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Ji B, Koley S, Slobodkin I, Remennik S, Banin U. ZnSe/ZnS Core/Shell Quantum Dots with Superior Optical Properties through Thermodynamic Shell Growth. NANO LETTERS 2020; 20:2387-2395. [PMID: 32134676 PMCID: PMC7467768 DOI: 10.1021/acs.nanolett.9b05020] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 03/03/2020] [Indexed: 05/22/2023]
Abstract
Epitaxial growth of a protective semiconductor shell on a colloidal quantum dot (QD) core is the key strategy for achieving high fluorescence quantum efficiency and essential stability for optoelectronic applications and biotagging with emissive QDs. Herein we investigate the effect of shell growth rate on the structure and optical properties in blue-emitting ZnSe/ZnS QDs with narrow emission line width. Tuning the precursor reactivity modifies the growth mode of ZnS shells on ZnSe cores transforming from kinetic (fast) to thermodynamic (slow) growth regimes. In the thermodynamic growth regime, enhanced fluorescence quantum yields and reduced on-off blinking are achieved. This high performance is ascribed to the effective avoidance of traps at the interface between the core and the shell, which are detrimental to the emission properties. Our study points to a general strategy to obtain high-quality core/shell QDs with enhanced optical properties through controlled reactivity yielding shell growth in the thermodynamic limit.
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Affiliation(s)
- Botao Ji
- Institute
of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- The
Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- Key
Laboratory of 3D Micro/Nano Fabrication and Characterization of Zhejiang
Province, School of Engineering, Westlake University and Institute
of Advanced Technology, Westlake Institute
for Advanced Study, Hangzhou 310024, China
| | - Somnath Koley
- Institute
of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- The
Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Ilya Slobodkin
- Institute
of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- The
Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Sergei Remennik
- The
Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Uri Banin
- Institute
of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- The
Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- E-mail:
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2
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Maity P, Ghosh HN. Strategies for extending charge separation in colloidal nanostructured quantum dot materials. Phys Chem Chem Phys 2019; 21:23283-23300. [PMID: 31621729 DOI: 10.1039/c9cp03551f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Semiconductor colloidal metal chalcogenides (II-VI) in the form of quantum dots (QDs) and different heterostructures (core/shell, alloys, etc.) are of extensive interest in scientific research for both a fundamental understanding and technological applications because of their quantized size and different optical properties; however, due to their small size, the exciton (bound electron and hole) experiences a strong Coulombic attraction, which has a remarkable impact on the charge separation and photophysical properties of QDs. Thus, to achieve an efficient charge separation, numerous attempts have been made via the formation of different heterostructures, QD/molecular adsorbate (either organic or inorganic) assemblies, etc. These hybrid materials ameliorated the absorption of the incident light as well as charge separation. This article reviews the strategies for extending charge separation in these colloidal nanocrystals (NCs), which is one of the crucial steps to elevate the solar to electrical energy conversion efficiency in a quantum dot-sensitized solar cell (QDSC). The article summarizes the benefits of co-sensitization and experimental shreds of evidence for the multiple charge transfer processes involved in a QDSC. Studies have shown that in the co-sensitization process, prolonged charge separation occurs via the dual behavior of the molecular adsorbate, sensitization (electron injection) and capture of holes from photoexcited QDs. This perspective emphases band edge engineering and control of charge carrier dynamics in various core/shell structures. The impact of colloidal alloy NCs on charge separation and interesting photophysical properties was recapitulated via the steady-state and time-resolved photoluminescence (PL) and femtosecond transient absorption spectroscopic techniques. Finally, the prolonged lifetime and extent of charge separation for these hybrid NCs (or the composites) assisted in the development of a better light harvester as compared to the case of their pure counterparts.
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Affiliation(s)
- Partha Maity
- Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Homi Bhabha National Institute, Mumbai-400085, India.
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3
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Chen D, Wang A, Buntine MA, Jia G. Recent Advances in Zinc‐Containing Colloidal Semiconductor Nanocrystals for Optoelectronic and Energy Conversion Applications. ChemElectroChem 2019. [DOI: 10.1002/celc.201900838] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Dechao Chen
- Curtin Institute of Functional Molecules and Interfaces School of Molecular and Life Sciences Curtin University WA-6845 Perth Australia
| | - Aixiang Wang
- School of Chemistry and Chemical Engineering Linyi University Linyi 276005 China
| | - Mark A. Buntine
- Curtin Institute of Functional Molecules and Interfaces School of Molecular and Life Sciences Curtin University WA-6845 Perth Australia
| | - Guohua Jia
- Curtin Institute of Functional Molecules and Interfaces School of Molecular and Life Sciences Curtin University WA-6845 Perth Australia
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4
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Chen D, Wang A, Li H, Abad Galán L, Su C, Yin Z, Massi M, Suvorova A, Saunders M, Li J, Sitt A, Jia G. Colloidal quasi-one-dimensional dual semiconductor core/shell nanorod couple heterostructures with blue fluorescence. NANOSCALE 2019; 11:10190-10197. [PMID: 31112179 DOI: 10.1039/c9nr02443c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Herein we report a nanorod couple heterostructure made of dual semiconductors, in which two parallelly aligned ZnSe nanorods are connected by the growth of ZnS on both end and side facets, producing hetero-ZnS (short arms)-ZnSe (long arms)/ZnS shell nanorod couples. As evidenced by electronic structure studies, both experimental and theoretical, such core/shell nanorod couple heterostructures can act as a platform to precisely tailor the quantum confinement of charge carriers between the constituting components within a single nano-object, generating blue fluorescence after the overgrowth of an alloyed ZnCdS layer on the heterostructures. We foresee the mechanistic insights gained and electronic structures revealed in this work would shed light on the rational design of more complex heterostructures with novel functionalities.
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Affiliation(s)
- Dechao Chen
- Curtin Institute of Functional Molecules and Interfaces, School of Molecular and Life Sciences, Curtin University, GPO Box U1987, WA 6845, Australia.
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Mehata MS, Ratnesh RK. Luminescence properties and exciton dynamics of core–multi-shell semiconductor quantum dots leading to QLEDs. Dalton Trans 2019; 48:7619-7631. [DOI: 10.1039/c9dt00989b] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Carrier relaxation processes in CdSe core QDs and core–multi-shell QDs under excitation at 450 nm.
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Affiliation(s)
- Mohan Singh Mehata
- Laser-Spectroscopy Laboratory
- Department of Applied Physics
- Delhi Technological University
- Delhi-110042
- India
| | - R. K. Ratnesh
- Laser-Spectroscopy Laboratory
- Department of Applied Physics
- Delhi Technological University
- Delhi-110042
- India
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6
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Enders F, Budweg A, Zeng P, Lauth J, Smith TA, Brida D, Boldt K. Switchable dissociation of excitons bound at strained CdTe/CdS interfaces. NANOSCALE 2018; 10:22362-22373. [PMID: 30474672 DOI: 10.1039/c8nr07973k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Charge carrier dynamics of semiconductor nano-heterostructures are determined by band alignment and lattice mismatch of the adjacent materials. However, quantum efficiencies for the separation of excited charge carriers at such an interface are hard to predict and cannot yet be easily controlled. In this work we examine nanorods with a severely strained, axial CdTe/CdS interface using femtosecond transient absorption spectroscopy. We show that charge separation is mitigated by equal contributions of valence band distortion and formation of coulomb pairs across the interface. Left undisturbed such localised excitons relax rapidly via non-radiative recombination channels. By adding a competitive hole acceptor that disrupts the coulomb interaction we overcome the synergetic co-localisation of the carriers and realise charge separation. The thus created long-lived state can be exploited for a broad range of applications such as photocatalysis, water splitting, and switchable nanodevices.
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Affiliation(s)
- Florian Enders
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany.
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7
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Li ZJ, Hofman E, Blaker A, Davis AH, Dzikovski B, Ma DK, Zheng W. Interface Engineering of Mn-Doped ZnSe-Based Core/Shell Nanowires for Tunable Host-Dopant Coupling. ACS NANO 2017; 11:12591-12600. [PMID: 29172442 DOI: 10.1021/acsnano.7b06773] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Transition metal ion doped one-dimensional (1-D) nanocrystals (NCs) have advantages of larger absorption cross sections and polarized absorption and emissions in comparison to 0-D NCs. However, direct synthesis of doped 1-D nanorods (NRs) or nanowires (NWs) has proven challenging. In this study, we report the synthesis of 1-D Mn-doped ZnSe NWs using a colloidal hot-injection method and shell passivation for core/shell NWs with tunable optical properties. Experimental results show optical properties of the NWs are controlled by the composition and thickness of the shell lattice. It was found that both the host-Mn energy transfer and Mn-Mn coupling are strongly dependent on the type of alloy at the interface of doped core/shell NWs. For Mn-doped type I ZnSe/ZnS core/shell NWs, the ZnS shell passivation can enhance florescence quantum yield with little effect on the location of the incorporated Mn dopant due to the identical cationic Zn2+ site available for Mn dopants throughout the core/shell NWs. However, for Mn-doped quasi type II ZnSe/CdS NWs and ZnSe/CdS/ZnS core/shell NWs, the cation alloying (Zn1-xCdxS(e)) can lead to metal dopant migration from the core to the alloyed interface and tunable host-dopant energy transfer efficiencies and Mn-Mn coupling. As a result, a tunable dual-band emission can be achieved for the doped NWs with the cation-alloyed interface. The interfacial alloying mediated energy transfer and Mn-Mn coupling provides a method to control the optical properties of the doped 1-D core/shell NWs.
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Affiliation(s)
- Zhi-Jun Li
- Department of Chemistry, Syracuse University , Syracuse, New York 13244, United States
| | - Elan Hofman
- Department of Chemistry, Syracuse University , Syracuse, New York 13244, United States
| | - Amanda Blaker
- Department of Chemistry, Syracuse University , Syracuse, New York 13244, United States
| | - Andrew Hunter Davis
- Department of Chemistry, Syracuse University , Syracuse, New York 13244, United States
| | - Boris Dzikovski
- National Biomedical Center for Advanced Electron Spin Resonance Technology , Ithaca, New York 14853, United States
| | - De-Kun Ma
- Zhejiang Key Laboratory of Carbon Materials, Wenzhou University , Wenzhou, Zhejiang 325027, People's Republic of China
| | - Weiwei Zheng
- Department of Chemistry, Syracuse University , Syracuse, New York 13244, United States
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8
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Debnath T, Parui K, Maiti S, Ghosh HN. An Insight into the Interface through Excited-State Carrier Dynamics for Promising Enhancement of Power Conversion Efficiency in a Mn-Doped CdZnSSe Gradient Alloy. Chemistry 2017; 23:3755-3763. [DOI: 10.1002/chem.201605612] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Tushar Debnath
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre; Mumbai 400 085 India), Fax
| | - Kausturi Parui
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre; Mumbai 400 085 India), Fax
| | - Sourav Maiti
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre; Mumbai 400 085 India), Fax
- Department of Chemistry; Savitribai Phule Pune University; Pune 411007 India
| | - Hirendra N. Ghosh
- Radiation & Photochemistry Division; Bhabha Atomic Research Centre; Mumbai 400 085 India), Fax
- Institute of Nano Science and Technology; Mohali Punjab 16062 India
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9
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Abstract
Abstract
The current state-of-the-art of the fabrication and photophysics of graded shells in quantum dots is reviewed. Graded shells, i.e. partially alloyed interfaces between core and shell or between two shells of semiconductor nanoheterostructures, have been demonstrated to improve fluorescence properties and suppress non-radiative pathways of exciton dynamics. By simply looking at linear optics on the level of single excitons this is reflected in increased photoluminescence quantum yields. However, it is shown that graded shells have further beneficial implications for band structure engineering and multiexciton dynamics such as optical gain and charge carrier multiplication.
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Affiliation(s)
- Klaus Boldt
- Department of Chemistry, University of Konstanz, 78457 Konstanz, Germany
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10
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Debnath T, Maiti S, Ghosh HN. Unusually Slow Electron Cooling to Charge-Transfer State in Gradient CdTeSe Alloy Nanocrystals Mediated through Mn Atom. J Phys Chem Lett 2016; 7:1359-1367. [PMID: 27003582 DOI: 10.1021/acs.jpclett.6b00348] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We have synthesized Mn-doped CdTeSe gradient alloy nanocrystals (NCs) by a colloidal synthetic method, and charge carrier dynamics have been revealed through ultrafast transient absorption (TA) spectroscopy. Due to the reactivity difference between Te and Se, a CdTe-rich core and CdSe-rich shell have been formed in the CdTeSe alloy with the formation of a gradient type II core-shell structure. Electron paramagnetic resonance studies suggest Mn atoms are located in the surface of the alloy NCs. Steady-state optical absorption and emission studies suggest formation of a charge-transfer (CT) state in which electrons are localized in a CdSe-rich shell and holes are localized in a CdTe-rich core which appears in the red region of the spectra. Electron transfer in the CT state is found to take place in the Marcus inverted region. To understand charge-transfer dynamics in the CdTeSe alloy NCs and to determine the effect of Mn doping on the alloy, ultrafast transient absorption studies have been carried out. In the case of the undoped alloy, formation of the CT state is found to take place through electron relaxation to the conduction band of the CT state with a time of 600 fs and through hole relaxation (from the CdSe-rich state to the CdTe-rich state) to the valence band of the CT state with a time scale of 1 ps. However, electron relaxation in the presence of Mn dopants takes place initially via an electron transfer to the Mn 3d state (d(5)) followed by transfer from the Mn 3d state (d(6)) to the CT state, which has been found to take place with a >700 ps time scale in addition to the hole relaxation time of 2 ps. Charge recombination time of the CT state is found to be extremely slow in the Mn-doped CdTeSe alloy NCs as compared to the undoped one, where the Mn atom acts as an electron storage center.
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Affiliation(s)
- Tushar Debnath
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre , Mumbai 400085, India
| | - Sourav Maiti
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre , Mumbai 400085, India
- Department of Chemistry, Savitribai Phule Pune University , Ganeshkhind, Pune 411007, India
| | - Hirendra N Ghosh
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre , Mumbai 400085, India
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11
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Li J, Jin H, Wang K, Xie D, Xu D, Xu X, Xu G. High luminance of CuInS2-based yellow quantum dot light emitting diodes fabricated by all-solution processing. RSC Adv 2016. [DOI: 10.1039/c6ra14241a] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In this work, all-solution processed, multi-layer yellow QLEDs, consisting of a hole transport layer of poly(9-vinylcarbazole), emissive layer of ligand exchanged CuInS2/ZnS QDs, and electron transport layer of ZnO nanoparticles, are fabricated.
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Affiliation(s)
- Jingling Li
- Key Laboratory of Renewable Energy
- Guangzhou Institute of Energy Conversion
- Chinese Academy of Sciences
- Guangzhou 510640
- China
| | - Hu Jin
- Key Laboratory of Renewable Energy
- Guangzhou Institute of Energy Conversion
- Chinese Academy of Sciences
- Guangzhou 510640
- China
| | - Kelai Wang
- Key Laboratory of Renewable Energy
- Guangzhou Institute of Energy Conversion
- Chinese Academy of Sciences
- Guangzhou 510640
- China
| | - Dehui Xie
- Key Laboratory of Renewable Energy
- Guangzhou Institute of Energy Conversion
- Chinese Academy of Sciences
- Guangzhou 510640
- China
| | - Dehua Xu
- Key Laboratory of Renewable Energy
- Guangzhou Institute of Energy Conversion
- Chinese Academy of Sciences
- Guangzhou 510640
- China
| | - Xueqing Xu
- Key Laboratory of Renewable Energy
- Guangzhou Institute of Energy Conversion
- Chinese Academy of Sciences
- Guangzhou 510640
- China
| | - Gang Xu
- Key Laboratory of Renewable Energy
- Guangzhou Institute of Energy Conversion
- Chinese Academy of Sciences
- Guangzhou 510640
- China
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Hu P, Gong G, Zhan F, Zhang Y, Li R, Cao Y. The hydrothermal evolution of the phase and shape of ZnS nanostructures and their gas-sensing properties. Dalton Trans 2016; 45:2409-16. [DOI: 10.1039/c5dt03783b] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The evolution of the phase of ZnS was achieved by adjusting the hydrothermal holding time or the dosage of the surfactant.
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Affiliation(s)
- Pengfei Hu
- Laboratory for Microstructure
- Shanghai University
- Shanghai 200444
- P. R. China
| | - Guodong Gong
- Laboratory for Microstructure
- Shanghai University
- Shanghai 200444
- P. R. China
| | - Fangyi Zhan
- Laboratory for Microstructure
- Shanghai University
- Shanghai 200444
- P. R. China
| | - Yuan Zhang
- Materials Genome Institute
- Shanghai University
- Shanghai 200444
- P. R. China
| | - Rong Li
- Nanoscience & Technology Research Center
- Shanghai University
- Shanghai 200444
- P. R. China
| | - Yali Cao
- Institute of Applied Chemistry
- Xinjiang University
- Urumqi
- P. R. China
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