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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: 32] [Impact Index Per Article: 32.0] [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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Klepzig LF, Biesterfeld L, Romain M, Niebur A, Schlosser A, Hübner J, Lauth J. Colloidal 2D PbSe nanoplatelets with efficient emission reaching the telecom O-, E- and S-band. NANOSCALE ADVANCES 2022; 4:590-599. [PMID: 36132696 PMCID: PMC9418099 DOI: 10.1039/d1na00704a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 12/14/2021] [Indexed: 05/14/2023]
Abstract
Colloidal two-dimensional (2D) lead chalcogenide nanoplatelets (NPLs) represent highly interesting materials for near- and short wave-infrared applications including innovative glass fiber optics exhibiting negligible attenuation. In this work, we demonstrate a direct synthesis route for 2D PbSe NPLs with cubic rock salt crystal structure at low reaction temperatures of 0 °C and room temperature. A lateral size tuning of the PbSe NPLs by controlling the temperature and by adding small amounts of octylamine to the reaction leads to excitonic absorption features in the range of 1.55-1.24 eV (800-1000 nm) and narrow photoluminescence (PL) reaching the telecom O-, E- and S-band (1.38-0.86 eV, 900-1450 nm). The PL quantum yield of the as-synthesized PbSe NPLs is more than doubled by a postsynthetic treatment with CdCl2 (e.g. from 14.7% to 37.4% for NPLs emitting at 980 nm with a FWHM of 214 meV). An analysis of the slightly asymmetric PL line shape of the PbSe NPLs and their characterization by ultrafast transient absorption and time-resolved PL spectroscopy reveal a surface trap related PL contribution which is successfully reduced by the CdCl2 treatment from 40% down to 15%. Our results open up new pathways for a direct synthesis and straightforward incorporation of colloidal PbSe NPLs as efficient infrared emitters at technologically relevant telecom wavelengths.
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Affiliation(s)
- Lars F Klepzig
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover Callinstr. 3A 30167 Hannover Germany
- Cluster of Excellence PhoenixD (Photonics, Optics, and Engineering - Innovation Across Disciplines) 30167 Hannover Germany
| | - Leon Biesterfeld
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover Callinstr. 3A 30167 Hannover Germany
- Cluster of Excellence PhoenixD (Photonics, Optics, and Engineering - Innovation Across Disciplines) 30167 Hannover Germany
| | - Michel Romain
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover Callinstr. 3A 30167 Hannover Germany
| | - André Niebur
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover Callinstr. 3A 30167 Hannover Germany
- Cluster of Excellence PhoenixD (Photonics, Optics, and Engineering - Innovation Across Disciplines) 30167 Hannover Germany
| | - Anja Schlosser
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover Callinstr. 3A 30167 Hannover Germany
- Laboratory of Nano and Quantum Engineering (LNQE), Leibniz Universität Hannover Schneiderberg 39 30167 Hannover Germany
| | - Jens Hübner
- Laboratory of Nano and Quantum Engineering (LNQE), Leibniz Universität Hannover Schneiderberg 39 30167 Hannover Germany
- Institute of Solid State Physics, Leibniz Universität Hannover Appelstraße 2 30167 Hannover Germany
| | - Jannika Lauth
- Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover Callinstr. 3A 30167 Hannover Germany
- Cluster of Excellence PhoenixD (Photonics, Optics, and Engineering - Innovation Across Disciplines) 30167 Hannover Germany
- Laboratory of Nano and Quantum Engineering (LNQE), Leibniz Universität Hannover Schneiderberg 39 30167 Hannover Germany
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3
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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: 13] [Impact Index Per Article: 6.5] [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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4
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Delikanli S, Erdem O, Isik F, Dehghanpour Baruj H, Shabani F, Yagci HB, Durmusoglu EG, Demir HV. Ultrahigh Green and Red Optical Gain Cross Sections from Solutions of Colloidal Quantum Well Heterostructures. J Phys Chem Lett 2021; 12:2177-2182. [PMID: 33630593 DOI: 10.1021/acs.jpclett.0c03836] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We demonstrate amplified spontaneous emission (ASE) in solution with ultralow thresholds of 30 μJ/cm2 in red and of 44 μJ/cm2 in green from engineered colloidal quantum well (CQW) heterostructures. For this purpose, CdSe/CdS core/crown CQWs, designed to hit the green region, and CdSe/CdS@CdxZn1-xS core/crown@gradient-alloyed shell CQWs, further tuned to reach the red region by shell alloying, were employed to achieve high-performance ASE in the visible range. The net modal gain of these CQWs reaches 530 cm-1 for the green and 201 cm-1 for the red, 2-3 orders of magnitude larger than those of colloidal quantum dots (QDs) in solution. To explain the root cause for ultrahigh gain coefficient in solution, we show for the first time that the gain cross sections of these CQWs is ≥3.3 × 10-14 cm2 in the green and ≥1.3 × 10-14 cm2 in the red, which are two orders of magnitude larger compared to those of CQDs.
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Affiliation(s)
- Savas Delikanli
- 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 Materials Sciences, Nanyang Technological University, Singapore 639798, Singapore
| | - Onur Erdem
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
| | - Furkan Isik
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
| | - Hamed Dehghanpour Baruj
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
| | - Farzan Shabani
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
| | - Huseyin Bilge Yagci
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800, Turkey
| | - Emek Goksu Durmusoglu
- Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, Nanyang Technological University, Singapore 639798, Singapore
| | - 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 Materials Sciences, Nanyang Technological University, Singapore 639798, Singapore
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5
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Skurlov I, Sokolova A, Galle T, Cherevkov S, Ushakova E, Baranov A, Lesnyak V, Fedorov A, Litvin A. Temperature-Dependent Photoluminescent Properties of PbSe Nanoplatelets. NANOMATERIALS 2020; 10:nano10122570. [PMID: 33371429 PMCID: PMC7767437 DOI: 10.3390/nano10122570] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 12/15/2020] [Accepted: 12/18/2020] [Indexed: 01/17/2023]
Abstract
Semiconductor colloidal nanoplatelets (NPLs) are a promising new class of nanostructures that can bring much impact on lightning technologies, light-emitting diodes (LED), and laser fabrication. Indeed, great progress has been made in optimizing the optical properties of the NPLs for the visible spectral range, which has already made the implementation of a number of effective devices on their basis possible. To date, state-of-the-art near-infrared (NIR)-emitting NPLs are significantly inferior to their visible-range counterparts, although it would be fair to say that they received significantly less research attention so far. In this study, we report a comprehensive analysis of steady-state and time-dependent photoluminescence (PL) properties of four monolayered (ML) PbSe NPLs. The PL measurements are performed in a temperature range of 78–300 K, and their results are compared to those obtained for CdSe NPLs and PbSe quantum dots (QDs). We show that multiple emissive states, both band-edge and trap-related, are responsible for the formation of the NPLs’ PL band. We demonstrate that the widening of the PL band is caused by the inhomogeneous broadening rather than homogeneous one, and analyze the possible contributions to PL broadening.
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Affiliation(s)
- Ivan Skurlov
- Center of Information Optical Technology, The Laboratory “Optics of Quantum Nanostructures”, ITMO University, 49 Kronverksky Pr., St. Petersburg 197101, Russia; (I.S.); (A.S.); (S.C.); (E.U.); (A.B.); (A.F.)
| | - Anastasiia Sokolova
- Center of Information Optical Technology, The Laboratory “Optics of Quantum Nanostructures”, ITMO University, 49 Kronverksky Pr., St. Petersburg 197101, Russia; (I.S.); (A.S.); (S.C.); (E.U.); (A.B.); (A.F.)
| | - Tom Galle
- Physical Chemistry, TU Dresden, Zellescher Weg 19, 01069 Dresden, Germany; (T.G.); (V.L.)
| | - Sergei Cherevkov
- Center of Information Optical Technology, The Laboratory “Optics of Quantum Nanostructures”, ITMO University, 49 Kronverksky Pr., St. Petersburg 197101, Russia; (I.S.); (A.S.); (S.C.); (E.U.); (A.B.); (A.F.)
| | - Elena Ushakova
- Center of Information Optical Technology, The Laboratory “Optics of Quantum Nanostructures”, ITMO University, 49 Kronverksky Pr., St. Petersburg 197101, Russia; (I.S.); (A.S.); (S.C.); (E.U.); (A.B.); (A.F.)
| | - Alexander Baranov
- Center of Information Optical Technology, The Laboratory “Optics of Quantum Nanostructures”, ITMO University, 49 Kronverksky Pr., St. Petersburg 197101, Russia; (I.S.); (A.S.); (S.C.); (E.U.); (A.B.); (A.F.)
| | - Vladimir Lesnyak
- Physical Chemistry, TU Dresden, Zellescher Weg 19, 01069 Dresden, Germany; (T.G.); (V.L.)
| | - Anatoly Fedorov
- Center of Information Optical Technology, The Laboratory “Optics of Quantum Nanostructures”, ITMO University, 49 Kronverksky Pr., St. Petersburg 197101, Russia; (I.S.); (A.S.); (S.C.); (E.U.); (A.B.); (A.F.)
| | - Aleksandr Litvin
- Center of Information Optical Technology, The Laboratory “Optics of Quantum Nanostructures”, ITMO University, 49 Kronverksky Pr., St. Petersburg 197101, Russia; (I.S.); (A.S.); (S.C.); (E.U.); (A.B.); (A.F.)
- Correspondence: ; Tel.: +7-950-0286240
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6
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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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7
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Liu B, Altintas Y, Wang L, Shendre S, Sharma M, Sun H, Mutlugun E, Demir HV. Record High External Quantum Efficiency of 19.2% Achieved in Light-Emitting Diodes of Colloidal Quantum Wells Enabled by Hot-Injection Shell Growth. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1905824. [PMID: 31867764 DOI: 10.1002/adma.201905824] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/13/2019] [Indexed: 06/10/2023]
Abstract
Colloidal quantum wells (CQWs) are regarded as a highly promising class of optoelectronic materials, thanks to their unique excitonic characteristics of high extinction coefficients and ultranarrow emission bandwidths. Although the exploration of CQWs in light-emitting diodes (LEDs) is impressive, the performance of CQW-LEDs lags far behind other types of soft-material LEDs (e.g., organic LEDs, colloidal-quantum-dot LEDs, and perovskite LEDs). Herein, high-efficiency CQW-LEDs reaching close to the theoretical limit are reported. A key factor for this high performance is the exploitation of hot-injection shell (HIS) growth of CQWs, which enables a near-unity photoluminescence quantum yield (PLQY), reduces nonradiative channels, ensures smooth films, and enhances the stability. Remarkably, the PLQY remains 95% in solution and 87% in film despite rigorous cleaning. Through systematically understanding their shape-, composition-, and device-engineering, the CQW-LEDs using CdSe/Cd0.25 Zn0.75 S core/HIS CQWs exhibit a maximum external quantum efficiency of 19.2%. Additionally, a high luminance of 23 490 cd m-2 , extremely saturated red color with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.715, 0.283), and stable emission are obtained. The findings indicate that HIS-grown CQWs enable high-performance solution-processed LEDs, which may pave the path for future CQW-based display and lighting technologies.
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Affiliation(s)
- Baiquan Liu
- Luminous! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 639798, Singapore
| | - Yemliha Altintas
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey
- Department of Materials Science and Nanotechnology and Department of Electrical-Electronics Engineering, Abdullah Gül University, Kayseri, TR-38080, Turkey
| | - Lin Wang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Sushant Shendre
- Luminous! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 639798, Singapore
| | - Manoj Sharma
- Luminous! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 639798, Singapore
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey
| | - Handong Sun
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
| | - Evren Mutlugun
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey
- Department of Materials Science and Nanotechnology and Department of Electrical-Electronics Engineering, Abdullah Gül University, Kayseri, TR-38080, Turkey
| | - Hilmi Volkan Demir
- Luminous! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering and School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 639798, Singapore
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore
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8
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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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9
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Yan F, Tan ST, Li X, Demir HV. Light Generation in Lead Halide Perovskite Nanocrystals: LEDs, Color Converters, Lasers, and Other Applications. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1902079. [PMID: 31650694 DOI: 10.1002/smll.201902079] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 08/22/2019] [Indexed: 05/22/2023]
Abstract
Facile solution processing lead halide perovskite nanocrystals (LHP-NCs) exhibit superior properties in light generation, including a wide color gamut, a high flexibility for tuning emissive wavelengths, a great defect tolerance and resulting high quantum yield; and intriguing electric feature of ambipolar transport with moderate and comparable mobility. As a result, LHP-NCs have accomplished great achievements in various light generation applications, including color converters for lighting and display, light-emitting diodes, low threshold lasing, X-ray scintillators, and single photon emitters. Herein, the considerable progress that has been made thus far is reviewed along with the current challenges and future prospects in the light generation applications of LHP-NCs.
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Affiliation(s)
- Fei Yan
- LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, TPI-The Photonics Institute, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Swee Tiam Tan
- LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, TPI-The Photonics Institute, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
| | - Xiao Li
- School of Chemical Engineering, University of Science and Technology Liaoning, Anshan, 114051, P. R. China
| | - Hilmi Volkan Demir
- LUMINOUS! Center of Excellence for Semiconductor Lighting and Displays, TPI-The Photonics Institute, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 639798, Singapore
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey
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10
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Erdem O, Gungor K, Guzelturk B, Tanriover I, Sak M, Olutas M, Dede D, Kelestemur Y, Demir HV. Orientation-Controlled Nonradiative Energy Transfer to Colloidal Nanoplatelets: Engineering Dipole Orientation Factor. NANO LETTERS 2019; 19:4297-4305. [PMID: 31185570 DOI: 10.1021/acs.nanolett.9b00681] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We proposed and showed strongly orientation-controlled Förster resonance energy transfer (FRET) to highly anisotropic CdSe nanoplatelets (NPLs). For this purpose, we developed a liquid-air interface self-assembly technique specific to depositing a complete monolayer of NPLs only in a single desired orientation, either fully stacked (edge-up) or fully nonstacked (face-down), with near-unity surface coverage and across large areas over 20 cm2. These NPL monolayers were employed as acceptors in an energy transfer working model system to pair with CdZnS/ZnS core/shell quantum dots (QDs) as donors. We found the resulting energy transfer from the QDs to be significantly accelerated (by up to 50%) to the edge-up NPL monolayer compared to the face-down one. We revealed that this acceleration of FRET is accounted for by the enhancement of the dipole-dipole interaction factor between a QD-NPL pair (increased from 1/3 to 5/6) as well as the closer packing of NPLs with stacking. Also systematically studying the distance-dependence of FRET between QDs and NPL monolayers via varying their separation (d) with a dielectric spacer, we found out that the FRET rate scales with d-4 regardless of the specific NPL orientation. Our FRET model, which is based on the original Förster theory, computes the FRET efficiencies in excellent agreement with our experimental results and explains well the enhancement of FRET to NPLs with stacking. These findings indicate that the geometrical orientation of NPLs and thereby their dipole interaction strength can be exploited as an additional degree of freedom to control and tune the energy transfer rate.
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Affiliation(s)
- Onur Erdem
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology , Bilkent University , Ankara 06800 , Turkey
| | - Kivanc Gungor
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology , Bilkent University , Ankara 06800 , Turkey
| | - Burak Guzelturk
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology , Bilkent University , Ankara 06800 , Turkey
| | - Ibrahim Tanriover
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology , Bilkent University , Ankara 06800 , Turkey
| | - Mustafa Sak
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology , Bilkent University , Ankara 06800 , Turkey
| | - Murat Olutas
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology , Bilkent University , Ankara 06800 , Turkey
| | - Didem Dede
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology , Bilkent University , Ankara 06800 , Turkey
| | - Yusuf Kelestemur
- Department of Electrical and Electronics Engineering, Department of Physics, UNAM - Institute of Materials Science and Nanotechnology , Bilkent University , Ankara 06800 , 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 , Nanyang Technological University , Nanyang Avenue , Singapore 639798 , Singapore
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11
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Liu Y, Rowell N, Willis M, Zhang M, Wang S, Fan H, Huang W, Chen X, Yu K. Photoluminescent Colloidal Nanohelices Self-Assembled from CdSe Magic-Size Clusters via Nanoplatelets. J Phys Chem Lett 2019; 10:2794-2801. [PMID: 31084015 DOI: 10.1021/acs.jpclett.9b00838] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Reports on photoluminescent colloidal semiconductor two-dimensional (2D) helical nanostructures with one-dimensional quantum confinement are relatively rare. Here, we discuss the formation of such photoluminescent nanostructures for CdSe. We show that when as-synthesized unpurified zero-dimensional (0D) CdSe magic-size clusters (MSCs) (passivated by carboxylate ligands with three-dimensional quantum confinement) are dispersed in a solvent (such as toluene or chloroform) containing hexadecylamine and then subjected to sonication, helical nanostructures are obtained, as observed by transmission electron microscopy. We demonstrate that the formation involves the self-assembly of 0D MSCs into 2D nanoplatelets, which act as intermediates. The CdSe MSCs and their self-assembled 2D nanostructures display almost identical static optical properties, namely, a sharp absorption doublet with peaks at 433 and 460 nm and a narrow emission peak at 465 nm; this is a subject for further study. This study introduces new methods for fabricating photoluminescent helical nanostructures via the self-assembly of photoluminescent MSCs.
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Affiliation(s)
- Yuanyuan Liu
- Institute of Atomic and Molecular Physics , Sichuan University , 610065 Sichuan , P. R. China
| | - Nelson Rowell
- Metrology Research Centre , National Research Council Canada , Ottawa , Ontario K1A 0R6 , Canada
| | - Maureen Willis
- School of Physical Science and Technology , Sichuan University , 610065 Sichuan , P. R. China
| | - Meng Zhang
- Institute of Atomic and Molecular Physics , Sichuan University , 610065 Sichuan , P. R. China
| | - Shanling Wang
- Analytical & Testing Center , Sichuan University , 610065 Sichuan , P. R. China
| | - Hongsong Fan
- Engineering Research Center in Biomaterials , Sichuan University , 610065 Sichuan , P. R. China
| | - Wen Huang
- Laboratory of Ethnopharmacology, West China School of Medicine , Sichuan University , 610065 Sichuan , People's Republic of China
| | - Xiaoqin Chen
- Engineering Research Center in Biomaterials , Sichuan University , 610065 Sichuan , P. R. China
| | - Kui Yu
- Institute of Atomic and Molecular Physics , Sichuan University , 610065 Sichuan , P. R. China
- Engineering Research Center in Biomaterials , Sichuan University , 610065 Sichuan , P. R. China
- State Key Laboratory of Polymer Materials Engineering , Sichuan University , 610065 Sichuan , P. R. China
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12
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Shendre S, Delikanli S, Li M, Dede D, Pan Z, Ha ST, Fu YH, Hernández-Martínez PL, Yu J, Erdem O, Kuznetsov AI, Dang C, Sum TC, Demir HV. Ultrahigh-efficiency aqueous flat nanocrystals of CdSe/CdS@Cd 1-xZn xS colloidal core/crown@alloyed-shell quantum wells. NANOSCALE 2018; 11:301-310. [PMID: 30534689 DOI: 10.1039/c8nr07879c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Colloidal semiconductor nanoplatelets (NPLs) are highly promising luminescent materials owing to their exceptionally narrow emission spectra. While high-efficiency NPLs in non-polar organic media can be obtained readily, NPLs in aqueous media suffer from extremely low quantum yields (QYs), which completely undermines their potential, especially in biological applications. Here, we show high-efficiency water-soluble CdSe/CdS@Cd1-xZnxS core/crown@shell NPLs formed by layer-by-layer grown and composition-tuned gradient Cd1-xZnxS shells on CdSe/CdS core/crown seeds. Such control of shell composition with monolayer precision and effective peripheral crown passivation, together with the compact capping density of short 3-mercaptopropionic acid ligands, allow for QYs reaching 90% in water, accompanied by a significantly increased photoluminescence lifetime (∼35 ns), indicating the suppression of nonradiative channels in these NPLs. We also demonstrate the controlled attachment of these NPLs without stacking at the nanoscale by taking advantage of their 2D geometry and hydrophilicity. This is a significant step in achieving controlled assemblies and overcoming the stacking process, which otherwise undermines their film formation and performance in optoelectronic applications. Moreover, we show that the parallel orientation of such NPLs achieved by the controlled attachment enables directed emission perpendicular to the surface of the NPL films, which is highly advantageous for light extraction in light-emitting platforms.
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Affiliation(s)
- Sushant Shendre
- LUMINOUS! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798.
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13
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Diroll BT, Cho W, Coropceanu I, Harvey SM, Brumberg A, Holtgrewe N, Crooker SA, Wasielewski MR, Prakapenka VB, Talapin DV, Schaller RD. Semiconductor Nanoplatelet Excimers. NANO LETTERS 2018; 18:6948-6953. [PMID: 30244582 DOI: 10.1021/acs.nanolett.8b02865] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Excimers, a portmanteau of "excited dimer", are transient species that are formed from the electronic interaction of a fluorophore in the excited state with a neighbor in the ground state, which have found extensive use as laser gain media. Although common in molecular fluorophores, this work presents evidence for the formation of excimers in a new class of materials: atomically precise two-dimensional semiconductor nanoplatelets. Colloidal nanoplatelets of CdSe display two-color photoluminescence resolved at low temperatures with one band attributed to band-edge fluorescence and a second, red band attributed to excimer fluorescence. Previously reasonable explanations for two-color fluorescence, such as charging, are shown to be inconsistent with additional evidence. As with excimers in other materials systems, excimer emission is increased by increasing nanoplatelet concentration and the degree of cofacial stacking. Consistent with their promise as low-threshold gain media, amplified spontaneous emission emerges from the excimer emission line.
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Affiliation(s)
- Benjamin T Diroll
- Center for Nanoscale Materials , Argonne National Laboratory , Lemont , Illinois 60439 , United States
| | - Wooje Cho
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States
| | - Igor Coropceanu
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , United States
| | - Samantha M Harvey
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
- Institute for Sustainability and Energy , Northwestern University , Evanston , Illinois 60208 , United States
| | - Alexandra Brumberg
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| | - Nicholas Holtgrewe
- Center for Advanced Radiation Sources , University of Chicago , Chicago , Illinois 60439 , United States
| | - Scott A Crooker
- National High Magnetic Field Laboratory , Los Alamos , New Mexico 87545 , United States
| | - Michael R Wasielewski
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
- Institute for Sustainability and Energy , Northwestern University , Evanston , Illinois 60208 , United States
| | - Vitali B Prakapenka
- Center for Advanced Radiation Sources , University of Chicago , Chicago , Illinois 60439 , United States
| | - Dmitri V Talapin
- Department of Chemistry , University of Chicago , Chicago , Illinois 60637 , 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
- Institute for Sustainability and Energy , Northwestern University , Evanston , Illinois 60208 , United States
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14
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Giovanella U, Pasini M, Lorenzon M, Galeotti F, Lucchi C, Meinardi F, Luzzati S, Dubertret B, Brovelli S. Efficient Solution-Processed Nanoplatelet-Based Light-Emitting Diodes with High Operational Stability in Air. NANO LETTERS 2018; 18:3441-3448. [PMID: 29722262 DOI: 10.1021/acs.nanolett.8b00456] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Colloidal nanoplatelets (NPLs), owing to their efficient and narrow-band luminescence, are considered as promising candidates for solution-processable light-emitting diodes (LEDs) with ultrahigh color purity. To date, however, the record efficiencies of NPL-LEDs are significantly lower than those of more-investigated devices based on spherical nanocrystals. This is particularly true for red-emitting NPL-LEDs, the best-reported external quantum efficiency (EQE) of which is limited to 0.63% (EQE = 5% for green NPL-LEDs). Here, we address this issue by introducing a charge-regulating layer of a polar and polyelectrolytic polymer specifically engineered with complementary trimethylammonium and phosphonate functionalities that provide high solubility in orthogonal polar media with respect to the NPL active layer, compatibility with the metal cathode, and the ability to control electron injection through the formation of a polarized interface under bias. Through this synergic approach, we achieve EQE = 5.73% at 658 nm (color saturation 98%) in completely solution processed LEDs. Remarkably, exposure to air increases the EQE to 8.39%, exceeding the best reports of red NPL-LEDs by over 1 order of magnitude and setting a new global record for quantum-dot LEDs of any color embedding solution-deposited organic interlayers. Considering the emission quantum yield of the NPLs (40 ± 5%), this value corresponds to a near-unity internal quantum efficiency. Notably, our devices show exceptional operational stability for over 5 h of continuous drive in air with no encapsulation, thus confirming the potential of NPLs for efficient, high-stability, saturated LEDs.
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Affiliation(s)
- Umberto Giovanella
- Istituto per lo Studio delle Macromolecole , Consiglio Nazionale delle Ricerche (ISMac-CNR) , Via Bassini 15 , 20133 Milano , Italy
| | - Mariacecilia Pasini
- Istituto per lo Studio delle Macromolecole , Consiglio Nazionale delle Ricerche (ISMac-CNR) , Via Bassini 15 , 20133 Milano , Italy
| | - Monica Lorenzon
- Dipartimento di Scienza dei Materiali , Università degli Studi di Milano-Bicocca , via Cozzi 55 , I-20125 Milano , Italy
| | - Francesco Galeotti
- Istituto per lo Studio delle Macromolecole , Consiglio Nazionale delle Ricerche (ISMac-CNR) , Via Bassini 15 , 20133 Milano , Italy
| | - Claudio Lucchi
- Dipartimento di Scienza dei Materiali , Università degli Studi di Milano-Bicocca , via Cozzi 55 , I-20125 Milano , Italy
| | - Francesco Meinardi
- Dipartimento di Scienza dei Materiali , Università degli Studi di Milano-Bicocca , via Cozzi 55 , I-20125 Milano , Italy
| | - Silvia Luzzati
- Istituto per lo Studio delle Macromolecole , Consiglio Nazionale delle Ricerche (ISMac-CNR) , Via Bassini 15 , 20133 Milano , Italy
| | - Benoit Dubertret
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI-ParisTech , PSL Research University, Sorbonne Université UPMC Université Paris 06, CNRS , 10 rue Vauquelin , 75005 Paris , France
| | - Sergio Brovelli
- Dipartimento di Scienza dei Materiali , Università degli Studi di Milano-Bicocca , via Cozzi 55 , I-20125 Milano , Italy
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15
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Shornikova EV, Biadala L, Yakovlev DR, Sapega VF, Kusrayev YG, Mitioglu AA, Ballottin MV, Christianen PCM, Belykh VV, Kochiev MV, Sibeldin NN, Golovatenko AA, Rodina AV, Gippius NA, Kuntzmann A, Jiang Y, Nasilowski M, Dubertret B, Bayer M. Addressing the exciton fine structure in colloidal nanocrystals: the case of CdSe nanoplatelets. NANOSCALE 2018; 10:646-656. [PMID: 29239445 DOI: 10.1039/c7nr07206f] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We study the band-edge exciton fine structure and in particular its bright-dark splitting in colloidal semiconductor nanocrystals by four different optical methods based on fluorescence line narrowing and time-resolved measurements at various temperatures down to 2 K. We demonstrate that all these methods provide consistent splitting values and discuss their advances and limitations. Colloidal CdSe nanoplatelets with thicknesses of 3, 4 and 5 monolayers are chosen for experimental demonstrations. The bright-dark splitting of excitons varies from 3.2 to 6.0 meV and is inversely proportional to the nanoplatelet thickness. Good agreement between experimental and theoretically calculated size dependence of the bright-dark exciton splitting is achieved. The recombination rates of the bright and dark excitons and the bright to dark relaxation rate are measured by time-resolved techniques.
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Affiliation(s)
- Elena V Shornikova
- Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany.
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16
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Bose S, Shendre S, Song Z, Sharma VK, Zhang DH, Dang C, Fan W, Demir HV. Temperature-dependent optoelectronic properties of quasi-2D colloidal cadmium selenide nanoplatelets. NANOSCALE 2017; 9:6595-6605. [PMID: 28475189 DOI: 10.1039/c7nr00163k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Colloidal cadmium selenide (CdSe) nanoplatelets (NPLs) are a recently developed class of efficient luminescent nanomaterials suitable for optoelectronic device applications. A change in temperature greatly affects their electronic bandstructure and luminescence properties. It is important to understand how and why the characteristics of NPLs are influenced, particularly at elevated temperatures, where both reversible and irreversible quenching processes come into the picture. Here we present a study of the effect of elevated temperatures on the characteristics of colloidal CdSe NPLs. We used an effective-mass envelope function theory based 8-band k·p model and density-matrix theory considering exciton-phonon interaction. We observed the photoluminescence (PL) spectra at various temperatures for their photon emission energy, PL linewidth and intensity by considering the exciton-phonon interaction with both acoustic and optical phonons using Bose-Einstein statistical factors. With a rise in temperature we observed a fall in the transition energy (emission redshift), matrix element, Fermi factor and quasi Fermi separation, with a reduction in intraband state gaps and increased interband coupling. Also, there was a fall in the PL intensity, along with spectral broadening due to an intraband scattering effect. The predicted transition energy values and simulated PL spectra at varying temperatures exhibit appreciable consistency with the experimental results. Our findings have important implications for the application of NPLs in optoelectronic devices, such as NPL lasers and LEDs, operating much above room temperature.
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Affiliation(s)
- Sumanta Bose
- School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
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