1
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Popelář T, Matějka F, Kopenec J, Morselli G, Ceroni P, Kůsová K. Why do Si quantum dots with stronger fast emission have lower external photoluminescence quantum yield? NANOSCALE ADVANCES 2024; 6:2644-2655. [PMID: 38752139 PMCID: PMC11093259 DOI: 10.1039/d3na01031g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 04/08/2024] [Indexed: 05/18/2024]
Abstract
Silicon quantum dots (QDs) are a promising non-toxic alternative to the already well-developed platform of light-emitting semiconductor QDs based on III-V and II-VI materials. Oxidized SiQDs or those surface-terminated with long alkyl chains typically feature long-lived orange-red photoluminescence originating in quantum-confined core states. However, sometimes an additional short-lived PL band, whose mechanism is still highly debated, is reported. Here, we perform a detailed study of the room-temperature PL of SiQDs using samples covering three main fabrication techniques. We find evidence for the presence of only one set of radiative processes in addition to the typical long-lived PL. Moreover, we experimentally determine the ratio between the short- and long-lived PL component, obtaining a wide range of values (0.003 - 0.1) depending on the type of sample. In accordance with an already published report, we observe a tendency of SiQDs with stronger short-lived PL to have lower external quantum yield. We explain this trend using a model of the optical performance of an ensemble of QDs with widely varying optical characteristics through a mechanism we call selective lifetime-based quenching.
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Affiliation(s)
- Tomáš Popelář
- Institute of Physics of the CAS v.v.i., Cukrovarnická 10 162 00 Prague 6 Czechia
| | - Filip Matějka
- Institute of Physics of the CAS v.v.i., Cukrovarnická 10 162 00 Prague 6 Czechia
- University of Chemistry and Technology Technická 5 166 28 Praha 6 Czechia
| | - Jakub Kopenec
- Institute of Physics of the CAS v.v.i., Cukrovarnická 10 162 00 Prague 6 Czechia
| | - Giacomo Morselli
- Chemistry Department "Giacomo Ciamician", University of Bologna Via F. Selmi 2 40126 Bologna Italy
| | - Paola Ceroni
- Chemistry Department "Giacomo Ciamician", University of Bologna Via F. Selmi 2 40126 Bologna Italy
| | - Kateřina Kůsová
- Institute of Physics of the CAS v.v.i., Cukrovarnická 10 162 00 Prague 6 Czechia
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2
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Shen H, Yu Z, Wang J, Lu M, Qiao C, Su WS, Zheng Y, Zhang R, Jia Y, Chen L, Wang C, Ho K, Wang S. Luminescence mechanism in hydrogenated silicon quantum dots with a single oxygen ligand. NANOSCALE ADVANCES 2021; 3:2245-2251. [PMID: 36133768 PMCID: PMC9417146 DOI: 10.1039/d0na00986e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 02/26/2021] [Indexed: 06/16/2023]
Abstract
Though photoluminescence (PL) of Si quantum dots (QDs) has been known for decades and both theoretical and experimental studies have been extensive, their luminescence mechanism has not been elaborated. Several models have been proposed to explain the mechanism. A deep insight into the origin of light emissions in Si QDs is necessary. This work calculated the ground- and excited state properties of hydrogenated Si QDs with various diameters, including full hydrogen passivation, single Si[double bond, length as m-dash]O ligands, single epoxide and coexisting Si[double bond, length as m-dash]O and epoxide structures in order to investigate the dominant contribution states for luminescence. The results revealed that even a single oxygen atom in hydrogenated Si QDs can dramatically change their electronic and optical properties. Intriguingly, we found that a size-independent emission, the strongest among all possible emissions, was induced by the single Si[double bond, length as m-dash]O passivated Si-QDs. In non-oxidized Si-QDs exhibiting a core-related size-tunable emission, the luminescence properties can be modulated by the ligands of Si QDs, and a very small number of oxygen ligands can strongly influence the luminescence of nanocrystalline silicon. Our findings deepen the understanding of the PL mechanism of Si QDs and can further promote the development of silicon-based optoelectronic devices.
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Affiliation(s)
- Hong Shen
- Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University Shanghai 200433 China
| | - Zhiyuan Yu
- Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University Shanghai 200433 China
| | - Jinjin Wang
- Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University Shanghai 200433 China
| | - Ming Lu
- Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University Shanghai 200433 China
| | - Chong Qiao
- Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University Shanghai 200433 China
| | - Wan-Sheng Su
- National Taiwan Science Education Center Taipei 11165 Taiwan
- Department of Electro-Optical Engineering, National Taipei University of Technology Taipei 10608 Taiwan
| | - Yuxiang Zheng
- Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University Shanghai 200433 China
| | - Rongjun Zhang
- Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University Shanghai 200433 China
| | - Yu Jia
- Key Laboratory for Special Functional Materials of Ministry of Education, Collaborative Innovation Center of Nano Functional Materials and Applications, School of Materials Science and Engineering, Henan University Kaifeng Henan 475001 China
| | - Liangyao Chen
- Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University Shanghai 200433 China
| | - Caizhuang Wang
- Ames Laboratory, U. S. Department of Energy and Department of Physics and Astronomy, Iowa State University Ames Iowa 50011 USA
| | - Kaiming Ho
- Ames Laboratory, U. S. Department of Energy and Department of Physics and Astronomy, Iowa State University Ames Iowa 50011 USA
| | - Songyou Wang
- Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Department of Optical Science and Engineering, Fudan University Shanghai 200433 China
- Key Laboratory for Information Science of Electromagnetic Waves (MoE) Shanghai 200433 China
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3
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Fujii M, Minami A, Sugimoto H. Precise size separation of water-soluble red-to-near-infrared-luminescent silicon quantum dots by gel electrophoresis. NANOSCALE 2020; 12:9266-9271. [PMID: 32313916 DOI: 10.1039/d0nr02764b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Gel electrophoresis, which is a standard method for separation and analysis of macromolecules such as DNA, RNA and proteins, is applied for the first time to silicon (Si) quantum dots (QDs) for size separation. In the Si QDs studied, boron (B) and phosphorus (P) are simultaneously doped. Codoping induces a negative potential on the surface of a Si QD and makes it dispersible in water. Si QDs with different B and P concentrations and grown at different temperatures (950 °C-1200 °C) are studied. It is shown that native polyacrylamide gel electrophoresis can separate codoped Si QDs by size. The capability of gel electrophoresis to immobilize size-separated QDs in a solid matrix makes detailed analyses of size-purified Si QDs possible. For example, the photoluminescence (PL) studies of the dried gel of Si QDs grown at 1100 °C demonstrate that a PL spectrum of a Si QD solution with the PL maximum around 1.4 eV can be separated into more than 15 spectra with the PL maximum changing from 1.2 to 1.8 eV depending on the migration distance. It is found that the relationship between the PL peak energy and the migration distance depends on the growth temperature of Si QDs as well as the B and P concentration. For all the samples with different impurity concentrations and grown at different temperatures, a clear trend is observed in the relationship between the full width at half maximum (FWHM) and the peak energy of the PL spectra in a wide energy range. The FWHM increases with the increasing peak energy and it is nearly twice larger than those observed for undoped Si QDs. The large PL FWHM of codoped Si QDs suggests that excitons are further localized in codoped Si QDs due to the existence of charged impurities.
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Affiliation(s)
- Minoru Fujii
- Department of Electrical and Electronic Engineering, Kobe University, 657-8501 Kobe, Japan.
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4
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Pringle TA, Hunter KI, Brumberg A, Anderson KJ, Fagan JA, Thomas SA, Petersen RJ, Sefannaser M, Han Y, Brown SL, Kilin DS, Schaller RD, Kortshagen UR, Boudjouk PR, Hobbie EK. Bright Silicon Nanocrystals from a Liquid Precursor: Quasi-Direct Recombination with High Quantum Yield. ACS NANO 2020; 14:3858-3867. [PMID: 32150383 DOI: 10.1021/acsnano.9b09614] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Silicon nanocrystals (SiNCs) with bright bandgap photoluminescence (PL) are of current interest for a range of potential applications, from solar windows to biomedical contrast agents. Here, we use the liquid precursor cyclohexasilane (Si6H12) for the plasma synthesis of colloidal SiNCs with exemplary core emission. Through size separation executed in an oxygen-shielded environment, we achieve PL quantum yields (QYs) approaching 70% while exposing intrinsic constraints on efficient core emission from smaller SiNCs. Time-resolved PL spectra of these fractions in response to femtosecond pulsed excitation reveal a zero-phonon radiative channel that anticorrelates with QY, which we model using advanced computational methods applied to a 2 nm SiNC. Our results offer additional insight into the photophysical interplay of the nanocrystal surface, quasi-direct recombination, and efficient SiNC core PL.
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Affiliation(s)
- Todd A Pringle
- Materials and Nanotechnology Program, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Katharine I Hunter
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Alexandra Brumberg
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Kenneth J Anderson
- Department of Chemistry & Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Jeffrey A Fagan
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Salim A Thomas
- Materials and Nanotechnology Program, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Reed J Petersen
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Mahmud Sefannaser
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Yulun Han
- Department of Chemistry & Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Samuel L Brown
- Materials and Nanotechnology Program, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Dmitri S Kilin
- Department of Chemistry & Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Richard D Schaller
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Uwe R Kortshagen
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Philip Raymond Boudjouk
- Department of Chemistry & Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States
| | - Erik K Hobbie
- Materials and Nanotechnology Program, North Dakota State University, Fargo, North Dakota 58108, United States
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108, United States
- Department of Coatings and Polymeric Materials, North Dakota State University, Fargo, North Dakota 58108, United States
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5
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Morozova S, Alikina M, Vinogradov A, Pagliaro M. Silicon Quantum Dots: Synthesis, Encapsulation, and Application in Light-Emitting Diodes. Front Chem 2020; 8:191. [PMID: 32318540 PMCID: PMC7154098 DOI: 10.3389/fchem.2020.00191] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 03/02/2020] [Indexed: 12/29/2022] Open
Abstract
Silicon quantum dots (SiQDs) are semiconductor Si nanoparticles ranging from 1 to 10 nm that hold great applicative potential as optoelectronic devices and fluorescent bio-marking agents due to their ability to fluoresce blue and red light. Their biocompatibility compared to conventional toxic Group II-VI and III-V metal-based quantum dots makes their practical utilization even more attractive to prevent environmental pollution and harm to living organisms. This work focuses on their possible use for light-emitting diode (LED) manufacturing. Summarizing the main achievements over the past few years concerning different Si quantum dot synthetic methods, LED formation and characteristics, and strategies for their stabilization by microencapsulation and modification of their surface by specific ligands, this work aims to provide guidance en route to the development of the first stable Si-based light-emitting diodes.
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Affiliation(s)
- Sofia Morozova
- Laboratory of Inkjet Printing of Functional Materials, SCAMT Institute, ITMO University, Saint-Petersburg, Russia
| | - Mariya Alikina
- Laboratory of Inkjet Printing of Functional Materials, SCAMT Institute, ITMO University, Saint-Petersburg, Russia
| | - Aleksandr Vinogradov
- Laboratory of Inkjet Printing of Functional Materials, SCAMT Institute, ITMO University, Saint-Petersburg, Russia
| | - Mario Pagliaro
- Istituto per lo Studio dei Materiali Nanostrutturati, CNR, Palermo, Italy
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6
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Ratiometric Detection of Rifampin by Using Self‐Assembled Nanocomposites with Dual Fluorescence Emissions and Analysis of Two‐Dimensional Correlation Spectroscopy. B KOREAN CHEM SOC 2020. [DOI: 10.1002/bkcs.11987] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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7
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Canham L. Introductory lecture: origins and applications of efficient visible photoluminescence from silicon-based nanostructures. Faraday Discuss 2020; 222:10-81. [DOI: 10.1039/d0fd00018c] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This review highlights many spectroscopy-based studies and selected phenomenological studies of silicon-based nanostructures that provide insight into their likely PL mechanisms, and also covers six application areas.
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Affiliation(s)
- Leigh Canham
- School of Physics and Astronomy
- University of Birmingham
- Birmingham
- UK
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8
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Awati A, Maimaiti H, Xu B, Wang S. A comparative study on the preparation methods and properties of coal‐based fluorescent carbon nanoparticles. SURF INTERFACE ANAL 2019. [DOI: 10.1002/sia.6727] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Abuduheiremu Awati
- Institute of Chemistry and Chemical Industry Xinjiang University, Urumqi China
| | - Halidan Maimaiti
- Institute of Chemistry and Chemical Industry Xinjiang University, Urumqi China
| | - Bo Xu
- Institute of Chemistry and Chemical Industry Xinjiang University, Urumqi China
| | - Shixin Wang
- Institute of Chemistry and Chemical Industry Xinjiang University, Urumqi China
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9
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Nitrogen-terminated silicon nanoparticles obtained via chemical etching and passivation are specific fluorescent probes for creatinine. Mikrochim Acta 2019; 186:387. [PMID: 31144038 DOI: 10.1007/s00604-019-3494-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 05/12/2019] [Indexed: 10/26/2022]
Abstract
A method is described here to prepare water-dispersible nitrogen-functionalized silicon nanoparticles (N-SiNPs). It consists of two steps, viz. etching of the oxidized shell of SiNPs and nitrogen-passivation of the exposed silicon. The resulting N-SiNPs have an average diameter of 2.6±0.7 nm and show blue fluorescence (with excitation/emission peaks at 340/420 nm). The fluorescence quantum yield is 23% and the decay time is in the nanosecond regime. Compared to etching methods using a plasma or hydrofluoric acid, the process described here (etching and passivation) is mild, continuous, fast, and air-compatible. The N-SiNPs modified with chlorotetracycline are shown to be a viable fluorescent probe for creatinine. Fluorescence drops in the 0 to 20 μM creatinine concentration range, and the limit of detection is 0.14 μM.
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10
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Angı A, Sinelnikov R, Heenen HH, Meldrum A, Veinot JGC, Scheurer C, Reuter K, Ashkenazy O, Azulay D, Balberg I, Millo O, Rieger B. The influence of conjugated alkynyl(aryl) surface groups on the optical properties of silicon nanocrystals: photoluminescence through in-gap states. NANOTECHNOLOGY 2018; 29:355705. [PMID: 29862985 DOI: 10.1088/1361-6528/aac9ef] [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
Developing new methods, other than size and shape, for controlling the optoelectronic properties of semiconductor nanocrystals is a highly desired target. Here we demonstrate that the photoluminescence (PL) of silicon nanocrystals (SiNCs) can be tuned in the range 685-800 nm solely via surface functionalization with alkynyl(aryl) (phenylacetylene, 2-ethynylnaphthalene, 2-ethynyl-5-hexylthiophene) surface groups. Scanning tunneling microscopy/spectroscopy on single nanocrystals revealed the formation of new in-gap states adjacent to the conduction band edge of the functionalized SiNCs. PL red-shifts were attributed to emission through these in-gap states, which reduce the effective band gap for the electron-hole recombination process. The observed in-gap states can be associated with new interface states formed via (-Si-C≡C-) bonds in combination with conjugated molecules as indicated by ab initio calculations. In contrast to alkynyl(aryl)s, the formation of in-gap states and shifts in PL maximum of the SiNCs were not observed with aryl (phenyl, naphthalene, 2-hexylthiophene) and alkynyl (1-dodecyne) surface groups. These outcomes show that surface functionalization with alkynyl(aryl) molecules is a valuable tool to control the electronic structure and optical properties of SiNCs via tuneable interface states, which may enhance the performance of SiNCs in semiconductor devices.
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Affiliation(s)
- Arzu Angı
- WACKER-Lehrstuhl für Makromolekulare Chemie, Technische Universität München, Lichtenbergstraße 4, D-85747, Germany. Catalysis Research Center, Ernst-Otto-Fischer-Straße 1, D-85748 Garching, Germany
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11
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Han Y, Anderson K, Hobbie EK, Boudjouk P, Kilin DS. Unraveling Photodimerization of Cyclohexasilane from Molecular Dynamics Studies. J Phys Chem Lett 2018; 9:4349-4354. [PMID: 30004709 DOI: 10.1021/acs.jpclett.8b01691] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Photoinduced reactions of a pair of cyclohexasilane (CHS) monomers are explored by time-dependent excited-state molecular dynamics (TDESMD) calculations. In TDESMD trajectories, one observes vivid reaction events including dimerization and fragmentation. A general reaction pathway is identified as (i) ring-opening formation of a dimer, (ii) rearrangement induced by bond breaking, and (iii) decomposition through the elimination of small fragments. The identified pathway supports the chemistry proposed for the fabrication of silicon-based materials using CHS as a precursor. In addition, we find dimers have smaller HOMO-LUMO gaps and exhibit a red shift and line-width broadening in the computed photoluminescence spectra compared with a pair of CHS monomers.
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Affiliation(s)
- Yulun Han
- Department of Chemistry and Biochemistry , North Dakota State University , Fargo , North Dakota 58102 , United States
| | - Kenneth Anderson
- Department of Chemistry and Biochemistry , North Dakota State University , Fargo , North Dakota 58102 , United States
| | - Erik K Hobbie
- Department of Chemistry and Biochemistry , North Dakota State University , Fargo , North Dakota 58102 , United States
| | - Philip Boudjouk
- Department of Chemistry and Biochemistry , North Dakota State University , Fargo , North Dakota 58102 , United States
| | - Dmitri S Kilin
- Department of Chemistry and Biochemistry , North Dakota State University , Fargo , North Dakota 58102 , United States
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12
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Zhang T, Zhang K, Chen X, Wang S, Zhang R, Shao J, Chen X, Dai N. Temperature-dependent Photoluminescence of Silicon Nanocrystals Embedded in SiO2 Matrix. Chem Res Chin Univ 2018. [DOI: 10.1007/s40242-018-7417-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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13
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So WY, Li Q, Legaspi CM, Redler B, Koe KM, Jin R, Peteanu LA. Mechanism of Ligand-Controlled Emission in Silicon Nanoparticles. ACS NANO 2018; 12:7232-7238. [PMID: 29812906 DOI: 10.1021/acsnano.8b03273] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Although bulk silicon (Si) is known to be a poor emitter, Si nanoparticles (NPs) exhibit size-dependent photoluminescence in the red or near-infrared due to quantum confinement. Recently, it has been shown that surface modification of Si NPs with nitrogen-capped ligands results in bluer emission wavelengths and quantum yields of up to 90%. However, the emission mechanism operating in these surface-modified Si NPs and the factors that determine their emission maxima are still unclear. Here, the emission in these species is shown to arise from a charge-transfer state between the Si surface and the ligand. The energy of this state is linearly correlated to the calculated ground-state dipole moment of the free ligand. This trend can be used in a predictive fashion for the design and synthesis of Si NPs with a broader range of emission wavelengths.
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Affiliation(s)
- Woong Young So
- Department of Chemistry , Carnegie Mellon University , Pittsburgh , PA 15213 , United States
| | - Qi Li
- Department of Chemistry , Carnegie Mellon University , Pittsburgh , PA 15213 , United States
| | - Christian M Legaspi
- Department of Chemistry , Carnegie Mellon University , Pittsburgh , PA 15213 , United States
| | - Brendan Redler
- Department of Biological Sciences , Carnegie Mellon University , Pittsburgh , PA 15213 , United States
| | - Krystle M Koe
- Department of Chemistry , Carnegie Mellon University , Pittsburgh , PA 15213 , United States
| | - Rongchao Jin
- Department of Chemistry , Carnegie Mellon University , Pittsburgh , PA 15213 , United States
| | - Linda A Peteanu
- Department of Chemistry , Carnegie Mellon University , Pittsburgh , PA 15213 , United States
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14
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Greben M, Khoroshyy P, Gutsch S, Hiller D, Zacharias M, Valenta J. Changes of the absorption cross section of Si nanocrystals with temperature and distance. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2017; 8:2315-2323. [PMID: 29181288 PMCID: PMC5687048 DOI: 10.3762/bjnano.8.231] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 09/29/2017] [Indexed: 06/07/2023]
Abstract
The absorption cross section (ACS) of silicon nanocrystals (Si NCs) in single-layer and multilayer structures with variable thickness of oxide barriers is determined via a photoluminescence (PL) modulation technique that is based on the analysis of excitation intensity-dependent PL kinetics under modulated pumping. We clearly demonstrate that roughly doubling the barrier thickness (from ca. 1 to 2.2 nm) induces a decrease of the ACS by a factor of 1.5. An optimum separation barrier thickness of ca. 1.6 nm is calculated to maximize the PL intensity yield. This large variation of ACS values with barrier thickness is attributed to a modulation of either defect population states or of the efficiency of energy transfer between confined NC layers. An exponential decrease of the ACS with decreasing temperature down to 120 K can be explained by smaller occupation number of phonons and expansion of the band gap of Si NCs at low temperatures. This study clearly shows that the ACS of Si NCs cannot be considered as independent on experimental conditions and sample parameters.
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Affiliation(s)
- Michael Greben
- Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16 Prague 2, Czech Republic
| | - Petro Khoroshyy
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo namesti 2, 160 00 Prague 6, Czech Republic
| | - Sebastian Gutsch
- Faculty of Engineering, IMTEK, Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany
| | - Daniel Hiller
- Faculty of Engineering, IMTEK, Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany
| | - Margit Zacharias
- Faculty of Engineering, IMTEK, Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany
| | - Jan Valenta
- Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 3, 121 16 Prague 2, Czech Republic
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15
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Mazzaro R, Romano F, Ceroni P. Long-lived luminescence of silicon nanocrystals: from principles to applications. Phys Chem Chem Phys 2017; 19:26507-26526. [DOI: 10.1039/c7cp05208a] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Understanding parameters affecting the luminescence of silicon nanocrystals will guide the design of improved systems for a plethora of applications.
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Affiliation(s)
- Raffaello Mazzaro
- Department of Chemistry “Giacomo Ciamician”
- University of Bologna, and Interuniversity Center for the Chemical Conversion of Solar Energy (SolarChem)
- 40126 Bologna
- Italy
| | - Francesco Romano
- Department of Chemistry “Giacomo Ciamician”
- University of Bologna, and Interuniversity Center for the Chemical Conversion of Solar Energy (SolarChem)
- 40126 Bologna
- Italy
| | - Paola Ceroni
- Department of Chemistry “Giacomo Ciamician”
- University of Bologna, and Interuniversity Center for the Chemical Conversion of Solar Energy (SolarChem)
- 40126 Bologna
- Italy
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