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Ossia Y, Levi A, Chefetz N, Peleg A, Remennik S, Vakahi A, Banin U. Seeing is believing: Correlating optoelectronic functionality with atomic scale imaging of single semiconductor nanocrystals. J Chem Phys 2024; 160:134201. [PMID: 38573848 DOI: 10.1063/5.0198140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 02/29/2024] [Indexed: 04/06/2024] Open
Abstract
A unique on-chip method for the direct correlation of optical properties, with atomic-scale chemical-structural characteristics for a single quantum dot (QD), is developed and utilized in various examples. This is based on performing single QD optical characterization on a modified glass substrate, followed by the extraction of the relevant region of interest by focused-ion-beam-scanning electron microscope processing into a lamella for high resolution scanning transmission electron microscopy (STEM) characterization with atomic scale resolution. The direct correlation of the optical response under an electric field with STEM analysis of the same particle allows addressing several single particle phenomena: first, the direct correlation of single QD photoluminescence (PL) polarization and its response to the external field with the QD crystal lattice alignment, so far inferred indirectly; second, the identification of unique yet rare few-QD assemblies, correlated directly with their special spectroscopic optical characteristics, serving as a guide for future designed assemblies; and third, the study on the effect of metal island growth on the PL behavior of hybrid semiconductor-metal nanoparticles, with relevance for their possible functionality in photocatalysis. This work, therefore, establishes the use of the direct on-chip optical-structural correlation method for numerous scenarios and timely questions in the field of QD research.
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Affiliation(s)
- Yonatan Ossia
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Adar Levi
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Nadav Chefetz
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Amir Peleg
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Sergei Remennik
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Atzmon Vakahi
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Uri Banin
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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2
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Ossia Y, Levi A, Panfil YE, Koley S, Scharf E, Chefetz N, Remennik S, Vakahi A, Banin U. Electric-field-induced colour switching in colloidal quantum dot molecules at room temperature. NATURE MATERIALS 2023; 22:1210-1217. [PMID: 37537354 DOI: 10.1038/s41563-023-01606-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 06/14/2023] [Indexed: 08/05/2023]
Abstract
Colloidal semiconductor quantum dots are robust emitters implemented in numerous prototype and commercial optoelectronic devices. However, active fluorescence colour tuning, achieved so far by electric-field-induced Stark effect, has been limited to a small spectral range, and accompanied by intensity reduction due to the electron-hole charge separation effect. Utilizing quantum dot molecules that manifest two coupled emission centres, we present a unique electric-field-induced instantaneous colour-switching effect. Reversible emission colour switching without intensity loss is achieved on a single-particle level, as corroborated by correlated electron microscopy imaging. Simulations establish that this is due to the electron wavefunction toggling between the two centres, induced by the electric field, and affected by the coupling strength. Quantum dot molecules manifesting two coupled emission centres may be tailored to emit distinct colours, opening the path for sensitive field sensing and colour-switchable devices such as a novel pixel design for displays or an electric-field-induced colour-tunable single-photon source.
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Affiliation(s)
- Yonatan Ossia
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Adar Levi
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Yossef E Panfil
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Somnath Koley
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Einav Scharf
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Nadav Chefetz
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Sergei Remennik
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Atzmon Vakahi
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Uri Banin
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel.
- The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem, Israel.
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3
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Lei Y, Ma J, Luo J, Huang S, Yu B, Song C, Xing Q, Wang F, Xie Y, Zhang J, Mu L, Ma Y, Wang C, Yan H. Layer-dependent exciton polarizability and the brightening of dark excitons in few-layer black phosphorus. Nat Commun 2023; 14:5314. [PMID: 37658093 PMCID: PMC10474117 DOI: 10.1038/s41467-023-41126-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 08/24/2023] [Indexed: 09/03/2023] Open
Abstract
The evolution of excitons from 2D to 3D is of great importance in photo-physics, yet the layer-dependent exciton polarizability hasn't been investigated in 2D semiconductors. Here, we determine the exciton polarizabilities for 3- to 11-layer black phosphorus-a direct bandgap semiconductor regardless of the thickness-through frequency-resolved photocurrent measurements on dual-gate devices and unveil the carrier screening effect in relatively thicker samples. By taking advantage of the broadband photocurrent spectra, we are also able to reveal the exciton response for higher-index subbands under the gate electrical field. Surprisingly, dark excitons are brightened with intensity even stronger than the allowed transitions above certain electrical field. Our study not only sheds light on the exciton evolution with sample thickness, but also paves a way for optoelectronic applications of few-layer BP in modulators, tunable photodetectors, emitters and lasers.
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Affiliation(s)
- Yuchen Lei
- State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano-Photonic Structures (Ministry of Education), and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Junwei Ma
- State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano-Photonic Structures (Ministry of Education), and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Jiaming Luo
- State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano-Photonic Structures (Ministry of Education), and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Shenyang Huang
- State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano-Photonic Structures (Ministry of Education), and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Boyang Yu
- State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano-Photonic Structures (Ministry of Education), and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Chaoyu Song
- State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano-Photonic Structures (Ministry of Education), and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Qiaoxia Xing
- State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano-Photonic Structures (Ministry of Education), and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Fanjie Wang
- State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano-Photonic Structures (Ministry of Education), and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Yuangang Xie
- State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano-Photonic Structures (Ministry of Education), and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Jiasheng Zhang
- State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano-Photonic Structures (Ministry of Education), and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Lei Mu
- State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano-Photonic Structures (Ministry of Education), and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Yixuan Ma
- State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano-Photonic Structures (Ministry of Education), and Department of Physics, Fudan University, Shanghai, 200433, China
| | - Chong Wang
- Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081, China
- Beijing Key Lab of Nanophotonics & Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081, China
| | - Hugen Yan
- State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano-Photonic Structures (Ministry of Education), and Department of Physics, Fudan University, Shanghai, 200433, China.
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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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5
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Quick MT, Ayari S, Owschimikow N, Jaziri S, Achtstein AW. THz mobility and polarizability: impact of transformation and dephasing on the spectral response of excitons in a 2D semiconductor. Phys Chem Chem Phys 2023; 25:3354-3360. [PMID: 36633188 DOI: 10.1039/d2cp03584g] [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
We introduce a response theory based transformation for excitonic polarizability into mobility, which allows an in-depth analysis of optical pump-THz probe conductivity experiments, and compare the results with those of a conventional oscillator model. THz spectroscopy is of high interest e.g. for investigations in high bandwidth and low noise nanoelectronics or solar energy harvesting nanomaterials. In contrast to simple ω scaling of estimated static polarizability, suggested in the literature, an appropriate transformation of the spectral response into mobility can be achieved in principle forward and backward due to the presence of dephasing, as we show for the exemplary system of CdSe nanoplatelets. Common analysis approaches capture the excitonic properties only under specific conditions, and do not apply in many cases. We demonstrate that a thermal distribution of excitons and transitions between higher states in general have to be considered and that dephasing has to be taken into account for a proper transformation at all temperatures. The presented in-depth understanding of the exciton mobility in nanoparticles can help improve e.g. solar hydrogen generation, charge extraction efficiencies of solar cells, or light emission performance of LEDs.
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Affiliation(s)
- Michael T Quick
- Institute of Optics and Atomic Physics, Technische Universität Berlin, 10623, Berlin, Germany.
| | - Sabrine Ayari
- Laboratoire de Physique de l'École normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Nina Owschimikow
- Institute of Optics and Atomic Physics, Technische Universität Berlin, 10623, Berlin, Germany.
| | - Sihem Jaziri
- Laboratoire de Physique des Matériaux Structure et Propriétés, Faculté des Sciences de Tunis, Laboratoire de Physique de la Matière Condensée, Département de Physique, Université Tunis el Manar, Campus Universitaire 2092 Tunis, Tunisia.,Laboratoire de Physique des Materiaux, Faculte des Sciences de Bizerte, Universite de Carthage, Jarzouna, 7021, Tunisia
| | - Alexander W Achtstein
- Institute of Optics and Atomic Physics, Technische Universität Berlin, 10623, Berlin, Germany.
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6
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Jasrasaria D, Weinberg D, Philbin JP, Rabani E. Simulations of nonradiative processes in semiconductor nanocrystals. J Chem Phys 2022; 157:020901. [PMID: 35840368 DOI: 10.1063/5.0095897] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The description of carrier dynamics in spatially confined semiconductor nanocrystals (NCs), which have enhanced electron-hole and exciton-phonon interactions, is a great challenge for modern computational science. These NCs typically contain thousands of atoms and tens of thousands of valence electrons with discrete spectra at low excitation energies, similar to atoms and molecules, that converge to the continuum bulk limit at higher energies. Computational methods developed for molecules are limited to very small nanoclusters, and methods for bulk systems with periodic boundary conditions are not suitable due to the lack of translational symmetry in NCs. This perspective focuses on our recent efforts in developing a unified atomistic model based on the semiempirical pseudopotential approach, which is parameterized by first-principle calculations and validated against experimental measurements, to describe two of the main nonradiative relaxation processes of quantum confined excitons: exciton cooling and Auger recombination. We focus on the description of both electron-hole and exciton-phonon interactions in our approach and discuss the role of size, shape, and interfacing on the electronic properties and dynamics for II-VI and III-V semiconductor NCs.
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Affiliation(s)
- Dipti Jasrasaria
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Daniel Weinberg
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - John P Philbin
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Eran Rabani
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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7
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Diroll BT, Brumberg A, Schaller RD. Gain roll-off in cadmium selenide colloidal quantum wells under intense optical excitation. Sci Rep 2022; 12:8016. [PMID: 35577869 PMCID: PMC9110332 DOI: 10.1038/s41598-022-11882-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 02/24/2022] [Indexed: 12/04/2022] Open
Abstract
Colloidal quantum wells, or nanoplatelets, show among the lowest thresholds for amplified spontaneous emission and lasing among solution-cast materials and among the highest modal gains of any known materials. Using solution measurements of colloidal quantum wells, this work shows that under photoexcitation, optical gain increases with pump fluence before rolling off due to broad photoinduced absorption at energies lower than the band gap. Despite the common occurrence of gain induced by an electron–hole plasma found in bulk materials and epitaxial quantum wells, under no measurement conditions was the excitonic absorption of the colloidal quantum wells extinguished and gain arising from a plasma observed. Instead, like gain, excitonic absorption reaches a minimum intensity near a photoinduced carrier sheet density of 2 × 1013 cm−2 above which the absorption peak begins to recover. To understand the origins of these saturation and reversal effects, measurements were performed with different excitation energies, which deposit differing amounts of excess energy above the band gap. Across many samples, it was consistently observed that less energetic excitation results in stronger excitonic bleaching and gain for a given carrier density. Transient and static optical measurements at elevated temperatures, as well as transient X-ray diffraction of the samples, suggest that the origin of gain saturation and reversal is a heating and disordering of the colloidal quantum wells which produces sub-gap photoinduced absorption.
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8
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Roy D, Shapira Z, Weiss S. Membrane Potential Sensing: Materials Design & Methods Development for Single Particle Optical Electrophysiology. J Chem Phys 2022; 156:084201. [DOI: 10.1063/5.0076522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Debjit Roy
- Department of Chemistry & Biochemistry, University of California Los Angeles, United States of America
| | - Zehavit Shapira
- Department of Physics, The institute of nanotechnology, Bar-Ilan University, Israel
| | - Shimon Weiss
- Department of Chemistry and Biochemistry, University of California Los Angeles Department of Chemistry and Biochemistry, United States of America
- Bar-Ilan University
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9
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Ben Amara I, Boustanji H, Jaziri S. Tuning optoelectronic response of lateral core-alloyed crown nanoplatelets: type-II CdSe-CdSe 1-xTe x. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:465301. [PMID: 34412039 DOI: 10.1088/1361-648x/ac1f4e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 08/19/2021] [Indexed: 06/13/2023]
Abstract
We present a theoretical study showing that the exciton emission in the CdSe-CdSe1-xTexcore-alloyed crown heterostructure results from the tunable quasi-type II to pure type II behavior by adjusting the Te to Se ratio. We suggest that the direct crown exciton or interface indirect exciton or a dual emission can be tuned due to the altered conduction band offset. We also found that these different emissions are red-shifted with increasing the nanoplatelets (NPLs) monolayer (ML) thickness due to the quantum confinement effect. The double exciton emission develops caused by the band bowing effect occurring in the alloyed crown. The band bowing is originated from the difference between the bonding nature of the Se and Te orbitals with the Cd orbitals in the conduction band edge states. We also found that the band bowing is sensitive on the alloyed-crown ML thickness and the in-plane strain due to hybridization magnitude between the cation (Cd) and anion (Se, Te). Our results are in accord with the available experimental data. We propose the CdSe-CdSe1-xTexcore-alloyed crown NPLs as a promising contender for the near-infrared-emitting heterostructures preparation used for light-harvesting applications.
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Affiliation(s)
- Imen Ben Amara
- Faculté des Sciences de Tunis, Laboratoire de Physique de la Matière Condensée, Université Tunis el Manar, Campus Universitaire 2092 Tunis, Tunisia
| | - Hela Boustanji
- Faculté des Sciences de Tunis, Laboratoire de Physique de la Matière Condensée, Université Tunis el Manar, Campus Universitaire 2092 Tunis, Tunisia
| | - Sihem Jaziri
- Faculté des Sciences de Tunis, Laboratoire de Physique de la Matière Condensée, Université Tunis el Manar, Campus Universitaire 2092 Tunis, Tunisia
- Faculté des Sciences de Bizerte, Laboratoire de Physique des Matériaux: Structure et Propriétés, Université de Carthage, 7021 Jarzouna, Tunisia
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10
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Quick MT, Owschimikow N, Achtstein AW. Terahertz Charge Carrier Mobility in 1D and 2D Semiconductor Nanoparticles. J Phys Chem Lett 2021; 12:7688-7695. [PMID: 34378384 DOI: 10.1021/acs.jpclett.1c02045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We investigate the charge carrier mobility in 1D and 2D semiconductor nanoparticle domains with a focus on the interpretation of THz mobility measurements. We provide a microscopic understanding of the frequency-dependent charge carrier transport in these structures of finite lateral size. Yet unexplored oscillations in the frequency-dependent complex conductivity and a strong size dependence of the mobility are observed. The quantum nature of the charge carrier states results in oscillations in the frequency-dependent mobility for subresonant THz probing, seen in experiments. The effect is based on the lack of an energy continuum for the charge motion. In 2D systems the mobility is further governed by transitions in the two orthogonal x- and y-directions and depends nontrivially on the THz polarization, as well as the quantum well lateral aspect ratio, defining the energetic detuning of the lowest THz-photon transitions in both directions. We analyze the frequency, length, and effective mass dependencies.
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Affiliation(s)
- Michael T Quick
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Nina Owschimikow
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
| | - Alexander W Achtstein
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany
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Dang TH, Vasanelli A, Todorov Y, Sirtori C, Prado Y, Chu A, Gréboval C, Khalili A, Cruguel H, Delerue C, Vincent G, Lhuillier E. Bias Tunable Spectral Response of Nanocrystal Array in a Plasmonic Cavity. NANO LETTERS 2021; 21:6671-6677. [PMID: 34339191 DOI: 10.1021/acs.nanolett.1c02193] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Nanocrystals (NCs) have gained considerable attention for their broadly tunable absorption from the UV to the THz range. Nevertheless, their optical features suffer from a lack of tunability once integrated into optoelectronic devices. Here, we show that bias tunable aspectral response is obtained by coupling a HgTe NC array with a plasmonic resonator. Up to 15 meV blueshift can be achieved from a 3 μm absorbing wavelength structure under a 3 V bias voltage when the NC exciton is coupled with a mode of the resonator. We demonstrate that the blueshift arises from the interplay between hopping transport and inhomogeneous absorption due to the presence of the photonic structure. The observed tunable spectral response is qualitatively reproduced in simulation by introducing a bias-dependent diffusion length in the charge transport. This work expands the realm of existing NC-based devices and paves the way toward light modulators.
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Affiliation(s)
- Tung Huu Dang
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
| | - Angela Vasanelli
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
| | - Yanko Todorov
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
| | - Carlo Sirtori
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
| | - Yoann Prado
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
| | - Audrey Chu
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
- ONERA - The French Aerospace Lab, 6, chemin de la Vauve aux Granges, BP 80100, 91123 Palaiseau, France
| | - Charlie Gréboval
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
| | - Adrien Khalili
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
| | - Herve Cruguel
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
| | - Christophe Delerue
- Univ. Lille, CNRS, Centrale Lille, Univ. Polytechnique Hauts-de-France, Junia, UMR 8520 - IEMN, F-59000 Lille, France
| | - Gregory Vincent
- ONERA - The French Aerospace Lab, 6, chemin de la Vauve aux Granges, BP 80100, 91123 Palaiseau, France
| | - Emmanuel Lhuillier
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP, 75005 Paris, France
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Geiregat P, Rodá C, Tanghe I, Singh S, Di Giacomo A, Lebrun D, Grimaldi G, Maes J, Van Thourhout D, Moreels I, Houtepen AJ, Hens Z. Localization-limited exciton oscillator strength in colloidal CdSe nanoplatelets revealed by the optically induced stark effect. LIGHT, SCIENCE & APPLICATIONS 2021; 10:112. [PMID: 34054127 PMCID: PMC8165098 DOI: 10.1038/s41377-021-00548-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 04/21/2021] [Accepted: 04/28/2021] [Indexed: 05/04/2023]
Abstract
2D materials are considered for applications that require strong light-matter interaction because of the apparently giant oscillator strength of the exciton transitions in the absorbance spectrum. Nevertheless, the effective oscillator strengths of these transitions have been scarcely reported, nor is there a consistent interpretation of the obtained values. Here, we analyse the transition dipole moment and the ensuing oscillator strength of the exciton transition in 2D CdSe nanoplatelets by means of the optically induced Stark effect (OSE). Intriguingly, we find that the exciton absorption line reacts to a high intensity optical field as a transition with an oscillator strength FStark that is 50 times smaller than expected based on the linear absorption coefficient. We propose that the pronounced exciton absorption line should be seen as the sum of multiple, low oscillator strength transitions, rather than a single high oscillator strength one, a feat we assign to strong exciton center-of-mass localization. Within the quantum mechanical description of excitons, this 50-fold difference between both oscillator strengths corresponds to the ratio between the coherence area of the exciton's center of mass and the total area, which yields a coherence area of a mere 6.1 nm2. Since we find that the coherence area increases with reducing temperature, we conclude that thermal effects, related to lattice vibrations, contribute to exciton localization. In further support of this localization model, we show that FStark is independent of the nanoplatelet area, correctly predicts the radiative lifetime, and lines up for strongly confined quantum dot systems.
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Affiliation(s)
- Pieter Geiregat
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Gent, Belgium.
- Center for Nano and Biophotonics, Ghent University, Gent, Belgium.
| | - Carmelita Rodá
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Gent, Belgium
| | - Ivo Tanghe
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Gent, Belgium
- Photonics Research Group, Ghent University, Gent, Belgium
| | - Shalini Singh
- Department of Chemical Sciences and Bernal Institute, University of Limerick, Limerick, Ireland
| | - Alessio Di Giacomo
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Gent, Belgium
| | - Delphine Lebrun
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Gent, Belgium
| | - Gianluca Grimaldi
- Center for Nanophotonics, NWO-Institute AMOLF, Science Park 104, 1098 XG, Amsterdam, The Netherlands
| | - Jorick Maes
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Gent, Belgium
| | - Dries Van Thourhout
- Center for Nano and Biophotonics, Ghent University, Gent, Belgium
- Photonics Research Group, Ghent University, Gent, Belgium
| | - Iwan Moreels
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Gent, Belgium
| | - Arjan J Houtepen
- Opto-Electronic Materials Section, Department of Chemical Engineering, Delft University, Delft, The Netherlands
| | - Zeger Hens
- Physics and Chemistry of Nanostructures, Department of Chemistry, Ghent University, Gent, Belgium
- Center for Nano and Biophotonics, Ghent University, Gent, Belgium
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13
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Shin AJ, Hossain AA, Tenney SM, Tan X, Tan LA, Foley JJ, Atallah TL, Caram JR. Dielectric Screening Modulates Semiconductor Nanoplatelet Excitons. J Phys Chem Lett 2021; 12:4958-4964. [PMID: 34010003 DOI: 10.1021/acs.jpclett.1c00624] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The influence of external dielectric environments is well understood for 2D semiconductor materials but overlooked for colloidally grown II-VI nanoplatelets (NPLs). In this work, we synthesize MX (M = Cd, Hg; X = Se, Te) NPLs of varying thicknesses and apply the Elliott model to extract exciton binding energies-reporting values in good agreement with prior methods and extending to less studied cadmium telluride and mercury chalcogenide NPLs. We find that the exciton binding energy is modulated both by the relative effect of internal vs external dielectric and by the thickness of the semiconductor material. An analytical model shows dielectric screening increases the exciton binding energy relative to the bulk by distorting the Coulombic potential across the NPL surface. We further confirm this effect by decreasing and recovering the exciton binding energy of HgTe NPLs through washing in polarizable solvents. Our results illustrate NPLs are colloidal analogues of van der Waals 2D semiconductors and point to surface modification as an approach to control photophysics and device properties.
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Affiliation(s)
- 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
| | - Azmain A Hossain
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States
| | - 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
| | - Xuanheng Tan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States
| | - Lauren A Tan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States
| | - Jonathan J Foley
- Department of Chemistry, William Paterson University, 300 Pompton Road, Wayne, New Jersey 07470, 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
| | - 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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14
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Lv B, Zhu T, Tang Y, Lv Y, Zhang C, Wang X, Shu D, Xiao M. Probing Permanent Dipole Moments and Removing Exciton Fine Structures in Single Perovskite Nanocrystals by an Electric Field. PHYSICAL REVIEW LETTERS 2021; 126:197403. [PMID: 34047589 DOI: 10.1103/physrevlett.126.197403] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 09/27/2020] [Accepted: 04/08/2021] [Indexed: 05/16/2023]
Abstract
Single perovskite nanocrystals have emerged as a novel type of semiconductor nanostructure capable of emitting single photons with rich exciton species and fine energy-level structures. Here we focus on single excitons and biexcitons in single perovskite CsPbI_{3} nanocrystals to show, for the first time, how their optical properties are modulated by an external electric field at the cryogenic temperature. The electric field can cause a blueshift in the photoluminescence peak of single excitons, from which the existence of a permanent dipole moment can be deduced. Meanwhile, the fine energy-level structures of single excitons and biexcitons in a single CsPbI_{3} nanocrystal can be simultaneously eliminated, thus preparing a potent platform for the potential generation of polarization-entangled photon pairs.
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Affiliation(s)
- Bihu Lv
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Tianyuan Zhu
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Ying Tang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yan Lv
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Chunfeng Zhang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Xiaoyong Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Dajun Shu
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Min Xiao
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA
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15
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Moghaddam N, Dabard C, Dufour M, Po H, Xu X, Pons T, Lhuillier E, Ithurria S. Surface Modification of CdE (E: S, Se, and Te) Nanoplatelets to Reach Thicker Nanoplatelets and Homostructures with Confinement-Induced Intraparticle Type I Energy Level Alignment. J Am Chem Soc 2021; 143:1863-1872. [PMID: 33471504 DOI: 10.1021/jacs.0c10336] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Two-dimensional II-VI semiconductor nanoplatelets (NPLs) present exceptionally narrow optical features due to their thickness defined at the atomic scale. Because thickness drives the band-edge energy, its control is of paramount importance. Here, we demonstrate that native carboxylate ligands can be replaced by halides that partially dissolve cadmium chalcogenide NPLs at the edges. The released monomers then recrystallize on the wide top and bottom facets, leading to an increase in NPL thickness. This dissolution/recrystallization method is used to increase NPL thickness to 9 ML while using 3 ML NPLs as the starting material. We also demonstrate that this method is not limited to CdSe and can be extended to CdS and CdTe to grow thick NPLs. When the metal halide precursor is introduced with a chalcogenide precursor on the NPLs, CdSe/CdSe, CdTe/CdTe, and CdSe/CdTe core/shell homo- and heterostructures are achieved. Finally, when an incomplete layer is grown, NPLs with steps are synthesized. These stress-free homostructures are comparable to type I heterostructures, leading to recombination of the exciton in the thicker area of the NPLs. Following the growth of core/crown and core/shell NPLs, it affords a new degree of freedom for the growth of structured NPLs with designed band engineering, which has so far been only achievable for heteromaterial nanostructures.
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Affiliation(s)
- Nicolas Moghaddam
- CNRS, Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université UPMC Univ Paris 06, 10 rue Vauquelin, 75005 Paris, France
| | - Corentin Dabard
- CNRS, Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université UPMC Univ Paris 06, 10 rue Vauquelin, 75005 Paris, France.,CNRS, Institut des NanoSciences de Paris, INSP, Sorbonne Université, F-75005 Paris, France
| | - Marion Dufour
- CNRS, Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université UPMC Univ Paris 06, 10 rue Vauquelin, 75005 Paris, France
| | - Hong Po
- CNRS, Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université UPMC Univ Paris 06, 10 rue Vauquelin, 75005 Paris, France
| | - Xiangzhen Xu
- CNRS, Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université UPMC Univ Paris 06, 10 rue Vauquelin, 75005 Paris, France
| | - Thomas Pons
- CNRS, Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université UPMC Univ Paris 06, 10 rue Vauquelin, 75005 Paris, France
| | - Emmanuel Lhuillier
- CNRS, Institut des NanoSciences de Paris, INSP, Sorbonne Université, F-75005 Paris, France
| | - Sandrine Ithurria
- CNRS, Laboratoire de Physique et d'Etude des Matériaux, ESPCI-Paris, PSL Research University, Sorbonne Université UPMC Univ Paris 06, 10 rue Vauquelin, 75005 Paris, France
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16
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Achtstein AW, Ayari S, Helmrich S, Quick MT, Owschimikow N, Jaziri S, Woggon U. Tuning exciton diffusion, mobility and emission line width in CdSe nanoplatelets via lateral size. NANOSCALE 2020; 12:23521-23531. [PMID: 33225335 DOI: 10.1039/d0nr04745g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We investigate the lateral size tunability of the exciton diffusion coefficient and mobility in colloidal quantum wells by means of line width analysis and theoretical modeling. We show that the exciton diffusion coefficient and mobility in laterally finite 2D systems like CdSe nanoplatelets can be tuned via the lateral size and aspect ratio. The coupling to acoustic and optical phonons can be altered via the lateral size and aspect ratio of the platelets. Subsequently the exciton diffusion and mobility become tunable since these phonon scattering processes determine and limit the mobility. At 4 K the exciton mobility increases from ∼ 4 × 103 cm2 V-1 s-1 to more than 1.4 × 104 cm2 V-1 s-1 for large platelets, while there are weaker changes with size and the mobility is around 8 × 101 cm2 V-1 s-1 for large platelets at room temperature. In turn at 4 K the exciton diffusion coefficient increases with the lateral size from ∼ 1.3 cm2 s-1 to ∼ 5 cm2 s-1, while it is around half the value for large platelets at room temperature. Our experimental results are in good agreement with theoretical modeling, showing a lateral size and aspect ratio dependence. The findings open up the possibility for materials with tunable exciton mobility, diffusion or emission line width, but quasi constant transition energy. High exciton mobility is desirable e.g. for solar cells and allows efficient excitation harvesting and extraction.
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Affiliation(s)
- Alexander W Achtstein
- Institute of Optics and Atomic Physics, Technische Universität Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
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17
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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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18
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Steinmetz V, Ramade J, Legrand L, Barisien T, Bernardot F, Lhuillier E, Bernard M, Vabre M, Saïdi I, Ghribi A, Boujdaria K, Testelin C, Chamarro M. Anisotropic shape of CsPbBr 3 colloidal nanocrystals: from 1D to 2D confinement effects. NANOSCALE 2020; 12:18978-18986. [PMID: 32915178 DOI: 10.1039/d0nr03901b] [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
We synthesized strongly anisotropic CsPbBr3 nanocrystals with very narrow emission and absorption lines associated to confinement effects along one or two dimensions, called respectively nanoplatelets (NPLs) and nanosticks (NSTs). Transmission Electron Microscopy (TEM) images, absorption and photoluminescence (PL) spectra taken at low temperature are very precise tools to determine which kind of confinement has to be considered and to deduce the shape, the size and the thickness of nanocrystals under focus. We show that the energy of the band-edge absorption and PL peaks versus the inverse of the square of the NPL thickness has a linear behaviour from 11 monolayers (MLs) i.e. a thickness of 6.38 nm, until 4 MLs (2.32 nm) showing that self-energy correction compensates the increase of the exciton binding energy in thin NPLs as already observed in Cadmium chalcogenides-based NPLs. We also show that slight changes in the morphology of NSTs leads to a very drastic modification of their absorption spectra. Time-resolved PL of NSTs has a non-monotonous behaviour with temperature. At 5 K, a quasi-single exponential with a lifetime of 80 ps is obtained; at intermediate temperature, the decay is bi-exponential and at 150 K, a quasi-single exponential decay is recovered (≈0.4 ns). For NSTs, the exciton interaction with LO phonons governs the broadening of the absorption and PL peaks at room temperature and is stronger than in chalcogenides quantum dots and NPLs.
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Affiliation(s)
- Violette Steinmetz
- Sorbonne Université, CNRS-UMR 7588, Institut des NanoSciences de Paris, INSP, 4 place Jussieu, F-75005, Paris, France.
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19
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Philbin JP, Brumberg A, Diroll BT, Cho W, Talapin DV, Schaller RD, Rabani E. Area and thickness dependence of Auger recombination in nanoplatelets. J Chem Phys 2020; 153:054104. [PMID: 32770880 DOI: 10.1063/5.0012973] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The ability to control both the thickness and the lateral dimensions of colloidal nanoplatelets offers a test-bed for area and thickness dependent properties in 2D materials. An important example is Auger recombination, which is typically the dominant process by which multiexcitons decay in nanoplatelets. Herein, we uncover fundamental properties of biexciton decay in nanoplatelets by comparing the Auger recombination lifetimes based on interacting and noninteracting formalisms with measurements based on transient absorption spectroscopy. Specifically, we report that electron-hole correlations in the initial biexcitonic state must be included in order to obtain Auger recombination lifetimes in agreement with experimental measurements and that Auger recombination lifetimes depend nearly linearly on the lateral area and somewhat more strongly on the thickness of the nanoplatelet. We also connect these scalings to those of the area and thickness dependencies of single exciton radiative recombination lifetimes, exciton coherence areas, and exciton Bohr radii in these quasi-2D materials.
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Affiliation(s)
- John P Philbin
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Alexandra Brumberg
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - Benjamin T Diroll
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Wooje Cho
- Department of Chemistry and James Franck Institute, University of Chicago, Chicago, Illinois 60637, USA
| | - Dmitri V Talapin
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Richard D Schaller
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - Eran Rabani
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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20
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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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21
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Di Nuzzo D, Cui L, Greenfield JL, Zhao B, Friend RH, Meskers SCJ. Circularly Polarized Photoluminescence from Chiral Perovskite Thin Films at Room Temperature. ACS NANO 2020; 14:7610-7616. [PMID: 32459955 DOI: 10.1021/acsnano.0c03628] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Hybrid organic-inorganic perovskites allow the synthesis of high-quality, nanostructured semiconducting films via easily accessible solution-based techniques. This has allowed tremendous development in optoelectronic applications, primarily solar cells and light-emitting diodes. Allowed by the ease of access to nanostructure, chirality has recently been introduced in semiconducting perovskites as a promising way to obtain advanced control of charge and spin and for developing circularly polarized light sources. Circular polarization of photoluminescence (CPL) is a powerful tool to probe the electronic structure of materials. However, CPL in chiral perovskites has been scarcely investigated, and a study in bulk thin films and at room temperature is still missing. In this work, we fabricate bromine-based chiral perovskites by using a bulky chiral organic cation mixed with CsBr, resulting in Ruddlesden-Popper perovskite thin films. We measure CPL on these films at room temperature and, by using unpolarized photoexcitation, we record a degree of circular polarization of photoluminescence in the order of 10-3 and provide a full spectral characterization of CPL. Our results show that chirality is imparted on the electronic structure of the semiconductor; we hypothesize that the excess in polarization of emitted light originates from the charge in the photogenerated Wannier exciton describing an orbit in a symmetry-broken environment. Furthermore, our experiments allow the direct measurement of the magnetic dipole moment of the optical transition, which we estimate to be ≥0.1 μB. Finally, we discuss the implications of our findings on the development of chiral semiconducting perovskites as sources of circularly polarized light.
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Affiliation(s)
- Daniele Di Nuzzo
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Linsong Cui
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Jake L Greenfield
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Baodan Zhao
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Richard H Friend
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Stefan C J Meskers
- Institute for Complex Molecular Systems, Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
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22
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Momper R, Zhang H, Chen S, Halim H, Johannes E, Yordanov S, Braga D, Blülle B, Doblas D, Kraus T, Bonn M, Wang HI, Riedinger A. Kinetic Control over Self-Assembly of Semiconductor Nanoplatelets. NANO LETTERS 2020; 20:4102-4110. [PMID: 32163287 PMCID: PMC7307971 DOI: 10.1021/acs.nanolett.9b05270] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 03/06/2020] [Indexed: 05/26/2023]
Abstract
Semiconductor nanoplatelets exhibit spectrally pure, directional fluorescence. To make polarized light emission accessible and the charge transport effective, nanoplatelets have to be collectively oriented in the solid state. We discovered that the collective nanoplatelets orientation in monolayers can be controlled kinetically by exploiting the solvent evaporation rate in self-assembly at liquid interfaces. Our method avoids insulating additives such as surfactants, making it ideally suited for optoelectronics. The monolayer films with controlled nanoplatelets orientation (edge-up or face-down) exhibit long-range ordering of transition dipole moments and macroscopically polarized light emission. Furthermore, we unveil that the substantial in-plane electronic coupling between nanoplatelets enables charge transport through a single nanoplatelets monolayer, with an efficiency that strongly depends on the orientation of the nanoplatelets. The ability to kinetically control the assembly of nanoplatelets into ordered monolayers with tunable optical and electronic properties paves the way for new applications in optoelectronic devices.
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Affiliation(s)
- Rebecca Momper
- Max-Planck-Institute
for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Heng Zhang
- Max-Planck-Institute
for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Shuai Chen
- Max-Planck-Institute
for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Henry Halim
- Max-Planck-Institute
for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Ewald Johannes
- Max-Planck-Institute
for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Stoyan Yordanov
- Max-Planck-Institute
for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Daniele Braga
- Fluxim AG, Katharina-Sulzer-Platz 2, 8400 Winterthur, Switzerland
| | - Balthasar Blülle
- Fluxim AG, Katharina-Sulzer-Platz 2, 8400 Winterthur, Switzerland
| | - David Doblas
- INM − Leibniz-Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
| | - Tobias Kraus
- INM − Leibniz-Institute for New Materials, Campus D2 2, 66123 Saarbrücken, Germany
- Colloid
and Interface Chemistry, Saarland University, Campus D2 2, 66123 Saarbruecken, Germany
| | - Mischa Bonn
- Max-Planck-Institute
for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Hai I. Wang
- Max-Planck-Institute
for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Andreas Riedinger
- Max-Planck-Institute
for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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23
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Yu J, Shendre S, Koh WK, Liu B, Li M, Hou S, Hettiarachchi C, Delikanli S, Hernández-Martínez P, Birowosuto MD, Wang H, Sum T, Demir HV, Dang C. Electrically control amplified spontaneous emission in colloidal quantum dots. SCIENCE ADVANCES 2019; 5:eaav3140. [PMID: 31692653 PMCID: PMC6814376 DOI: 10.1126/sciadv.aav3140] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 09/14/2019] [Indexed: 05/29/2023]
Abstract
Colloidal quantum dots (CQDs) are highly promising materials for light amplification thanks to their efficient photoluminescence, tunable emission wavelength and low-cost synthesis. Unfortunately, CQDs are suffering from band-edge state degeneracy which demands multiple excitons to achieve population inversion. As a result, non-radiative Auger recombination increases the lasing threshold and limits the gain lifetime. Here, benefiting from the negative charging, we demonstrate that the amplified spontaneous emission (ASE) threshold is controllable in a device where CQD film is exposed to an external electric field. Specifically, singly charged CQDs lower the threshold due to the preexisting electron in the conduction band, while strongly enhanced Auger recombination in doubly charged CQDs stymies the ASE. Experimental results and kinetic equation model show that ASE threshold reduces 10% even if our device only charges ~17% of the CQD population. Our results open new possibilities for controlling exciton recombination dynamics and achieving electrically pumped CQD lasers.
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Affiliation(s)
- Junhong Yu
- LUMINOUS! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore, Singapore
| | - Sushant Shendre
- LUMINOUS! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore, Singapore
| | - Weon-kyu Koh
- LUMINOUS! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore, Singapore
| | - Baiquan Liu
- LUMINOUS! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore, Singapore
| | - Mingjie Li
- School of Physical and Mathematical Sciences, Nanyang Technological University, 639798 Singapore, Singapore
| | - Songyan Hou
- CINTRA UMI CNRS/NTU/THALES 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, 637553 Singapore, Singapore
| | - Chathuranga Hettiarachchi
- Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering & The Photonics Institute, Nanyang Technological University, 639798 Singapore, Singapore
| | - Savas Delikanli
- LUMINOUS! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore, Singapore
| | - Pedro Hernández-Martínez
- LUMINOUS! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore, Singapore
| | - Muhammad Danang Birowosuto
- CINTRA UMI CNRS/NTU/THALES 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, 637553 Singapore, Singapore
| | - Hong Wang
- CINTRA UMI CNRS/NTU/THALES 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, 637553 Singapore, Singapore
- Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering & The Photonics Institute, Nanyang Technological University, 639798 Singapore, Singapore
| | - TzeChien Sum
- School of Physical and Mathematical Sciences, Nanyang Technological University, 639798 Singapore, Singapore
| | - Hilmi Volkan Demir
- LUMINOUS! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore, Singapore
- School of Physical and Mathematical Sciences, Nanyang Technological University, 639798 Singapore, Singapore
- Department of Electrical and Electronics Engineering and Department of Physics, UNAM–Institute of Materials Science and Nanotechnology, Bilkent University, Bilkent, Ankara, 06800, Turkey
| | - Cuong Dang
- LUMINOUS! Centre of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 Singapore, Singapore
- CINTRA UMI CNRS/NTU/THALES 3288, Research Techno Plaza, 50 Nanyang Drive, Border X Block, Level 6, 637553 Singapore, Singapore
- Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering & The Photonics Institute, Nanyang Technological University, 639798 Singapore, Singapore
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24
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Brumberg A, Harvey SM, Philbin JP, Diroll BT, Lee B, Crooker SA, Wasielewski MR, Rabani E, Schaller RD. Determination of the In-Plane Exciton Radius in 2D CdSe Nanoplatelets via Magneto-optical Spectroscopy. ACS NANO 2019; 13:8589-8596. [PMID: 31251582 DOI: 10.1021/acsnano.9b02008] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Colloidal, two-dimensional semiconductor nanoplatelets (NPLs) exhibit quantum confinement in only one dimension, which results in an electronic structure that is significantly altered compared to that of other quantum-confined nanomaterials. Whereas it is often assumed that the lack of quantum confinement in the lateral plane yields a spatially extended exciton, reduced dielectric screening potentially challenges this picture. Here, we implement absorption spectroscopy in pulsed magnetic fields up to 60 T for three different CdSe NPL thicknesses and lateral areas. Based on diamagnetic shifts, we find that the exciton lateral extent is comparable to NPL thickness, indicating that the quantum confinement and reduced screening concomitant with few-monolayer thickness strongly reduces the exciton lateral extent. Atomistic electronic structure calculations of the exciton size for varying lengths, widths, and thicknesses support the substantially smaller in-plane exciton extent.
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Affiliation(s)
| | | | - John P Philbin
- Department of Chemistry , University of California , Berkeley , California 94720 , United States
| | | | | | - Scott A Crooker
- National High Magnetic Field Laboratory , Los Alamos National Laboratory , Los Alamos , New Mexico 87545 , United States
| | | | - Eran Rabani
- Department of Chemistry , University of California , Berkeley , California 94720 , United States
- The Sackler Center for Computational Molecular and Materials Science , Tel Aviv University , Tel Aviv 69978 , Israel
- Materials Science Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
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25
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Zelewski SJ, Nawrot KC, Zak A, Gladysiewicz M, Nyk M, Kudrawiec R. Exciton Binding Energy of Two-Dimensional Highly Luminescent Colloidal Nanostructures Determined from Combined Optical and Photoacoustic Spectroscopies. J Phys Chem Lett 2019; 10:3459-3464. [PMID: 31180226 DOI: 10.1021/acs.jpclett.9b00591] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Reduced dimensionality of structures such as 0D quantum dots, 1D nanorods, and 2D nanoplatelets is predicted to favor the creation of tightly bound excitons stable at room temperature, making experimental determination of the exciton binding energy ( R x) crucial for evaluating the performance of semiconductor nanoparticles. We propose a fully optical approach for R x determination based on a complementary combination of photoacoustic and transmission spectra, using 5.5, 4.5, and 3.5 ML CdSe nanoplatelets as a benchmark system. The absence of excitonic features in photoacoustic spectra allows for probing the band-to-band transition, leading to the band gap determination. Such an unusual effect is explained by efficient re-emission of the absorbed radiation typical for high quantum yield structures, keeping the crystal lattice from excess phonon generation. The determined exciton binding energy for CdSe nanoplatelets ranges from 130 to 230 meV, confirming the presence of robust excitons in highly confined 2D systems.
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Affiliation(s)
- Szymon J Zelewski
- Department of Experimental Physics, Faculty of Fundamental Problems of Technology , Wroclaw University of Science and Technology , Wybrzeże Wyspiańskiego 27 , 50-370 Wroclaw , Poland
| | - Katarzyna C Nawrot
- Advanced Materials Engineering and Modelling Group, Faculty of Chemistry , Wroclaw University of Science and Technology , Wybrzeże Wyspiańskiego 27 , 50-370 Wroclaw , Poland
| | - Andrzej Zak
- Department of Material Science, Welding and Strength of Materials, Faculty of Mechanical Engineering , Wroclaw University of Science and Technology , Wybrzeże Wyspiańskiego 27 , 50-370 Wroclaw , Poland
| | - Marta Gladysiewicz
- Department of Experimental Physics, Faculty of Fundamental Problems of Technology , Wroclaw University of Science and Technology , Wybrzeże Wyspiańskiego 27 , 50-370 Wroclaw , Poland
| | - Marcin Nyk
- Advanced Materials Engineering and Modelling Group, Faculty of Chemistry , Wroclaw University of Science and Technology , Wybrzeże Wyspiańskiego 27 , 50-370 Wroclaw , Poland
| | - Robert Kudrawiec
- Department of Experimental Physics, Faculty of Fundamental Problems of Technology , Wroclaw University of Science and Technology , Wybrzeże Wyspiańskiego 27 , 50-370 Wroclaw , Poland
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26
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Scott R, Prudnikau AV, Antanovich A, Christodoulou S, Riedl T, Bertrand GHV, Owschimikow N, Lindner JKN, Hens Z, Moreels I, Artemyev M, Woggon U, Achtstein AW. A comparative study demonstrates strong size tunability of carrier-phonon coupling in CdSe-based 2D and 0D nanocrystals. NANOSCALE 2019; 11:3958-3967. [PMID: 30762858 DOI: 10.1039/c8nr09458f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In a comparative study we investigate the carrier-phonon coupling in CdSe based core-only and hetero 2D as well as 0D nanoparticles. We demonstrate that the coupling can be strongly tuned by the lateral size of nanoplatelets, while, due to the weak lateral confinement, the transition energies are only altered by tens of meV. Our analysis shows that an increase in the lateral platelet area results in a strong decrease in the phonon coupling to acoustic modes due to deformation potential interaction, yielding an exciton deformation potential of 3.0 eV in line with theory. In contrast, coupling to optical modes tends to increase with the platelet area. This cannot be explained by Fröhlich interaction, which is generally dominant in II-VI materials. We compare CdSe/CdS nanoplatelets with their equivalent, spherical CdSe/CdS nanoparticles. Universally, in both systems the introduction of a CdS shell is shown to result in an increase of the average phonon coupling, mainly related to an increase of the coupling to acoustic modes, while the coupling to optical modes is reduced with increasing CdS layer thickness. The demonstrated size and CdS overgrowth tunability has strong implications for applications like tuning carrier cooling and carrier multiplication - relevant for solar energy harvesting applications. Other implications range from transport in nanosystems e.g. for field effect transistors or dephasing control. Our results open up a new toolbox for the design of photonic materials.
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Affiliation(s)
- Riccardo Scott
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
| | - 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
| | | | - Thomas Riedl
- Department of Physics, Paderborn University, Warburger Strasse 100, 33098 Paderborn, Germany
| | - Guillaume H V Bertrand
- CEA Saclay, 91191 Gif-sur-Yvette, France and Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Nina Owschimikow
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
| | - Jörg K N Lindner
- Department of Physics, Paderborn University, Warburger Strasse 100, 33098 Paderborn, Germany
| | - Zeger Hens
- Department of Chemistry, Ghent University, Krijgslaan 281 - S3, 9000 Gent, Belgium
| | - Iwan Moreels
- Department of Chemistry, Ghent University, Krijgslaan 281 - S3, 9000 Gent, Belgium and Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Mikhail Artemyev
- Research Institute for Physical Chemical Problems of Belarusian State University, 220006, Minsk, Belarus
| | - Ulrike Woggon
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
| | - Alexander W Achtstein
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, 10623 Berlin, Germany.
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27
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Cho SJ, Kong GD, Park S, Park J, Byeon SE, Kim T, Yoon HJ. Molecularly Controlled Stark Effect Induces Significant Rectification in Polycyclic-Aromatic-Hydrocarbon-Terminated n-Alkanethiolates. NANO LETTERS 2019; 19:545-553. [PMID: 30582703 DOI: 10.1021/acs.nanolett.8b04488] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The variation of the electronic structure of individual molecules as a function of the applied bias matters for the performance of molecular and organic electronic devices. Understanding the structure-electric-field relationship, however, remains a challenge because of the lack of in-operando spectroscopic technique and complexity arising from the ill-defined on-surface structure of molecules and organic-electrode interfaces within devices. We report that a reliable and reproducible molecular diode can be achieved by control of the conjugation length in polycyclic-aromatic-hydrocarbon (PAH)-terminated n-alkanethiolate (denoted as SC11PAH), incorporated into liquid-metal-based large-area tunnel junctions in the form of a self-assembled monolayer. By taking advantage of the structural simplicity and tunability of SC11PAH and the high-yielding feature of the junction technique, we demonstrate that the increase in the conjugation length of the PAH terminal group leads to a significant rectification ratio up to ∼1.7 × 102 at ±740 mV. Further study suggests that the Stark shift of the molecular energy resonance of the PAH breaks the symmetry of the energy topography across the junction and induces rectification in a temperature-independent charge-transport regime.
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Affiliation(s)
- Soo Jin Cho
- Department of Chemistry , Korea University , Seoul 136-701 , Korea
| | - Gyu Don Kong
- Department of Chemistry , Korea University , Seoul 136-701 , Korea
| | - Sohyun Park
- Department of Chemistry , Korea University , Seoul 136-701 , Korea
| | - Jeongwoo Park
- Department of Physics , Hankuk University of Foreign Studies , Yongin 449-791 , Korea
| | - Seo Eun Byeon
- Department of Chemistry , Korea University , Seoul 136-701 , Korea
| | - Taekyeong Kim
- Department of Physics , Hankuk University of Foreign Studies , Yongin 449-791 , Korea
| | - Hyo Jae Yoon
- Department of Chemistry , Korea University , Seoul 136-701 , Korea
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28
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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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29
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Achtstein AW, Marquardt O, Scott R, Ibrahim M, Riedl T, Prudnikau AV, Antanovich A, Owschimikow N, Lindner JKN, Artemyev M, Woggon U. Impact of Shell Growth on Recombination Dynamics and Exciton-Phonon Interaction in CdSe-CdS Core-Shell Nanoplatelets. ACS NANO 2018; 12:9476-9483. [PMID: 30192515 DOI: 10.1021/acsnano.8b04803] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We investigate the impact of shell growth on the carrier dynamics and exciton-phonon coupling in CdSe-CdS core-shell nanoplatelets with varying shell thickness. We observe that the recombination dynamics can be prolonged by more than one order of magnitude, and analyze the results in a global rate model as well as with simulations including strain and excitonic effects. We reveal that type I band alignment in the hetero platelets is maintained at least up to three monolayers of CdS, resulting in approximately constant radiative rates. Hence, observed changes of decay dynamics are not the result of an increasingly different electron and hole exciton wave function delocalization as often assumed, but an increasingly better passivation of nonradiative surface defects by the shell. Based on a global analysis of time-resolved and time-integrated data, we recover and model the temperature dependent quantum yield of these nanostructures and show that CdS shell growth leads to a strong enhancement of the photoluminescence quantum yield. Our results explain, for example, the very high lasing gain observed in CdSe-CdS nanoplatelets due to the type I band alignment that also makes them interesting as solar energy concentrators. Further, we reveal that the exciton-LO-phonon coupling is strongly tunable by the CdS shell thickness, enabling emission line width and coherence length control.
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Affiliation(s)
- Alexander W Achtstein
- Institute of Optics and Atomic Physics , Technical University of Berlin , Strasse des 17. Juni 135 , 10623 Berlin , Germany
| | - Oliver Marquardt
- Weierstraß Institute for Applied Analysis and Stochastics , Mohrenstraße 39 , 10117 Berlin , Germany
| | - Riccardo Scott
- Institute of Optics and Atomic Physics , Technical University of Berlin , Strasse des 17. Juni 135 , 10623 Berlin , Germany
| | - Mohamed Ibrahim
- Institute of Optics and Atomic Physics , Technical University of Berlin , Strasse des 17. Juni 135 , 10623 Berlin , Germany
| | - Thomas Riedl
- Department of Physics , Paderborn University , Warburger Strasse 100 , 33098 Paderborn , Germany
| | - Anatol V Prudnikau
- Research Institute for Physical Chemical Problems of Belarusian State University , 220006 Minsk , Belarus
- Physical Chemistry , TU Dresden , Bergstrasse 66b , 01062 Dresden , Germany
| | - Artsiom Antanovich
- Research Institute for Physical Chemical Problems of Belarusian State University , 220006 Minsk , Belarus
| | - Nina Owschimikow
- Institute of Optics and Atomic Physics , Technical University of Berlin , Strasse des 17. Juni 135 , 10623 Berlin , Germany
| | - Jörg K N Lindner
- Department of Physics , Paderborn University , Warburger Strasse 100 , 33098 Paderborn , Germany
| | - Mikhail Artemyev
- Research Institute for Physical Chemical Problems of Belarusian State University , 220006 Minsk , Belarus
| | - Ulrike Woggon
- Institute of Optics and Atomic Physics , Technical University of Berlin , Strasse des 17. Juni 135 , 10623 Berlin , Germany
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30
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Bar-Elli O, Steinitz D, Yang G, Tenne R, Ludwig A, Kuo Y, Triller A, Weiss S, Oron D. Rapid Voltage Sensing with Single Nanorods via the Quantum Confined Stark Effect. ACS PHOTONICS 2018; 5:2860-2867. [PMID: 30042952 PMCID: PMC6053642 DOI: 10.1021/acsphotonics.8b00206] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Indexed: 05/05/2023]
Abstract
Properly designed colloidal semiconductor quantum dots (QDs) have already been shown to exhibit high sensitivity to external electric fields via the quantum confined Stark effect (QCSE). Yet, detection of the characteristic spectral shifts associated with the effect of the QCSE has traditionally been painstakingly slow, dramatically limiting the sensitivity of these QD sensors to fast transients. We experimentally demonstrate a new detection scheme designed to achieve shot-noise-limited sensitivity to emission wavelength shifts in QDs, showing feasibility for their use as local electric field sensors on the millisecond time scale. This regime of operation is already potentially suitable for detection of single action potentials in neurons at a high spatial resolution.
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Affiliation(s)
- Omri Bar-Elli
- Department of Physics
of Complex Systems, Weizmann Institute of
Science, Rehovot 76100, Israel
| | - Dan Steinitz
- Department of Physics
of Complex Systems, Weizmann Institute of
Science, Rehovot 76100, Israel
| | - Gaoling Yang
- Department of Physics
of Complex Systems, Weizmann Institute of
Science, Rehovot 76100, Israel
| | - Ron Tenne
- Department of Physics
of Complex Systems, Weizmann Institute of
Science, Rehovot 76100, Israel
| | - Anastasia Ludwig
- L’Ecole
Normale Superieure, Institute of Biologie
(IBENS), Paris Sciences et Lettres (PSL), CNRS UMR 8197, Inserm 1024, 46 Rue d’Ulm, Paris 75005, France
| | - Yung Kuo
- Department of Chemistry and Biochemistry, Department of Physiology,
and California NanoSystems Institute, University
of California Los Angeles, Los
Angeles, California 90095, United States
| | - Antoine Triller
- L’Ecole
Normale Superieure, Institute of Biologie
(IBENS), Paris Sciences et Lettres (PSL), CNRS UMR 8197, Inserm 1024, 46 Rue d’Ulm, Paris 75005, France
| | - Shimon Weiss
- Department of Chemistry and Biochemistry, Department of Physiology,
and California NanoSystems Institute, University
of California Los Angeles, Los
Angeles, California 90095, United States
- Department of Physics, Institute for Nanotechnology
and Advanced Materials, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Dan Oron
- Department of Physics
of Complex Systems, Weizmann Institute of
Science, Rehovot 76100, Israel
- E-mail:
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31
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Hung SF, Chen ZZ, Chang CC, Hsu CS, Tsai MK, Kang CC, Chen HM. Dual-Hole Excitons Activated Photoelectrolysis in Neutral Solution. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1704047. [PMID: 29457346 DOI: 10.1002/smll.201704047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Revised: 12/21/2017] [Indexed: 06/08/2023]
Abstract
II-VI semiconductors exhibit unique behaviors that can generate dual-holes ("heavy and light"), but the application in photocatalysis is still missing. Herein, an empirical utilization of light/heavy holes in a hybrid metal cluster-2D semiconductor nanoplatelets is reported. This hybrid material can boost the hole-transfer at the surface and suppress the recombination. Different roles are enacted by light-holes and heavy-holes, in which the light-holes with higher energy and mobility can facilitate the slow kinetics of water oxidation and further reduce the onset voltage, while the massive heavy-holes can increase the resulting photocurrent by about five times, achieving a photocurrent of 2 mA cm-2 at 1.23 V versus RHE under AM 1.5 G illumination in nonsacrificial neutral solution. These strategies can be the solutions for photoelectrolysis and be beneficial for sustainable development in solar conversion.
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Affiliation(s)
- Sung-Fu Hung
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
| | - Zhi-Zhong Chen
- Department of Chemistry, Fu Jen Catholic University, New Taipei City, 242, Taiwan
| | - Chun-Chih Chang
- Department of Chemistry, National Taiwan Normal University, Taipei, 116, Taiwan
| | - Chia-Shuo Hsu
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
| | - Ming-Kang Tsai
- Department of Chemistry, National Taiwan Normal University, Taipei, 116, Taiwan
| | - Chia-Cheng Kang
- Department of Chemistry, Fu Jen Catholic University, New Taipei City, 242, Taiwan
| | - Hao Ming Chen
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
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32
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Black A, Roberts J, Acebrón M, Bernardo-Gavito R, Alsharif G, Urbanos FJ, Juárez BH, Kolosov OV, Robinson BJ, Miranda R, Vázquez de Parga AL, Granados D, Young RJ. Large-Area Heterostructures from Graphene and Encapsulated Colloidal Quantum Dots via the Langmuir-Blodgett Method. ACS APPLIED MATERIALS & INTERFACES 2018; 10:6805-6809. [PMID: 29436818 DOI: 10.1021/acsami.7b17102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This work explores the assembly of large-area heterostructures comprised of a film of silica-encapsulated, semiconducting colloidal quantum dots, deposited via the Langmuir-Blodgett method, sandwiched between two graphene sheets. The luminescent, electrically insulating film served as a dielectric, with the top graphene sheet patterned into an electrode and successfully used as a top gate for an underlying graphene field-effect transistor. This heterostructure paves the way for developing novel hybrid optoelectronic devices through the integration of 2D and 0D materials.
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Affiliation(s)
| | - Jonathan Roberts
- Physics Department, Lancaster University , Lancaster LA1 4YB, United Kingdom
| | | | | | - Ghazi Alsharif
- Physics Department, Lancaster University , Lancaster LA1 4YB, United Kingdom
- Physics Department, Faculty of Science, Taibah University , Tayba, Medina 42353, Saudi Arabia
| | | | | | - Oleg V Kolosov
- Physics Department, Lancaster University , Lancaster LA1 4YB, United Kingdom
| | - Benjamin J Robinson
- Physics Department, Lancaster University , Lancaster LA1 4YB, United Kingdom
| | | | | | | | - Robert J Young
- Physics Department, Lancaster University , Lancaster LA1 4YB, United Kingdom
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33
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Scott R, Heckmann J, Prudnikau AV, Antanovich A, Mikhailov A, Owschimikow N, Artemyev M, Climente JI, Woggon U, Grosse NB, Achtstein AW. Directed emission of CdSe nanoplatelets originating from strongly anisotropic 2D electronic structure. NATURE NANOTECHNOLOGY 2017; 12:1155-1160. [PMID: 28920964 DOI: 10.1038/nnano.2017.177] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 07/26/2017] [Indexed: 05/24/2023]
Abstract
Intrinsically directional light emitters are potentially important for applications in photonics including lasing and energy-efficient display technology. Here, we propose a new route to overcome intrinsic efficiency limitations in light-emitting devices by studying a CdSe nanoplatelets monolayer that exhibits strongly anisotropic, directed photoluminescence. Analysis of the two-dimensional k-space distribution reveals the underlying internal transition dipole distribution. The observed directed emission is related to the anisotropy of the electronic Bloch states governing the exciton transition dipole moment and forming a bright plane. The strongly directed emission perpendicular to the platelet is further enhanced by the optical local density of states and local fields. In contrast to the emission directionality, the off-resonant absorption into the energetically higher 2D-continuum of states is isotropic. These contrasting optical properties make the oriented CdSe nanoplatelets, or superstructures of parallel-oriented platelets, an interesting and potentially useful class of semiconductor-based emitters.
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Affiliation(s)
- Riccardo Scott
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, Berlin 10623, Germany
| | - Jan Heckmann
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, Berlin 10623, Germany
| | - Anatol V Prudnikau
- Research Institute for Physical Chemical Problems of Belarusian State University, Minsk 220006, Belarus
| | - Artsiom Antanovich
- Research Institute for Physical Chemical Problems of Belarusian State University, Minsk 220006, Belarus
| | - Aleksandr Mikhailov
- Research Institute for Physical Chemical Problems of Belarusian State University, Minsk 220006, Belarus
| | - Nina Owschimikow
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, Berlin 10623, Germany
| | - Mikhail Artemyev
- Research Institute for Physical Chemical Problems of Belarusian State University, Minsk 220006, Belarus
| | - Juan I Climente
- Departament de Química Física i Analítica, Universitat Jaume I, Castelló de la Plana E-12080, Spain
| | - Ulrike Woggon
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, Berlin 10623, Germany
| | - Nicolai B Grosse
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, Berlin 10623, Germany
| | - Alexander W Achtstein
- Institute of Optics and Atomic Physics, Technical University of Berlin, Strasse des 17. Juni 135, Berlin 10623, Germany
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34
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Antanovich A, Achtstein AW, Matsukovich A, Prudnikau A, Bhaskar P, Gurin V, Molinari M, Artemyev M. A strain-induced exciton transition energy shift in CdSe nanoplatelets: the impact of an organic ligand shell. NANOSCALE 2017; 9:18042-18053. [PMID: 29131231 DOI: 10.1039/c7nr05065h] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We study the influence of surface passivating ligands on the optical and structural properties of zinc blende CdSe nanoplatelets. Ligand exchange of native oleic acid with aliphatic thiol or phosphonic acid on the surface of nanoplatelets results in a large shift of exciton transition energy for up to 240 meV. Ligand exchange also leads to structural changes (strain) in the nanoplatelet's core analysed by wide-angle X-ray diffraction. By correlating the experimental data with theoretical calculations we demonstrate that the exciton energy shift is mainly caused by the ligand-induced anisotropic transformation of the crystalline structure altering the well width of the CdSe core. Further the exciton reduced mass in these CdSe quantum wells is determined by a new method and this agrees well with the expected values substantiating that ligand-strain induced changes in the colloidal quantum well thickness are responsible for the observed spectral shifts. Our findings are important for theoretical modeling of other anisotropically strained systems and demonstrate an approach to tune the optical properties of 2D semiconductor nanocrystals over a broad region thus widening the range of possible applications of AIIBVI nanoplatelets in optics and optoelectronics.
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Affiliation(s)
- A Antanovich
- Research Institute for Physical Chemical Problems of the Belarusian State University, 220006 Minsk, Belarus.
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35
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Ma X, Diroll BT, Cho W, Fedin I, Schaller RD, Talapin DV, Gray SK, Wiederrecht GP, Gosztola DJ. Size-Dependent Biexciton Quantum Yields and Carrier Dynamics of Quasi-Two-Dimensional Core/Shell Nanoplatelets. ACS NANO 2017; 11:9119-9127. [PMID: 28787569 DOI: 10.1021/acsnano.7b03943] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Quasi-two-dimensional nanoplatelets (NPLs) possess fundamentally different excitonic properties from zero-dimensional quantum dots. We study lateral size-dependent photon emission statistics and carrier dynamics of individual NPLs using second-order photon correlation (g(2)(τ)) spectroscopy and photoluminescence (PL) intensity-dependent lifetime analysis. Room-temperature radiative lifetimes of NPLs can be derived from maximum PL intensity periods in PL time traces. It first decreases with NPL lateral size and then stays constant, deviating from the electric dipole approximation. Analysis of the PL time traces further reveals that the single exciton quantum yield in NPLs decreases with NPL lateral size and increases with protecting shell thickness, indicating the importance of surface passivation on NPL emission quality. Second-order photon correlation (g(2)(τ)) studies of single NPLs show that the biexciton quantum yield is strongly dependent on the lateral size and single exciton quantum yield of the NPLs. In large NPLs with unity single exciton quantum yield, the corresponding biexciton quantum yield can reach unity. These findings reveal that by careful growth control and core-shell material engineering, NPLs can be of great potential for light amplification and integrated quantum photonic applications.
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Affiliation(s)
- Xuedan Ma
- Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Benjamin T Diroll
- Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Wooje Cho
- Department of Chemistry and James Franck Institute, University of Chicago , Chicago, Illinois 60637, United States
| | - Igor Fedin
- Department of Chemistry and James Franck Institute, University of Chicago , Chicago, Illinois 60637, United States
| | - Richard D Schaller
- Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States
- Department of Chemistry, Northwestern University , Evanston, Illinois 60208, United States
| | - Dmitri V Talapin
- Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States
- Department of Chemistry and James Franck Institute, University of Chicago , Chicago, Illinois 60637, United States
| | - Stephen K Gray
- Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Gary P Wiederrecht
- Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - David J Gosztola
- Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States
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36
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Gerdes F, Navío C, Juárez BH, Klinke C. Size, Shape, and Phase Control in Ultrathin CdSe Nanosheets. NANO LETTERS 2017; 17:4165-4171. [PMID: 28585822 DOI: 10.1021/acs.nanolett.7b00937] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Ultrathin two-dimensional nanosheets raise a rapidly increasing interest due to their unique dimensionality-dependent properties. Most of the two-dimensional materials are obtained by exfoliation of layered bulk materials or are grown on substrates by vapor deposition methods. To produce free-standing nanosheets, solution-based colloidal methods are emerging as promising routes. In this work, we demonstrate ultrathin CdSe nanosheets with controllable size, shape, and phase. The key of our approach is the use of halogenated alkanes as additives in a hot-injection synthesis. Increasing concentrations of bromoalkanes can tune the shape from sexangular to quadrangular to triangular and the phase from zinc blende to wurtzite. Geometry and crystal structure evolution of the nanosheets take place in the presence of halide ions, acting as cadmium complexing agents and as surface X-type ligands, according to mass spectrometry and X-ray photoelectron spectroscopies. Our experimental findings show that the degree of these changes depends on the molecular structure of the halogen alkanes and the type of halogen atom.
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Affiliation(s)
- Frauke Gerdes
- Institute of Physical Chemistry, University of Hamburg , Grindelallee 117, 20146 Hamburg, Germany
| | - Cristina Navío
- Madrid Institute of Advanced Studies in Nanoscience, IMDEA Nanoscience , Faraday 9, Cantoblanco, 28049 Madrid, Spain
| | - Beatriz H Juárez
- Madrid Institute of Advanced Studies in Nanoscience, IMDEA Nanoscience , Faraday 9, Cantoblanco, 28049 Madrid, Spain
- Applied Physical-Chemistry Department, Universidad Autónoma de Madrid , Cantoblanco, 28049 Madrid, Spain
| | - Christian Klinke
- Institute of Physical Chemistry, University of Hamburg , Grindelallee 117, 20146 Hamburg, Germany
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