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Shabani F, Martinez PLH, Shermet N, Korkut H, Sarpkaya I, Dehghanpour Baruj H, Delikanli S, Isik F, Durmusoglu EG, Demir HV. Gradient Type-II CdSe/CdSeTe/CdTe Core/Crown/Crown Heteronanoplatelets with Asymmetric Shape and Disproportional Excitonic Properties. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2205729. [PMID: 36650974 DOI: 10.1002/smll.202205729] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 12/22/2022] [Indexed: 06/17/2023]
Abstract
Characterized by their strong 1D confinement and long-lifetime red-shifted emission spectra, colloidal nanoplatelets (NPLs) with type-II electronic structure provide an exciting ground to design complex heterostructures with remarkable properties. This work demonstrates the synthesis and optical characterization of CdSe/CdSeTe/CdTe core/crown/crown NPLs having a step-wise gradient electronic structure and disproportional wavefunction distribution, in which the excitonic properties of the electron and hole can be finely tuned through adjusting the geometry of the intermediate crown. The first crown with staggered configuration gives rise to a series of direct and indirect transition channels that activation/deactivation of each channel is possible through wavefunction engineering. Moreover, these NPLs allow for switching between active channels with temperature, where lattice contraction directly affects the electron-hole (e-h) overlap. Dominated by the indirect transition channels over direct transitions, the lifetime of the NPLs starts to increase at 9 K, indicative of low dark-bright exciton splitting energy. The charge transfer states from the two type-II interfaces promote a large number of indirect transitions, which effectively increase the absorption of low-energy photons critical for nonlinear properties. As a result, these NPLs demonstrate exceptionally high two-photon absorption cross-sections with the highest value of 12.9 × 106 GM and superlinear behavior.
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Affiliation(s)
- Farzan Shabani
- UNAM - Institute of Materials Science and Nanotechnology and National Nanotechnology Research Center, Department of Electrical and Electronics Engineering, Department of Physics, Bilkent University, Ankara, 06800, Turkey
| | - Pedro Ludwig Hernandez Martinez
- LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, School of Materials Science and Nanotechnology, Nanyang Technological University, Singapore, 639798, Singapore
| | - Nina Shermet
- UNAM - Institute of Materials Science and Nanotechnology and National Nanotechnology Research Center, Department of Electrical and Electronics Engineering, Department of Physics, Bilkent University, Ankara, 06800, Turkey
| | - Hilal Korkut
- UNAM - Institute of Materials Science and Nanotechnology and National Nanotechnology Research Center, Department of Electrical and Electronics Engineering, Department of Physics, Bilkent University, Ankara, 06800, Turkey
| | - Ibrahim Sarpkaya
- UNAM - Institute of Materials Science and Nanotechnology and National Nanotechnology Research Center, Department of Electrical and Electronics Engineering, Department of Physics, Bilkent University, Ankara, 06800, Turkey
| | - Hamed Dehghanpour Baruj
- UNAM - Institute of Materials Science and Nanotechnology and National Nanotechnology Research Center, Department of Electrical and Electronics Engineering, Department of Physics, Bilkent University, Ankara, 06800, Turkey
| | - Savas Delikanli
- UNAM - Institute of Materials Science and Nanotechnology and National Nanotechnology Research Center, Department of Electrical and Electronics Engineering, Department of Physics, Bilkent University, Ankara, 06800, Turkey
- LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, School of Materials Science and Nanotechnology, Nanyang Technological University, Singapore, 639798, Singapore
| | - Furkan Isik
- UNAM - Institute of Materials Science and Nanotechnology and National Nanotechnology Research Center, Department of Electrical and Electronics Engineering, Department of Physics, Bilkent University, Ankara, 06800, Turkey
| | - Emek Goksu Durmusoglu
- LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, School of Materials Science and Nanotechnology, Nanyang Technological University, Singapore, 639798, Singapore
| | - Hilmi Volkan Demir
- UNAM - Institute of Materials Science and Nanotechnology and National Nanotechnology Research Center, Department of Electrical and Electronics Engineering, Department of Physics, Bilkent University, Ankara, 06800, Turkey
- LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, School of Materials Science and Nanotechnology, Nanyang Technological University, Singapore, 639798, Singapore
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2
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Li W, Li K, Zhao X, Liu C, Coudert FX. Defective Nature of CdSe Quantum Dots Embedded in Inorganic Matrices. J Am Chem Soc 2022; 144:11296-11305. [PMID: 35713308 DOI: 10.1021/jacs.2c03039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Quantum dots (QDs) embedded in inorganic matrices have been extensively studied for their potential applications in lighting, displays, and solar cells. While a significant amount of research studies focused on their experimental fabrication, the origin of their relatively low photoluminescence quantum yield has not been investigated yet, although it severely hinders practical applications. In this study, we use time-dependent density functional theory (TDDFT) to pinpoint the nature of excited states of CdSe QDs embedded in various inorganic matrices. The formation of undercoordinated Se atoms and nonbridging oxygen atoms at the QD/glass interface is responsible for the localization of a hole wave function, leading to the formation of low-energy excited states with weak oscillator strength. These states provide pathways for nonradiative processes and compete with radiative emission. The photoluminescence performance is predicted for CdSe QDs in different matrices and validated by experiments. The results of this study have significant implications for understanding the underlying photophysics of CdSe QDs embedded in inorganic matrices that would facilitate the fabrication of highly luminescent glasses.
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Affiliation(s)
- Wenke Li
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Hubei 430070, China.,Chimie ParisTech, PSL University, CNRS, Institut de Recherche de Chimie Paris, Paris 75005, France
| | - Kai Li
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Hubei 430070, China
| | - Xiujian Zhao
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Hubei 430070, China
| | - Chao Liu
- State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Hubei 430070, China
| | - François-Xavier Coudert
- Chimie ParisTech, PSL University, CNRS, Institut de Recherche de Chimie Paris, Paris 75005, France
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3
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Yu S, Xu J, Shang X, Ma E, Lin F, Zheng W, Tu D, Li R, Chen X. Unusual Temperature Dependence of Bandgap in 2D Inorganic Lead-Halide Perovskite Nanoplatelets. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2100084. [PMID: 34382362 PMCID: PMC8498867 DOI: 10.1002/advs.202100084] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 06/28/2021] [Indexed: 05/29/2023]
Abstract
Understanding the origin of temperature-dependent bandgap in inorganic lead-halide perovskites is essential and important for their applications in photovoltaics and optoelectronics. Herein, it is found that the temperature dependence of bandgap in CsPbBr3 perovskites is variable with material dimensionality. In contrast to the monotonous redshift ordinarily observed in bulk-like CsPbBr3 nanocrystals (NCs), the bandgap of 2D CsPbBr3 nanoplatelets (NPLs) exhibits an initial blueshift then redshift trend with decreasing temperature (290-10 K). The Bose-Einstein two-oscillator modeling manifests that the blueshift-redshift crossover of bandgap in the NPLs is attributed to the significantly larger weight of contribution from electron-optical phonon interaction to the bandgap renormalization in the NPLs than in the NCs. These new findings may gain deep insights into the origin of bandgap shift with temperature for both fundamentals and applications of perovskite semiconductor materials.
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Affiliation(s)
- Shaohua Yu
- CAS Key Laboratory of Design and Assembly of Functional NanostructuresState Key Laboratory of Structural Chemistryand Fujian Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian350002China
- University of Chinese Academy of SciencesBeijing100049China
| | - Jin Xu
- CAS Key Laboratory of Design and Assembly of Functional NanostructuresState Key Laboratory of Structural Chemistryand Fujian Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian350002China
- Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of ChinaFuzhouFujian350108China
| | - Xiaoying Shang
- CAS Key Laboratory of Design and Assembly of Functional NanostructuresState Key Laboratory of Structural Chemistryand Fujian Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian350002China
| | - En Ma
- CAS Key Laboratory of Design and Assembly of Functional NanostructuresState Key Laboratory of Structural Chemistryand Fujian Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian350002China
- Xiamen Institute of Rare Earth MaterialsHaixi InstituteChinese Academy of SciencesXiamenFujian361021China
| | - Fulin Lin
- CAS Key Laboratory of Design and Assembly of Functional NanostructuresState Key Laboratory of Structural Chemistryand Fujian Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian350002China
- Xiamen Institute of Rare Earth MaterialsHaixi InstituteChinese Academy of SciencesXiamenFujian361021China
| | - Wei Zheng
- CAS Key Laboratory of Design and Assembly of Functional NanostructuresState Key Laboratory of Structural Chemistryand Fujian Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian350002China
- Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of ChinaFuzhouFujian350108China
| | - Datao Tu
- CAS Key Laboratory of Design and Assembly of Functional NanostructuresState Key Laboratory of Structural Chemistryand Fujian Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian350002China
- Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of ChinaFuzhouFujian350108China
| | - Renfu Li
- CAS Key Laboratory of Design and Assembly of Functional NanostructuresState Key Laboratory of Structural Chemistryand Fujian Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian350002China
- Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of ChinaFuzhouFujian350108China
| | - Xueyuan Chen
- CAS Key Laboratory of Design and Assembly of Functional NanostructuresState Key Laboratory of Structural Chemistryand Fujian Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian350002China
- University of Chinese Academy of SciencesBeijing100049China
- Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of ChinaFuzhouFujian350108China
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Dzhagan V, Stroyuk O, Raievska O, Isaieva O, Kapush O, Selyshchev O, Yukhymchuk V, Valakh M, Zahn DRT. Photoinduced Enhancement of Photoluminescence of Colloidal II-VI Nanocrystals in Polymer Matrices. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E2565. [PMID: 33371226 PMCID: PMC7766198 DOI: 10.3390/nano10122565] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/11/2020] [Accepted: 12/19/2020] [Indexed: 01/03/2023]
Abstract
The environment strongly affects both the fundamental physical properties of semiconductor nanocrystals (NCs) and their functionality. Embedding NCs in polymer matrices is an efficient way to create a desirable NC environment needed for tailoring the NC properties and protecting NCs from adverse environmental factors. Luminescent NCs in optically transparent polymers have been investigated due to their perspective applications in photonics and bio-imaging. Here, we report on the manifestations of photo-induced enhancement of photoluminescence (PL) of aqueous colloidal NCs embedded in water-soluble polymers. Based on the comparison of results obtained on bare and core/shell NCs, NCs of different compounds (CdSe, CdTe, ZnO) as well as different embedding polymers, we conclude on the most probable mechanism of the photoenhancement for these sorts of systems. Contrary to photoenhancement observed earlier as a result of surface photocorrosion, we do not observe any change in peak position and width of the excitonic PL. Therefore, we suggest that the saturation of trap states by accumulated photo-excited charges plays a key role in the observed enhancement of the radiative recombination. This suggestion is supported by the unique temperature dependence of the trap PL band as well as by power-dependent PL measurement.
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Affiliation(s)
- Volodymyr Dzhagan
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 01601 Kyiv, Ukraine; (O.I.); (O.K.); (V.Y.); (M.V.)
- Department of Physics, Taras Shevchenko National University of Kyiv, 64 Volodymyrs’ka St., 01601 Kyiv, Ukraine
| | - Oleksandr Stroyuk
- Forschungszentrum Julich GmbH, Helmholtz-Institut Erlangen Nürnberg für Erneuerbare Energien (HI ERN), Immerwahrstr. 2, 91058 Erlangen, Germany;
| | - Oleksandra Raievska
- Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany; (O.R.); (O.S.); (D.R.T.Z.)
- Center for Materials, Architectures, and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09107 Chemnitz, Germany
- L.V. Pysarzhevsky Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 03028 Kyiv, Ukraine
| | - Oksana Isaieva
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 01601 Kyiv, Ukraine; (O.I.); (O.K.); (V.Y.); (M.V.)
| | - Olga Kapush
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 01601 Kyiv, Ukraine; (O.I.); (O.K.); (V.Y.); (M.V.)
| | - Oleksandr Selyshchev
- Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany; (O.R.); (O.S.); (D.R.T.Z.)
| | - Volodymyr Yukhymchuk
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 01601 Kyiv, Ukraine; (O.I.); (O.K.); (V.Y.); (M.V.)
| | - Mykhailo Valakh
- V. Lashkaryov Institute of Semiconductors Physics, National Academy of Sciences of Ukraine, 01601 Kyiv, Ukraine; (O.I.); (O.K.); (V.Y.); (M.V.)
| | - Dietrich R. T. Zahn
- Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany; (O.R.); (O.S.); (D.R.T.Z.)
- Center for Materials, Architectures, and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09107 Chemnitz, Germany
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5
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Majid F, Malik A, Ata S, Hussain Z, Bibi I, Iqbal M, Rafay M, Rizvi H. Structural and Optical Properties of Multilayer Heterostructure of CdTe/CdSe Thin Films. Z PHYS CHEM 2018. [DOI: 10.1515/zpch-2018-1339] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
CdTe/CdSe multilayer heterostructures thin films were prepared by thermal evaporation method. The CdTe/CdSe layers deposited on glass substrate and effects of annealing temperature on optical and structural properties of thin films were investigated. The XRD analysis revealed that CdTe and CdSe were in cubic (111) and hexagonal (100) forms. By increasing the annealing temperature, intensity of XRD peaks increased for multilayer heterostructures. Band alignment in heterostructures of CdTe/CdSe was of type II. Energy band gaps values for CdTe/CdSe multilayer heterostructures increased with respect to bulk compounds. During emission, red and blue shifts are observed in visible region in photoluminescence spectrum of CdTe/CdSe samples. Due to better crystallinity of multilayer thin film, 1LO, 2LO and 3LO phonon modes were observed in Raman spectrum.
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Affiliation(s)
- Farzana Majid
- Department of Physics , University of the Punjab , Lahore , Pakistan
| | - Abdul Malik
- National Institute for Laser and Optronics (NILOP) , Islamabad , Pakistan
| | - Sadia Ata
- Institute of Chemistry, University of the Punjab , Lahore , Pakistan
| | - Zaheer Hussain
- Department of Physics , University of the Punjab , Lahore , Pakistan
| | - Ismat Bibi
- Department of Chemistry , The Islamia University of Bahawalpur , Bahawalpur , Pakistan
| | - Munawar Iqbal
- Department of Chemistry , University of Lahore , Lahore , Pakistan
| | - Muhammad Rafay
- Department of Forestry, Range and Wildlife Management , The Islamia University of Bahawalpur , Bahawalpur , Pakistan
| | - Hina Rizvi
- Department of Environmental Sciences and Engineering , Government College University , Faisalabad , Pakistan
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6
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Subila K, Sandeep K, Thomas EM, Ghatak J, Shivaprasad SM, Thomas KG. CdSe-CdTe Heterojunction Nanorods: Role of CdTe Segment in Modulating the Charge Transfer Processes. ACS OMEGA 2017; 2:5150-5158. [PMID: 31457790 PMCID: PMC6641699 DOI: 10.1021/acsomega.7b00995] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 08/08/2017] [Indexed: 06/10/2023]
Abstract
Heterojunction nanorods having dissimilar semiconductors possess charge transfer (CT) properties and are proposed as active elements in optoelectronic systems. Herein, we describe the synthetic methodologies for controlling the charge carrier recombination dynamics in CdSe-CdTe heterojunction nanorods through the precise growth of CdTe segment from one of the tips of CdSe nanorods. The location of heterojunction was established through a point-by-point collection of the energy-dispersive X-ray spectra using scanning transmission electron microscopy. The possibilities of the growth of CdTe from both the tips of CdSe nanorods and the overcoating of CdTe over CdSe segment were also ruled out. The CT emission in the heterojunction nanorods originates through an interfacial excitonic recombination and was further tuned to the near-infrared region by varying the two parameters: the aspect ratio of CdSe and the length of CdTe segment. These aspects are evidenced from the emission lifetime and the femtosecond transient absorption studies.
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Affiliation(s)
- Kurukkal
Balakrishnan Subila
- School
of Chemistry, Indian Institute of Science
Education and Research Thiruvananthapuram (IISER-TVM), Vithura, Maruthamala (PO), Thiruvananthapuram 695551, India
| | - Kulangara Sandeep
- School
of Chemistry, Indian Institute of Science
Education and Research Thiruvananthapuram (IISER-TVM), Vithura, Maruthamala (PO), Thiruvananthapuram 695551, India
| | - Elizabeth Mariam Thomas
- School
of Chemistry, Indian Institute of Science
Education and Research Thiruvananthapuram (IISER-TVM), Vithura, Maruthamala (PO), Thiruvananthapuram 695551, India
| | - Jay Ghatak
- Chemistry
and Physics of Materials Unit, Jawaharlal
Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur (PO), Bangalore 560064, India
| | - Sonnada Math Shivaprasad
- Chemistry
and Physics of Materials Unit, Jawaharlal
Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur (PO), Bangalore 560064, India
| | - K. George Thomas
- School
of Chemistry, Indian Institute of Science
Education and Research Thiruvananthapuram (IISER-TVM), Vithura, Maruthamala (PO), Thiruvananthapuram 695551, India
- Chemistry
and Physics of Materials Unit, Jawaharlal
Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur (PO), Bangalore 560064, India
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7
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Patty K, Sadeghi SM, Nejat A, Mao CB. Enhancement of emission efficiency of colloidal CdSe quantum dots on silicon substrate via an ultra-thin layer of aluminum oxide. NANOTECHNOLOGY 2014; 25:155701. [PMID: 24642896 DOI: 10.1088/0957-4484/25/15/155701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We demonstrate that an ultra-thin layer of aluminum oxide can significantly enhance the emission efficiency of colloidal quantum dots on a Si substrate. For an ensemble of single quantum dots, our results show that this super brightening process can increase the fluorescence of CdSe quantum dots, forming well-resolved spectra, while in the absence of this layer the emission remains mostly at the noise level. We demonstrate that this process can be further enhanced with irradiation of the quantum dots, suggesting a significant photo-induced fluorescence enhancement via considerable suppression of non-radiative decay channels of the quantum dots. We study the impact of the Al oxide thickness on Si and interdot interactions, and discuss the results in terms of photo-induced catalytic properties of the Al oxide and the effects of such an oxide on the Coulomb blockade responsible for suppression of photo-ionization of the quantum dots.
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Affiliation(s)
- K Patty
- Department of Physics, University of Alabama in Huntsville, Huntsville, AL 35899, USA
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8
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High fluorescence quantum efficiency of CdSe/ZnS quantum dots embedded in GPTS/TEOS-derived organic/silica hybrid colloids. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2014.03.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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9
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Pejova B. Three-dimensional assemblies built up by quantum dots in size-quantization regime: Band gap shifts due to size-distribution of cadmium selenide nanoparticles. J SOLID STATE CHEM 2013. [DOI: 10.1016/j.jssc.2013.09.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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10
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Pilla V, Alves LP, Iwazaki AN, Andrade AA, Antunes A, Munin E. Thermo-optical characterization of cadmium selenide/zinc sulfide (CdSe/ZnS) quantum dots embedded in biocompatible materials. APPLIED SPECTROSCOPY 2013; 67:997-1002. [PMID: 24067629 DOI: 10.1366/12-06836] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Cadmium selenide/zinc sulfide (CdSe/ZnS) core-shell quantum dots (QDs) embedded in biocompatible materials were thermally and optically characterized with a thermal lens (TL) technique. Transient TL measurements were performed with a mode-mismatched, dual-beam (excitation and probe) configuration. A thermo-optical study of the CdSe/ZnS QDs was performed for different core diameters (3.5, 4.0, 5.2, and 6.6 nm) in aqueous solution and synthetic saliva, and three different core diameters (2.4, 2.9, and 4.1 nm) embedded in restorative dental resin (0.025% by mass). The thermal diffusivity results are characteristic of the biocompatible matrices. The radiative quantum efficiencies for aqueous solution and biofluid materials are dependent on the core size of the CdSe/ZnS core-shell QDs. The results obtained from the fluorescence spectral measurements for the biocompatible materials support the TL results.
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Affiliation(s)
- Viviane Pilla
- Instituto de Física, Universidade Federal de Uberlândia, Av. João Naves de Ávila 2121, CEP 38.400-902, Uberlândia, MG, Brazil
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11
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Liu Y, Zhang C, Zhang H, Wang R, Hua Z, Wang X, Zhang J, Xiao M. Broadband optical non-linearity induced by charge-transfer excitons in type-II CdSe/ZnTe nanocrystals. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2013; 25:4397-4402. [PMID: 23765798 DOI: 10.1002/adma.201301559] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 05/01/2013] [Indexed: 06/02/2023]
Abstract
Benefiting from excitonic charge-transfer states, an efficient non-linear optical response is observed in type-II nanocrystals by four-wave mixing when the incident photon energy lies below the bandgaps of constituent semiconductors. The non-linear optical properties in nanocrystals can be manipulated by the band alignment of the core-shell components, which serves as a promising platform to design broadband non-linear optical devices.
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Affiliation(s)
- Yunlong Liu
- National Laboratory of Solid State Microstructures, School of Physics, School of Engineering and Applied Science, Nanjing University, Nanjing, China
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12
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O'Connor T, Panov MS, Mereshchenko A, Tarnovsky AN, Lorek R, Perera D, Diederich G, Lambright S, Moroz P, Zamkov M. The effect of the charge-separating interface on exciton dynamics in photocatalytic colloidal heteronanocrystals. ACS NANO 2012; 6:8156-65. [PMID: 22881284 DOI: 10.1021/nn302810y] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Ultrafast transient absorption spectroscopy was used to investigate the nature of photoinduced charge transfer processes taking place in ZnSe/CdS/Pt colloidal heteronanocrystals. These nanoparticles consist of a dot-in-a-rod semiconductor domain (ZnSe/CdS) coupled to a Pt tip. Together the three components are designed to dissociate an electron-hole pair by pinning the hole in the ZnSe domain while allowing the electron to transfer into the Pt tip. Separated charges can then induce a catalytic reaction, such as the light-driven hydrogen production. Present measurements demonstrate that the internal electron-hole separation is fast and results in the localization of both charges in nonadjacent parts of the nanoparticle. In particular, we show that photoinduced holes become confined within the ZnSe domain in less than 2 ps, while electrons take approximately 15 ps to transition into a Pt tip. More importantly, we demonstrate that the presence of the ZnSe dot within the CdS nanorods plays a key role both in enabling photoinduced separation of charges and in suppressing their backward recombination. The implications of the observed exciton dynamics to photocatalytic function of ZnSe/CdS/Pt heteronanocrystals are discussed.
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Affiliation(s)
- Timothy O'Connor
- The Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, United States
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13
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Wen X, Sitt A, Yu P, Toh YR, Tang J. Temperature dependent spectral properties of type-I and quasi type-II CdSe/CdS dot-in-rod nanocrystals. Phys Chem Chem Phys 2012; 14:3505-12. [DOI: 10.1039/c2cp23844f] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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15
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Royo M, Climente JI, Movilla JL, Planelles J. Dielectric confinement of excitons in type-I and type-II semiconductor nanorods. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:015301. [PMID: 21406821 DOI: 10.1088/0953-8984/23/1/015301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We theoretically study the effect of the dielectric environment on the exciton ground state of CdSe and CdTe/CdSe/CdTe nanorods. We show that insulating environments enhance the exciton recombination rate and blueshift the emission peak by tens of meV. These effects are particularly pronounced for type-II nanorods. In these structures, the dielectric confinement may even modify the spatial distribution of the electron and hole charges. A critical electric field is required to separate electrons from holes, whose value increases with the insulating strength of the surroundings.
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Affiliation(s)
- M Royo
- Departament de Química Física i Analítica, Universitat Jaume I, E-12080, Castelló, Spain
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Lo SS, Mirkovic T, Chuang CH, Burda C, Scholes GD. Emergent properties resulting from type-II band alignment in semiconductor nanoheterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2011; 23:180-197. [PMID: 21069886 DOI: 10.1002/adma.201002290] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The development of elegant synthetic methodologies for the preparation of monocomponent nanocrystalline particles has opened many possibilities for the preparation of heterostructured semiconductor nanostructures. Each of the integrated nanodomains is characterized by its individual physical properties, surface chemistry, and morphology, yet, these multicomponent hybrid particles present ideal systems for the investigation of the synergetic properties that arise from the material combination in a non-additive fashion. Of particular interest are type-II heterostructures, where the relative band alignment of their constituent semiconductor materials promotes a spatial separation of the electron and hole following photoexcitation, a highly desirable property for photovoltaic applications. This article highlights recent progress in both synthetic strategies, which allow for material and architectural modulation of novel nanoheterostructures, as well as the experimental work that provides insight into the photophysical properties of type-II heterostructures. The effects of external factors, such as electric fields, temperature, and solvent are explored in conjunction with exciton and multiexciton dynamics and charge transfer processes typical for type-II semiconductor heterostructures.
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Affiliation(s)
- Shun S Lo
- Department of Chemistry, Institute for Optical Science, and Center for Quantum Information and Quantum Contro, l80 St. George Street, University of Toronto, Ontario M5S 3H6, Canada
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Abstract
Type-II heterostructure nanorods hold good prospects for efficient charge separation in nano solar cells. Here we employed local density approximation (LDA) quality plane wave pseudopotential methods to study exciton dissociation in CdSe/CdTe collinear nanorods. We corrected the LDA band gap by approximating GW equations, and studied the correlation effect with configuration interaction methods. The calculated binding energy and radiative decay time of the charge transfer excitons agree well with experiments. The thermally activated escaping time is estimated to be shorter than the radiative recombination time, indicating the possibility of exciton dissociation if the nonradiative channel is ignored.
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Affiliation(s)
- Shuzhi Wang
- Computational Research Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Mail Stop 50 F, Berkeley, California 94720, United States
| | - Lin-Wang Wang
- Computational Research Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Mail Stop 50 F, Berkeley, California 94720, United States
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