescence by isolating active luminescence centers. ACS APPLIED MATERIALS & INTERFACES 2011; 3:4431-4436. [PMID: 22017276 DOI: 10.1021/am2012118] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Solid-state reaction is the most common method for preparing luminescent materials. However, the luminescent dopants in the hosts tend to aggregate in the high-temperature annealing process, which causes adverse effect in photoluminescence. Herein, we report a novel europium (II)-doped zeolite derivative prepared by a combined ion-exchange and solid-state reaction method, in which the europium (II) ions are isolated to a large extent by the micropores of the zeolite. Excited by a broad ultraviolet band from 250 to 420 nm, a strong blue emission peaking at 450 nm was observed for these Eu-embedded zeolites annealed at 800 °C in a reducing atmosphere. The zeolite host with pores of molecular dimension was found to be an excellent host to isolate and stabilize the Eu(2+) ions. The as-obtained europium (II)-doped zeolite derivative showed an approximately 9 fold enhancement in blue emission compared to that of the general europium (II)-doped aluminosilicates obtained by conventional solid-state reaction, indicating that, by isolating active luminescence centers, it is promising to achieve highly luminescent materials. Also, the strong blue emission with broad UV excitation band suggests a potential candidate of phosphor for ultraviolet excited light-emitting diode.
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Affiliation(s)
- Xuyong Yang
- School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798
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47
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Falcaro P, Hill AJ, Nairn KM, Jasieniak J, Mardel JI, Bastow TJ, Mayo SC, Gimona M, Gomez D, Whitfield HJ, Riccò R, Patelli A, Marmiroli B, Amenitsch H, Colson T, Villanova L, Buso D. A new method to position and functionalize metal-organic framework crystals. Nat Commun 2011; 2:237. [PMID: 21407203 PMCID: PMC3072101 DOI: 10.1038/ncomms1234] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Accepted: 02/09/2011] [Indexed: 11/11/2022] Open
Abstract
With controlled nanometre-sized pores and surface areas of thousands of square metres per gram, metal-organic frameworks (MOFs) may have an integral role in future catalysis, filtration and sensing applications. In general, for MOF-based device fabrication, well-organized or patterned MOF growth is required, and thus conventional synthetic routes are not suitable. Moreover, to expand their applicability, the introduction of additional functionality into MOFs is desirable. Here, we explore the use of nanostructured poly-hydrate zinc phosphate (α-hopeite) microparticles as nucleation seeds for MOFs that simultaneously address all these issues. Affording spatial control of nucleation and significantly accelerating MOF growth, these α-hopeite microparticles are found to act as nucleation agents both in solution and on solid surfaces. In addition, the introduction of functional nanoparticles (metallic, semiconducting, polymeric) into these nucleating seeds translates directly to the fabrication of functional MOFs suitable for molecular size-selective applications. Metal-organic frameworks (MOFs) have potential catalysis, filtration and sensing applications, but device fabrication will require controlled MOF growth. Here, α-hopeite microparticles are used to achieve spatial control of MOF nucleation, and accelerate MOF growth.
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Affiliation(s)
- Paolo Falcaro
- CSIRO, Division of Materials Science and Engineering, Clayton South MDC, Victoria 3169, Australia.
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48
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Ning Z, Molnár M, Chen Y, Friberg P, Gan L, Ågren H, Fu Y. Role of surface ligands in optical properties of colloidal CdSe/CdS quantum dots. Phys Chem Chem Phys 2011; 13:5848-54. [PMID: 21327188 DOI: 10.1039/c0cp02688c] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In order to study the role of surface ligands in determining optical properties of colloidal quantum dots (QDs), we have selectively fabricated and studied CdSe/CdS core-shell QDs with strongly confined electron and hole states attached with commonly used surface ligands. Optical properties, viz. absorption and fluorescence of these QDs, are characterized from which salient changes have been observed for different ligand substitutions which, through theoretical analysis, can be associated with electronic structure properties of the QD-ligand composite systems, in particular localization of wave functions of electrons and holes in the QDs and the band matching of the HOMO-LUMO gap of the ligands. The findings can be utilized to facilitate the understanding and optimization of properties of QD biomarkers with functionalizing surface ligands for targeting cellular objects.
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Affiliation(s)
- Zhijun Ning
- Department of Theoretical Chemistry, School of Biotechnology, Royal Institute of Technology, Stockholm, Sweden
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49
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Leventis HC, O'Mahony F, Akhtar J, Afzaal M, O'Brien P, Haque SA. Transient optical studies of interfacial charge transfer at nanostructured metal oxide/PbS quantum dot/organic hole conductor heterojunctions. J Am Chem Soc 2010; 132:2743-50. [PMID: 20128629 DOI: 10.1021/ja909172p] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report a transient absorption and luminescence study addressing the charge separation, recombination, and regeneration reactions at nanostructured metal oxide/PbS quantum dot/organic hole conductor heterojunctions. We show that yields of charge separation are significantly higher at PbS/SnO(2) interfaces relative to PbS/TiO(2) interfaces, and conclude that this behavior is a result of the ca. 300-500 meV lower conduction band edge in SnO(2) as compared to TiO(2). We also report a correlation between the PbS particle size and the yield of charge separation at PbS/SnO(2) interfaces, with a smaller PbS particle radius resulting a higher yield of charge separation. Finally we investigated the regeneration of the photooxidized PbS by an organic hole transporting material, namely, spiro-OMeTAD. The overall spiro-OMeTAD(+) yield is found to be 27% at a SnO(2)/PbS (approximately 3 nm diameter)/spiro-OMeTAD heterojunction. The addition of a lithium salt was found to raise the overall spiro-OMeTAD(+) yield from its initial value of 27% (where no Li(+) is present) to 50%. We believe this to be a result of an increase in the primary charge injection yield to near unity as the SnO(2) conduction band is lowered (with increasing [Li(+)]), increasing the driving force for electron injection. The present findings are discussed with relevance to the design of PbS-sensitized metal oxide layers for DSSCs.
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Affiliation(s)
- Henry C Leventis
- Nanostructured Materials and Devices Group, Department of Chemistry, Imperial College London, SW7 2AZ, United Kingdom
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50
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McArthur EA, Morris-Cohen AJ, Knowles KE, Weiss EA. Charge Carrier Resolved Relaxation of the First Excitonic State in CdSe Quantum Dots Probed with Near-Infrared Transient Absorption Spectroscopy. J Phys Chem B 2010; 114:14514-20. [DOI: 10.1021/jp102101f] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Eric A. McArthur
- Department of Chemistry, Northwestern University, 2145 Sheridan Rd., Evanston, Illinois 60208-3113
| | - Adam J. Morris-Cohen
- Department of Chemistry, Northwestern University, 2145 Sheridan Rd., Evanston, Illinois 60208-3113
| | - Kathryn E. Knowles
- Department of Chemistry, Northwestern University, 2145 Sheridan Rd., Evanston, Illinois 60208-3113
| | - Emily A. Weiss
- Department of Chemistry, Northwestern University, 2145 Sheridan Rd., Evanston, Illinois 60208-3113
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