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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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2
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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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3
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Brumberg A, Watkins NE, Diroll BT, Schaller RD. Acceleration of Biexciton Radiative Recombination at Low Temperature in CdSe Nanoplatelets. NANO LETTERS 2022; 22:6997-7004. [PMID: 36018835 DOI: 10.1021/acs.nanolett.2c01791] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Colloidal semiconductor nanocrystals offer bandgap tunability, high photoluminescence quantum yield, and colloidal processing of benefit to optoelectronics, however rapid nonradiative Auger recombination (AR) deleteriously affects device efficiencies at elevated excitation intensities. AR is understood to transition from temperature-dependent behavior in bulk semiconductors to temperature-independent behavior in zero-dimensional quantum dots (QDs) as a result of discretized band structure that facilitates satisfaction of linear momentum conservation. For nanoplatelets (NPLs), two-dimensional morphology renders prediction of photophysical behaviors challenging. Here, we investigate and compare the temperature dependence of excited-stated lifetime and fluence-dependent emission of CdSe NPLs and QDs. For NPLs, upon temperature reduction, biexciton lifetime surprisingly decreases (even becoming shorter lived than trion emission) and emission intensity increases nearly linearly with fluence rather than saturating, consistent with dominance of radiative recombination rather than AR. CdSe NPLs thus differ fundamentally from core-only QDs and foster increased utility of photogenerated excitons and multiexcitons at low temperatures.
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Affiliation(s)
- Alexandra Brumberg
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Nicolas E Watkins
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Benjamin T Diroll
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Richard D Schaller
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
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4
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Yu J, Han Y, Zhang H, Ding X, Qiao L, Hu J. Excimer Formation in the Non-Van-Der-Waals 2D Semiconductor Bi 2 O 2 Se. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2204227. [PMID: 35781340 DOI: 10.1002/adma.202204227] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/21/2022] [Indexed: 06/15/2023]
Abstract
The layered semiconductor Bi2 O2 Se is a promising new-type 2D material that holds layered structure via electrostatic forces instead of van der Waals (vdW) attractions. Aside from the huge success in device performance, the non-vdW nature in Bi2 O2 Se with a built-in interlayer electric field has also provided an appealing platform for investigating unique photoexcited carrier dynamics. Here, experimental evidence for the observation of excimers in multilayer Bi2 O2 Se nanosheets via transient absorption spectroscopy is presented. It is found that the excimer formation is the primary decay pathway of photoexcited excitons and three-stage excimer dynamics with corresponding time scales are established. Excitation-fluence-dependent excimer dynamics further suggest that the excimer is diffusive and its formation can be simply described as excitons relaxed to an excimer geometry. This work indicates the outstanding promise of unique excitonic processes in Bi2 O2 Se, which may motivate novel device designs.
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Affiliation(s)
- Junhong Yu
- Laboratory for Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, 621900, China
- State Key Laboratory for Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang, 621010, China
| | - Yadong Han
- Laboratory for Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, 621900, China
| | - Hang Zhang
- Laboratory for Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, 621900, China
- State Key Laboratory for Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang, 621010, China
| | - Xiang Ding
- School of Physics, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Liang Qiao
- School of Physics, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Jianbo Hu
- Laboratory for Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, 621900, China
- State Key Laboratory for Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang, 621010, China
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5
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Jana S, Martins R, Fortunato E. Stacking-Dependent Electrical Transport in a Colloidal CdSe Nanoplatelet Thin-Film Transistor. NANO LETTERS 2022; 22:2780-2785. [PMID: 35343708 DOI: 10.1021/acs.nanolett.1c04822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Here, we report an exceptional feature of the one-dimensional threadlike assemblies of a four-monolayer colloidal CdSe nanoplatelet (NPL)-based thin-film transistor. A series of different lengths of threads (200-1200 nm) was used as an active n channel in thin-film transistors (TFTs) to understand the change in mobility with the length of the threads. The film with the longest threads shows the highest conductivity of ∼12 S/cm and electron mobility of ∼14.3 cm2 V-1 s-1 for an applied gate voltage of 2 V. The mobility trends with the length seem to be driven mostly by the lower defects in threads, where the loss of electron hopping is less. Furthermore, our results show the mobility trends in stacking-dependent CdSe NPL threads and provide a new insight into fabricating high-mobility TFTs with the use of colloidal CdSe NPLs.
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Affiliation(s)
- Santanu Jana
- CENIMAT/i3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia-Universidade Nova de Lisboa and CEMOP/Uninova, Campus de Caparica, 2829-516 Caparica, Portugal
| | - Rodrigo Martins
- CENIMAT/i3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia-Universidade Nova de Lisboa and CEMOP/Uninova, Campus de Caparica, 2829-516 Caparica, Portugal
| | - Elvira Fortunato
- CENIMAT/i3N, Departamento de Ciência dos Materiais, Faculdade de Ciências e Tecnologia-Universidade Nova de Lisboa and CEMOP/Uninova, Campus de Caparica, 2829-516 Caparica, Portugal
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6
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Diroll BT, Banerjee T. Transient reshaping of intraband transitions by hot electrons. NANOSCALE 2022; 14:1340-1346. [PMID: 35015024 DOI: 10.1039/d1nr06203d] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Hot electrons, far above the lattice temperature of a material, present opportunities for enhanced solar energy harvesting or performance of otherwise unfavorable chemistry. The spectroscopic signatures and dynamics of hot carrier absorption and emission have been extensively studied in bulk and nanoscopic semiconductors, but the effects on intraband transitions are largely unexplored. Here, the effect of hot electrons on the properties of colloidal quantum wells made of cadmium selenide is examined using ultrafast spectroscopy. Similar to expitaxial quantum wells, these atomically precise materials support intersubband transitions (a class of intraband transitions in 1D and 2D materials) in the near-infrared spectral window. Using energy-dependent photoexcitation, it is shown that electrons reach effective temperatures of 2000 K or greater. This results in a substantial transient shift in the oscillator strength of the instersubband transition to lower energies on a sub-picosecond time-scale. Similar heating of electrons is achieved under mid-infrared re-excitation, which permits ultrafast transmittance modulation throughout the near-infrared.
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Affiliation(s)
| | - Tathagata Banerjee
- Center for Nanoscale Materials, Argonne National Laboratory, USA.
- Department of Physics, University of Illinois Urbana-Champaign, USA
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7
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Guillemeney L, Lermusiaux L, Landaburu G, Wagnon B, Abécassis B. Curvature and self-assembly of semi-conducting nanoplatelets. Commun Chem 2022; 5:7. [PMID: 36697722 PMCID: PMC9814859 DOI: 10.1038/s42004-021-00621-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 12/21/2021] [Indexed: 01/28/2023] Open
Abstract
Semi-conducting nanoplatelets are two-dimensional nanoparticles whose thickness is in the nanometer range and controlled at the atomic level. They have come up as a new category of nanomaterial with promising optical properties due to the efficient confinement of the exciton in the thickness direction. In this perspective, we first describe the various conformations of these 2D nanoparticles which display a variety of bent and curved geometries and present experimental evidences linking their curvature to the ligand-induced surface stress. We then focus on the assembly of nanoplatelets into superlattices to harness the particularly efficient energy transfer between them, and discuss different approaches that allow for directional control and positioning in large scale assemblies. We emphasize on the fundamental aspects of the assembly at the colloidal scale in which ligand-induced forces and kinetic effects play a dominant role. Finally, we highlight the collective properties that can be studied when a fine control over the assembly of nanoplatelets is achieved.
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Affiliation(s)
- Lilian Guillemeney
- grid.463879.70000 0004 0383 1432Univ. Lyon, ENS de Lyon, CNRS, Laboratoire de Chimie, 69342 Lyon, France
| | - Laurent Lermusiaux
- grid.463879.70000 0004 0383 1432Univ. Lyon, ENS de Lyon, CNRS, Laboratoire de Chimie, 69342 Lyon, France
| | - Guillaume Landaburu
- grid.463879.70000 0004 0383 1432Univ. Lyon, ENS de Lyon, CNRS, Laboratoire de Chimie, 69342 Lyon, France
| | - Benoit Wagnon
- grid.463879.70000 0004 0383 1432Univ. Lyon, ENS de Lyon, CNRS, Laboratoire de Chimie, 69342 Lyon, France
| | - Benjamin Abécassis
- grid.463879.70000 0004 0383 1432Univ. Lyon, ENS de Lyon, CNRS, Laboratoire de Chimie, 69342 Lyon, France
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8
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Vong AF, Irgen-Gioro S, Wu Y, Weiss EA. Origin of Low Temperature Trion Emission in CdSe Nanoplatelets. NANO LETTERS 2021; 21:10040-10046. [PMID: 34843260 DOI: 10.1021/acs.nanolett.1c03726] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Colloidal semiconductor nanoplatelets (NPLs) are a scalable materials platform for optoelectronic applications requiring fast and narrow emission, including spin-to-photon transduction within quantum information networks. In particular, three-particle negative trions of NPLs are appealing emitters since, unlike excitons, they do not have an optically "dark" sublevel. In CdSe NPLs, trion emission dominates the photoluminescence (PL) spectrum at low temperature but using them as single photon-emitting states requires more knowledge about their preparation, since trions in these materials are not directly optically accessible from the ground state. This work demonstrates, using power-dependent time-resolved transient absorptions (TA) of CdSe NPLs, that trions form via biexciton decay in 1.6 ps. The scaling of the trion population and formation lifetime with excitation power indicates that they do not form through collisional mechanisms typical for 2D materials, but rather by a unimolecular hole transfer. This work is a step toward deterministic single photon emission from trions.
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Affiliation(s)
- Albert F Vong
- Department of Materials Science and Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Shawn Irgen-Gioro
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Yue Wu
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Emily A Weiss
- Department of Materials Science and Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
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9
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Zhang Z, Thung YT, Wang L, Chen X, Ding L, Fan W, Sun H. Surface Depletion Effects in Bromide-Ligated Colloidal Cadmium Selenide Nanoplatelets: Toward Efficient Emission at High Temperature. J Phys Chem Lett 2021; 12:9086-9093. [PMID: 34519516 DOI: 10.1021/acs.jpclett.1c02623] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The colloidal semiconductor nanoplatelet (NPL) with broad ligand-semiconductor interface is an ideal system for surface science investigation, but the study regarding depletion effects in NPLs remains lacking. Herein we explore such effects in colloidal CdSe NPLs through Br ligation. Apart from improved brightness and red-shifted optical features, we also experimentally observed abnormal negative thermal quenching phenomena in bromide-ligated CdSe NPLs over 200 K under a cryogenic environment and up to 383 K under an ambient environment, which was absent in pristine NPLs. We speculate that the surface depletion effect shall account for these anomalous phenomena due to the susceptibility of the surface depletion region on photoexcited carrier concentration and surface condition. The existence of the depletion layer in NPLs is also validated quantitatively with k·p simulation. Besides offering an alternative explanation on the red-shifted optical properties of CdSe NPLs by Br-ligation, our findings pave the new route toward solution-processed NPLs-based optoelectronics with boosted thermal resistance.
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Affiliation(s)
- Zitong Zhang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Yi Tian Thung
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Lin Wang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
- Key Laboratory of Advanced Display and System Applications of Ministry of Education, Shanghai University, 149 Yanchang Road, Shanghai 200072, China
| | - Xiaoxuan Chen
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Lu Ding
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Singapore 138634, Singapore
| | - Weijun Fan
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
| | - Handong Sun
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
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10
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Qiao T, Son DH. Synthesis and Properties of Strongly Quantum-Confined Cesium Lead Halide Perovskite Nanocrystals. Acc Chem Res 2021; 54:1399-1408. [PMID: 33566565 DOI: 10.1021/acs.accounts.0c00706] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
ConspectusSemiconducting metal halide perovskite (MHP) nanocrystals have emerged as an important new class of materials as the source of photons and charges for various applications that can outperform many other semiconductor nanocrystals utilized for the same purposes. However, the majority of the studies of MHP nanocrystals focused on weakly or nonconfined systems, where the quantum confinement giving rise to various size-dependent and confinement-enhanced photophysical properties cannot be explored readily. This was partially due to the challenge in producing strongly quantum-confined MHP nanocrystals, since the traditional kinetic control approach was less effective for the size control. Recent synthetic progress in MHP nanocrystals utilizing the equilibrium-based size control achieved the precise control of quantum confinement with high ensemble uniformity, enabling the exploration of the unique properties of MHP nanocrystals under strong quantum confinement. In this Account, we review the recent progress made in the synthesis of strongly quantum-confined cesium lead halide nanocrystals and investigation of the properties of exciton modified by strong quantum confinement. The main body of this Account discusses the key results of the research in this field in two separate sections. Section 2 describes the thermodynamic equilibrium-based synthesis method to control the size of cesium lead halide perovskite quantum dots in strongly confined regime. Size control in anisotropic nanocrystals with one- and two-dimensional quantum confinement is also discussed. Section 3 covers the following three topics that highlight the effects of quantum confinement on various spectroscopic properties of excitons in cesium lead halide perovskite nanocrystals: (1) Size-dependent absorption cross section of cesium lead halide quantum dots; (2) confinement effect on exciton fine structure and access to the dark exciton exhibiting intense and long-lived photoluminescence; (3) activation of forbidden exciton transition via dynamic lattice distortion by the photoexcited charge carriers enhanced by quantum confinement. The impact of strong quantum confinement goes beyond the properties of excitons covered in this Account and is expected to expand the functionality of MHP nanocrystals as the source of photons and charges. For instance, realization of the possible enhancement of photon down- and upconversion and hot carrier generation via quantum confinement will further increase the usefulness of strongly confined MHP nanocrystals in their applications.
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Affiliation(s)
- Tian Qiao
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Dong Hee Son
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
- Center for Nanomedicine, Institute for Basic Science (IBS) and Graduate Program of Nano Biomedical Engineering (BME), Advanced Science Institute, Yonsei University, Seoul 03722, Republic of Korea
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11
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Xiao J, Liu Y, Steinmetz V, Çaǧlar M, Mc Hugh J, Baikie T, Gauriot N, Nguyen M, Ruggeri E, Andaji-Garmaroudi Z, Stranks SD, Legrand L, Barisien T, Friend RH, Greenham NC, Rao A, Pandya R. Optical and Electronic Properties of Colloidal CdSe Quantum Rings. ACS NANO 2020; 14:14740-14760. [PMID: 33044058 DOI: 10.1021/acsnano.0c01752] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Luminescent colloidal CdSe nanorings are a recently developed type of semiconductor structure that have attracted interest due to the potential for rich physics arising from their nontrivial toroidal shape. However, the exciton properties and dynamics of these materials with complex topology are not yet well understood. Here, we use a combination of femtosecond vibrational spectroscopy, temperature-resolved photoluminescence (PL), and single-particle measurements to study these materials. We find that on transformation of CdSe nanoplatelets to nanorings, by perforating the center of platelets, the emission lifetime decreases and the emission spectrum broadens due to ensemble variations in the ring size and thickness. The reduced PL quantum yield of nanorings (∼10%) compared to platelets (∼30%) is attributed to an enhanced coupling between (i) excitons and CdSe LO-phonons at 200 cm-1 and (ii) negatively charged selenium-rich traps, which give nanorings a high surface charge (∼-50 mV). Population of these weakly emissive trap sites dominates the emission properties with an increased trap emission at low temperatures relative to excitonic emission. Our results provide a detailed picture of the nature of excitons in nanorings and the influence of phonons and surface charge in explaining the broad shape of the PL spectrum and the origin of PL quantum yield losses. Furthermore, they suggest that the excitonic properties of nanorings are not solely a consequence of the toroidal shape but also a result of traps introduced by puncturing the platelet center.
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Affiliation(s)
- James Xiao
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Yun Liu
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Violette Steinmetz
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Mustafa Çaǧlar
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Jeffrey Mc Hugh
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Tomi Baikie
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Nicolas Gauriot
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Malgorzata Nguyen
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Edoardo Ruggeri
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Zahra Andaji-Garmaroudi
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
- Department of Chemical Engineering & Biotechnology, University of Cambridge, Philippa Fawcett Drive, CB3 0AS, Cambridge, United Kingdom
| | - Samuel D Stranks
- Sorbonne Université, CNRS-UMR 7588, Institut des NanoSciences de Paris, INSP, 4 Place Jussieu, F-75005 Paris, France
| | - Laurent Legrand
- Sorbonne Université, CNRS-UMR 7588, Institut des NanoSciences de Paris, INSP, 4 Place Jussieu, F-75005 Paris, France
| | - Thierry Barisien
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Richard H Friend
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Neil C Greenham
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
| | - Akshay Rao
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, CB3 0HE, Cambridge, United Kingdom
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12
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Diroll BT. Circularly Polarized Optical Stark Effect in CdSe Colloidal Quantum Wells. NANO LETTERS 2020; 20:7889-7895. [PMID: 33118352 DOI: 10.1021/acs.nanolett.0c02409] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Colloidal quantum wells, or nanoplatelets, exhibit large, circularly polarized optical Stark effects under sub-band-gap femtosecond illumination. The optical Stark effect is measured for CdSe colloidal quantum wells of several thicknesses and separately as a measure of pump photon energy, pump fluence, and temperature. These measurements show that optical Stark effects in colloidal quantum wells shift the absorption features up to 5 meV, at the intensities up to 2.9 GW·cm-2 and large detuning (>400 meV) of the pump photon energy from the band edge absorption. Optical Stark shifts are underpinned by large transition dipoles of the colloidal quantum wells (μ = 15-23 D), which are larger than those of any reported colloidal quantum dots or epitaxial quantum wells. The rapid (<500 fs), narrow band blue shift of the excitonic features under circular excitation indicates the viability of these materials beyond light emission such as spintronics or all-optical switching.
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Affiliation(s)
- Benjamin T Diroll
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, Illinois 60439, United States
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13
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Rossi D, Liu X, Lee Y, Khurana M, Puthenpurayil J, Kim K, Akimov AV, Cheon J, Son DH. Intense Dark Exciton Emission from Strongly Quantum-Confined CsPbBr 3 Nanocrystals. NANO LETTERS 2020; 20:7321-7326. [PMID: 32845638 DOI: 10.1021/acs.nanolett.0c02714] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Dark exciton as the lowest-energy (ground) exciton state in metal halide perovskite nanocrystals is a subject of much interest. This is because the superior performance of perovskites as the photon source combined with long lifetime of dark exciton can be attractive for many applications of exciton. However, the direct observation of the intense and long-lived dark exciton emission, indicating facile access to dark ground exciton state, has remained elusive. Here, we report the intense photoluminescence from dark exciton with microsecond lifetime in strongly confined CsPbBr3 nanocrystals and reveal the crucial role of confinement in accessing the dark ground exciton state. This study establishes the potential of strongly quantum-confined perovskite nanostructures as the excellent platform to harvest the benefits of extremely long-lived dark exciton.
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Affiliation(s)
- Daniel Rossi
- Center for NanoMedicine, Institute for Basic Science (IBS), Seoul 03722, Republic of Korea
| | - Xiaohan Liu
- Department of Physics, Texas A&M University, College Station, Texas 777843, United States
| | - Yangjin Lee
- Center for NanoMedicine, Institute for Basic Science (IBS), Seoul 03722, Republic of Korea
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
| | - Mohit Khurana
- Department of Physics, Texas A&M University, College Station, Texas 777843, United States
| | - Joseph Puthenpurayil
- Department of Chemistry, Texas A&M University, College Station, Texas 777843, United States
| | - Kwanpyo Kim
- Center for NanoMedicine, Institute for Basic Science (IBS), Seoul 03722, Republic of Korea
- Department of Physics, Yonsei University, Seoul 03722, Republic of Korea
| | - Alexey V Akimov
- Department of Physics, Texas A&M University, College Station, Texas 777843, United States
- Russian Quantum Center, Skolkovo, Moscow 143025, Russia
- PN Lebedev Institute RAS, Moscow 119991, Russia
| | - Jinwoo Cheon
- Center for NanoMedicine, Institute for Basic Science (IBS), Seoul 03722, Republic of Korea
- Department of Chemistry, Yonsei University, Seoul 03722, Republic of Korea
- Graduate Program of Nano Biomedical Engineering (BME), Advanced Science Institute, Yonsei University, Seoul 03722, Republic of Korea
| | - Dong Hee Son
- Center for NanoMedicine, Institute for Basic Science (IBS), Seoul 03722, Republic of Korea
- Department of Chemistry, Texas A&M University, College Station, Texas 777843, United States
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14
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Diroll BT, Schaller RD. Intersubband Relaxation in CdSe Colloidal Quantum Wells. ACS NANO 2020; 14:12082-12090. [PMID: 32864955 DOI: 10.1021/acsnano.0c05459] [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
The dynamics of intersubband relaxation are critical to quantum well technologies such as quantum cascade lasers and quantum well infrared photodetectors. Here, intersubband relaxation in CdSe colloidal quantum wells, or nanoplatelets, is studied via pump-push-probe transient spectroscopy. An initial interband pump pulse is followed by a secondary infrared push excitation, resonant with intersubband absorption, which promotes electrons from the first conduction band of the quantum well to the second conduction band. A probe pulse monitors subsequent electron cooling to the band edge of the quantum well. Using this technique, intersubband relaxation is studied as a function of critical variables such as colloidal quantum well size and thickness, surface ligand chemistry, temperature, and excitation pulse intensity. Larger quantum well sizes, judicious selection of surface ligand chemistry (e.g., thiolates), low temperatures, and elevated push pulse fluences slow intersubband relaxation. However, compared to resonant intraband relaxation in colloidal quantum dots (up to hundreds of picoseconds), intersubband relaxation in colloidal quantum wells is rapid (<1 ps) under all examined conditions. These experiments indicate that rapid relaxation is driven by both LO phonon and surface scattering. The short time scale of relaxation observed in these materials may hinder intersubband technologies such as mid-infrared detectors, although such rapid relaxation may prove valuable in optical switching.
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Affiliation(s)
- Benjamin T Diroll
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Richard D Schaller
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
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15
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Jiang Y, Weiss EA. Colloidal Quantum Dots as Photocatalysts for Triplet Excited State Reactions of Organic Molecules. J Am Chem Soc 2020; 142:15219-15229. [DOI: 10.1021/jacs.0c07421] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Yishu Jiang
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Emily A. Weiss
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
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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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Ayari S, Quick MT, Owschimikow N, Christodoulou S, Bertrand GHV, Artemyev M, Moreels I, Woggon U, Jaziri S, Achtstein AW. Tuning trion binding energy and oscillator strength in a laterally finite 2D system: CdSe nanoplatelets as a model system for trion properties. NANOSCALE 2020; 12:14448-14458. [PMID: 32618327 DOI: 10.1039/d0nr03170d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We present a theoretical study combined with experimental validations demonstrating that CdSe nanoplatelets are a model system to investigate the tunability of trions and excitons in laterally finite 2D semiconductors. Our results show that the trion binding energy can be tuned from 36 meV to 18 meV with the lateral size and decreasing aspect ratio, while the oscillator strength ratio of trions to excitons decreases. In contrast to conventional quantum dots, the trion oscillator strength in a nanoplatelet at low temperature is smaller than that of the exciton. The trion and exciton Bohr radii become lateral size tunable, e.g. from ∼3.5 to 4.8 nm for the trion. We show that dielectric screening has strong impact on these properties. By theoretical modeling of transition energies, binding energies and oscillator strength of trions and excitons and comparison with experimental findings, we demonstrate that these properties are lateral size and aspect ratio tunable and can be engineered by dielectric confinement, allowing to suppress e.g. detrimental trion emission in devices. Our results strongly impact further in-depth studies, as the demonstrated lateral size tunable trion and exciton manifold is expected to influence properties like gain mechanisms, lasing, quantum efficiency and transport even at room temperature due to the high and tunable trion binding energies.
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Affiliation(s)
- Sabrine Ayari
- Laboratoire de Physique des Materiaux, Faculte des Sciences de Bizerte, Universite de Carthage, Jarzouna 7021, Tunisia
| | - Michael T Quick
- Institute of Optics and Atomic Physics, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
| | - Nina Owschimikow
- Institute of Optics and Atomic Physics, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
| | | | | | - Mikhail Artemyev
- Research Institute for Physical Chemical Problems of Belarusian State University, 220006 Minsk, Belarus
| | - Iwan Moreels
- Department of Chemistry, Ghent University, Krijgslaan 281 - S3, 9000 Gent, Belgium
| | - Ulrike Woggon
- Institute of Optics and Atomic Physics, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
| | - Sihem Jaziri
- Laboratoire de Physique des Materiaux, Faculte des Sciences de Bizerte, Universite de Carthage, Jarzouna 7021, Tunisia and Laboratoire de Physique de la Matiere Condensee, Departement de Physique, Faculte des Sciences de Tunis, Campus Universitaire, 1060 Tunis, Tunisia
| | - Alexander W Achtstein
- Institute of Optics and Atomic Physics, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
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18
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Dozov I, Goldmann C, Davidson P, Abécassis B. Probing permanent dipoles in CdSe nanoplatelets with transient electric birefringence. NANOSCALE 2020; 12:11040-11054. [PMID: 32373875 DOI: 10.1039/d0nr00884b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Zinc-blende CdSe semiconducting nanoplatelets (NPL) show outstanding quantum confinement properties thanks to their small, atomically-controlled, thickness. For example, they display extremely sharp absorption peaks and ultra-fast recombination rates that make them very interesting objects for optoelectronic applications. However, the presence of a ground-state electric dipole for these nanoparticles has not yet been investigated. We therefore used transient electric birefringence (TEB) to probe the electric dipole of 5-monolayer thick zinc blende CdSe NPL with a parallelepipedic shape. We studied a dilute dispersion of isolated NPL coated with branched ligands and we measured, as a function of time, the birefringence induced by DC and AC field pulses. The electro-optic behavior proves the presence of a large dipolar moment (>245 D) oriented along the length of the platelets. We then induced the slow face-to-face stacking of the NPL by adding oleic acid. In these stacks, the in-plane dipole components of consecutive NPL cancel whereas their normal components add. Moreover, interestingly, the excess polarizability tensor of the NPL stacks gives rise to an electro-optic contribution opposite to that of the electric dipole. By monitoring the TEB signal of the slowly-growing stacks over up to a year, we extracted the evolution of their average length with time and we showed that their electro-optic response can be explained by the presence of a 80 D dipolar component parallel to their normal. In spite of the 4[combining macron]3m space group of bulk zinc blende CdSe, these NPL thus bear an important ground-state dipole whose magnitude per unit volume is twice that found for wurtzite CdSe nanorods. We discuss the possible origin of this electric dipole, its consequences for the optical properties of these nanoparticles, and how it could explain their strong stacking propensity that severely hampers their colloidal stability.
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Affiliation(s)
- Ivan Dozov
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, Université Paris-Sud, UMR 8502, 91405 Orsay, France.
| | - Claire Goldmann
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, Université Paris-Sud, UMR 8502, 91405 Orsay, France.
| | - Patrick Davidson
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, Université Paris-Sud, UMR 8502, 91405 Orsay, France.
| | - Benjamin Abécassis
- Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, Université Paris-Sud, UMR 8502, 91405 Orsay, France. and Univ Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F69342, Lyon, France
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19
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Piveteau L, Dirin DN, Gordon CP, Walder BJ, Ong TC, Emsley L, Copéret C, Kovalenko MV. Colloidal-ALD-Grown Core/Shell CdSe/CdS Nanoplatelets as Seen by DNP Enhanced PASS-PIETA NMR Spectroscopy. NANO LETTERS 2020; 20:3003-3018. [PMID: 32078332 PMCID: PMC7227022 DOI: 10.1021/acs.nanolett.9b04870] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Ligand exchange and CdS shell growth onto colloidal CdSe nanoplatelets (NPLs) using colloidal atomic layer deposition (c-ALD) were investigated by solid-state nuclear magnetic resonance (NMR) experiments, in particular, dynamic nuclear polarization (DNP) enhanced phase adjusted spinning sidebands-phase incremented echo-train acquisition (PASS-PIETA). The improved sensitivity and resolution of DNP enhanced PASS-PIETA permits the identification and study of the core, shell, and surface species of CdSe and CdSe/CdS core/shell NPLs heterostructures at all stages of c-ALD. The cadmium chemical shielding was found to be proportionally dependent on the number and nature of coordinating chalcogen-based ligands. DFT calculations permitted the separation of the the 111/113Cd chemical shielding into its different components, revealing that the varying strength of paramagnetic and spin-orbit shielding contributions are responsible for the chemical shielding trend of cadmium chalcogenides. Overall, this study points to the roughening and increased chemical disorder at the surface during the shell growth process, which is not readily captured by the conventional characterization tools such as electron microscopy.
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Affiliation(s)
- Laura Piveteau
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
- Empa-Swiss
Federal Laboratories for Materials Science and Technology, Dübendorf, Überlandstrasse
129, Zurich CH-8600, Switzerland
| | - Dmitry N. Dirin
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
- Empa-Swiss
Federal Laboratories for Materials Science and Technology, Dübendorf, Überlandstrasse
129, Zurich CH-8600, Switzerland
| | - Christopher P. Gordon
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
| | - Brennan J. Walder
- Institut
des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Ta-Chung Ong
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
| | - Lyndon Emsley
- Institut
des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Christophe Copéret
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
- E-mail:
| | - Maksym V. Kovalenko
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, Zurich CH-8093, Switzerland
- Empa-Swiss
Federal Laboratories for Materials Science and Technology, Dübendorf, Überlandstrasse
129, Zurich CH-8600, Switzerland
- E-mail:
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20
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Movilla JL, Planelles J, Climente JI. Dielectric Confinement Enables Molecular Coupling in Stacked Colloidal Nanoplatelets. J Phys Chem Lett 2020; 11:3294-3300. [PMID: 32272016 DOI: 10.1021/acs.jpclett.0c00855] [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
We show theoretically that carriers confined in semiconductor colloidal nanoplatelets (NPLs) sense the presence of neighbor, cofacially stacked NPLs in their energy spectrum. When approaching identical NPLs, the otherwise degenerate energy levels red-shift and split, forming (for large stacks) minibands that are several millielectronvolts in width. Unlike in epitaxial structures, the molecular behavior does not result from quantum tunneling but from changes in the dielectric confinement. The associated excitonic absorption spectrum shows a rich structure of bright and dark states, whose optical activity and multiplicity can be understood from reflection symmetry and Coulomb tunneling. We predict spectroscopic signatures that should confirm the formation of molecular states, whose practical realization would pave the way for the development of nanocrystal chemistry based on NPLs.
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Affiliation(s)
- José L Movilla
- Departament d'Educació i Didàctiques Específiques, Universitat Jaume I, 12080 Castelló, Spain
| | - Josep Planelles
- Departament de Química Física i Analítica, Universitat Jaume I, E-12080 Castelló de la Plana, Spain
| | - Juan I Climente
- Departament de Química Física i Analítica, Universitat Jaume I, E-12080 Castelló de la Plana, Spain
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21
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Tenney SM, Vilchez V, Sonnleitner ML, Huang C, Friedman HC, Shin AJ, Atallah TL, Deshmukh AP, Ithurria S, Caram JR. Mercury Chalcogenide Nanoplatelet-Quantum Dot Heterostructures as a New Class of Continuously Tunable Bright Shortwave Infrared Emitters. J Phys Chem Lett 2020; 11:3473-3480. [PMID: 32293896 DOI: 10.1021/acs.jpclett.0c00958] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Despite broad applications in imaging, energy conversion, and telecommunications, few nanoscale moieties emit light efficiently in the shortwave infrared (SWIR, 1000-2000 nm or 1.24-0.62 eV). We report quantum-confined mercury chalcogenide (HgX, where X = Se or Te) nanoplatelets (NPLs) can be induced to emit bright (QY > 30%) and tunable (900-1500+ nm) infrared emission from attached quantum dot (QD) "defect" states. We demonstrate near unity energy transfer from NPL to these QDs, which completely quench NPL emission and emit with a high QY through the SWIR. This QD defect emission is kinetically tunable, enabling controlled midgap emission from NPLs. Spectrally resolved photoluminescence demonstrates energy-dependent lifetimes, with radiative rates 10-20 times faster than those of their PbX analogues in the same spectral window. Coupled with their high quantum yield, midgap emission HgX dots on HgX NPLs provide a potential platform for novel optoelectronics in the SWIR.
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Affiliation(s)
- Stephanie M Tenney
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States
| | - Victoria Vilchez
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States
| | - Mikayla L Sonnleitner
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States
| | - Chengye Huang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States
| | - Hannah C Friedman
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States
| | - Ashley J Shin
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States
| | - Timothy L Atallah
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States
| | - Arundhati P Deshmukh
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States
| | - Sandrine Ithurria
- Laboratoire de Physique et d'Étude des Matériaux, PSL Research University, CNRS UMR 8213, ESPCI ParisTech, 10 rue Vauquelin, 75005 Paris, France
| | - Justin R Caram
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States
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22
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Diroll BT, Kamysbayev V, Coropceanu I, Talapin DV, Schaller RD. Heat-driven acoustic phonons in lamellar nanoplatelet assemblies. NANOSCALE 2020; 12:9661-9668. [PMID: 32319509 DOI: 10.1039/d0nr00695e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Colloidal CdSe nanoplatelets, with the electronic structure of quantum wells, self-assemble into lamellar stacks due to large co-facial van der Waals attractions. These lamellar stacks are shown to display coherent acoustic phonons that are detected from oscillatory changes in the absorption spectrum observed in infrared pump, electronic probe measurements. Rather than direct electronic excitation of the nanocrystals using a femtosecond laser, impulsive transfer of heat from the organic ligand shell, excited at C-H stretching vibrational resonances, to the inorganic core of individual nanoplatelets occurs on a time-scale of <100 ps. This heat transfer drives in-phase longitudinal acoustic phonons of the nanoplatelet lamellae, which are accompanied by subtle deformations along the nanoplatelet short axes. The frequencies of the oscillations vary from 0.7 to 2 GHz (3-8 μeV and 0.5-1 ns oscillation period) depending on the thickness of the nanoplatelets-but not their lateral areas-and the temperature of the sample. Temperature-dependence of the acoustic phonon frequency conveys a substantial stiffening of the organic ligand bonds between nanoplatelets with reduced temperature. These results demonstrate a potential for acoustic modulation of the excitonic structure of nanocrystal assemblies in self-assembled anisotropic semiconductor systems at temperatures at or above 300 K.
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Affiliation(s)
- Benjamin T Diroll
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, IL 60439, USA.
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23
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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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24
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Yu J, Zhang C, Pang G, Sun XW, Chen R. Effect of Lateral Size and Surface Passivation on the Near-Band-Edge Excitonic Emission from Quasi-Two-Dimensional CdSe Nanoplatelets. ACS APPLIED MATERIALS & INTERFACES 2019; 11:41821-41827. [PMID: 31613084 DOI: 10.1021/acsami.9b16044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
As a new type of quasi-two-dimensional nanomaterial, CdSe nanoplatelets (NPLs) possess excellent properties such as narrow emission peak, large absorption cross section, and a low threshold of amplified spontaneous emission. However, the origin of emission especially at low temperatures has not been studied clearly up till now. Here, we study the temperature-dependent photoluminescence of CdSe NPLs which show two emission peaks at low temperatures. It is interesting to note that the intensity of the low-energy peak shows a correlation with laser irradiation time. Moreover, the low-temperature PL spectra of four CdSe NPLs with different lateral sizes demonstrate the relationship of low-energy peaks with the surface. It has been confirmed that CdSe NPLs with larger surface areas to volume ratio have stronger low-energy emissions, which is ascribed to the surface-state-related emission. Finally, surface passivation of CdSe NPLs attenuates the intensity of the low-energy peak, which further verifies our model. Our results demonstrate the critical significance of surface in CdSe NPLs for their optical properties, which is crucial for the application of optoelectronic devices.
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Affiliation(s)
- Jiahao Yu
- Department of Electrical and Electronic Engineering , Southern University of Science and Technology , Shenzhen , Guangdong 518055 , P. R. China
- Harbin Institute of Technology , Harbin 150001 , P. R. China
| | - Chaojian Zhang
- Department of Electrical and Electronic Engineering , Southern University of Science and Technology , Shenzhen , Guangdong 518055 , P. R. China
| | - Guotao Pang
- Department of Electrical and Electronic Engineering , Southern University of Science and Technology , Shenzhen , Guangdong 518055 , P. R. China
| | - Xiao Wei Sun
- Department of Electrical and Electronic Engineering , Southern University of Science and Technology , Shenzhen , Guangdong 518055 , P. R. China
| | - Rui Chen
- Department of Electrical and Electronic Engineering , Southern University of Science and Technology , Shenzhen , Guangdong 518055 , P. R. China
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25
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Diroll BT, Chen M, Coropceanu I, Williams KR, Talapin DV, Guyot-Sionnest P, Schaller RD. Polarized near-infrared intersubband absorptions in CdSe colloidal quantum wells. Nat Commun 2019; 10:4511. [PMID: 31586067 PMCID: PMC6778118 DOI: 10.1038/s41467-019-12503-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 09/06/2019] [Indexed: 01/21/2023] Open
Abstract
Colloidal quantum wells are two-dimensional materials grown with atomically-precise thickness that dictates their electronic structure. Although intersubband absorption in epitaxial quantum wells is well-known, analogous observations in non-epitaxial two-dimensional materials are sparse. Here we show that CdSe nanoplatelet quantum wells have narrow (30-200 meV), polarized intersubband absorption features when photoexcited or under applied bias, which can be tuned by thickness across the near-infrared (NIR) spectral window (900-1600 nm) inclusive of important telecommunications wavelengths. By examination of the optical absorption and polarization-resolved measurements, the NIR absorptions are assigned to electron intersubband transitions. Under photoexcitation, the intersubband features display hot carrier and Auger recombination effects similar to excitonic absorptions. Sequenced two-color photoexcitation permits the sub-picosecond modulation of the carrier temperature in such colloidal quantum wells. This work suggests that colloidal quantum wells may be promising building blocks for NIR technologies.
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Affiliation(s)
- Benjamin T Diroll
- Center for Nanoscale Materials, Argonne National Laboratory, 9700S. Cass Avenue, Lemont, IL, 60439, USA.
| | - Menglu Chen
- Department of Physics, University of Chicago, 2720S. Ellis Avenue, Chicago, IL, 60637, USA
| | - Igor Coropceanu
- Department of Chemistry, University of Chicago, 5735S. Ellis Avenue, Chicago, IL, 60637, USA
| | - Kali R Williams
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA
| | - Dmitri V Talapin
- Center for Nanoscale Materials, Argonne National Laboratory, 9700S. Cass Avenue, Lemont, IL, 60439, USA
- Department of Chemistry, University of Chicago, 5735S. Ellis Avenue, Chicago, IL, 60637, USA
| | - Philippe Guyot-Sionnest
- Department of Physics, University of Chicago, 2720S. Ellis Avenue, Chicago, IL, 60637, USA
- Department of Chemistry, University of Chicago, 5735S. Ellis Avenue, Chicago, IL, 60637, USA
| | - Richard D Schaller
- Center for Nanoscale Materials, Argonne National Laboratory, 9700S. Cass Avenue, Lemont, IL, 60439, USA.
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.
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26
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Specht JF, Scott R, Corona Castro M, Christodoulou S, Bertrand GHV, Prudnikau AV, Antanovich A, Siebbeles LDA, Owschimikow N, Moreels I, Artemyev M, Woggon U, Achtstein AW, Richter M. Size-dependent exciton substructure in CdSe nanoplatelets and its relation to photoluminescence dynamics. NANOSCALE 2019; 11:12230-12241. [PMID: 31204756 DOI: 10.1039/c9nr03161h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
CdSe nanoplatelets can be synthesized with different lateral sizes; very small nanoplatelets have almost quantum dot like features (almost discrete exciton states), while very large ones are expected to have properties of colloidal quantum wells (exciton continuum). However, nanoplatelets can be in an intermediate confinement regime with a rich substructure of excitons, which is neither quantum dot like nor an ideal 2D exciton. In this manuscript, we discuss the experimental transition energies and relaxation dynamics of exciton states in CdSe platelets with varying lateral dimensions and compare them with a microscopic theoretical model including exciton-phonon scattering. The model takes special care of the interplay of confinement and Coulomb coupling in the intermediate regime showing strong changes with respect to simple weak or strong confinement models by solving the full four dimensional lateral factorization free exciton wavefunction. Depending on the platelet size broad resonances previously attributed to just ground and excited states are actually composed of a rich substructure of several exciton states in their temporal dynamics. We show that these factorization free exciton states can explain the spectral features observed in photoluminescence experiments. Furthermore we demonstrate that the interplay of exciton bright and dark states provides principle insights into the overall temporal relaxation dynamics, and allows tuning of the exciton cooling via lateral platelet size. Our results and theoretical approach are directly relevant for understanding e.g. the size tuneability of lasing, excitonic cooling dynamics or light harvesting applications in these and similar 2D systems of finite lateral size.
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Affiliation(s)
- Judith F Specht
- Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
| | - Riccardo Scott
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Strasse des 17 Juni 135, 10623 Berlin, Germany.
| | - Marta Corona Castro
- Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
| | - Sotirios Christodoulou
- ICFO-Institut de Ciencies Fotoniques, 08860 Castelldefels, Barcelona, Spain and Istituto Italiano di Tecnologia, IT-16163 Genova, Italy
| | - Guillaume H V Bertrand
- Istituto Italiano di Tecnologia, IT-16163 Genova, Italy and CEA Saclay, 91191 Gif-sur-Yvette, France
| | - Anatol V Prudnikau
- Research Institute for Physical Chemical Problems of Belarusian State University, 220006, Minsk, Belarus
| | - Artsiom Antanovich
- Research Institute for Physical Chemical Problems of Belarusian State University, 220006, Minsk, Belarus
| | - Laurens D A Siebbeles
- Optoelectronic Materials Section, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Nina Owschimikow
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Strasse des 17 Juni 135, 10623 Berlin, Germany.
| | - Iwan Moreels
- Istituto Italiano di Tecnologia, IT-16163 Genova, Italy and Department of Chemistry, Ghent University, Krijgslaan 281 - S3, 9000 Gent, Belgium
| | - Mikhail Artemyev
- Research Institute for Physical Chemical Problems of Belarusian State University, 220006, Minsk, Belarus
| | - Ulrike Woggon
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Strasse des 17 Juni 135, 10623 Berlin, Germany.
| | - Alexander W Achtstein
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Strasse des 17 Juni 135, 10623 Berlin, Germany.
| | - Marten Richter
- Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
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27
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Geiregat P, Tomar R, Chen K, Singh S, Hodgkiss JM, Hens Z. Thermodynamic Equilibrium between Excitons and Excitonic Molecules Dictates Optical Gain in Colloidal CdSe Quantum Wells. J Phys Chem Lett 2019; 10:3637-3644. [PMID: 31187998 DOI: 10.1021/acs.jpclett.9b01607] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We show that optical gain in 2D CdSe colloidal quantum wells (CQWs) shows little saturation and coexists with exciton absorption over a broad range of excitation densities, in stark contrast with 0D CdSe colloidal quantum dots (CQDs). In addition, we demonstrate that photoexcited CQWs can absorb or emit light through the thermodynamically driven formation or radiative recombination of singlet excitonic molecules. Invoking stimulated emission through the molecule-exciton transition, we can quantify all of the remarkable gain characteristics of CQWs using only experimentally determined parameters, an advance that highlights a fundamental difference between multiexcitons in CQWs and CQDs. While strong confinement prohibits the dissociation of multiexcitons into separate excitons in 0D CQDs, excitons and excitonic molecules coexist in a 2D CQW at room temperature, with densities governed by an association/dissociation equilibrium, not by state-filling. Our finding points out future directions to optimize stimulated emission by excitonic 2D materials in general.
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Affiliation(s)
- Pieter Geiregat
- Physics and Chemistry of Nanostructures , Ghent University , Gent 9000 , Belgium
- Center for Nano and Biophotonics , Gent 9000 , Belgium
| | - Renu Tomar
- Physics and Chemistry of Nanostructures , Ghent University , Gent 9000 , Belgium
- Center for Nano and Biophotonics , Gent 9000 , Belgium
| | - Kai Chen
- The MacDiarmid Institute for Advanced Materials and Nanotechnology , Wellington 6012 , New Zealand
- School of Chemical and Physical Sciences , Victoria University of Wellington , Wellington 6012 , New Zealand
- The Dodd-Walls Centre for Photonic and Quantum Technologies , Dunedin 9054 , New Zealand
| | - Shalini Singh
- Physics and Chemistry of Nanostructures , Ghent University , Gent 9000 , Belgium
- Center for Nano and Biophotonics , Gent 9000 , Belgium
| | - Justin M Hodgkiss
- The MacDiarmid Institute for Advanced Materials and Nanotechnology , Wellington 6012 , New Zealand
- School of Chemical and Physical Sciences , Victoria University of Wellington , Wellington 6012 , New Zealand
- The Dodd-Walls Centre for Photonic and Quantum Technologies , Dunedin 9054 , New Zealand
| | - Zeger Hens
- Physics and Chemistry of Nanostructures , Ghent University , Gent 9000 , Belgium
- Center for Nano and Biophotonics , Gent 9000 , Belgium
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28
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Guzelturk B, Pelton M, Olutas M, Demir HV. Giant Modal Gain Coefficients in Colloidal II-VI Nanoplatelets. NANO LETTERS 2019; 19:277-282. [PMID: 30539638 DOI: 10.1021/acs.nanolett.8b03891] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Modal gain coefficient is a key figure of merit for a laser material. Previously, net modal gain coefficients larger than a few thousand cm-1 were achieved in II-VI and III-V semiconductor gain media, but this required operation at cryogenic temperatures. In this work, using pump-fluence-dependent variable-stripe-length measurements, we show that colloidal CdSe nanoplatelets enable giant modal gain coefficients at room temperature up to 6600 cm-1 under pulsed optical excitation. Furthermore, we show that exceptional gain performance is common to the family of CdSe nanoplatelets, as shown by examining samples having different vertical thicknesses and lateral areas. Overall, colloidal II-VI nanoplatelets with superior optical gain properties are promising for a broad range of applications, including high-speed light amplification and loss compensation in plasmonic photonic circuits.
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Affiliation(s)
- Burak Guzelturk
- Stanford Institute for Materials and Energy Sciences , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology , Bilkent University , Ankara 06800 Turkey
| | - Matthew Pelton
- Department of Physics , University of Maryland, Baltimore County , Baltimore , Maryland 21250 , United States
| | - Murat Olutas
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology , Bilkent University , Ankara 06800 Turkey
- Department of Physics , Bolu Abant Izzet Baysal University , Bolu 14030 , Turkey
| | - Hilmi Volkan Demir
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology , Bilkent University , Ankara 06800 Turkey
- Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Mathematical Sciences, School of Materials Science and Engineering , Nanyang Technological University , Nanyang Avenue , Singapore 639798 , Singapore
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