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He S, Ni A, Gebre ST, Hang R, McBride JR, Kaledin AL, Yang W, Lian T. Doping of Colloidal Nanocrystals for Optimizing Interfacial Charge Transfer: A Double-Edged Sword. J Am Chem Soc 2024. [PMID: 39189788 DOI: 10.1021/jacs.4c06110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/28/2024]
Abstract
Doping of colloidal nanocrystals offers versatile ways to improve their optoelectronic properties, with potential applications in photocatalysis and photovoltaics. However, the precise role of dopants on the interfacial charge transfer properties of nanocrystals remains poorly understood. Here, we use a Cu-doped InP@ZnSe quantum dot as a model system to investigate the dopant effects on both the intrinsic photophysics and their interfacial charge transfer by combining time-resolved transient absorption and photoluminescent spectroscopic methods. Our results revealed that the Cu dopant can cause the generation of the self-trapped exciton, which prolongs the exciton lifetime from 48.3 ± 1.7 to 369.0 ± 4.3 ns, facilitating efficient charge separation to slow electron and hole acceptors. However, hole localization into the Cu site alters their energetic levels, slowing hole transfer and accelerating charge recombination loss. This double-edged sword role of dopants in charge transfer properties is important in the future design of nanocrystals for their optoelectronic and photocatalytic applications.
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Affiliation(s)
- Sheng He
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
| | - Anji Ni
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
| | - Sara T Gebre
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
| | - Rui Hang
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
| | - James R McBride
- Department of Chemistry, The Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Alexey L Kaledin
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
- The Cherry L. Emerson Center for Scientific Computation, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
| | - Wenxing Yang
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
| | - Tianquan Lian
- Department of Chemistry, Emory University, 1515 Dickey Drive Northeast, Atlanta, Georgia 30322, United States
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2
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Rana G, Das S, Singha PK, Ali F, Maji R, Datta A. The effect of Cu(I)-doping on the photoinduced electron transfer from aqueous CdS quantum dots. J Chem Phys 2024; 161:024705. [PMID: 38990118 DOI: 10.1063/5.0218548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2024] [Accepted: 06/24/2024] [Indexed: 07/12/2024] Open
Abstract
The doping of CdS quantum dots (QDs) with Cu(I) disrupts electron-hole correlation due to hole trapping by the dopant ion, post-photoexcitation. The present paper examines the effect of such disruption on the rate of photoinduced electron transfer (PET) from the QDs to methyl viologen (MV2+), with implications in their photocatalytic activity. A significantly greater efficiency of PL quenching by MV2+ is observed for the doped QDs than for the undoped ones. Interestingly, the Stern-Volmer plots constructed using PL intensities exhibit an upward curvature for both the cases, while the PL lifetimes remain unaffected. This observation is rationalized by considering the adsorption of the quencher on the surface of the QDs and ultrafast PET post-photoexcitation. Ultrafast transient absorption experiments confirm a faster electron transfer for the doped QDs. It is also realized that the transient absorption experiment yields a more accurate estimate of the binding constant of the quencher with the QDs, than the PL experiment.
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Affiliation(s)
- Gourab Rana
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Sharmistha Das
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Prajit Kumar Singha
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Fariyad Ali
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Rohan Maji
- Department of Chemistry, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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3
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Chou KC, Li LC, Tsai KA, Zeitz DC, Pu YC, Zhang JZ. Effect of Lattice Disorder on Exciton Dynamics in Copper-Doped InP/ZnSe xS 1-x Core/Shell Quantum Dots. J Phys Chem Lett 2024; 15:4311-4318. [PMID: 38619190 DOI: 10.1021/acs.jpclett.4c00689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
InP/ZnSexS1-x core/shell quantum dots (QDs) with varying Cu concentrations were synthesized by a one-pot hot-injection method. X-ray diffraction and high-resolution transmission electron microscopy results indicate that Cu doping did not alter the crystal structure or particle size of the QDs. The optical shifts in UV-visible absorption and photoluminescence (PL) suggest changes in the electronic structure and induction of lattice disorder due to Cu doping. Ultrafast transient absorption spectroscopy (TAS) reveled that a higher Cu-doping level leads to faster charge carrier recombination, likely due to increased nonradiative decay from defect states. Time-resolved PL (TRPL) studies show longer average lifetimes of charge carriers with increased Cu doping. These findings informed the development of a kinetic model to better understand how Cu-induced disorder affects charge carrier dynamics in the QDs, which is important for emerging applications of Cu-doped InP/ZnSexS1-x QDs in optoelectronics.
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Affiliation(s)
- Kai-Chun Chou
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Le-Chun Li
- Department of Materials Science, National University of Tainan, Tainan 70005, Taiwan
| | - Kai-An Tsai
- Department of Materials Science, National University of Tainan, Tainan 70005, Taiwan
| | - David C Zeitz
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Ying-Chih Pu
- Department of Materials Science, National University of Tainan, Tainan 70005, Taiwan
| | - Jin Z Zhang
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
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4
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Deswal P, Samanta K, Ghosh D. The impact of spatially heterogeneous chemical doping on the electronic properties of CdSe quantum dots: insights from ab initio computation. NANOSCALE 2023; 15:17055-17067. [PMID: 37846794 DOI: 10.1039/d3nr04342h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
The introduction of copper (Cu) impurity in semiconductor CdSe quantum dots (QDs) gives rise to unique photoluminescence (PL) bands exhibiting distinctive characteristics, like broad line width, significant Stokes shift, and complex temporal decay. The atomistic origins of these spectral features are yet to be understood comprehensively. We employed multiple computational techniques to systematically study the impact of the spatial heterogeneity of Cu atoms on the stability and photophysical properties, including the emission linewidth of doped QDs under ambient conditions. The Cu substitution introduces a spin-polarized intragap state, the energetic position of which is strongly dependent on the dopant location and causes spectral broadening in QD ensembles. Furthermore, the dopant dynamics under ambient conditions are significantly influenced by the specific arrangement of Cu within the QDs. The dynamic electronic structures of surface-doped CdSe illustrate more pronounced perturbations and vary the mid-gap state position more drastically than those of the core-doped QDs. Vibronic coupling broadens the photoluminescence peaks associated with the conduction band-to-defect level transition for individual QDs. These insights into the dynamic structure-photophysical property relationship suggest viable approaches, such as tuning the operational temperature and selective co-doping, to enhance the functional performances of doped CdSe QDs strategically.
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Affiliation(s)
- Priyanka Deswal
- Department of Physics, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India
| | - Kushal Samanta
- Department of Materials Science and Engineering, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India.
| | - Dibyajyoti Ghosh
- Department of Materials Science and Engineering, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India.
- Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India
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5
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Mondal P, Sathiyamani S, Das S, Viswanatha R. Electronic structure study of dual-doped II-VI semiconductor quantum dots towards single-source white light emission. NANOSCALE 2023; 15:15288-15297. [PMID: 37681636 DOI: 10.1039/d3nr03542e] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Abstract
Single-source white light emitting colloidal semiconductor quantum dots (QDs) is one of the most exciting and promising high-quality solid-state light sources to meet the current global demand for sustainable resources. While most of the previous methods involve dual (green-red) emissive nanostructures coated on blue LEDs to achieve white light, this work describes a single-source white light emitter of robust and superior quality using dual-doping. A modified synthesis method for intense white light emitting Cu, Mn dual-doped ZnSe QDs is engineered such that the extent of doping and concentration of ligands can alter their electronic structures. This is then customized to obtain various types of white light emissions ranging from warm white to cool white. Further, the composition-driven change in the electronic structure of the host QDs is exploited to achieve emission tunability over the entire visible range.
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Affiliation(s)
- Payel Mondal
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India.
| | - Sowmeya Sathiyamani
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India.
| | - Subham Das
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India.
| | - Ranjani Viswanatha
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India.
- International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
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6
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Dehnel J, Harchol A, Barak Y, Meir I, Horani F, Shapiro A, Strassberg R, de Mello Donegá C, Demir HV, Gamelin DR, Sharma K, Lifshitz E. Optically detected magnetic resonance spectroscopic analyses on the role of magnetic ions in colloidal nanocrystals. J Chem Phys 2023; 159:071001. [PMID: 37581419 DOI: 10.1063/5.0160787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 07/26/2023] [Indexed: 08/16/2023] Open
Abstract
Incorporating magnetic ions into semiconductor nanocrystals has emerged as a prominent research field for manipulating spin-related properties. The magnetic ions within the host semiconductor experience spin-exchange interactions with photogenerated carriers and are often involved in the recombination routes, stimulating special magneto-optical effects. The current account presents a comparative study, emphasizing the impact of engineering nanostructures and selecting magnetic ions in shaping carrier-magnetic ion interactions. Various host materials, including the II-VI group, halide perovskites, and I-III-VI2 in diverse structural configurations such as core/shell quantum dots, seeded nanorods, and nanoplatelets, incorporated with magnetic ions such as Mn2+, Ni2+, and Cu1+/2+ are highlighted. These materials have recently been investigated by us using state-of-the-art steady-state and transient optically detected magnetic resonance (ODMR) spectroscopy to explore individual spin-dynamics between the photogenerated carriers and magnetic ions and their dependence on morphology, location, crystal composition, and type of the magnetic ion. The information extracted from the analyses of the ODMR spectra in those studies exposes fundamental physical parameters, such as g-factors, exchange coupling constants, and hyperfine interactions, together providing insights into the nature of the carrier (electron, hole, dopant), its local surroundings (isotropic/anisotropic), and spin dynamics. The findings illuminate the importance of ODMR spectroscopy in advancing our understanding of the role of magnetic ions in semiconductor nanocrystals and offer valuable knowledge for designing magnetic materials intended for various spin-related technologies.
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Affiliation(s)
- Joanna Dehnel
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Adi Harchol
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Yahel Barak
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Itay Meir
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Faris Horani
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA
| | - Arthur Shapiro
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Rotem Strassberg
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Celso de Mello Donegá
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3584 CC Utrecht, The Netherlands
| | - Hilmi Volkan Demir
- Luminous Center of Excellence for Semiconductor Lighting and Displays, TPI, School of Electrical and Electronic Engineering, School of Physical and Mathematical Sciences, School of Materials Science and Engineering, Nanyang Technological University-NTU Singapore, 639798, Singapore
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Türkiye
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA
| | - Kusha Sharma
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Efrat Lifshitz
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
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7
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Das S, Rana G, Ali F, Datta A. Single particle level dynamics of photoactivation and suppression of Auger recombination in aqueous Cu-doped CdS quantum dots. NANOSCALE 2023; 15:4469-4476. [PMID: 36752332 DOI: 10.1039/d2nr06688b] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Cu-doped CdS quantum dots (QDs) have been synthesized in water using 3-mercaptopropionic acid (3-MPA) as the capping agent. They exhibit intense photoluminescence and excellent color tunability, unlike most of the QDs synthesized/dispersed in water so far. Complete characterization of these aqueous doped CdS QDs has been performed for the first time, along with a single particle level elucidation of their exciton dynamics using fluorescence correlation spectroscopy. Photoactivation via dim/dark to bright particle conversion is observed at higher excitation powers. Dispersive blinking kinetics in undoped QDs reflects the involvement of a broad distribution of trap states. A lesser extent of dispersity is observed for doped QDs, in which hole-capture by Cu-defect states predominates. Excitation fluence dependence of the blinking rate highlights the role of Auger recombination in undoped QDs, which is suppressed significantly upon doping, due to disruption of the electron-hole correlation.
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Affiliation(s)
- Sharmistha Das
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
| | - Gourab Rana
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
| | - Fariyad Ali
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
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8
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Bai B, Zhang C, Dou Y, Kong L, Wang L, Wang S, Li J, Zhou Y, Liu L, Liu B, Zhang X, Hadar I, Bekenstein Y, Wang A, Yin Z, Turyanska L, Feldmann J, Yang X, Jia G. Atomically flat semiconductor nanoplatelets for light-emitting applications. Chem Soc Rev 2023; 52:318-360. [PMID: 36533300 DOI: 10.1039/d2cs00130f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The last decade has witnessed extensive breakthroughs and significant progress in atomically flat two-dimensional (2D) semiconductor nanoplatelets (NPLs) in terms of synthesis, growth mechanisms, optical and electronic properties and practical applications. Such NPLs have electronic structures similar to those of quantum wells in which excitons are predominantly confined along the vertical direction, while electrons are free to move in the lateral directions, resulting in unique optical properties, such as extremely narrow emission line width, short photoluminescence (PL) lifetime, high gain coefficient, and giant oscillator strength transition (GOST). These unique optical properties make NPLs favorable for high color purity light-emitting applications, in particular in light-emitting diodes (LEDs), backlights for liquid crystal displays (LCDs) and lasers. This review article first introduces the intrinsic characteristics of 2D semiconductor NPLs with atomic flatness. Subsequently, the approaches and mechanisms for the controlled synthesis of atomically flat NPLs are summarized followed by an insight on recent progress in the mediation of core/shell, core/crown and core/crown@shell structures by selective epitaxial growth of passivation layers on different planes of NPLs. Moreover, an overview of the unique optical properties and the associated light-emitting applications is elaborated. Despite great progress in this research field, there are some issues relating to heavy metal elements such as Cd2+ in NPLs, and the ambiguous gain mechanisms of NPLs and others are the main obstacles that prevent NPLs from widespread applications. Therefore, a perspective is included at the end of this review article, in which the current challenges in this stimulating research field are discussed and possible solutions to tackle these challenges are proposed.
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Affiliation(s)
- Bing Bai
- Key Lab for Special Functional Materials, Ministry of Education, National and Local Joint Engineering Research Center for High-Efficiency Display and Lighting Technology, School of Materials Science and Engineering, and Collaborative Innovation Center of Nano Functional Materials and Applications, Henaon University, Kaifeng 475004, China
| | - Chengxi Zhang
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, China.
| | - Yongjiang Dou
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, China.
| | - Lingmei Kong
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, China.
| | - Lin Wang
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, China.
| | - Sheng Wang
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, China.
| | - Jun Li
- Key Lab for Special Functional Materials, Ministry of Education, National and Local Joint Engineering Research Center for High-Efficiency Display and Lighting Technology, School of Materials Science and Engineering, and Collaborative Innovation Center of Nano Functional Materials and Applications, Henaon University, Kaifeng 475004, China
| | - Yi Zhou
- Key Lab for Special Functional Materials, Ministry of Education, National and Local Joint Engineering Research Center for High-Efficiency Display and Lighting Technology, School of Materials Science and Engineering, and Collaborative Innovation Center of Nano Functional Materials and Applications, Henaon University, Kaifeng 475004, China
| | - Long Liu
- Key Lab for Special Functional Materials, Ministry of Education, National and Local Joint Engineering Research Center for High-Efficiency Display and Lighting Technology, School of Materials Science and Engineering, and Collaborative Innovation Center of Nano Functional Materials and Applications, Henaon University, Kaifeng 475004, China
| | - Baiquan Liu
- School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Xiaoyu Zhang
- Key Laboratory of Automobile Materials, Ministry of Education, College of Materials Science and Engineering, Jilin Provincial International Cooperation Key Laboratory of High-Efficiency Clean Energy Materials, Electron Microscopy Center, Jilin University, Changchun 130012, China
| | - Ido Hadar
- Institute of Chemistry, and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Yehonadav Bekenstein
- Department of Materials Science and Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Aixiang Wang
- School of Chemistry and Chemical Engineering, Linyi University, Linyi 276005, P. R. China
| | - Zongyou Yin
- Research School of Chemistry, The Australian National University, ACT 2601, Australia
| | - Lyudmila Turyanska
- Faculty of Engineering, The University of Nottingham, Additive Manufacturing Building, Jubilee Campus, University Park, Nottingham NG7 2RD, UK
| | - Jochen Feldmann
- Chair for Photonics and Optoelectronics, Nano-Institute Munich and Department of Physics, Ludwig-Maximilians-Universität (LMU), Königinstr. 10, Munich 80539, Germany
| | - Xuyong Yang
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, Shanghai 200072, China.
| | - Guohua Jia
- School of Molecular and Life Sciences, Curtin University, Perth, WA 6102, Australia.
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9
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Wei T, Lian K, Tao J, Zhang H, Xu D, Han J, Fan C, Zhang Z, Bi W, Sun C. Mn-Doped Multiple Quantum Well Perovskites for Efficient Large-Area Luminescent Solar Concentrators. ACS APPLIED MATERIALS & INTERFACES 2022; 14:44572-44580. [PMID: 36125906 DOI: 10.1021/acsami.2c12834] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Luminescent solar concentrators (LSCs) can be used as large-area sunlight collectors, which show great potential in the application of building-integrated photovoltaic areas. Achieving highly efficient LSCs requires the suppression of reabsorption losses while maintaining a high photoluminescence quantum yield (PLQY) and broad absorption. Perovskites as the superstar fluorophores have recently emerged as candidates for large-area LSCs. However, highly emissive perovskites with a large Stokes shift and broad absorption have not been obtained up to now. Here, we devised a facile synthetic route to obtain Mn-doped multiple quantum well (MQW) Br-based perovskites. The Br-based perovskite host ensures broad absorption. Efficient energy transfer from the exciton to the Mn dopant produces a large Stokes shift and high PLQY simultaneously. By further coating the perovskites with Al2O3, the stability and PLQY are greatly elevated. A large area of liquid LSC (40 cm × 40 cm × 0.5 cm) is fabricated, which possesses an internal quantum efficiency (ηint) of 47% and an optical conversion efficiency (ηopt) reaching 11 ± 1%, which shows the highest value for large-area LSCs.
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Affiliation(s)
- Tong Wei
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Tianjin Key Laboratory of Electronic Materials and Devices, School of Electronics and Information Engineering, Hebei University of Technology, 5340 Xiping Road, Tianjin 300401, P. R. China
| | - Kai Lian
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Tianjin Key Laboratory of Electronic Materials and Devices, School of Electronics and Information Engineering, Hebei University of Technology, 5340 Xiping Road, Tianjin 300401, P. R. China
| | - Jiaqi Tao
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Tianjin Key Laboratory of Electronic Materials and Devices, School of Electronics and Information Engineering, Hebei University of Technology, 5340 Xiping Road, Tianjin 300401, P. R. China
| | - Hu Zhang
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Tianjin Key Laboratory of Electronic Materials and Devices, School of Electronics and Information Engineering, Hebei University of Technology, 5340 Xiping Road, Tianjin 300401, P. R. China
| | - Da Xu
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Tianjin Key Laboratory of Electronic Materials and Devices, School of Electronics and Information Engineering, Hebei University of Technology, 5340 Xiping Road, Tianjin 300401, P. R. China
| | - Jiachen Han
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Tianjin Key Laboratory of Electronic Materials and Devices, School of Electronics and Information Engineering, Hebei University of Technology, 5340 Xiping Road, Tianjin 300401, P. R. China
| | - Chao Fan
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Tianjin Key Laboratory of Electronic Materials and Devices, School of Electronics and Information Engineering, Hebei University of Technology, 5340 Xiping Road, Tianjin 300401, P. R. China
| | - Zihui Zhang
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Tianjin Key Laboratory of Electronic Materials and Devices, School of Electronics and Information Engineering, Hebei University of Technology, 5340 Xiping Road, Tianjin 300401, P. R. China
| | - Wengang Bi
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Tianjin Key Laboratory of Electronic Materials and Devices, School of Electronics and Information Engineering, Hebei University of Technology, 5340 Xiping Road, Tianjin 300401, P. R. China
| | - Chun Sun
- State Key Laboratory of Reliability and Intelligence of Electrical Equipment, Tianjin Key Laboratory of Electronic Materials and Devices, School of Electronics and Information Engineering, Hebei University of Technology, 5340 Xiping Road, Tianjin 300401, P. R. China
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10
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Harchol A, Barak Y, Hughes KE, Hartstein KH, Jöbsis HJ, Prins PT, de Mello Donegá C, Gamelin DR, Lifshitz E. Optically Detected Magnetic Resonance Spectroscopy of Cu-Doped CdSe/CdS and CuInS 2 Colloidal Quantum Dots. ACS NANO 2022; 16:12866-12877. [PMID: 35913892 DOI: 10.1021/acsnano.2c05130] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Copper-doped II-VI and copper-based I-III-VI2 colloidal quantum dots (CQDs) have been at the forefront of interest in nanocrystals over the past decade, attributable to their optically activated copper states. However, the related recombination mechanisms are still unclear. The current work elaborates on recombination processes in such materials by following the spin properties of copper-doped CdSe/CdS (Cu@CdSe/CdS) and of CuInS2 and CuInS2/(CdS, ZnS) core/shell CQDs using continuous-wave and time-resolved optically detected magnetic resonance (ODMR) spectroscopy. The Cu@CdSe/CdS ODMR showed two distinct resonances with different g factors and spin relaxation times. The best fit by a spin Hamiltonian simulation suggests that emission comes from recombination of a delocalized electron at the conduction band edge with a hole trapped in a Cu2+ site with a weak exchange coupling between the two spins. The ODMR spectra of CuInS2 CQDs (with and without shells) differ significantly from those of the copper-doped II-VI CQDs. They are comprised of a primary resonance accompanied by another resonance at half-field, with a strong correlation between the two, indicating the involvement of a triplet exciton and hence stronger electron-hole exchange coupling than in the doped core/shell CQDs. The spin Hamiltonian simulation shows that the hole is again associated with a photogenerated Cu2+ site. The electron resides near this Cu2+ site, and its ODMR spectrum shows contributions from superhyperfine coupling to neighboring indium atoms. These observations are consistent with the occurrence of a self-trapped exciton associated with the copper site. The results presented here support models under debate for over a decade and help define the magneto-optical properties of these important materials.
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Affiliation(s)
- Adi Harchol
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Yahel Barak
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Kira E Hughes
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Kimberly H Hartstein
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Huygen J Jöbsis
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3584 CC Utrecht, The Netherlands
| | - P Tim Prins
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3584 CC Utrecht, The Netherlands
| | - Celso de Mello Donegá
- Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3584 CC Utrecht, The Netherlands
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Efrat Lifshitz
- Schulich Faculty of Chemistry, Solid State Institute, Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 3200003, Israel
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11
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Yu Q, Li J, Zhang X, Yang S, Zhou P, Xia J, Deng T, Yu C. Dual-Emission ZAISe/ZnS Quantum Dots for Multi-level Bio-Imaging: Foam Cells and Atherosclerotic Plaque Imaging. J Colloid Interface Sci 2022; 629:399-408. [DOI: 10.1016/j.jcis.2022.08.134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 08/02/2022] [Accepted: 08/21/2022] [Indexed: 11/16/2022]
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12
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Perego J, Bezuidenhout CX, Villa I, Cova F, Crapanzano R, Frank I, Pagano F, Kratochwill N, Auffray E, Bracco S, Vedda A, Dujardin C, Sozzani PE, Meinardi F, Comotti A, Monguzzi A. Highly luminescent scintillating hetero-ligand MOF nanocrystals with engineered Stokes shift for photonic applications. Nat Commun 2022; 13:3504. [PMID: 35715391 PMCID: PMC9205964 DOI: 10.1038/s41467-022-31163-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 05/25/2022] [Indexed: 11/09/2022] Open
Abstract
Large Stokes shift fast emitters show a negligible reabsorption of their luminescence, a feature highly desirable for several applications such as fluorescence imaging, solar-light managing, and fabricating sensitive scintillating detectors for medical imaging and high-rate high-energy physics experiments. Here we obtain high efficiency luminescence with significant Stokes shift by exploiting fluorescent conjugated acene building blocks arranged in nanocrystals. Two ligands of equal molecular length and connectivity, yet complementary electronic properties, are co-assembled by zirconium oxy-hydroxy clusters, generating crystalline hetero-ligand metal-organic framework (MOF) nanocrystals. The diffusion of singlet excitons within the MOF and the matching of ligands absorption and emission properties enables an ultrafast activation of the low energy emission in the 100 ps time scale. The hybrid nanocrystals show a fluorescence quantum efficiency of ~60% and a Stokes shift as large as 750 meV (~6000 cm−1), which suppresses the emission reabsorption also in bulk devices. The fabricated prototypal nanocomposite fast scintillator shows benchmark performances which compete with those of some inorganic and organic commercial systems. The development of highly luminescent materials such as large Stokes shift fast emitters is desirable for their potential application in photonics. Here the authors engineer hetero-ligand metal-organic frameworks nanoparticles to achieve high emission yield, large Stokes shift and realize a prototypal fast scintillator.
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Affiliation(s)
- J Perego
- Dipartimento di Scienza dei Materiali, Università degli Studi Milano-Bicocca, via R. Cozzi 55, 20125, Milano, Italy
| | - Charl X Bezuidenhout
- Dipartimento di Scienza dei Materiali, Università degli Studi Milano-Bicocca, via R. Cozzi 55, 20125, Milano, Italy
| | - I Villa
- FZU Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - F Cova
- Dipartimento di Scienza dei Materiali, Università degli Studi Milano-Bicocca, via R. Cozzi 55, 20125, Milano, Italy
| | - R Crapanzano
- Dipartimento di Scienza dei Materiali, Università degli Studi Milano-Bicocca, via R. Cozzi 55, 20125, Milano, Italy
| | - I Frank
- CERN, Geneva, Switzerland.,Ludwig Maximilian University of Munich, Geschwister-Scholl-Platz 1, Munich, Germany
| | - F Pagano
- CERN, Geneva, Switzerland.,Dipartimento di Fisica "Giuseppe Occhialini", Università degli Studi Milano-Bicocca, Piazza della Scienza 3, 20126, Milano, Italy
| | - N Kratochwill
- CERN, Geneva, Switzerland.,University of Vienna, Vienna, Austria
| | | | - S Bracco
- Dipartimento di Scienza dei Materiali, Università degli Studi Milano-Bicocca, via R. Cozzi 55, 20125, Milano, Italy
| | - A Vedda
- Dipartimento di Scienza dei Materiali, Università degli Studi Milano-Bicocca, via R. Cozzi 55, 20125, Milano, Italy
| | - C Dujardin
- Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622, Villeurbanne cedex, France
| | - P E Sozzani
- Dipartimento di Scienza dei Materiali, Università degli Studi Milano-Bicocca, via R. Cozzi 55, 20125, Milano, Italy
| | - F Meinardi
- Dipartimento di Scienza dei Materiali, Università degli Studi Milano-Bicocca, via R. Cozzi 55, 20125, Milano, Italy
| | - A Comotti
- Dipartimento di Scienza dei Materiali, Università degli Studi Milano-Bicocca, via R. Cozzi 55, 20125, Milano, Italy.
| | - A Monguzzi
- Dipartimento di Scienza dei Materiali, Università degli Studi Milano-Bicocca, via R. Cozzi 55, 20125, Milano, Italy.
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13
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Mondal P, Viswanatha R. Insights into the Oxidation State of Cu Dopants in II-VI Semiconductor Nanocrystals. J Phys Chem Lett 2022; 13:1952-1961. [PMID: 35188398 DOI: 10.1021/acs.jpclett.1c04076] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Luminescent Cu-doped semiconductor nanocrystals have played a pivotal role in the emergence of lighting and display applications for a long time. However, consensus regarding the Cu oxidation state and hence their emission mechanism has not been attained. Distinction between seemingly simple optically and magnetically active Cu2+ and inactive Cu1+ has surprisingly been the subject matter of debate in the literature for more than a decade. In this Perspective, we first discuss the fundamental quantum mechanical phenomenon explaining the optical properties of the monovalent and divalent Cu dopants. We then focus down on various techniques used to differentiate between these two fundamental mechanisms, their benefits, and their pitfalls arising in large part because of the lack of spatial separation. Hence, to obtain a cohesive story consistent with all the observations, we discuss recent results from single-molecule spectroscopy to understand the optical properties and hence the oxidation state of internally doped Cu in doped nanocrystals.
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14
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Nishimura H, Enomoto K, Pu YJ, Kim D. Hydrothermal synthesis of water-soluble Mn- and Cu-doped CdSe quantum dots with multi-shell structures and their photoluminescence properties. RSC Adv 2022; 12:6255-6264. [PMID: 35424533 PMCID: PMC8982036 DOI: 10.1039/d1ra08491g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 02/16/2022] [Indexed: 12/03/2022] Open
Abstract
Optical properties of semiconductor quantum dots (QDs) can be tuned by doping with transition metal ions. In this study, water-soluble CdSe/ZnS:Mn/ZnS QDs with the core/shell/shell structure were synthesized through a hydrothermal method, in which the surface of the CdSe core was coated with a ZnS:Mn shell and ZnS capping shell. Herein, the CdSe core QDs were prepared first and then doped with Mn2+; therefore, the QD size and doping level could be controlled independently and interference from the self-purifying effect could be avoided. When CdSe cores with diameters less than 1.9 nm were used, Mn-related photoluminescence (PL) was observed as the main PL band, whereas the band-edge PL was mainly observed when larger CdSe cores were used. Furthermore, using ZnS:Cu as the doping shell layer, CdSe/ZnS:Cu/ZnS and ZnSe/ZnS:Cu/ZnS nanoparticles were successfully synthesized, and Cu-related PL was clearly observed. These results indicate that the core/shell/shell QD structure with doping in the shell layer is a versatile method for synthesizing doped QDs.
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Affiliation(s)
- Hisaaki Nishimura
- Department of Applied Physics, Osaka City University Osaka 558-8585 Japan
| | - Kazushi Enomoto
- RIKEN Center for Emergent Matter Science (CEMS) Saitama 351-0198 Japan
| | - Yong-Jin Pu
- RIKEN Center for Emergent Matter Science (CEMS) Saitama 351-0198 Japan
| | - DaeGwi Kim
- Department of Applied Physics, Osaka City University Osaka 558-8585 Japan
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15
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Malik P, Thareja R, Singh J, Kakkar R. II-VI core/shell quantum dots and doping with transition metal ions as a means of tuning the magnetoelectronic properties of CdS/ZnS core/shell QDs: A DFT study. J Mol Graph Model 2021; 111:108099. [PMID: 34871980 DOI: 10.1016/j.jmgm.2021.108099] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 11/14/2021] [Accepted: 11/27/2021] [Indexed: 10/19/2022]
Abstract
This paper examines the alterations in the properties of II-VI Quantum Dots (QDs) when these are coated with a shell made of another material of the same family and investigates the structural, electronic and magnetic properties of doped CdS/ZnS core/shell QDs. The core/shell QDs have been constructed by building the shell over the bare core QD and it is found that this construction of a shell over the bare QD can bring about dramatic changes in its optical properties. On changing the shell by varying either the cation or the anion, substantial variations are brought about in the band gap and electrophilicity. The trend of Fermi energies is more negative for core/shell QDs than for the QDs without a shell, and the value is almost the same for core/shell QDs with the same core. Swapping of the core and the shell materials brings greater stability in the case of shells of the wider band gap materials. Binding energy data demonstrates that the CdS/ZnS, CdSe/ZnSe, CdSe/CdS core/shell systems are more stable than ZnS/CdS, ZnSe/CdSe, CdS/CdSe core/shell systems, respectively. An augmentation in the properties is found on doping the QD with transition metal ions. The binding energies are found to be functions of the kind of dopant as well as the spin multiplicity and account for the stability of one spin state over the other at a specific site of the QD. The most fascinating property that plays a decisive role in the extant work is the introduction of magnetism in core/shell QDs as a result of the entry of unpaired electrons within the CdS/ZnS QDs on doping with transition metal ions. The deviation of the observed magnetic moments from the expected values increases as the dopant is varied from Mn2+ to Fe2+ to Co2+ to Ni2+ to Cu2+. Hirshfeld charge analysis shows that the doped ion accepts negative charge from the sulfide ions in the core, with the smallest charge transfer seen in the case of Hg2+ ions. As we move from Mn2+ to Hg2+, the trend followed for the Hirshfeld charges indicates that the overall charge on the core is lower and that on the shell is higher for all the doped cases in comparison to the undoped CdS/ZnS core/shell QD. The band gap values reveal that the Fe2+ doped CdS/ZnS core/shell structures have the smallest band gaps. Hence, we expect that this paper will help researchers to develop a strategy to produce QDs of the anticipated properties for various applications, and transition metal ions can be successfully employed for modification of various magnetoelectronic properties of the host semiconductor for future applications in nanotechnology.
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Affiliation(s)
- Pragati Malik
- Computational Chemistry Laboratory, Department of Chemistry, University of Delhi, Delhi, 110 007, India
| | - Rakhi Thareja
- Computational Chemistry Laboratory, Department of Chemistry, University of Delhi, Delhi, 110 007, India
| | - Jyoti Singh
- Computational Chemistry Laboratory, Department of Chemistry, University of Delhi, Delhi, 110 007, India
| | - Rita Kakkar
- Computational Chemistry Laboratory, Department of Chemistry, University of Delhi, Delhi, 110 007, India.
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16
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Zhao F, Hu S, Xu C, Xiao H, Zhou X, Zu X, Peng S. Effect of Copper Doping on Electronic Structure and Optical Absorption of Cd 33Se 33 Quantum Dots. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:2531. [PMID: 34684972 PMCID: PMC8538518 DOI: 10.3390/nano11102531] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 09/21/2021] [Accepted: 09/23/2021] [Indexed: 01/18/2023]
Abstract
The photophysical properties of Cu-doped CdSe quantum dots (QDs) can be affected by the oxidation state of Cu impurity, but disagreement still exists on the Cu oxidation state (+1 or +2) in these QDs, which is debated and poorly understood for many years. In this work, by using density functional theory (DFT)-based calculations with the Heyd-Scuseria-Ernzerhof (HSE) screened hybrid functional, we clearly demonstrate that the incorporation of Cu dopants into the surface of the magic sized Cd33Se33 QD leads to non-magnetic Cu 3d orbitals distribution and Cu+1 oxidation state, while doping Cu atoms in the core region of QDs can lead to both Cu+1 and Cu+2 oxidation states, depending on the local environment of Cu atoms in the QDs. In addition, it is found that the optical absorption of the Cu-doped Cd33Se33 QD in the visible region is mainly affected by Cu concentration, while the absorption in the infrared regime is closely related to the oxidation state of Cu. The present results enable us to use the doping of Cu impurity in CdSe QDs to achieve special photophysical properties for their applications in high-efficiency photovoltaic devices. The methods used here to resolve the electronic and optical properties of Cu-doped CdSe QDs can be extended to other II-VI semiconductor QDs incorporating transition-metal ions with variable valence.
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Affiliation(s)
- Fengai Zhao
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China; (F.Z.); (C.X.); (X.Z.)
| | - Shuanglin Hu
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China; (F.Z.); (C.X.); (X.Z.)
| | - Canhui Xu
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China; (F.Z.); (C.X.); (X.Z.)
| | - Haiyan Xiao
- School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, China; (H.X.); (X.Z.)
| | - Xiaosong Zhou
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China; (F.Z.); (C.X.); (X.Z.)
| | - Xiaotao Zu
- School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, China; (H.X.); (X.Z.)
| | - Shuming Peng
- Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China; (F.Z.); (C.X.); (X.Z.)
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17
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Eren GO, Sadeghi S, Shahzad M, Nizamoglu S. Protocol on synthesis and characterization of copper-doped InP/ZnSe quantum dots as ecofriendly luminescent solar concentrators with high performance and large area. STAR Protoc 2021; 2:100664. [PMID: 34308379 PMCID: PMC8283155 DOI: 10.1016/j.xpro.2021.100664] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Luminescent solar concentrators (LSCs) are simple and cost-effective solar energy-harvesting devices. Indium phosphide (InP)-based colloidal quantum dots (QDs) are promising QDs for efficient LSC devices due to their environmentally benign nature. One major challenge in LSC devices is reabsorption losses. To minimize the reabsorption, Stokes shift engineering is a critical process to designing the QD material. Here, we present a protocol that contains the preparation of structurally engineered copper-doped InP/ZnSe QDs and their LSC application. For complete details on the use and execution of this protocol, please refer to Sadeghi et al. (2020).
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Affiliation(s)
- Guncem Ozgun Eren
- Department of Biomedical Science and Engineering, Koç University, Istanbul 34450, Turkey
| | - Sadra Sadeghi
- Department of Electrical and Electronics Engineering, Koç University, Istanbul 34450, Turkey
| | - Mehwish Shahzad
- Graduate School of Material Science and Engineering, Koç University, Istanbul 34450, Turkey
| | - Sedat Nizamoglu
- Department of Biomedical Science and Engineering, Koç University, Istanbul 34450, Turkey
- Department of Electrical and Electronics Engineering, Koç University, Istanbul 34450, Turkey
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18
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Ali F, Das S, Banerjee S, Maddala BG, Rana G, Datta A. Intense photoluminescence from Cu-doped CdSe nanotetrapods triggered by ultrafast hole capture. NANOSCALE 2021; 13:14228-14235. [PMID: 34477705 DOI: 10.1039/d1nr03833h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Brightly photoluminescent Cu-doped CdSe nanotetrapods (NTPs) have been prepared by a modified hot injection method. Their photoluminescence (PL) has a quantum yield of 38% and decays slowly over a few microseconds, while the PL in undoped NTPs has a rather small quantum yield of 1.7% and decays predominantly in tens of picoseconds, with a minor component in the nanosecond time regime. PL spectra of doped NTPs are significantly Stokes shifted compared to the band edge (BE). Efficient PL quenching by a hole scavenger confirms the oxidation state of +I for the dopant ion and establishes hole capture by this ion to be the primary event that leads to the Stokes shifted PL. A fast decay of the photoinduced absorption band, along with a similar decay in PL, observed in a femtosecond optical gating experiment, yields a time constant of about a picosecond for the hole capture from the valence band (VB) by Cu+. The remarkably long PL lifetime in the doped NTPs is ascribed to the decrease in the overlap between the wavefunctions of the photogenerated electrons and the captured hole. Hot carrier relaxation processes, triggered by excitation at energies greater than the band gap, leave their signature in a rise time of few hundreds of femtoseconds, in the ground state bleach recovery kinetics. Hence, a complete picture of exciton dynamics in the doped NTPs has been obtained using ultrafast spectroscopic techniques working in tandem.
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Affiliation(s)
- Fariyad Ali
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
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19
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Carulli F, Pinchetti V, Zaffalon ML, Camellini A, Rotta Loria S, Moro F, Fanciulli M, Zavelani-Rossi M, Meinardi F, Crooker SA, Brovelli S. Optical and Magneto-Optical Properties of Donor-Bound Excitons in Vacancy-Engineered Colloidal Nanocrystals. NANO LETTERS 2021; 21:6211-6219. [PMID: 34260252 PMCID: PMC8397387 DOI: 10.1021/acs.nanolett.1c01818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/30/2021] [Indexed: 06/13/2023]
Abstract
Controlled insertion of electronic states within the band gap of semiconductor nanocrystals (NCs) is a powerful tool for tuning their physical properties. One compelling example is II-VI NCs incorporating heterovalent coinage metals in which hole capture produces acceptor-bound excitons. To date, the opposite donor-bound exciton scheme has not been realized because of the unavailability of suitable donor dopants. Here, we produce a model system for donor-bound excitons in CdSeS NCs engineered with sulfur vacancies (VS) that introduce a donor state below the conduction band (CB), resulting in long-lived intragap luminescence. VS-localized electrons are almost unaffected by trapping, and suppression of thermal quenching boosts the emission efficiency to 85%. Magneto-optical measurements indicate that the VS are not magnetically coupled to the NC bands and that the polarization properties are determined by the spin of the valence-band photohole, whose spin flip is massively slowed down due to suppressed exchange interaction with the donor-localized electron.
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Affiliation(s)
- Francesco Carulli
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | - Valerio Pinchetti
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | - Matteo L. Zaffalon
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | - Andrea Camellini
- Dipartimento
di Energia, Politecnico di Milano, IT-20133 Milano, Italy
| | | | - Fabrizio Moro
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | - Marco Fanciulli
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | | | - Francesco Meinardi
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | - Scott A. Crooker
- National
High Magnetic Field Laboratory, Los Alamos
National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Sergio Brovelli
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
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20
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Vaishanav SK, Korram J, Nagwanshi R, Karbhal I, Dewangan L, Ghosh KK, Satnami ML. Interaction of Folic Acid with Mn 2+ Doped CdTe/ZnS Quantum Dots: In Situ Detection of Folic Acid. J Fluoresc 2021; 31:951-960. [PMID: 33821436 DOI: 10.1007/s10895-021-02708-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 02/18/2021] [Indexed: 02/28/2023]
Abstract
To utilize the nanomaterials as an effective carrier for the drug delivery applications, it is important to study the interaction between nanomaterials and drug or biomolecules. In this study GSH functionalized Mn2+-doped CdTe/ZnS QDs has been utilized as a model nanomaterial due to its high luminescence property. Folic acid (FA) gradually quenches the FL of GSH functionalized Mn2+ - doped CdTe/ZnS QDs. The Stern-Volmer quenching constant (Ksv), binding constant (Ks) and effective quenching constant (Ka) for the FA-QDs system is calculated to be 1.32 × 105 M-1, 1.92 × 105 and 0.27 × 105 M-1, respectively under optimized condition (Temp. 300 K, pH 8.0, incubation time 40 min.). The effects of temperature, pH, and incubation time on FA-QDs system have also been studied. Statistical analysis of the quenched FL intensity versus FA concentration revealed a linear range from 1 × 10-7 to 5.0 × 10-5 for FA detection. The LOD of the current nano-sensor for FA was calculated to be 0.2 μM. The effect of common interfering metal ions and other relevant biomolecules on the detection of FA (12.0 μM) have also been investigated. L-cysteine and glutathione displayed moderate effect on FA detection. Similarly, the common metal ions (Na+, K+, Ca2+ and Mg2+) produced minute interference while Zn2+ Cu2+ and Fe3+ exert moderate interference. Toxic metal ions (Hg2+ and Pb2+) produced severe interferences in FA detection.Graphical abstract GSH-Mn2+ CdTe/ZnS QDs based Fluorescence Nanosensor for Folic acid.
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Affiliation(s)
- Sandeep K Vaishanav
- School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur, C.G., 492010, India
- State Forensic Science Laboratory, Police line Campus, Tikrapara, Raipur, Chhattisgarh, India
| | - Jyoti Korram
- School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur, C.G., 492010, India
| | - Rekha Nagwanshi
- Department of Chemistry, Govt. Madhav P. G. Science College, Ujjain, M. P., 456010, India
| | - Indrapal Karbhal
- School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur, C.G., 492010, India
| | - Lakshita Dewangan
- School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur, C.G., 492010, India
| | - Kallol K Ghosh
- School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur, C.G., 492010, India
| | - Manmohan L Satnami
- School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur, C.G., 492010, India.
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21
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Volnianska O. Computational studies of the electronic structure of copper-doped ZnO quantum dots. J Chem Phys 2021; 154:124710. [PMID: 33810646 DOI: 10.1063/5.0039522] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Copper-doped ZnO quantum dots (QDs) have attracted substantial interest. The electronic structure and optical and magnetic properties of Cu3+(d8)-, Cu2+(d9)-, and Cu+(d10)-doped ZnO QDs with sizes up to 1.5 nm are investigated using the GGA+U approximation, with the +U corrections applied to d (Zn), p(O), and d(Cu) orbitals. Taking +Us parameters, as optimized in previous bulk calculations, we obtain the correct band structure of ZnO QDs. Both the description of electronic structure and thermodynamic charge state transitions of Cu in ZnO QDs agree with the results of bulk calculations due to the strong localization of Cu defect energy levels. Atomic displacements around Cu are induced by strong Jahn-Teller distortion and affect Kohn-Sham energies and thermodynamic transition levels. The average bond length of Cu-O and the defect structure are crucial factors influencing the electronic properties of Cu in ZnO QDs. The analysis of the optical properties of Cu in ZnO QDs is reported. The GGA+U results, compared with the available experimental data, support Dingle's model [Phys. Rev. Lett. 23, 579 (1969)], in which the structured green luminescence observed in bulk and nanocrystals originates from the [(Cu+, hole) → Cu2+] transition. We also examine the magnetic interaction between the copper pair for two charge states: 0 and +2, and four positions relative to the center of QDs. Ferromagnetic interaction between ions is obtained for every investigated configuration. The magnitude of ferromagnetism increases for positive charge defects due to the strong hybridization of the d(Cu) and p(O) states.
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Affiliation(s)
- O Volnianska
- Institute of Physics PAS, al. Lotników 32/46, 02-668 Warsaw, Poland
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22
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Najafi A, Sharma M, Delikanli S, Bhattacharya A, Murphy JR, Pientka J, Sharma A, Quinn AP, Erdem O, Kattel S, Kelestemur Y, Kovalenko MV, Rice WD, Demir HV, Petrou A. Light-Induced Paramagnetism in Colloidal Ag +-Doped CdSe Nanoplatelets. J Phys Chem Lett 2021; 12:2892-2899. [PMID: 33724845 DOI: 10.1021/acs.jpclett.1c00398] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We describe a study of the magneto-optical properties of Ag+-doped CdSe colloidal nanoplatelets (NPLs) that were grown using a novel doping technique. In this work, we used magnetic circularly polarized luminescence and magnetic circular dichroism spectroscopy to study light-induced magnetism for the first time in 2D solution-processed structures doped with nominally nonmagnetic Ag+ impurities. The excitonic circular polarization (PX) and the exciton Zeeman splitting (ΔEZ) were recorded as a function of the magnetic field (B) and temperature (T). Both ΔEZ and PX have a Brillouin-function-like dependence on B and T, verifying the presence of paramagnetism in Ag+-doped CdSe NPLs. The observed light-induced magnetism is attributed to the transformation of nonmagnetic Ag+ ions into Ag2+, which have a nonzero magnetic moment. This work points to the possibility of incorporating these nanoplatelets into spintronic devices, in which light can be used to control the spin injection.
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Affiliation(s)
- Arman Najafi
- Department of Physics, University at Buffalo SUNY, Buffalo, New York 14260, United States
| | - Manoj Sharma
- Luminous! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639798
- Department of Electrical and Electronics Engineering and Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Savas Delikanli
- Luminous! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639798
- Department of Electrical and Electronics Engineering and Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Arinjoy Bhattacharya
- Department of Physics, University at Buffalo SUNY, Buffalo, New York 14260, United States
| | - Joseph R Murphy
- Department of Chemistry and Physics, Southeast Missouri State University, Cape Girardeau, Missouri 63701, United States
- Department of Physics and Astronomy, University of Wyoming, Laramie, Wyoming 82071, United States
| | - James Pientka
- Department of Physics, St. Bonaventure University, St. Bonaventure, New York 14778, United States
| | - Ashma Sharma
- Luminous! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639798
| | - Alexander P Quinn
- Department of Physics, University at Buffalo SUNY, Buffalo, New York 14260, United States
| | - Onur Erdem
- Department of Electrical and Electronics Engineering and Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Subash Kattel
- Department of Physics and Astronomy, University of Wyoming, Laramie, Wyoming 82071, United States
| | - Yusuf Kelestemur
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland
- Department of Metallurgical and Materials Engineering, Atilim University, Ankara 06830, Turkey
| | - Maksym V Kovalenko
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir Prelog Weg 1, CH-8093 Zürich, Switzerland
- Empa-Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland
| | - William D Rice
- Department of Physics and Astronomy, University of Wyoming, Laramie, Wyoming 82071, United States
| | - Hilmi Volkan Demir
- Luminous! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 639798
- Department of Electrical and Electronics Engineering and Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara, Turkey
| | - Athos Petrou
- Department of Physics, University at Buffalo SUNY, Buffalo, New York 14260, United States
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23
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Bhattacharyya B, Mukherjee A, Mahadevu R, Pandey A. Tuning radiative lifetimes in semiconductor quantum dots. J Chem Phys 2021; 154:074707. [PMID: 33607898 DOI: 10.1063/5.0036676] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Photonic devices stand to benefit from the development of chromophores with tunable, precisely controlled spontaneous emission lifetimes. Here, we demonstrate a method to continuously tune the radiative emission lifetimes of a class of chromophores by varying the density of electronic states involved in the emission process. In particular, we examined the peculiar composition-dependent electronic structure of copper doped CdZnSe quantum dots. It is shown that the nature and density of electronic states involved with the emission process is a function of copper inclusion level, providing a very direct handle for controlling the spontaneous lifetimes. The spontaneous emission lifetimes are estimated by examining the ratios of emission lifetimes to absolute quantum yields and also measured directly by ultrafast luminescence upconversion experiments. We find excellent agreement between these classes of experiments. This scheme enables us to tune spontaneous emission lifetimes by three orders of magnitude from ∼15 ns to over ∼7 µs, which is unprecedented in existing lumophores.
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Affiliation(s)
- Biswajit Bhattacharyya
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Arpita Mukherjee
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Rekha Mahadevu
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Anshu Pandey
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
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24
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Unique Cation Exchange in Nanocrystal Matrix via Surface Vacancy Engineering Overcoming Chemical Kinetic Energy Barriers. Chem 2020. [DOI: 10.1016/j.chempr.2020.08.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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25
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Hofman E, Khammang A, Wright JT, Li ZJ, McLaughlin PF, Davis AH, Franck JM, Chakraborty A, Meulenberg RW, Zheng W. Decoupling and Coupling of the Host-Dopant Interaction by Manipulating Dopant Movement in Core/Shell Quantum Dots. J Phys Chem Lett 2020; 11:5992-5999. [PMID: 32633980 DOI: 10.1021/acs.jpclett.0c01861] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Doping through the incorporation of transition metal ions allows for the emergence of new optical, electrical, and magnetic properties in quantum dots (QDs). While dopants can be introduced into QDs through many synthetic methods, the control of dopant location and host-dopant (H-D) coupling through directional dopant movement is still largely unexplored. In this work, we have studied dopant behaviors in Mn:CdS/ZnS core/shell QDs and found that dopant transport behavior is very sensitive to the temperature and microenvironments within the QDs. The migration of Mn toward the alloyed interface of the core/shell QDs, below a temperature boundary (Tb) at ∼200 °C, weakens the H-D interactions. At temperatures higher than the Tb, however, dopant ejection and global alloying of CdS/ZnS QDs can occur, leading to stronger H-D coupling. The behavior of incorporated dopants inside QDs is fundamentally important for understanding doping mechanisms and the host-dopant interaction-dependent properties of doped nanomaterials.
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Affiliation(s)
- Elan Hofman
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | - Alex Khammang
- Department of Physics and Astronomy and Frontier Institute for Research in Sensor Technologies, University of Maine, Orono, Maine 04469, United States
| | - Joshua T Wright
- Department of Physics, Illinois Institute of Technology, Chicago, Illinois 60616, United States
| | - Zhi-Jun Li
- 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
| | - John Mark Franck
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | - Arindam Chakraborty
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, United States
| | - Robert W Meulenberg
- Department of Physics and Astronomy and Frontier Institute for Research in Sensor Technologies, University of Maine, Orono, Maine 04469, United States
| | - Weiwei Zheng
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, United States
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26
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Mondal P, Chakraborty S, Grandhi GK, Viswanatha R. Copper Doping in II-VI Semiconductor Nanocrystals: Single-Particle Fluorescence Study. J Phys Chem Lett 2020; 11:5367-5372. [PMID: 32522003 DOI: 10.1021/acs.jpclett.0c01570] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Copper doping in II-VI semiconductor nanocrystals (NCs) has sparked enormous debate regarding the oxidation state of Cu ions and their hugely differing consequences in optoelectronic applications. The identity of a magnetically active Cu2+ ion or a magnetically inactive d10 Cu+ ion has generally been probed using optical techniques, and confusion arises from the spatial clutter that is part of the technique. One major probe that could declutter the data obtained from ensemble emission is single-particle fluorescence spectroscopy. In this work, using this very technique along with X-ray absorption spectroscopy probing the local environment of dopant ions, we study Cu-doped II-VI semiconductor NCs to find conclusive evidence on the oxidation state of Cu dopants and hence the mechanism of their emission. Detailed analysis of blinking properties has been used to study the single-particle nature of the NCs.
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27
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Mrad R, Poggi M, Ben Chaâbane R, Negrerie M. Role of surface defects in colloidal cadmium selenide (CdSe) nanocrystals in the specificity of fluorescence quenching by metal cations. J Colloid Interface Sci 2020; 571:368-377. [DOI: 10.1016/j.jcis.2020.03.058] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 03/11/2020] [Accepted: 03/16/2020] [Indexed: 12/27/2022]
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28
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Luo D, Wang L, Qiu Y, Huang R, Liu B. Emergence of Impurity-Doped Nanocrystal Light-Emitting Diodes. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E1226. [PMID: 32599722 PMCID: PMC7353084 DOI: 10.3390/nano10061226] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/17/2020] [Accepted: 06/17/2020] [Indexed: 11/16/2022]
Abstract
In recent years, impurity-doped nanocrystal light-emitting diodes (LEDs) have aroused both academic and industrial interest since they are highly promising to satisfy the increasing demand of display, lighting, and signaling technologies. Compared with undoped counterparts, impurity-doped nanocrystal LEDs have been demonstrated to possess many extraordinary characteristics including enhanced efficiency, increased luminance, reduced voltage, and prolonged stability. In this review, recent state-of-the-art concepts to achieve high-performance impurity-doped nanocrystal LEDs are summarized. Firstly, the fundamental concepts of impurity-doped nanocrystal LEDs are presented. Then, the strategies to enhance the performance of impurity-doped nanocrystal LEDs via both material design and device engineering are introduced. In particular, the emergence of three types of impurity-doped nanocrystal LEDs is comprehensively highlighted, namely impurity-doped colloidal quantum dot LEDs, impurity-doped perovskite LEDs, and impurity-doped colloidal quantum well LEDs. At last, the challenges and the opportunities to further improve the performance of impurity-doped nanocrystal LEDs are described.
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Affiliation(s)
- Dongxiang Luo
- Institute of Semiconductors, South China Normal University, Guangzhou 510631, China;
| | - Lin Wang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore;
| | - Ying Qiu
- Guangdong R&D Center for Technological Economy, Guangzhou 510000, China
| | - Runda Huang
- School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, China;
| | - Baiquan Liu
- State Key Laboratory of Optoelectronic Materials and Technologies and the Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
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29
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Sadeghi S, Bahmani Jalali H, Srivastava SB, Melikov R, Baylam I, Sennaroglu A, Nizamoglu S. High-Performance, Large-Area, and Ecofriendly Luminescent Solar Concentrators Using Copper-Doped InP Quantum Dots. iScience 2020; 23:101272. [PMID: 32590328 PMCID: PMC7322176 DOI: 10.1016/j.isci.2020.101272] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 06/02/2020] [Accepted: 06/09/2020] [Indexed: 02/01/2023] Open
Abstract
Colloidal quantum dots (QDs) are promising building blocks for luminescent solar concentrators (LSCs). For their widespread use, they need to simultaneously satisfy non-toxic material content, low reabsorption, high photoluminescence quantum yield, and large-scale production. Here, copper doping of zinc carboxylate-passivated InP core and nano-engineering of ZnSe shell facilitated high in-device quantum efficiency of QDs over 80%, having well-matched spectral emission profile with the photo-response of silicon solar cells. The optimized QD-LSCs showed an optical quantum efficiency of 37% and an internal concentration factor of 4.7 for a 10 × 10-cm2 device area under solar illumination, which is comparable with the state-of-the-art LSCs based on cadmium-containing QDs and lead-containing perovskites. Synthesis of the copper-doped InP/ZnSe QDs in gram-scale and large-area deposition (3,000 cm2) onto commercial window glasses via doctor-blade technique showed their scalability for mass production. These results position InP-based QDs as a promising alternative for efficient solar energy harvesting. The luminescent solar concentrators based on copper-doped InP QDs are demonstrated Efficient excitation transfer led to the exceptionally high in-film PLQY of 81.2% The LSCs based on copper-doped QDs showed the optical quantum efficiency of 37% The gram-scale synthesis of QDs led to the fabrication of large-area LSCs (3,000 cm2)
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Affiliation(s)
- Sadra Sadeghi
- Graduate School of Materials Science and Engineering, Koç University, Istanbul 34450, Turkey
| | - Houman Bahmani Jalali
- Department of Biomedical Sciences and Engineering, Koç University, Istanbul 34450, Turkey
| | | | - Rustamzhon Melikov
- Department of Electrical and Electronics Engineering, Koç University, Istanbul 34450, Turkey
| | - Isinsu Baylam
- Koç University Surface Science and Technology Center (KUYTAM), Koç University, Istanbul 34450, Turkey
| | - Alphan Sennaroglu
- Koç University Surface Science and Technology Center (KUYTAM), Koç University, Istanbul 34450, Turkey; Laser Research Laboratory, Departments of Physics and Electrical-Electronics Engineering, Koç University, Istanbul 34450, Turkey
| | - Sedat Nizamoglu
- Graduate School of Materials Science and Engineering, Koç University, Istanbul 34450, Turkey; Department of Biomedical Sciences and Engineering, Koç University, Istanbul 34450, Turkey; Department of Electrical and Electronics Engineering, Koç University, Istanbul 34450, Turkey.
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30
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Yadav AN, Singh AK, Chauhan D, Solanki PR, Kumar P, Singh K. Evaluation of dopant energy and Stokes shift in Cu-doped CdS quantum dots via spectro-electrochemical probing. NEW J CHEM 2020. [DOI: 10.1039/d0nj03004j] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Copper (Cu) doped II–VI semiconductor quantum dots (QDs) manifest high luminescent dopant emission with excellent tunability.
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Affiliation(s)
- Amar Nath Yadav
- School of Physical Sciences
- Jawaharlal Nehru University
- New Delhi-110067
- India
| | | | - Deepika Chauhan
- Special Centre for Nanoscience
- Jawaharlal Nehru University
- New Delhi-110067
- India
| | - Pratima R. Solanki
- Special Centre for Nanoscience
- Jawaharlal Nehru University
- New Delhi-110067
- India
| | | | - Kedar Singh
- School of Physical Sciences
- Jawaharlal Nehru University
- New Delhi-110067
- India
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31
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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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32
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Observation of a phonon bottleneck in copper-doped colloidal quantum dots. Nat Commun 2019; 10:4532. [PMID: 31586066 PMCID: PMC6778069 DOI: 10.1038/s41467-019-12558-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Accepted: 09/18/2019] [Indexed: 11/09/2022] Open
Abstract
Hot electrons can dramatically improve the efficiency of solar cells and sensitize energetically-demanding photochemical reactions. Efficient hot electron devices have been hindered by sub-picosecond intraband cooling of hot electrons in typical semiconductors via electron-phonon scattering. Semiconductor quantum dots were predicted to exhibit a “phonon bottleneck” for hot electron relaxation as their quantum-confined electrons would couple very inefficiently to phonons. However, typical cadmium selenide dots still exhibit sub-picosecond hot electron cooling, bypassing the phonon bottleneck possibly via an Auger-like process whereby the excessive energy of the hot electron is transferred to the hole. Here we demonstrate this cooling mechanism can be suppressed in copper-doped cadmium selenide colloidal quantum dots due to femtosecond hole capturing by copper-dopants. As a result, we observe a lifetime of ~8.6 picosecond for 1Pe hot electrons which is more than 30-fold longer than that in same-sized, undoped dots (~0.25 picosecond). Weak electron-phonon scattering that can enable long-lived hot electrons in semiconductors is of interest in hot carrier solar cells. Here, the authors report copper-doped colloidal cadmium-selenide quantum dots with hot electron lifetime extended by more than 30-fold compared to undoped dots.
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33
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Li C, Wu P. Cu-doped quantum dots: a new class of near-infrared emitting fluorophores for bioanalysis and bioimaging. LUMINESCENCE 2019; 34:782-789. [PMID: 31297953 DOI: 10.1002/bio.3679] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 06/07/2019] [Accepted: 06/13/2019] [Indexed: 01/25/2023]
Abstract
Transition metal ion-doped quantum dots (QDs) exhibit unique optical and photophysical properties that offer significant advantages over undoped QDs, such as larger Stokes shift to avoid self-absorption/energy transfer, longer excited-state lifetimes, wider spectral window, and improved chemical and thermal stability. Among the doped QDs emitters, Cu is widely introduced into the doped QDs as novel, efficient, stable, and tunable optical materials that span a wide spectrum from blue to near-infrared (NIR) light. Their unique physical and chemical characteristics enable the use of Cu-doped QDs as NIR labels for bioanalysis and bioimaging. In this review, we discuss doping mechanisms and optical properties of Cu-doped QDs that are capable of NIR emission. Applications of Cu-doped QDs in in vitro biosensing and in in vivo bioimaging are highlighted. Moreover, a prospect of the future of Cu-doped QDs for bioanalysis and bioimaging are also summarized.
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Affiliation(s)
- Chenghui Li
- Analytical & Testing Centre, Sichuan University, Chengdu, China
| | - Peng Wu
- Analytical & Testing Centre, Sichuan University, Chengdu, China
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34
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Lim M, Lee W, Bang G, Lee WJ, Park Y, Kwon Y, Jung Y, Kim S, Bang J. Synthesis of far-red- and near-infrared-emitting Cu-doped InP/ZnS (core/shell) quantum dots with controlled doping steps and their surface functionalization for bioconjugation. NANOSCALE 2019; 11:10463-10471. [PMID: 31112192 DOI: 10.1039/c9nr02192b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
In this study, we designed and synthesized far-red- and near-infrared-emitting Cu-doped InP-based quantum dots (QDs), and we also demonstrated their highly specific and sensitive biological imaging ability. Cu-doped InP/ZnS (core/shell) QDs were prepared using the hot colloidal synthesis method in the organic phase. The ZnS shell passivates the surface and improves the photoluminescence (PL) intensity. However, the InP : Cu/ZnS (core : dopants/shell) QDs, which were obtained after the Cu dopant was incorporated into bare InP QDs, followed by ZnS shell coating, had relatively low PL intensities (maximum PL quantum yield (QY) was only ∼16%) presumably due to the formation of defect sites in the InP-core QDs caused by dopant migration from the InP core to the ZnS shell. We prepared high-quality InP/ZnS : Cu/ZnS (core/shell : dopant/outer-shell) QDs, where thin ZnS shell layers were grown on bare InP QDs prior to Cu ion doping to prevent dopant migration and obtained PL QYs as high as 40%. The native hydrophobic ligands of the as-synthesized Cu-doped QDs were replaced with hydrophilic ligands including dihydrolipoic acid and a zwitterionic ligand, which rendered the QDs water-soluble. These QDs exhibited remarkable colloidal stabilities over a wide pH range, with hydrodynamic diameters less than 10 nm. Modified QD surfaces can also be used in conjugation with other functional moieties to apply highly specific and sensitive imaging probes with very low background levels. As a proof-of-concept study, we successfully demonstrated the selective imaging of streptavidin beads with biotin-conjugated QDs. These decorated Cu-doped InP/ZnS (core/shell) QDs are promising biological-probe candidates for imaging and assaying with reduced concerns regarding toxicity.
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Affiliation(s)
- Mihye Lim
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Namgu, Pohang 37673, Republic of Korea.
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35
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Berends AC, Mangnus MJJ, Xia C, Rabouw FT, de Mello Donega C. Optoelectronic Properties of Ternary I-III-VI 2 Semiconductor Nanocrystals: Bright Prospects with Elusive Origins. J Phys Chem Lett 2019; 10:1600-1616. [PMID: 30883139 PMCID: PMC6452418 DOI: 10.1021/acs.jpclett.8b03653] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Colloidal nanocrystals of ternary I-III-VI2 semiconductors are emerging as promising alternatives to Cd- and Pb-chalcogenide nanocrystals because of their inherently lower toxicity, while still offering widely tunable photoluminescence. These properties make them promising materials for a variety of applications. However, the realization of their full potential has been hindered by both their underdeveloped synthesis and the poor understanding of their optoelectronic properties, whose origins are still under intense debate. In this Perspective, we provide novel insights on the latter aspect by critically discussing the accumulated body of knowledge on I-III-VI2 nanocrystals. From our analysis, we conclude that the luminescence in these nanomaterials most likely originates from the radiative recombination of a delocalized conduction band electron with a hole localized at the group-I cation, which results in broad bandwidths, large Stokes shifts, and long exciton lifetimes. Finally, we highlight the remaining open questions and propose experiments to address them.
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36
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Capitani C, Pinchetti V, Gariano G, Santiago-González B, Santambrogio C, Campione M, Prato M, Brescia R, Camellini A, Bellato F, Carulli F, Anand A, Zavelani-Rossi M, Meinardi F, Crooker SA, Brovelli S. Quantized Electronic Doping towards Atomically Controlled "Charge-Engineered" Semiconductor Nanocrystals. NANO LETTERS 2019; 19:1307-1317. [PMID: 30663314 DOI: 10.1021/acs.nanolett.8b04904] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
"Charge engineering" of semiconductor nanocrystals (NCs) through so-called electronic impurity doping is a long-standing challenge in colloidal chemistry and holds promise for ground-breaking advancements in many optoelectronic, photonic, and spin-based nanotechnologies. To date, our knowledge is limited to a few paradigmatic studies on a small number of model compounds and doping conditions, with important electronic dopants still unexplored in nanoscale systems. Equally importantly, fine-tuning of charge engineered NCs is hampered by the statistical limitations of traditional approaches. The resulting intrinsic doping inhomogeneity restricts fundamental studies to statistically averaged behaviors and complicates the realization of advanced device concepts based on their advantageous functionalities. Here we aim to address these issues by realizing the first example of II-VI NCs electronically doped with an exact number of heterovalent gold atoms, a known p-type acceptor impurity in bulk chalcogenides. Single-dopant accuracy across entire NC ensembles is obtained through a novel non-injection synthesis employing ligand-exchanged gold clusters as "quantized" dopant sources to seed the nucleation of CdSe NCs in organic media. Structural, spectroscopic, and magneto-optical investigations trace a comprehensive picture of the physical processes resulting from the exact doping level of the NCs. Gold atoms, doped here for the first time into II-VI NCs, are found to incorporate as nonmagnetic Au+ species activating intense size-tunable intragap photoluminescence and artificially offsetting the hole occupancy of valence band states. Fundamentally, the transient conversion of Au+ to paramagnetic Au2+ (5d9 configuration) under optical excitation results in strong photoinduced magnetism and diluted magnetic semiconductor behavior revealing the contribution of individual paramagnetic impurities to the macroscopic magnetism of the NCs. Altogether, our results demonstrate a new chemical approach toward NCs with physical functionalities tailored to the single impurity level and offer a versatile platform for future investigations and device exploitation of individual and collective impurity processes in quantum confined structures.
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Affiliation(s)
- Chiara Capitani
- Glass to Power SpA, Via Fortunato Zeni 8 , I-38068 Rovereto, , Italy
| | | | - Graziella Gariano
- Glass to Power SpA, Via Fortunato Zeni 8 , I-38068 Rovereto, , Italy
| | - Beatriz Santiago-González
- International Iberian Nanotechnology Laboratory, Nanophotonics Department , Ultrafast Bio- and Nanophotonics Group , Avenida Mestre José Veiga s/n , 4715-330 Braga , Portugal
| | - Carlo Santambrogio
- Dipartimento di Biotecnologie e Bioscienze , Università degli Studi di Milano-Bicocca , Piazza della Scienza 2 , I-20126 Milano , Italy
| | | | - Mirko Prato
- Istituto Italiano di Tecnologia , Via Morego 30 , 16163 Genova , Italy
| | - Rosaria Brescia
- Istituto Italiano di Tecnologia , Via Morego 30 , 16163 Genova , Italy
| | - Andrea Camellini
- Dipartimento di Energia , Politecnico di Milano and IFN-CNR , Milano , Italy
| | | | | | | | | | | | - Scott A Crooker
- National High Magnetic Field Laboratory , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
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Dou J, Zhang Y, Wang Q, Abate A, Li Y, Wei M. Highly efficient Zn2SnO4 perovskite solar cells through band alignment engineering. Chem Commun (Camb) 2019; 55:14673-14676. [DOI: 10.1039/c9cc07398a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The fine-tuning of the halide ratio in a mixed cation mixed halide perovskite leads to a device with a PCE of 20.26%.
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Affiliation(s)
- Jie Dou
- Fujian Provincial Key Laboratory of Electrochemcial Energy Storage Materials
- Fuzhou University
- Fuzhou
- China
- State Key Laboratory of Photocatalysis on Energy and Environment
| | - Ying Zhang
- Fujian Provincial Key Laboratory of Electrochemcial Energy Storage Materials
- Fuzhou University
- Fuzhou
- China
- State Key Laboratory of Photocatalysis on Energy and Environment
| | - Qiong Wang
- Helmholtz-Zentrum Berlin fur Materialien und Energie
- Berlin I 12489
- Germany
| | - Antonio Abate
- Fujian Provincial Key Laboratory of Electrochemcial Energy Storage Materials
- Fuzhou University
- Fuzhou
- China
- Helmholtz-Zentrum Berlin fur Materialien und Energie
| | - Yafeng Li
- Fujian Provincial Key Laboratory of Electrochemcial Energy Storage Materials
- Fuzhou University
- Fuzhou
- China
- State Key Laboratory of Photocatalysis on Energy and Environment
| | - Mingdeng Wei
- Fujian Provincial Key Laboratory of Electrochemcial Energy Storage Materials
- Fuzhou University
- Fuzhou
- China
- State Key Laboratory of Photocatalysis on Energy and Environment
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38
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Pandey N, Kumar A, Chakrabarti S. Investigation of the structural, electronic, and optical properties of Mn-doped CsPbCl3: theory and experiment. RSC Adv 2019; 9:29556-29565. [PMID: 35531544 PMCID: PMC9071989 DOI: 10.1039/c9ra05685h] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 09/02/2019] [Indexed: 11/21/2022] Open
Abstract
Wide energy gap inorganic halide perovskites have become emerging candidates for potential applications in modern optoelectronics devices.
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Affiliation(s)
- Nivedita Pandey
- Department of Electrical Engineering
- Indian Institute of Technology Bombay
- India-400076
| | - Abhishek Kumar
- Department of Electrical Engineering
- Indian Institute of Technology Bombay
- India-400076
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39
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Ghaemi B, Shaabani E, Najafi-Taher R, Jafari Nodooshan S, Sadeghpour A, Kharrazi S, Amani A. Intracellular ROS Induction by Ag@ZnO Core-Shell Nanoparticles: Frontiers of Permanent Optically Active Holes in Breast Cancer Theranostic. ACS APPLIED MATERIALS & INTERFACES 2018; 10:24370-24381. [PMID: 29932633 DOI: 10.1021/acsami.8b03822] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In this study, we investigated whether ZnO coating on Ag nanoparticles (NPs) tunes electron flux and hole figuration at the metal-semiconductor interface under UV radiation. This effect triggers the photoactivity and generation of reactive oxygen species from Ag@ZnO NPs, which results in enhanced cytotoxic effects and apoptotic cell death in human breast cancer cells (MDA-MB231). In this context, upregulation of apoptotic cascade proteins (i.e., Bax/Bcl2 association, p53, cytochrome c, and caspase-3) along with activation of oxidative stress proteins suggested the occurrence of apoptosis by Ag@ZnO NPs in cancer cells through the mitochondrial pathway. Also, preincubation of breast cancer cells with Ag@ZnO NPs in dark conditions muted NP-related toxic effects and consequent apoptotic fate, highlighting biocompatible properties of unexcited Ag@ZnO NPs. Furthermore, the diagnostic efficacy of Ag@ZnO NPs as computed tomography (CT)/optical nanoprobes was investigated. Results confirmed the efficacy of the photoactivated system in obtaining desirable outcomes from CT/optical imaging, which represents novel theranostic NPs for simultaneous imaging and treatment of cancer.
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Affiliation(s)
| | | | | | | | - Amin Sadeghpour
- Centre for X-Ray Analytics, Department of Material Meet Life , Swiss Federal Laboratories for Material Science and Technology (Empa) , 9014 St. Gallen , Switzerland
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40
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Sadeghi S, Bahmani Jalali H, Melikov R, Ganesh Kumar B, Mohammadi Aria M, Ow-Yang CW, Nizamoglu S. Stokes-Shift-Engineered Indium Phosphide Quantum Dots for Efficient Luminescent Solar Concentrators. ACS APPLIED MATERIALS & INTERFACES 2018; 10:12975-12982. [PMID: 29589740 PMCID: PMC5997383 DOI: 10.1021/acsami.7b19144] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Luminescent solar concentrators (LSCs) show promise because of their potential for low-cost, large-area, and high-efficiency energy harvesting. Stokes shift engineering of luminescent quantum dots (QDs) is a favorable approach to suppress reabsorption losses in LSCs; however, the use of highly toxic heavy metals in QDs constitutes a serious concern for environmental sustainability. Here, we report LSCs based on cadmium-free InP/ZnO core/shell QDs with type-II band alignment that allow for the suppression of reabsorption by Stokes shift engineering. The spectral emission and absorption overlap was controlled by the growth of a ZnO shell on an InP core. At the same time, the ZnO layer also facilitates the photostability of the QDs within the host matrix. We analyzed the optical performance of indium-based LSCs and identified the optical efficiency as 1.45%. The transparency, flexibility, and cadmium-free content of the LSCs hold promise for solar window applications.
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Affiliation(s)
- Sadra Sadeghi
- Graduate
School of Materials Science and Engineering, Department of Biomedical
Sciences and Engineering, and Department of Electrical and Electronics Engineering, Koç University, Istanbul 34450, Turkey
| | - Houman Bahmani Jalali
- Graduate
School of Materials Science and Engineering, Department of Biomedical
Sciences and Engineering, and Department of Electrical and Electronics Engineering, Koç University, Istanbul 34450, Turkey
| | - Rustamzhon Melikov
- Graduate
School of Materials Science and Engineering, Department of Biomedical
Sciences and Engineering, and Department of Electrical and Electronics Engineering, Koç University, Istanbul 34450, Turkey
| | - Baskaran Ganesh Kumar
- Graduate
School of Materials Science and Engineering, Department of Biomedical
Sciences and Engineering, and Department of Electrical and Electronics Engineering, Koç University, Istanbul 34450, Turkey
| | - Mohammad Mohammadi Aria
- Graduate
School of Materials Science and Engineering, Department of Biomedical
Sciences and Engineering, and Department of Electrical and Electronics Engineering, Koç University, Istanbul 34450, Turkey
| | - Cleva W. Ow-Yang
- Department
of Engineering and Natural Sciences, Sabanci
University, Istanbul 34956, Turkey
| | - Sedat Nizamoglu
- Graduate
School of Materials Science and Engineering, Department of Biomedical
Sciences and Engineering, and Department of Electrical and Electronics Engineering, Koç University, Istanbul 34450, Turkey
- E-mail:
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41
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Bhattacharyya B, Gahlot K, Viswanatha R, Pandey A. Optical Signatures of Impurity-Impurity Interactions in Copper Containing II-VI Alloy Semiconductors. J Phys Chem Lett 2018; 9:635-640. [PMID: 29337575 DOI: 10.1021/acs.jpclett.7b03087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We study the optical properties of copper containing II-VI alloy quantum dots (CuxZnyCd1-x-ySe). Copper mole fractions within the host are varied from 0.001 to 0.35. No impurity phases are observed over this composition range, and the formation of secondary phases of copper selenide are observed only at xCu > 0.45. The optical absorption and emission spectra of these materials are observed to be a strong function of xCu, and provide information regarding composition induced impurity-impurity interactions. In particular, the integrated cross section of optical absorption per copper atom changes sharply (from 1 × 10 -2 nm3 to 4 × 10 -2 nm3) at xCu = 0.12, suggesting a composition induced change in local electronic structure. These materials may serve as model systems to understand the electronic structure of I-III-VI2 semiconductor compounds.
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Affiliation(s)
- Biswajit Bhattacharyya
- Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore-560012, India
| | - Kushagra Gahlot
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore-560064, India
| | - Ranjani Viswanatha
- New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore-560064, India
- International Centre for Materials Science, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, Bangalore-560064, India
| | - Anshu Pandey
- Solid State and Structural Chemistry Unit, Indian Institute of Science , Bangalore-560012, India
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42
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Pinchetti V, Di Q, Lorenzon M, Camellini A, Fasoli M, Zavelani-Rossi M, Meinardi F, Zhang J, Crooker SA, Brovelli S. Excitonic pathway to photoinduced magnetism in colloidal nanocrystals with nonmagnetic dopants. NATURE NANOTECHNOLOGY 2018; 13:145-151. [PMID: 29255289 DOI: 10.1038/s41565-017-0024-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 11/03/2017] [Indexed: 06/07/2023]
Abstract
Electronic doping of colloidal semiconductor nanostructures holds promise for future device concepts in optoelectronic and spin-based technologies. Ag+ is an emerging electronic dopant in III-V and II-VI nanostructures, introducing intragap electronic states optically coupled to the host conduction band. With its full 4d shell Ag+ is nonmagnetic, and the dopant-related luminescence is ascribed to decay of the conduction-band electron following transfer of the photoexcited hole to Ag+. This optical activation process and the associated modification of the electronic configuration of Ag+ remain unclear. Here, we trace a comprehensive picture of the excitonic process in Ag-doped CdSe nanocrystals and demonstrate that, in contrast to expectations, capture of the photohole leads to conversion of Ag+ to paramagnetic Ag2+. The process of exciton recombination is thus inextricably tied to photoinduced magnetism. Accordingly, we observe strong optically activated magnetism and diluted magnetic semiconductor behaviour, demonstrating that optically switchable magnetic nanomaterials can be obtained by exploiting excitonic processes involving nonmagnetic impurities.
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Affiliation(s)
- Valerio Pinchetti
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca, Milano, Italy
| | - Qiumei Di
- Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications, School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, China
| | - Monica Lorenzon
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca, Milano, Italy
| | | | - Mauro Fasoli
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca, Milano, Italy
| | | | - Francesco Meinardi
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca, Milano, Italy
| | - Jiatao Zhang
- Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications, School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, China.
| | - Scott A Crooker
- National High Magnetic Field Laboratory, Los Alamos, NM, USA
| | - Sergio Brovelli
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca, Milano, Italy.
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43
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Mahadevu R, Pandey A. Thermodynamic Model for Quantum Dot Assemblies Formed Because of Charge Transfer. ACS OMEGA 2018; 3:266-272. [PMID: 31457892 PMCID: PMC6641234 DOI: 10.1021/acsomega.7b01486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 12/25/2017] [Indexed: 06/10/2023]
Abstract
Two initially neutral semiconductor quantum dots with appropriate band offsets can participate in a ground state charge transfer process. The charge transfer manifests itself in the form of bleaching of optical transitions and also causes the quantum dots to precipitate from solution, giving rise to assemblies with unusual properties. As this represents a postsynthetic modification of the electronic structure of quantum dots, it holds tremendous potential for improving the characteristics of quantum dot devices. Here, we study the dependencies of the properties of these assemblies on the structure of the participating quantum dots. In particular, we find that for assemblies formed out of Cu:CdS and ZnTe/CdS quantum dots, the composition of the assembly varies from 1:1.26 to 1:0.23 ZnTe/CdS to Cu:CdS as the shell thickness of CdS in ZnTe/CdS is increased. In contrast, the composition changes from 1:1.1 to 1:15 for PbSe/CdSe and Cu:CdS quantum dots, as the size of the PbSe core is increased. These observations are explained on the basis of a phenomenological thermodynamic model. The applicability of thermodynamics to this example of self-assembly is verified empirically.
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44
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Hughes KE, Hartstein KH, Gamelin DR. Photodoping and Transient Spectroscopies of Copper-Doped CdSe/CdS Nanocrystals. ACS NANO 2018; 12:718-728. [PMID: 29286633 DOI: 10.1021/acsnano.7b07879] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Colloidal Cu+-doped CdSe/CdS core/shell semiconductor nanocrystals (NCs) are investigated in their as-prepared and degenerately n-doped forms using time-resolved photoluminescence and transient-absorption spectroscopies. Photoluminescence from Cu+:CdSe/CdS NCs is dominated by recombination of delocalized conduction-band (CB) electrons with copper-localized holes. In addition to prominent bleaching of the first excitonic absorption feature, transient-absorption measurements show bleaching of the sub-bandgap copper-to-CB charge-transfer (MLCBCT) absorption band and also reveal a photoinduced midgap valence-band (VB)-to-copper charge-transfer (LVBMCT) absorption band that extends into the near-infrared, as predicted by recent computations. The photoluminescence of these NCs is substantially diminished upon introduction of excess CB electrons via photodoping. Time-resolved photoluminescence measurements reveal that the MLCBCT excited state is still formed upon photoexcitation of the n-doped Cu+:CdSe/CdS NCs, but its luminescence is quenched by a fast (picosecond) three-carrier trap-assisted Auger recombination process involving two CB electrons and one copper-bound hole.
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Affiliation(s)
- Kira E Hughes
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Kimberly H Hartstein
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
| | - Daniel R Gamelin
- Department of Chemistry, University of Washington , Seattle, Washington 98195-1700, United States
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45
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Geiregat P, Houtepen AJ, Sagar LK, Infante I, Zapata F, Grigel V, Allan G, Delerue C, Van Thourhout D, Hens Z. Continuous-wave infrared optical gain and amplified spontaneous emission at ultralow threshold by colloidal HgTe quantum dots. NATURE MATERIALS 2018; 17:35-42. [PMID: 29035357 DOI: 10.1038/nmat5000] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 09/01/2017] [Indexed: 05/20/2023]
Abstract
Colloidal quantum dots (QDs) raise more and more interest as solution-processable and tunable optical gain materials. However, especially for infrared active QDs, optical gain remains inefficient. Since stimulated emission involves multifold degenerate band-edge states, population inversion can be attained only at high pump power and must compete with efficient multi-exciton recombination. Here, we show that mercury telluride (HgTe) QDs exhibit size-tunable stimulated emission throughout the near-infrared telecom window at thresholds unmatched by any QD studied before. We attribute this unique behaviour to surface-localized states in the bandgap that turn HgTe QDs into 4-level systems. The resulting long-lived population inversion induces amplified spontaneous emission under continuous-wave optical pumping at power levels compatible with solar irradiation and direct current electrical pumping. These results introduce an alternative approach for low-threshold QD-based gain media based on intentional trap states that paves the way for solution-processed infrared QD lasers and amplifiers.
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Affiliation(s)
- Pieter Geiregat
- Physics and Chemistry of Nanostructures group, Ghent University, B-9000 Gent, Belgium
- Photonics Research Group, Ghent University, B-9000 Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, B-9000 Gent, Belgium
| | - Arjan J Houtepen
- Physics and Chemistry of Nanostructures group, Ghent University, B-9000 Gent, Belgium
- Opto-Electronic Materials Section, Delft University of Technology, 2628 BL Delft, the Netherlands
| | - Laxmi Kishore Sagar
- Physics and Chemistry of Nanostructures group, Ghent University, B-9000 Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, B-9000 Gent, Belgium
| | - Ivan Infante
- Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling (ACMM), VU University Amsterdam, 1081 HV Amsterdam, the Netherlands
| | - Felipe Zapata
- Department of Theoretical Chemistry and Amsterdam Center for Multiscale Modeling (ACMM), VU University Amsterdam, 1081 HV Amsterdam, the Netherlands
| | - Valeriia Grigel
- Physics and Chemistry of Nanostructures group, Ghent University, B-9000 Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, B-9000 Gent, Belgium
| | - Guy Allan
- IEMN, Département Institut Supérieur d'Electronique et du Numérique, UMR CNRS, 8520 Lille, France
| | - Christophe Delerue
- IEMN, Département Institut Supérieur d'Electronique et du Numérique, UMR CNRS, 8520 Lille, France
| | - Dries Van Thourhout
- Photonics Research Group, Ghent University, B-9000 Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, B-9000 Gent, Belgium
| | - Zeger Hens
- Physics and Chemistry of Nanostructures group, Ghent University, B-9000 Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, B-9000 Gent, Belgium
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46
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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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47
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Choi D, Pyo JY, Jang DJ. Impurity Location-Dependent Relaxation Dynamics of Cu:CdS Quantum Dots. NANOSCALE RESEARCH LETTERS 2017; 12:49. [PMID: 28101854 PMCID: PMC5241571 DOI: 10.1186/s11671-017-1832-3] [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: 05/27/2016] [Accepted: 01/03/2017] [Indexed: 06/06/2023]
Abstract
Various types of 2% Cu-incorporated CdS (Cu:CdS) quantum dots (QDs) with very similar sizes have been prepared via a water soluble colloidal method. The locations of Cu impurities in CdS host nanocrystals have been controlled by adopting three different synthetic ways of doping, exchange, and adsorption to understand the impurity location-dependent relaxation dynamics of charge carriers. The oxidation state of incorporated Cu impurities has been found to be +1 and the band-gap energy of Cu:CdS QDs decreases as Cu2S forms at the surfaces of CdS QDs. Broad and red-shifted emission with a large Stokes shift has been observed for Cu:CdS QDs as newly produced Cu-related defects become luminescent centers. The energetically favored hole trapping of thiol molecules, as well as the local environment, inhibits the radiative recombination processes of Cu:CdS QDs, thus resulting in low photoluminescence. Upon excitation, an electron is promoted to the conduction band, leaving a hole on the valence band. The hole is transferred to the Cu+ d-state, changing Cu+ into Cu2+, which then participates in radiative recombination with an electron. Electrons in the conduction band are ensnared into shallow-trap sites within 52 ns. The electrons can be further captured on the time scale of 260 ns into deep-trap sites, where electrons recombine with holes in 820 ns. Our in-depth analysis of carrier relaxation has shown that the possibilities of both nonradiative recombination and energy transfer to Cu impurities become high when Cu ions are located at the surface of CdS QDs.
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Affiliation(s)
- Dayeon Choi
- Department of Chemistry, Seoul National University, NS60, Seoul, 08826 Republic of Korea
| | - Ji-Young Pyo
- Department of Chemistry, Seoul National University, NS60, Seoul, 08826 Republic of Korea
| | - Du-Jeon Jang
- Department of Chemistry, Seoul National University, NS60, Seoul, 08826 Republic of Korea
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48
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Hassan A, Zhang X, Liu X, Rowland CE, Jawaid AM, Chattopadhyay S, Gulec A, Shamirian A, Zuo X, Klie RF, Schaller RD, Snee PT. Charge Carriers Modulate the Bonding of Semiconductor Nanoparticle Dopants As Revealed by Time-Resolved X-ray Spectroscopy. ACS NANO 2017; 11:10070-10076. [PMID: 28846841 DOI: 10.1021/acsnano.7b04414] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Understanding the electronic structure of doped semiconductors is essential to realize advancements in electronics and in the rational design of nanoscale devices. Reported here are the results of time-resolved X-ray absorption studies on copper-doped cadmium sulfide nanoparticles that provide an explicit description of the electronic dynamics of the dopants. The interaction of a dopant ion and an excess charge carrier is unambiguously observed via monitoring the oxidation state. The experimental data combined with DFT calculations demonstrate that dopant bonding to the host matrix is modulated by its interaction with charge carriers. Furthermore, the transient photoluminescence and the kinetics of dopant oxidation reveal the presence of two types of surface-bound ions that create midgap states.
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Affiliation(s)
| | | | | | - Clare E Rowland
- Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | | | | | | | | | | | | | - Richard D Schaller
- Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
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49
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Pinchetti V, Lorenzon M, McDaniel H, Lorenzi R, Meinardi F, Klimov VI, Brovelli S. Spectro-electrochemical Probing of Intrinsic and Extrinsic Processes in Exciton Recombination in I-III-VI 2 Nanocrystals. NANO LETTERS 2017; 17:4508-4517. [PMID: 28613906 DOI: 10.1021/acs.nanolett.7b02040] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Ternary CuInS2 nanocrystals (CIS NCs) are attracting attention as nontoxic alternatives to heavy metal-based chalcogenides for many technologically relevant applications. The photophysical processes underlying their emission mechanism are, however, still under debate. Here we address this problem by applying, for the first time, spectro-electrochemical methods to core-only CIS and core/shell CIS/ZnS NCs. The application of an electrochemical potential enables us to reversibly tune the NC Fermi energy and thereby control the occupancy of intragap defects involved in exciton decay. The results indicate that, in analogy to copper-doped II-VI NCs, emission occurs via radiative capture of a conduction-band electron by a hole localized on an intragap state likely associated with a Cu-related defect. We observe the increase in the emission efficiency under reductive electrochemical potential, which corresponds to raising the Fermi level, leading to progressive filling of intragap states with electrons. This indicates that the factor limiting the emission efficiency in these NCs is nonradiative electron trapping, while hole trapping is of lesser importance. This observation also suggests that the centers for radiative recombination are Cu2+ defects (preexisting and/or accumulated as a result of photoconversion of Cu1+ ions) as these species contain a pre-existing hole without the need for capturing a valence-band hole generated by photoexcitation. Temperature-controlled photoluminescence experiments indicate that the intrinsic limit on the emission efficiency is imposed by multiphonon nonradiative recombination of a band-edge electron and a localized hole. This process affects both shelled and unshelled CIS NCs to a similar degree, and it can be suppressed by cooling samples to below 100 K. Finally, using experimentally measured decay rates, we formulate a model that describes the electrochemical modulation of the PL efficiency in terms of the availability of intragap electron traps as well as direct injection of electrons into the NC conduction band, which activates nonradiative Auger recombination, or electrochemical conversion of the Cu2+ states into the Cu1+ species that are less emissive due to the need for their "activation" by the capture of photogenerated holes.
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Affiliation(s)
- Valerio Pinchetti
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , via R. Cozzi 55, I-20125 Milano, Italy
| | - Monica Lorenzon
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , via R. Cozzi 55, I-20125 Milano, Italy
| | - Hunter McDaniel
- UbiQD, Los Alamos, New Mexico 87544, United States
- Chemistry Division and Center for Advanced Solar Photophysics, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Roberto Lorenzi
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , via R. Cozzi 55, I-20125 Milano, Italy
| | - Francesco Meinardi
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , via R. Cozzi 55, I-20125 Milano, Italy
| | - Victor I Klimov
- Chemistry Division and Center for Advanced Solar Photophysics, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Sergio Brovelli
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , via R. Cozzi 55, I-20125 Milano, Italy
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50
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Santiago-González B, Monguzzi A, Pinchetti V, Casu A, Prato M, Lorenzi R, Campione M, Chiodini N, Santambrogio C, Meinardi F, Manna L, Brovelli S. "Quantized" Doping of Individual Colloidal Nanocrystals Using Size-Focused Metal Quantum Clusters. ACS NANO 2017; 11:6233-6242. [PMID: 28485979 DOI: 10.1021/acsnano.7b02369] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The insertion of intentional impurities, commonly referred to as doping, into colloidal semiconductor quantum dots (QDs) is a powerful paradigm for tailoring their electronic, optical, and magnetic behaviors beyond what is obtained with size-control and heterostructuring motifs. Advancements in colloidal chemistry have led to nearly atomic precision of the doping level in both lightly and heavily doped QDs. The doping strategies currently available, however, operate at the ensemble level, resulting in a Poisson distribution of impurities across the QD population. To date, the synthesis of monodisperse ensembles of QDs individually doped with an identical number of impurity atoms is still an open challenge, and its achievement would enable the realization of advanced QD devices, such as optically/electrically controlled magnetic memories and intragap state transistors and solar cells, that rely on the precise tuning of the impurity states (i.e., number of unpaired spins, energy and width of impurity levels) within the QD host. The only approach reported to date relies on QD seeding with organometallic precursors that are intrinsically unstable and strongly affected by chemical or environmental degradation, which prevents the concept from reaching its full potential and makes the method unsuitable for aqueous synthesis routes. Here, we overcome these issues by demonstrating a doping strategy that bridges two traditionally orthogonal nanostructured material systems, namely, QDs and metal quantum clusters composed of a "magic number" of atoms held together by stable metal-to-metal bonds. Specifically, we use clusters composed of four copper atoms (Cu4) capped with d-penicillamine to seed the growth of CdS QDs in water at room temperature. The elemental analysis, performed by electrospray ionization mass spectrometry, X-ray fluorescence, and inductively coupled plasma mass spectrometry, side by side with optical spectroscopy and transmission electron microscopy measurements, indicates that each Cu:CdS QD in the ensemble incorporates four Cu atoms originating from one Cu4 cluster, which acts as a "quantized" source of dopant impurities.
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Affiliation(s)
- Beatriz Santiago-González
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , Via R. Cozzi 55, IT-20125 Milano, Italy
| | - Angelo Monguzzi
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , Via R. Cozzi 55, IT-20125 Milano, Italy
| | - Valerio Pinchetti
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , Via R. Cozzi 55, IT-20125 Milano, Italy
| | - Alberto Casu
- Nanochemistry Department, Istituto Italiano di Tecnologia , Via Morego 30, IT-16163 Genova, Italy
| | - Mirko Prato
- Materials Characterization Facility, Istituto Italiano di Tecnologia , Via Morego 30, IT-16163 Genova, Italy
| | - Roberto Lorenzi
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , Via R. Cozzi 55, IT-20125 Milano, Italy
| | - Marcello Campione
- Dipartimento di Scienze dell'Ambiente e della Terra, Università degli Studi di Milano-Bicocca , Piazza della Scienza 4, IT-20126 Milano, Italy
| | - Norberto Chiodini
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , Via R. Cozzi 55, IT-20125 Milano, Italy
| | - Carlo Santambrogio
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca Piazza della Scienza 2, IT-20126 Milano, Italy
| | - Francesco Meinardi
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , Via R. Cozzi 55, IT-20125 Milano, Italy
| | - Liberato Manna
- Nanochemistry Department, Istituto Italiano di Tecnologia , Via Morego 30, IT-16163 Genova, Italy
| | - Sergio Brovelli
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , Via R. Cozzi 55, IT-20125 Milano, Italy
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