101
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Wright JT, Forsythe K, Hutchins J, Meulenberg RW. Implications of orbital hybridization on the electronic properties of doped quantum dots: the case of Cu:CdSe. NANOSCALE 2016; 8:9417-9424. [PMID: 27093918 DOI: 10.1039/c6nr00494f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This paper investigates how chemical dopants affect the electronic properties of CdSe quantum dots (QDs) and why a model that incorporates the concepts of orbital hybridization must be used to understand these properties. Extended X-ray absorption fine structure spectroscopy measurements show that copper dopants in CdSe QDs occur primarily through a statistical doping mechanism. Ultraviolet photoemission spectroscopy (UPS) experiments provide a detailed insight on the valence band (VB) structure of doped and undoped QDs. Using UPS measurements, we are able to observe photoemission from the Cu d-levels above VB maximum of the QDs which allows a complete picture of the energy band landscape of these materials. This information provides insights into many of the physical properties of doped QDs, including the highly debated near-infrared photoluminescence in Cu doped CdSe QDs. We show that all our results point to a common theme of orbital hybridization in Cu doped CdSe QDs which leads to optically and electronically active states below the conduction band minimum. Our model is supported from current-voltage measurements of doped and undoped materials, which exhibit Schottky to Ohmic behavior with Cu doping, suggestive of a tuning of the lowest energy states near the Fermi level.
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Affiliation(s)
- Joshua T Wright
- Department of Physics, Illinois Institute of Technology, Chicago, IL 60616, USA
| | - Kyle Forsythe
- Department of Physics and Astronomy, University of Maine, Orono, ME 04469, USA
| | - Jamie Hutchins
- Department of Physics and Astronomy, University of Maine, Orono, ME 04469, USA
| | - Robert W Meulenberg
- Department of Physics and Astronomy, University of Maine, Orono, ME 04469, USA and Laboratory for Surface Science and Technology, University of Maine, Orono, ME 04469, USA.
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102
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Jara DH, Stamplecoskie KG, Kamat PV. Two Distinct Transitions in Cu(x)InS2 Quantum Dots. Bandgap versus Sub-Bandgap Excitations in Copper-Deficient Structures. J Phys Chem Lett 2016; 7:1452-9. [PMID: 27043435 DOI: 10.1021/acs.jpclett.6b00571] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Cu-deficient CuInS2 quantum dots (QDs) synthesized by varying the [Cu]:[In] ratio allow modulation of optical properties as well as identification of the radiative emission pathways. Absorption and emission spectral features showed a strong dependence on the [Cu]:[In] ratio of CuxInS2 QDs, indicating two independent optical transitions. These effects are pronounced in transient absorption spectra. The bleaching of band edge absorption and broad tail absorption bands in the subpicosecond-nanosecond time scale provide further evidence for the dual optical transitions. The recombination process as monitored by photoemission decay indicated the involvement of surface traps in addition to the bandgap and sub-bandgap transitions. Better understanding of the origin of the optical transitions and their influence on the photodynamics will enable utilization of ternary semiconductor quantum dots in display and photovoltaic devices.
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Affiliation(s)
- Danilo H Jara
- Radiation Laboratory, Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Kevin G Stamplecoskie
- Radiation Laboratory, Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Prashant V Kamat
- Radiation Laboratory, Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
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103
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van der Stam W, Berends AC, de Mello Donega C. Prospects of Colloidal Copper Chalcogenide Nanocrystals. Chemphyschem 2016; 17:559-81. [DOI: 10.1002/cphc.201500976] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Indexed: 01/19/2023]
Affiliation(s)
- Ward van der Stam
- Debye Institute for Nanomaterials Science; Utrecht University; P.O. Box 80000 3508 TA Utrecht The Netherlands
| | - Anne C. Berends
- Debye Institute for Nanomaterials Science; Utrecht University; P.O. Box 80000 3508 TA Utrecht The Netherlands
| | - Celso de Mello Donega
- Debye Institute for Nanomaterials Science; Utrecht University; P.O. Box 80000 3508 TA Utrecht The Netherlands
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104
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Wu K, Liang G, Kong D, Chen J, Chen Z, Shan X, McBride JR, Lian T. Quasi-type II CuInS 2/CdS core/shell quantum dots. Chem Sci 2016; 7:1238-1244. [PMID: 29910880 PMCID: PMC5975837 DOI: 10.1039/c5sc03715h] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 11/12/2015] [Indexed: 02/03/2023] Open
Abstract
Ternary chalcopyrite CuInS2 quantum dots (QDs) have been extensively studied in recent years as an alternative to conventional QDs for solar energy conversion applications. However, compared with the well-established photophysics in prototypical CdSe QDs, much less is known about the excited properties of CuInS2 QDs. In this work, using ultrafast spectroscopy, we showed that both conduction band (CB) edge electrons and copper vacancy (VCu) localized holes were susceptible to surface trappings in CuInS2 QDs. These trap states could be effectively passivated by forming quasi-type II CuInS2/CdS core/shell QDs, leading to a single-exciton (with electrons delocalized among CuInS2/CdS CB and holes localized in VCu) half lifetime of as long as 450 ns. Because of reduced electron-hole overlap in quasi-type II QDs, Auger recombination of multiple excitons was also suppressed and the bi-exciton lifetime was prolonged to 42 ps in CuInS2/CdS QDs from 10 ps in CuInS2 QDs. These demonstrated advantages, including passivated trap states, long single and multiple exciton lifetimes, suggest that quasi-type II CuInS2/CdS QDs are promising materials for photovoltaic and photocatalytic applications.
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Affiliation(s)
- Kaifeng Wu
- Department of Chemistry , Emory University , 1515 Dickey Drive, NE , Atlanta , Georgia 30322 , USA .
| | - Guijie Liang
- Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices , Hubei University of Arts and Science , Xiangyang 441053 , Hubei Province , P. R. China
| | - Degui Kong
- College of Electronic Engineering , Heilongjiang University , Harbin 150080 , P. R. China
| | - Jinquan Chen
- Department of Chemistry , Emory University , 1515 Dickey Drive, NE , Atlanta , Georgia 30322 , USA .
| | - Zheyuan Chen
- Department of Chemistry , Emory University , 1515 Dickey Drive, NE , Atlanta , Georgia 30322 , USA .
| | - Xinhe Shan
- Department of Chemistry , Emory University , 1515 Dickey Drive, NE , Atlanta , Georgia 30322 , USA .
| | - James R McBride
- Department of Chemistry , The Vanderbilt Institute of Nanoscale Science and Engineering , Vanderbilt University , Nashville TN 37235 , USA
| | - Tianquan Lian
- Department of Chemistry , Emory University , 1515 Dickey Drive, NE , Atlanta , Georgia 30322 , USA .
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105
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Jethi L, Mack TG, Krause MM, Drake S, Kambhampati P. The Effect of Exciton-Delocalizing Thiols on Intrinsic Dual Emitting Semiconductor Nanocrystals. Chemphyschem 2016; 17:665-9. [PMID: 26752223 DOI: 10.1002/cphc.201501049] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Lakshay Jethi
- Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, QC, H3A0B8, Canada
| | - Timothy G Mack
- Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, QC, H3A0B8, Canada
| | - Michael M Krause
- Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, QC, H3A0B8, Canada
| | - Sebastian Drake
- Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, QC, H3A0B8, Canada
| | - Patanjali Kambhampati
- Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, QC, H3A0B8, Canada.
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106
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Yuan X, Ma R, Hua J, Liu Y, Li J, Zhang W, Zhao J, Li H. Thermal stability of photoluminescence in Cu-doped Zn–In–S quantum dots for light-emitting diodes. Phys Chem Chem Phys 2016; 18:10976-82. [DOI: 10.1039/c6cp00240d] [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]
Abstract
Recombination between the donor–acceptor pair and/or between the host conduction band and the Cu ion state contributes to the emission of Cu:Zn–In–S QDs.
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Affiliation(s)
- Xi Yuan
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education
- Jilin Normal University
- Siping 136000
- China
| | - Ruixin Ma
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education
- Jilin Normal University
- Siping 136000
- China
| | - Jie Hua
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education
- Jilin Normal University
- Siping 136000
- China
| | - Yang Liu
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education
- Jilin Normal University
- Siping 136000
- China
| | - Ji Li
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education
- Jilin Normal University
- Siping 136000
- China
| | - Wenjin Zhang
- Xingzi New Material Technology Development Co., Ltd
- Shanghai 200333
- China
| | - Jialong Zhao
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education
- Jilin Normal University
- Siping 136000
- China
| | - Haibo Li
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education
- Jilin Normal University
- Siping 136000
- China
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107
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Li J, Liu Y, Hua J, Tian L, Zhao J. Photoluminescence properties of transition metal-doped Zn–In–S/ZnS core/shell quantum dots in solid films. RSC Adv 2016. [DOI: 10.1039/c6ra05485d] [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] Open
Abstract
The photoluminescence (PL) properties of transition metal ion (Mn2+ or Cu+) doped Zn–In–S/ZnS core/shell quantum dots (QDs) in solution and solid films were investigated by using steady-state and time-resolved PL spectra.
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Affiliation(s)
- Jiaming Li
- Department of Physics
- Yanbian University
- Yanji 133002
- China
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education
| | - Yang Liu
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education
- Jilin Normal University
- Siping 136000
- China
| | - Jie Hua
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education
- Jilin Normal University
- Siping 136000
- China
| | - Lianhua Tian
- Department of Physics
- Yanbian University
- Yanji 133002
- China
| | - Jialong Zhao
- Key Laboratory of Functional Materials Physics and Chemistry of the Ministry of Education
- Jilin Normal University
- Siping 136000
- China
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