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Yan JY, Chen C, Zhang XD, Wang YT, Babin HG, Wieck AD, Ludwig A, Meng Y, Hu X, Duan H, Chen W, Fang W, Cygorek M, Lin X, Wang DW, Jin CY, Liu F. Coherent control of a high-orbital hole in a semiconductor quantum dot. NATURE NANOTECHNOLOGY 2023; 18:1139-1146. [PMID: 37488220 DOI: 10.1038/s41565-023-01442-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 06/06/2023] [Indexed: 07/26/2023]
Abstract
Coherently driven semiconductor quantum dots are one of the most promising platforms for non-classical light sources and quantum logic gates which form the foundation of photonic quantum technologies. However, to date, coherent manipulation of single charge carriers in quantum dots is limited mainly to their lowest orbital states. Ultrafast coherent control of high-orbital states is obstructed by the demand for tunable terahertz pulses. To break this constraint, we demonstrate an all-optical method to control high-orbital states of a hole via a stimulated Auger process. The coherent nature of the Auger process is proved by Rabi oscillation and Ramsey interference. Harnessing this coherence further enables the investigation of the single-hole relaxation mechanism. A hole relaxation time of 161 ps is observed and attributed to the phonon bottleneck effect. Our work opens new possibilities for understanding the fundamental properties of high-orbital states in quantum emitters and for developing new types of orbital-based quantum photonic devices.
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Affiliation(s)
- Jun-Yong Yan
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, China
| | - Chen Chen
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, China
| | - Xiao-Dong Zhang
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, China
| | - Yu-Tong Wang
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, China
| | - Hans-Georg Babin
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Bochum, Germany
| | - Andreas D Wieck
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Bochum, Germany
| | - Arne Ludwig
- Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Bochum, Germany
| | - Yun Meng
- School of Precision Instrument and Optoelectronic Engineering, Tianjin University, Tianjin, China
- Key Laboratory of Optoelectronic Information Science and Technology, Ministry of Education, Tianjin, China
| | - Xiaolong Hu
- School of Precision Instrument and Optoelectronic Engineering, Tianjin University, Tianjin, China
- Key Laboratory of Optoelectronic Information Science and Technology, Ministry of Education, Tianjin, China
| | - Huali Duan
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, China
- ZJU-UIUC Institute, International Campus, Zhejiang University, Haining, China
| | - Wenchao Chen
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, China
- ZJU-UIUC Institute, International Campus, Zhejiang University, Haining, China
| | - Wei Fang
- College of Optical Science and Engineering, Zhejiang University, Hangzhou, China
| | - Moritz Cygorek
- SUPA, Institute of Photonics and Quantum Sciences, Heriot-Watt University, Edinburgh, UK
| | - Xing Lin
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, China
| | - Da-Wei Wang
- Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, Zhejiang University, Hangzhou, China
| | - Chao-Yuan Jin
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, China
- International Joint Innovation Center, Zhejiang University, Haining, China
- Center for Information Technology Application Innovation, Shaoxing Institute, Zhejiang University, Shaoxing, China
| | - Feng Liu
- Interdisciplinary Center for Quantum Information, State Key Laboratory of Extreme Photonics and Instrumentation, College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, China.
- International Joint Innovation Center, Zhejiang University, Haining, China.
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2
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Liu H, Chen P, Zhang X, Wang X, He T, Chen R. Lateral surface passivation of CdSe nanoplatelets through crown management. NANOSCALE 2023; 15:14140-14145. [PMID: 37584662 DOI: 10.1039/d3nr03133k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/17/2023]
Abstract
Two-dimensional colloidal CdSe nanoplatelets (NPLs) have been considered as ideal emitting materials for high performance light-emitting devices due to their excellent optical properties. However, the understanding of defect related radiative and nonradiative recombination centers in CdSe NPLs is still far from sufficient, especially their physical distribution locations. In this work, CdSe core and CdSe/CdS core/crown NPLs have been successfully synthesized and their optical properties have been characterized by laser spectroscopies. It is found that the photoluminescence quantum yield of CdSe NPLs is improved by a factor of 4 after the growth of the CdS crown. At low temperatures, the change in the ratio of low and high energy emission intensities from NPLs suggests that the radiative recombination centers are mainly located on the lateral surface of the samples. This finding is further confirmed by the surface passivation experiment. Meanwhile, the nonradiative recombination centers of NPLs located on the lateral surface are also confirmed by ligand exchange. These results demonstrate the importance of understanding the optical properties of the lateral surface of NPLs, which are important for the design of material structures for optoelectronic applications.
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Affiliation(s)
- Huan Liu
- Harbin Institute of Technology, Harbin 150001, China
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Peixian Chen
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.
| | - Xuanyu Zhang
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Xiongbin Wang
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
| | - Tingchao He
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China.
| | - Rui Chen
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
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3
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Diroll BT, Guzelturk B, Po H, Dabard C, Fu N, Makke L, Lhuillier E, Ithurria S. 2D II-VI Semiconductor Nanoplatelets: From Material Synthesis to Optoelectronic Integration. Chem Rev 2023; 123:3543-3624. [PMID: 36724544 DOI: 10.1021/acs.chemrev.2c00436] [Citation(s) in RCA: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The field of colloidal synthesis of semiconductors emerged 40 years ago and has reached a certain level of maturity thanks to the use of nanocrystals as phosphors in commercial displays. In particular, II-VI semiconductors based on cadmium, zinc, or mercury chalcogenides can now be synthesized with tailored shapes, composition by alloying, and even as nanocrystal heterostructures. Fifteen years ago, II-VI semiconductor nanoplatelets injected new ideas into this field. Indeed, despite the emergence of other promising semiconductors such as halide perovskites or 2D transition metal dichalcogenides, colloidal II-VI semiconductor nanoplatelets remain among the narrowest room-temperature emitters that can be synthesized over a wide spectral range, and they exhibit good material stability over time. Such nanoplatelets are scientifically and technologically interesting because they exhibit optical features and production advantages at the intersection of those expected from colloidal quantum dots and epitaxial quantum wells. In organic solvents, gram-scale syntheses can produce nanoparticles with the same thicknesses and optical properties without inhomogeneous broadening. In such nanoplatelets, quantum confinement is limited to one dimension, defined at the atomic scale, which allows them to be treated as quantum wells. In this review, we discuss the synthetic developments, spectroscopic properties, and applications of such nanoplatelets. Covering growth mechanisms, we explain how a thorough understanding of nanoplatelet growth has enabled the development of nanoplatelets and heterostructured nanoplatelets with multiple emission colors, spatially localized excitations, narrow emission, and high quantum yields over a wide spectral range. Moreover, nanoplatelets, with their large lateral extension and their thin short axis and low dielectric surroundings, can support one or several electron-hole pairs with large exciton binding energies. Thus, we also discuss how the relaxation processes and lifetime of the carriers and excitons are modified in nanoplatelets compared to both spherical quantum dots and epitaxial quantum wells. Finally, we explore how nanoplatelets, with their strong and narrow emission, can be considered as ideal candidates for pure-color light emitting diodes (LEDs), strong gain media for lasers, or for use in luminescent light concentrators.
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Affiliation(s)
- Benjamin T Diroll
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439, United States
| | - Burak Guzelturk
- X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Avenue, Lemont, Illinois 60439, United States
| | - Hong Po
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Corentin Dabard
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Ningyuan Fu
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Lina Makke
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
| | - Emmanuel Lhuillier
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
| | - Sandrine Ithurria
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université Univ Paris 06, CNRS UMR 8213, 10 rue Vauquelin 75005 Paris, France
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4
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Ashokan A, Han J, Hutchison JA, Mulvaney P. Spectroelectrochemistry of CdSe/Cd xZn 1-xS Nanoplatelets. ACS NANO 2023; 17:1247-1254. [PMID: 36629376 DOI: 10.1021/acsnano.2c09298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
We report an unexpected enhancement of photoluminescence (PL) in CdSe-based core/shell nanoplatelets (NPLs) upon electrochemical hole injection. Moderate hole doping densities induce an enhancement of more than 50% in PL intensity. This is accompanied by a narrowing and blue-shift of the PL spectrum. Simultaneous, time-resolved PL experiments reveal a slower luminescence decay. Such hole-induced PL brightening in NPLs is in stark contrast to the usual observation of PL quenching of CdSe-based quantum dots following hole injection. We propose that hole injection removes surface traps responsible for the formation of negative trions, thereby blocking nonradiative Auger processes. Continuous photoexcitation causes the enhanced PL intensity to decrease back to its initial level, indicating that photocharging is a key step leading to loss of PL luminescence during normal aging. Modulating the potential can be used to reversibly enhance or quench the PL, which enables electro-optical switching.
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Affiliation(s)
- Arun Ashokan
- ARC Centre of Excellence in Exciton Science, School of Chemistry, University of Melbourne, Parkville, Victoria3010, Australia
| | - Jiho Han
- ARC Centre of Excellence in Exciton Science, School of Chemistry, University of Melbourne, Parkville, Victoria3010, Australia
| | - James A Hutchison
- ARC Centre of Excellence in Exciton Science, School of Chemistry, University of Melbourne, Parkville, Victoria3010, Australia
| | - Paul Mulvaney
- ARC Centre of Excellence in Exciton Science, School of Chemistry, University of Melbourne, Parkville, Victoria3010, Australia
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5
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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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6
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Geuchies JJ, Dijkhuizen R, Koel M, Grimaldi G, du Fossé I, Evers WH, Hens Z, Houtepen AJ. Zero-Threshold Optical Gain in Electrochemically Doped Nanoplatelets and the Physics Behind It. ACS NANO 2022; 16:18777-18788. [PMID: 36256901 PMCID: PMC9706803 DOI: 10.1021/acsnano.2c07519] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 10/13/2022] [Indexed: 06/07/2023]
Abstract
Colloidal nanoplatelets (NPLs) are promising materials for lasing applications. The properties are usually discussed in the framework of 2D materials, where strong excitonic effects dominate the optical properties near the band edge. At the same time, NPLs have finite lateral dimensions such that NPLs are not true extended 2D structures. Here we study the photophysics and gain properties of CdSe/CdS/ZnS core-shell-shell NPLs upon electrochemical n doping and optical excitation. Steady-state absorption and PL spectroscopy show that excitonic effects are weaker in core-shell-shell nanoplatelets due to the decreased exciton binding energy. Transient absorption studies reveal a gain threshold of only one excitation per nanoplatelet. Using electrochemical n doping, we observe the complete bleaching of the band edge exciton transitions. Combining electrochemical doping with transient absorption spectroscopy, we demonstrate that the gain threshold is fully removed over a broad spectral range and gain coefficients of several thousand cm-1 are obtained. These doped NPLs are the best performing colloidal nanomaterial gain medium reported to date, with the lowest gain threshold and broadest gain spectrum and gain coefficients that are 4 times higher than in n-doped colloidal quantum dots. The low exciton binding energy due to the CdS and ZnS shells, in combination with the relatively small lateral size of the NPLs, results in excited states that are effectively delocalized over the entire platelet. Core-shell NPLs are thus on the border between strong confinement in QDs and dominant Coulombic effects in 2D materials. We demonstrate that this limit is in effect ideal for optical gain and that it results in an optimal lateral size of the platelets where the gain threshold per nm2 is minimal.
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Affiliation(s)
- Jaco J. Geuchies
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2926 HZDelft, The Netherlands
| | - Robbert Dijkhuizen
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2926 HZDelft, The Netherlands
| | - Marijn Koel
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2926 HZDelft, The Netherlands
| | - Gianluca Grimaldi
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2926 HZDelft, The Netherlands
| | - Indy du Fossé
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2926 HZDelft, The Netherlands
| | - Wiel H. Evers
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2926 HZDelft, The Netherlands
| | - Zeger Hens
- Department
of Chemistry and Center for Nano and Biophotonics, Ghent University, 9000Ghent, Belgium
| | - Arjan J. Houtepen
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2926 HZDelft, The Netherlands
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7
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Baghdasaryan DA, Harutyunyan VA, Hayrapetyan DB, Kazaryan EM, Baskoutas S, Sarkisyan HA. Exciton States and Optical Absorption in CdSe and PbS Nanoplatelets. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:nano12203690. [PMID: 36296880 PMCID: PMC9611409 DOI: 10.3390/nano12203690] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 10/11/2022] [Accepted: 10/13/2022] [Indexed: 06/12/2023]
Abstract
The exciton states and their influence on the optical absorption spectrum of CdSe and PbS nanoplatelets (NPLs) are considered theoretically in this paper. The problem is discussed in cases of strong, intermediate, and weak size quantization regimes of charge carrier motion in NPLs. For each size quantization regime, the corresponding potential that adequately describes the electron-hole interaction in this mode of space quantization of charge carriers is chosen. The single-particle energy spectra and corresponding wave functions for strong intermediate and weak size quantization regimes have been revealed. The dependence of material parameters on the number of monolayers in the sample has been considered. The related selection rules and the dependence of the absorption coefficient on the frequency and polarization direction of the incident light wave were obtained. The interband transition threshold energy dependencies were obtained for each size quantization regime. The effect of dielectric coefficient mismatch and different models of electron-hole interaction potentials have been studied in CdSe and PbS NPLs. It is also shown that with an increase in the linear dimensions of the structure, the threshold frequency of absorption decreases. The binding energies and absorption coefficient results for NPL with different thicknesses agree with the experimental data. The values of the absorption exciton peaks measured experimentally are close to our calculated values for CdSe and PbS samples.
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Affiliation(s)
- Davit A. Baghdasaryan
- Institute of Engineering and Physics, Russian-Armenian University, H. Emin 123, Yerevan 0051, Armenia
| | - Volodya A. Harutyunyan
- Institute of Engineering and Physics, Russian-Armenian University, H. Emin 123, Yerevan 0051, Armenia
| | - David B. Hayrapetyan
- Institute of Engineering and Physics, Russian-Armenian University, H. Emin 123, Yerevan 0051, Armenia
| | - Eduard M. Kazaryan
- Institute of Engineering and Physics, Russian-Armenian University, H. Emin 123, Yerevan 0051, Armenia
| | - Sotirios Baskoutas
- Department of Materials Science, University of Patras, 26504 Patras, Greece
| | - Hayk A. Sarkisyan
- Institute of Engineering and Physics, Russian-Armenian University, H. Emin 123, Yerevan 0051, Armenia
- Institute of Electronics and Telecommunications, Peter the Great St. Petersburg Polytechnic University, 195251 Saint Petersburg, Russia
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8
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Panfil Y, Cui J, Koley S, Banin U. Complete Mapping of Interacting Charging States in Single Coupled Colloidal Quantum Dot Molecules. ACS NANO 2022; 16:5566-5576. [PMID: 35289161 PMCID: PMC9047002 DOI: 10.1021/acsnano.1c10329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 03/10/2022] [Indexed: 06/14/2023]
Abstract
Colloidal quantum dots (CQDs), major building blocks in modern optoelectronic devices, have so far been synthesized with only one emission center where the exciton resides. Recent development of coupled colloidal quantum dots molecules (CQDM), where two core-shell CQDs are fused to form two emission centers in close proximity, allows exploration of how charge carriers in one CQD affect the charge carriers in the other CQD. Cryogenic single particle spectroscopy reveals that while CQD monomers manifest a simple emission spectrum comprising a main emission peak with well-defined phonon sidebands, CQDMs exhibit a complex spectrum with multiple peaks that are not all spaced according to the known phonon frequencies. Based on complementary emission polarization and time-resolved analysis, this is assigned to fluorescence of the two coupled emission centers. Moreover, the complex peak structure shows correlated spectral diffusion indicative of the coupling between the two emission centers. Utilizing Schrödinger-Poisson self-consistent calculations, we directly map the spectral behavior, alternating between neutral and charged states of the CQDM. Spectral shifts related to electrostatic interaction between a charged emission center and the second emission center are thus fully mapped. Furthermore, effects of moving surface charges are identified, whereby the emission center proximal to the charge shows larger shifts. Instances where the two emission centers are negatively charged simultaneously are also identified. Such detailed mapping of charging states is enabled by the coupling within the CQDM and its anisotropic structure. This understanding of the coupling interactions is progress toward quantum technology and sensing applications based on CQDMs.
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Chen L, He C, Yin J, Chen S, Zhao W, Zhao C. Clearance of methylene blue by CdS enhanced composite hydrogel materials. ENVIRONMENTAL TECHNOLOGY 2022; 43:355-366. [PMID: 32579426 DOI: 10.1080/09593330.2020.1788170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 06/20/2020] [Indexed: 06/11/2023]
Abstract
Hydrogel material is considered to be one of the effective adsorbents widely used to remove organic pollutants. However, the poor mechanical properties of some hydrogels limit their applications. Herein, we prepared composite hydrogels, for which acrylic acid (AA) and acrylamide (AM) were cross-linked and polymerised as the main substrate with adsorption function, while CdS nanoparticles were mainly used as reinforced material. Scanning electron microscope (SEM), Fourier transform infrared spectrometer (FTIR), two-dimensional infrared vibrational echo spectroscopy (2D-IR), and thermal gravimetric analyzer (TGA) were used to determine the physical and chemical structures of the hydrogels. The effects of the composition of AA, AM, and CdS on the mechanical properties and adsorption behaviours of the hydrogels were investigated. Besides, based on the great potential photocatalytic application value for wastewater remediation under the sunlight of CdS, the influence of the CdS doping amount on the photocatalytic property was also studied. As a result, when the mass ratio of AA to AM was 5:5, the hydrogel showed the best mechanical properties, and along with increasing the amount of CdS, the mechanical strength of the hydrogel was significantly enhanced from 0.445 MPa to 1.014 MPa. Besides, the composite hydrogels showed high adsorption and photocatalytic degradation synergistic clearance effect on methylene blue. Thus, the introduction of CdS photocatalytic nanoparticles may be an efficient and economical approach towards bifunctional hydrogel materials with enhanced mechanical property and photocatalytic degradation for wastewater remediation.
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Affiliation(s)
- Lei Chen
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, People's Republic of China
| | - Chao He
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, People's Republic of China
| | - Jiarui Yin
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, People's Republic of China
| | - Shengqiu Chen
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, People's Republic of China
| | - Weifeng Zhao
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, People's Republic of China
| | - Changsheng Zhao
- College of Polymer Science and Engineering, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, People's Republic of China
- National Engineering Research Center for Biomaterials, Sichuan University, Chengdu, People's Republic of China
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10
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Chen L, Hao C, Cai J, Chen C, Ma W, Xu C, Xu L, Kuang H. Chiral Self-Assembled Film from Semiconductor Nanorods with Ultra-Strong Circularly Polarized Luminescence. Angew Chem Int Ed Engl 2021; 60:26276-26280. [PMID: 34608731 DOI: 10.1002/anie.202112582] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Indexed: 11/09/2022]
Abstract
Chiroptical nanomaterials have generated significant levels of interest for generating strong circularly polarized luminescence (CPL) signals. We used the Langmuir-Schaeffer technique to generate the continuous and compact assembly of CdSe/CdS chiral film. We assembled achiral CdSe/CdS nanorods by controlling the number of layers and angles between different layers. This allowed us to tailor chiroptical properties to achieve high CPL signals. The chiral film was symmetrical and had the highest circular dichroism (CD) response and CPL signals with ten layers (RH (right-handed)-/LH (left-handed)-5 + 5 layers) and a 45° inter-angle. Specifically, RH-5+5 of the chiral film exhibited 1431 mdeg of CD activity and strong CPL signals with a dissymmetry factor (glum) of 0.0997. The helical stacked crystal plates with linear birefringence resulted in strong circular birefringence, as determined by the Reusch model. Electromagnetic simulations indicated that such remarkable optical activity was attributed to the birefringence and dichroism of the well-aligned CdSe/CdS nanorod layers in the chiral films. Under right/left circular polarized (RCP/LCP) light excitation, the well aligned semiconductor nanorods exhibited differences in the coupling efficiencies to RCP and LCP light. Our CdSe/CdS chiral films, which exhibit ultra-strong CPL activity, will provide a novel strategy for the fabrication of chiroptical devices.
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Affiliation(s)
- Lijing Chen
- State Key Lab of Food Science and Technology, International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, P. R. China
| | - Changlong Hao
- State Key Lab of Food Science and Technology, International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, P. R. China
| | - Jiarong Cai
- State Key Lab of Food Science and Technology, International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, P. R. China
| | - Chen Chen
- State Key Lab of Food Science and Technology, International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, P. R. China
| | - Wei Ma
- State Key Lab of Food Science and Technology, International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, P. R. China
| | - Chuanlai Xu
- State Key Lab of Food Science and Technology, International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, P. R. China
| | - Liguang Xu
- State Key Lab of Food Science and Technology, International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, P. R. China
| | - Hua Kuang
- State Key Lab of Food Science and Technology, International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, P. R. China
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11
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Chen L, Hao C, Cai J, Chen C, Ma W, Xu C, Xu L, Kuang H. Chiral Self‐Assembled Film from Semiconductor Nanorods with Ultra‐Strong Circularly Polarized Luminescence. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202112582] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Lijing Chen
- State Key Lab of Food Science and Technology International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology Jiangnan University Wuxi Jiangsu 214122 P. R. China
| | - Changlong Hao
- State Key Lab of Food Science and Technology International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology Jiangnan University Wuxi Jiangsu 214122 P. R. China
| | - Jiarong Cai
- State Key Lab of Food Science and Technology International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology Jiangnan University Wuxi Jiangsu 214122 P. R. China
| | - Chen Chen
- State Key Lab of Food Science and Technology International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology Jiangnan University Wuxi Jiangsu 214122 P. R. China
| | - Wei Ma
- State Key Lab of Food Science and Technology International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology Jiangnan University Wuxi Jiangsu 214122 P. R. China
| | - Chuanlai Xu
- State Key Lab of Food Science and Technology International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology Jiangnan University Wuxi Jiangsu 214122 P. R. China
| | - Liguang Xu
- State Key Lab of Food Science and Technology International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology Jiangnan University Wuxi Jiangsu 214122 P. R. China
| | - Hua Kuang
- State Key Lab of Food Science and Technology International Joint Research Laboratory for Biointerface and Biodetection, School of Food Science and Technology Jiangnan University Wuxi Jiangsu 214122 P. R. China
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12
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Abstract
In a radiative Auger process, optical decay leaves other carriers in excited states, resulting in weak red-shifted satellite peaks in the emission spectrum. The appearance of radiative Auger in the emission directly leads to the question if the process can be inverted: simultaneous photon absorption and electronic demotion. However, excitation of the radiative Auger transition has not been shown, neither on atoms nor on solid-state quantum emitters. Here, we demonstrate the optical driving of the radiative Auger transition, linking few-body Coulomb interactions and quantum optics. We perform our experiments on a trion in a semiconductor quantum dot, where the radiative Auger and the fundamental transition form a Λ-system. On driving both transitions simultaneously, we observe a reduction of the fluorescence signal by up to 70%. Our results suggest the possibility of turning resonance fluorescence on and off using radiative Auger as well as THz spectroscopy with optics close to the visible regime. Radiative Auger is a process that leads to a red-shift of the optical emission of an atom or a charged solid-state quantum emitter. Here, the authors realize the inverse process by optically driving the radiative Auger transition of a short-lived electronic state in a semiconductor quantum dot.
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13
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Lubin G, Tenne R, Ulku AC, Antolovic IM, Burri S, Karg S, Yallapragada VJ, Bruschini C, Charbon E, Oron D. Heralded Spectroscopy Reveals Exciton-Exciton Correlations in Single Colloidal Quantum Dots. NANO LETTERS 2021; 21:6756-6763. [PMID: 34398604 PMCID: PMC8397400 DOI: 10.1021/acs.nanolett.1c01291] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Multiply excited states in semiconductor quantum dots feature intriguing physics and play a crucial role in nanocrystal-based technologies. While photoluminescence provides a natural probe to investigate these states, room-temperature single-particle spectroscopy of their emission has proved elusive due to the temporal and spectral overlap with emission from the singly excited and charged states. Here, we introduce biexciton heralded spectroscopy enabled by a single-photon avalanche diode array based spectrometer. This allows us to directly observe biexciton-exciton emission cascades and measure the biexciton binding energy of single quantum dots at room temperature, even though it is well below the scale of thermal broadening and spectral diffusion. Furthermore, we uncover correlations hitherto masked in ensembles of the biexciton binding energy with both charge-carrier confinement and fluctuations of the local electrostatic potential. Heralded spectroscopy has the potential of greatly extending our understanding of charge-carrier dynamics in multielectron systems and of parallelization of quantum optics protocols.
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Affiliation(s)
- Gur Lubin
- Deptartment
of Physics of Complex Systems, Weizmann
Institute of Science, Rehovot 7610001, Israel
| | - Ron Tenne
- Deptartment
of Physics of Complex Systems, Weizmann
Institute of Science, Rehovot 7610001, Israel
- Department
of Physics and Center for Applied Photonics, University of Konstanz, Konstanz D-78457, Germany
| | - Arin Can Ulku
- School
of Engineering, École Polytechnique
Fédérale de Lausanne (EPFL), Neuchâtel 2002, Switzerland
| | - Ivan Michel Antolovic
- School
of Engineering, École Polytechnique
Fédérale de Lausanne (EPFL), Neuchâtel 2002, Switzerland
| | - Samuel Burri
- School
of Engineering, École Polytechnique
Fédérale de Lausanne (EPFL), Neuchâtel 2002, Switzerland
| | - Sean Karg
- Deptartment
of Physics of Complex Systems, Weizmann
Institute of Science, Rehovot 7610001, Israel
| | | | - Claudio Bruschini
- School
of Engineering, École Polytechnique
Fédérale de Lausanne (EPFL), Neuchâtel 2002, Switzerland
| | - Edoardo Charbon
- School
of Engineering, École Polytechnique
Fédérale de Lausanne (EPFL), Neuchâtel 2002, Switzerland
| | - Dan Oron
- Deptartment
of Physics of Complex Systems, Weizmann
Institute of Science, Rehovot 7610001, Israel
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14
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Pun AB, Mazzotti S, Mule AS, Norris DJ. Understanding Discrete Growth in Semiconductor Nanocrystals: Nanoplatelets and Magic-Sized Clusters. Acc Chem Res 2021; 54:1545-1554. [PMID: 33660971 DOI: 10.1021/acs.accounts.0c00859] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
ConspectusSemiconductor nanocrystals (NCs) fluoresce with a color that strongly depends on their size and shape. Thus, to obtain homogeneous optical properties, researchers have strived to synthesize particles that are uniform. However, because NCs typically grow through continuous, incremental addition of material, slight differences in the growth process between individual crystallites yield statistical distributions in size and shape, leading to inhomogeneities in their optical characteristics. Much work has focused on improving synthetic protocols to control these distributions and enhance performance. Interestingly, during these efforts, several syntheses were discovered that exhibit a different type of growth process. The NCs jump from one discrete size to the next. Through purification methods, one of these sizes can then be isolated, providing a different approach to uniform NCs. Unfortunately, the fundamental mechanism behind such discrete growth and how it differs from the conventional continuous process have remained poorly understood.Discrete growth has been observed in two major classes of NCs: semiconductor nanoplatelets (NPLs) and magic-sized clusters (MSCs). NPLs are quasi-two-dimensional crystallites that exhibit a precise thickness of only a few atomic layers but much larger lateral dimensions. During growth, NPLs slowly appear with an increasing number of monolayers. By halting this process at a specific time, NPLs with a desired thickness can then be isolated (e.g., four monolayers). Because the optical properties are primarily governed by this thickness, which is uniform, NPLs exhibit improved optical properties such as narrower fluorescence line widths.While NPLs have highly anisotropic shapes and show discrete growth only in one dimension (thickness), MSCs are isotropic particles. The name "magic" arose because a specific set of NC sizes appear during synthesis. They have been believed to represent special atomic arrangements that possess enhanced structural stability. Historically, they were very small, hence molecular-scale "clusters." Isolation of one of the MSC sizes can then, in principle, provide a uniform sample of NCs. More recently, MSC growth has been extended to larger sizes, beyond what is commonly considered to be the "cluster" regime, challenging the conventional explanation for these materials.This Account summarizes recent work by our group to understand the mechanism that governs discrete growth in semiconductor NCs. We begin by describing the synthesis of NPLs. Next, we discuss the mechanism behind the highly anisotropic shape of NPLs. We build on this by examining the ripening process in NPLs. We show that NPLs slowly appear with increasing thickness, counterintuitively through lateral growth. Then, we turn to the synthesis of MSCs, in particular focusing on their growth mechanism. Our findings indicate a strong connection between NPLs and MSCs. Finally, we review several remaining challenges for the growth of NPLs and MSCs and give a brief outlook on the future of discrete growth. By understanding the underlying process, we believe that it can be exploited more broadly, potentially moving us toward more uniform nanomaterials.
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Affiliation(s)
- Andrew B. Pun
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Sergio Mazzotti
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Aniket S. Mule
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - David J. Norris
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
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15
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Achtstein AW, Ayari S, Helmrich S, Quick MT, Owschimikow N, Jaziri S, Woggon U. Tuning exciton diffusion, mobility and emission line width in CdSe nanoplatelets via lateral size. NANOSCALE 2020; 12:23521-23531. [PMID: 33225335 DOI: 10.1039/d0nr04745g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We investigate the lateral size tunability of the exciton diffusion coefficient and mobility in colloidal quantum wells by means of line width analysis and theoretical modeling. We show that the exciton diffusion coefficient and mobility in laterally finite 2D systems like CdSe nanoplatelets can be tuned via the lateral size and aspect ratio. The coupling to acoustic and optical phonons can be altered via the lateral size and aspect ratio of the platelets. Subsequently the exciton diffusion and mobility become tunable since these phonon scattering processes determine and limit the mobility. At 4 K the exciton mobility increases from ∼ 4 × 103 cm2 V-1 s-1 to more than 1.4 × 104 cm2 V-1 s-1 for large platelets, while there are weaker changes with size and the mobility is around 8 × 101 cm2 V-1 s-1 for large platelets at room temperature. In turn at 4 K the exciton diffusion coefficient increases with the lateral size from ∼ 1.3 cm2 s-1 to ∼ 5 cm2 s-1, while it is around half the value for large platelets at room temperature. Our experimental results are in good agreement with theoretical modeling, showing a lateral size and aspect ratio dependence. The findings open up the possibility for materials with tunable exciton mobility, diffusion or emission line width, but quasi constant transition energy. High exciton mobility is desirable e.g. for solar cells and allows efficient excitation harvesting and extraction.
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Affiliation(s)
- Alexander W Achtstein
- Institute of Optics and Atomic Physics, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
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16
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Antolinez FV, Rabouw FT, Rossinelli AA, Keitel RC, Cocina A, Becker MA, Norris DJ. Trion Emission Dominates the Low-Temperature Photoluminescence of CdSe Nanoplatelets. NANO LETTERS 2020; 20:5814-5820. [PMID: 32589429 DOI: 10.1021/acs.nanolett.0c01707] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Colloidal nanoplatelets (NPLs) are atomically flat, quasi-two-dimensional particles of a semiconductor. Despite intense interest in their optical properties, several observations concerning the emission of CdSe NPLs remain puzzling. While their ensemble photoluminescence spectrum consists of a single narrow peak at room temperature, two distinct emission features appear at temperatures below ∼160 K. Several competing explanations for the origin of this two-color emission have been proposed. Here, we present temperature- and time-dependent experiments demonstrating that the two emission colors are due to two subpopulations of uncharged and charged NPLs. We study dilute films of isolated NPLs, thus excluding any explanation relying on collective effects due to NPL stacking. Temperature-dependent measurements explain that trion emission from charged NPLs is bright at cryogenic temperatures, while temperature activation of nonradiative Auger recombination quenches the trion emission above 160 K. Our findings clarify many of the questions surrounding the photoluminescence of CdSe NPLs.
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Affiliation(s)
- Felipe V Antolinez
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Freddy T Rabouw
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Aurelio A Rossinelli
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Robert C Keitel
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Ario Cocina
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Michael A Becker
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
- IBM Research Europe - Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - David J Norris
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
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17
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Vovk IA, Lobanov VV, Litvin AP, Leonov MY, Fedorov AV, Rukhlenko ID. Band Structure and Intersubband Transitions of Three-Layer Semiconductor Nanoplatelets. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:nano10050933. [PMID: 32408535 PMCID: PMC7279220 DOI: 10.3390/nano10050933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/29/2020] [Accepted: 05/07/2020] [Indexed: 06/11/2023]
Abstract
This paper presents the first general theory of electronic band structure and intersubband transitions in three-layer semiconductor nanoplatelets. We find a dispersion relation and wave functions of the confined electrons and use them to analyze the band structure of core/shell nanoplatelets with equal thicknesses of the shell layers. It is shown that the energies of electrons localized inside the shell layers can be degenerate for certain electron wave vectors and certain core and shell thicknesses. We also show that the energies of intersubband transitions can be nonmonotonic functions of the core and shell thicknesses, exhibiting pronounced local minima and maxima which can be observed in the infrared absorption spectra. Our results will prove useful for the design of photonic devices based on multilayered semiconductor nanoplatelets operating at infrared frequencies.
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Affiliation(s)
- Ilia A. Vovk
- ITMO University, Center of Information Optical Technology, Saint Petersburg 197101, Russia; (I.A.V.); (V.V.L.); (A.P.L.); (M.Y.L.); (A.V.F.)
| | - Vladimir V. Lobanov
- ITMO University, Center of Information Optical Technology, Saint Petersburg 197101, Russia; (I.A.V.); (V.V.L.); (A.P.L.); (M.Y.L.); (A.V.F.)
| | - Aleksandr P. Litvin
- ITMO University, Center of Information Optical Technology, Saint Petersburg 197101, Russia; (I.A.V.); (V.V.L.); (A.P.L.); (M.Y.L.); (A.V.F.)
| | - Mikhail Yu. Leonov
- ITMO University, Center of Information Optical Technology, Saint Petersburg 197101, Russia; (I.A.V.); (V.V.L.); (A.P.L.); (M.Y.L.); (A.V.F.)
| | - Anatoly V. Fedorov
- ITMO University, Center of Information Optical Technology, Saint Petersburg 197101, Russia; (I.A.V.); (V.V.L.); (A.P.L.); (M.Y.L.); (A.V.F.)
| | - Ivan D. Rukhlenko
- The University of Sydney, Institute of Photonics and Optical Science (IPOS), School of Physics, Camperdown, NSW 2006, Australia
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18
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Shornikova EV, Yakovlev DR, Biadala L, Crooker SA, Belykh VV, Kochiev MV, Kuntzmann A, Nasilowski M, Dubertret B, Bayer M. Negatively Charged Excitons in CdSe Nanoplatelets. NANO LETTERS 2020; 20:1370-1377. [PMID: 31960677 DOI: 10.1021/acs.nanolett.9b04907] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The low-temperature emission spectrum of CdSe colloidal nanoplatelets (NPLs) consists of two narrow lines. The high-energy line stems from the recombination of neutral excitons. The origin of the low-energy line is currently debated. We experimentally study the spectral shift, emission dynamics, and spin polarization of both lines at low temperatures down to 1.5 K and in high magnetic fields up to 60 T and show that the low-energy line originates from the recombination of negatively charged excitons (trions). This assignment is confirmed by the NPL photocharging dynamics and associated variations in the spectrum. We show that the negatively charged excitons are considerably less sensitive to the presence of surface spins than the neutral excitons. The trion binding energy in three-monolayer-thick NPLs is as large as 30 meV, which is 4 times larger than its value in the two-dimensional limit of a conventional CdSe quantum well confined between semiconductor barriers. A considerable part of this enhancement is gained by the dielectric enhancement effect, which is due to the small dielectric constant of the environment surrounding the NPLs.
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Affiliation(s)
- Elena V Shornikova
- Experimentelle Physik 2 , Technische Universität Dortmund , 44221 Dortmund , Germany
| | - Dmitri R Yakovlev
- Experimentelle Physik 2 , Technische Universität Dortmund , 44221 Dortmund , Germany
- Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg , Russia
| | - Louis Biadala
- Institut d'Electronique, de Microélectronique et de Nanotechnologie, CNRS , 59652 Villeneuve-d'Ascq , France
| | - Scott A Crooker
- National High Magnetic Field Laboratory , Los Alamos National Laboratory , Los Alamos , 87545 New Mexico , United States
| | - Vasilii V Belykh
- P. N. Lebedev Physical Institute, Russian Academy of Sciences , 119991 Moscow , Russia
| | - Mikhail V Kochiev
- P. N. Lebedev Physical Institute, Russian Academy of Sciences , 119991 Moscow , Russia
| | - Alexis Kuntzmann
- Laboratoire de Physique et d'Etude des Matériaux , ESPCI, CNRS , 75231 Paris , France
| | - Michel Nasilowski
- Laboratoire de Physique et d'Etude des Matériaux , ESPCI, CNRS , 75231 Paris , France
| | - Benoit Dubertret
- Laboratoire de Physique et d'Etude des Matériaux , ESPCI, CNRS , 75231 Paris , France
| | - Manfred Bayer
- Experimentelle Physik 2 , Technische Universität Dortmund , 44221 Dortmund , Germany
- Ioffe Institute, Russian Academy of Sciences , 194021 St. Petersburg , Russia
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