1
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Kambhampati P. Unraveling the excitonics of light emission from metal-halide perovskite quantum dots. NANOSCALE 2024. [PMID: 39052235 DOI: 10.1039/d4nr01481b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
Metal halide semicondictor perovskites have been under intense investigation for their promise in light absorptive applications like photovoltaics. They have more recently experienced interest for their promise in light emissive applications. A key aspect of perovskites is their glassy, ionic lattice that exhibits dynamical disorder. One possible result of this dynamical disorder is their strong coupling between electronic and lattice degrees of freedom which may confer remarkable properties for light emission such as defect tolerance. How does the system, comprised of excitons, couple to the bath, comprised of lattice modes? How does this system-bath interaction give rise to novel light emissive properties and how do these properties give insight into the nature of these materials? We review recent work from this group in which time-resolved photoluminescence spectroscopy is used to reveal such insights. Based upon a fast time resolution of 3 ps, energy resolution, and temperature dependence, a wide variety of insights are gleaned. These insights include: lattice contributions to the emission linewidths, multiexciton formation, hot carrier cooling, excitonic fine structure, single dot superradiance, and a breakdown of the Condon approximation, all due to complex structural dynamics in these materials.
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2
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De A, Bhunia S, Cai Y, Binyamin T, Etgar L, Ruhman S. Spectator Exciton Effects in Nanocrystals III: Unveiling the Stimulated Emission Cross Section in Quantum Confined CsPbBr 3 Nanocrystals. J Am Chem Soc 2024; 146:20241-20250. [PMID: 39007415 PMCID: PMC11273341 DOI: 10.1021/jacs.4c05412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 07/04/2024] [Accepted: 07/08/2024] [Indexed: 07/16/2024]
Abstract
Quantifying stimulated emission in semiconductor nanocrystals (NCs) remains challenging due to masking of its effects on pump-probe spectra by excited state absorption and ground state bleaching signals. The absence of this defining photophysical parameter in turn impedes assignment of band edge electronic structure in many of these important fluorophores. Here we employ a generally applicable 3-pulse ultrafast spectroscopic method coined the "Spectator Exciton" (SX) approach to measure stimulated-emission efficiency in quantum confined inorganic perovskite CsPbBr3 NCs, the band edge electronic structure of which is the subject of lively ongoing debate. Our results show that in 5-6 nm CsPbBr3 NCs, a single exciton bleaches more than half of the intense band edge absorption band, while the cross section for stimulated emission from the same state is nearly 6 times weaker. Discussion of these findings in light of several recent electronic structure models for this material proves them unable to simultaneously explain both measures, proving the importance of this new input to resolving this debate. Along with femtosecond time-resolved photoluminescence measurements on the same sample, SX results also verify that biexciton interaction energy is intensely attractive with a magnitude of ∼80 meV. In light of this observation, our previous suggestion that biexciton interaction is repulsive is reassigned to hot phonon induced slowdown of carrier relaxation leading to direct Auger recombination from an excited state. The mechanism behind the extreme slowing of carrier cooling after several stages of exciton recombination remains to be determined.
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Affiliation(s)
- Apurba De
- Institute
of Chemistry, The Hebrew University of Jerusalem, Jerusalem-91904, Israel
| | - Soumyadip Bhunia
- Institute
of Chemistry, The Hebrew University of Jerusalem, Jerusalem-91904, Israel
| | - Yichao Cai
- Institute
of Chemistry, The Hebrew University of Jerusalem, Jerusalem-91904, Israel
| | - Tal Binyamin
- Institute
of Chemistry, The Hebrew University of Jerusalem, Jerusalem-91904, Israel
| | - Lioz Etgar
- Institute
of Chemistry, The Hebrew University of Jerusalem, Jerusalem-91904, Israel
| | - Sanford Ruhman
- Institute
of Chemistry, The Hebrew University of Jerusalem, Jerusalem-91904, Israel
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3
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Amara MR, Huo C, Voisin C, Xiong Q, Diederichs C. Impact of Bright-Dark Exciton Thermal Population Mixing on the Brightness of CsPbBr 3 Nanocrystals. NANO LETTERS 2024; 24:4265-4271. [PMID: 38557055 DOI: 10.1021/acs.nanolett.4c00605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Understanding the interplay between bright and dark exciton states is crucial for deciphering the luminescence properties of low-dimensional materials. The origin of the outstanding brightness of lead halide perovskites remains elusive. Here, we analyze temperature-dependent time-resolved photoluminescence to investigate the population mixing between bright and dark exciton sublevels in individual CsPbBr3 nanocrystals in the intermediate confinement regime. We extract bright and dark exciton decay rates and show quantitatively that the decay dynamics can only be reproduced with second-order phonon transitions. Furthermore, we find that any exciton sublevel ordering is compatible with the most likely population transfer mechanism. The remarkable brightness of lead halide perovskite nanocrystals rather stems from a reduced asymmetry between bright-to-dark and dark-to-bright conversion originating from the peculiar second-order phonon-assisted transitions that freeze bright-dark conversion at low temperatures together with the very fast radiative recombination and favorable degeneracy of the bright exciton state.
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Affiliation(s)
- Mohamed-Raouf Amara
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Cité, F-75005 Paris, France
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore
| | - Caixia Huo
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore
- Institute of Materials/School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China
- Shaoxing Institute of Technology, Shanghai University, Zhejiang 312000, China
| | - Christophe Voisin
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Cité, F-75005 Paris, France
| | - Qihua Xiong
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Frontier Science Center for Quantum Information, Beijing 100084, People's Republic of China
- Collaborative Innovation Center of Quantum Matter, Beijing 100084, People's Republic of China
- Beijing Academy of Quantum Information Sciences, Beijing 100193, People's Republic of China
| | - Carole Diederichs
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Cité, F-75005 Paris, France
- Institut Universitaire de France (IUF), 75231 Paris, France
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4
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Shcherbakov-Wu W, Saris S, Sheehan TJ, Wong NN, Powers ER, Krieg F, Kovalenko MV, Willard AP, Tisdale WA. Persistent enhancement of exciton diffusivity in CsPbBr 3 nanocrystal solids. SCIENCE ADVANCES 2024; 10:eadj2630. [PMID: 38381813 PMCID: PMC10881049 DOI: 10.1126/sciadv.adj2630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 01/19/2024] [Indexed: 02/23/2024]
Abstract
In semiconductors, exciton or charge carrier diffusivity is typically described as an inherent material property. Here, we show that the transport of excitons among CsPbBr3 perovskite nanocrystals (NCs) depends markedly on how recently those NCs were occupied by a previous exciton. Using transient photoluminescence microscopy, we observe a striking dependence of the apparent exciton diffusivity on excitation laser power that does not arise from nonlinear exciton-exciton interactions or thermal heating. We interpret our observations with a model in which excitons cause NCs to transition to a long-lived metastable configuration that markedly increases exciton transport. The exciton diffusivity observed here (>0.15 square centimeters per second) is considerably higher than that observed in other NC systems, revealing unusually strong excitonic coupling between NCs. The finding of a persistent enhancement in excitonic coupling may help explain other photophysical behaviors observed in CsPbBr3 NCs, such as superfluorescence, and inform the design of optoelectronic devices.
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Affiliation(s)
- Wenbi Shcherbakov-Wu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Seryio Saris
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Laboratory of Nanochemistry for Energy (LNCE), Institute of Chemical Sciences and Engineering (ISIC), École Polytechnique Fédérale de Lausanne, CH-1950 Sion, Switzerland
| | - Thomas John Sheehan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Narumi Nagaya Wong
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Eric R. Powers
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Franziska Krieg
- Department of Chemistry and Applied Bioscience, ETH Zürich, Zürich, Switzerland
- Laboratory for Thin Films and Photovoltaics and Laboratory for Transport at Nanoscale Interfaces, Empa – Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - Maksym V. Kovalenko
- Department of Chemistry and Applied Bioscience, ETH Zürich, Zürich, Switzerland
- Laboratory for Thin Films and Photovoltaics and Laboratory for Transport at Nanoscale Interfaces, Empa – Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - Adam P. Willard
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - William A. Tisdale
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
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5
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Strandell DP, Zenatti D, Nagpal P, Ghosh A, Dirin DN, Kovalenko MV, Kambhampati P. Hot Excitons Cool in Metal Halide Perovskite Nanocrystals as Fast as CdSe Nanocrystals. ACS NANO 2024; 18:1054-1062. [PMID: 38109401 DOI: 10.1021/acsnano.3c10301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
The idea of phonon bottlenecks has long been pursued in nanoscale materials for their application in hot exciton devices, such as photovoltaics. Decades ago, it was shown that there is no quantum phonon bottleneck in strongly confined quantum dots due to their physics of quantum confinement. More recently, it was proposed that there are hot phonon bottlenecks in metal halide perovskites due to their physics. Recent work has called into question these bottlenecks in metal halide perovskites. Here, we compare hot exciton cooling in a range of sizes of CsPbBr3 nanocrystals from weakly to strongly confined. These results are compared to strongly confined CdSe quantum dots of two sizes and degrees of quantum confinement. CdSe is a model system as a ruler for measuring hot exciton cooling being fast, by virtue of its efficient Auger-assisted processes. By virtue of 3 ps time resolution, the hot exciton photoluminescence can now be directly observed, which is the most direct measure of the presence of hot excitons and their lifetimes. The hot exciton photoluminescence decays on nearly the same 2 ps time scale on both the weakly confined perovskite and the larger CdSe quantum dots, much faster than the 10 ps cooling predicted by transient absorption experiments. The smaller CdSe quantum dot has still faster cooling, as expected from quantum size effects. The quantum dots of perovskites show extremely fast hot exciton cooling, decaying faster than detection limits of <1 ps, even faster than the CdSe system, suggesting the efficiency of Auger processes in these metal halide perovskite nanocrystals and especially in their quantum dot form. These results across a range of sizes of nanocrystals reveal extremely fast hot exciton cooling at high exciton density, independent of composition, but dependent upon size. Hence these metal halide perovskite nanocrystals seem to cool heavily following quantum dot physics.
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Affiliation(s)
| | - Davide Zenatti
- Department of Chemistry, McGill University, Montreal, H3A 0B8, Canada
| | - Priya Nagpal
- Department of Chemistry, McGill University, Montreal, H3A 0B8, Canada
| | - Arnab Ghosh
- Department of Chemistry, McGill University, Montreal, H3A 0B8, Canada
| | - Dmitry N Dirin
- Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
| | - Maksym V Kovalenko
- Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
- Empa-Swiss Federal Laboratories for Materials Science and Technology, 8600 Dubendorf, Switzerland
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6
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Guilloux V, Ghribi A, Majrab S, Margaillan F, Bernard M, Bernardot F, Legrand L, Lhuillier E, Boujdaria K, Chamarro M, Testelin C, Barisien T. Exciton Fine Structure of CsPbCl 3 Nanocrystals: An Interplay of Electron-Hole Exchange Interaction, Crystal Structure, Shape Anisotropy, and Dielectric Mismatch. ACS NANO 2023. [PMID: 37366625 DOI: 10.1021/acsnano.3c00772] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
In the semiconducting perovskite materials family, the cesium-lead-chloride compound (CsPbCl3) supports robust excitons characterized by a blue-shifted transition and the largest binding energy, thus presenting a high potential to achieve demanding solid-state room-temperature photonic or quantum devices. Here we study the fundamental emission properties of cubic-shaped colloidal CsPbCl3 nanocrystals (NCs), examining in particular individual NC responses using micro-photoluminescence in order to unveil the exciton fine structure (EFS) features. Within this work, NCs with average dimensions ⟨Lα⟩ ≈ 8 nm (α = x, y, z) are studied with a level of dispersity in their dimensions that allows disentangling the effects of size and shape anisotropy in the analysis. We find that most of the NCs exhibit an optical response under the form of a doublet with crossed polarized peaks and an average inter-bright-state splitting, ΔBB ≈ 1.53 meV, but triplets are also observed though being a minority. The origin of the EFS patterns is discussed in the frame of the electron-hole exchange model by taking into account the dielectric mismatch at the NC interface. The different features (large dispersity in the ΔBB values and occasional occurrence of triplets) are reconciled by incorporating a moderate degree of shape anisotropy, observed in the structural characterization, by preserving the relatively high degree of the NC lattice symmetry. The energy distance between the optically inactive state and the bright manifold, ΔBD, is also extracted from time-resolved photoluminescence measurements (ΔBD ≈ 10.7 meV), in good agreement with our theoretical predictions.
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Affiliation(s)
- Victor Guilloux
- Institut des NanoSciences de Paris, CNRS UMR 7588, Sorbonne Université, F-75005 Paris, France
| | - Amal Ghribi
- LR01ES15 Laboratoire de Physique des Matériaux: Structure et Propriétés, Faculté des Sciences de Bizerte, Université de Carthage, Bizerte 7021, Tunisia
| | - Silbé Majrab
- Institut des NanoSciences de Paris, CNRS UMR 7588, Sorbonne Université, F-75005 Paris, France
| | - Florent Margaillan
- Institut des NanoSciences de Paris, CNRS UMR 7588, Sorbonne Université, F-75005 Paris, France
| | - Mathieu Bernard
- Institut des NanoSciences de Paris, CNRS UMR 7588, Sorbonne Université, F-75005 Paris, France
| | - Frédérick Bernardot
- Institut des NanoSciences de Paris, CNRS UMR 7588, Sorbonne Université, F-75005 Paris, France
| | - Laurent Legrand
- Institut des NanoSciences de Paris, CNRS UMR 7588, Sorbonne Université, F-75005 Paris, France
| | - Emmanuel Lhuillier
- Institut des NanoSciences de Paris, CNRS UMR 7588, Sorbonne Université, F-75005 Paris, France
| | - Kaïs Boujdaria
- LR01ES15 Laboratoire de Physique des Matériaux: Structure et Propriétés, Faculté des Sciences de Bizerte, Université de Carthage, Bizerte 7021, Tunisia
| | - Maria Chamarro
- Institut des NanoSciences de Paris, CNRS UMR 7588, Sorbonne Université, F-75005 Paris, France
| | - Christophe Testelin
- Institut des NanoSciences de Paris, CNRS UMR 7588, Sorbonne Université, F-75005 Paris, France
| | - Thierry Barisien
- Institut des NanoSciences de Paris, CNRS UMR 7588, Sorbonne Université, F-75005 Paris, France
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7
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Weinberg D, Park Y, Limmer DT, Rabani E. Size-Dependent Lattice Symmetry Breaking Determines the Exciton Fine Structure of Perovskite Nanocrystals. NANO LETTERS 2023. [PMID: 37229762 DOI: 10.1021/acs.nanolett.3c00861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The order of bright and dark excitonic states in lead-halide perovskite nanocrystals is debated. It has been proposed that the Rashba effect, driven by lattice-induced symmetry breaking, causes a bright excitonic ground state. Direct measurements of excitonic spectra, however, show the signatures of a dark ground state, bringing the role of the Rashba effect into question. We use an atomistic theory to model the exciton fine structure of perovskite nanocrystals, accounting for realistic lattice distortions. We calculate optical gaps and excitonic features that compare favorably with experimental works. The exciton fine structure splittings show a nonmonotonic size dependence due to a structural transition between cubic and orthorhombic phases. Additionally, the excitonic ground state is found to be dark with spin triplet character, exhibiting a small Rashba coupling. We additionally explore the effects of nanocrystal shape on the fine structure, clarifying observations on polydisperse nanocrystals.
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Affiliation(s)
- Daniel Weinberg
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Yoonjae Park
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - David T Limmer
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Kavli Energy NanoScience Institute, Berkeley, California 94720, United States
| | - Eran Rabani
- Department of Chemistry, University of California, Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- The Raymond and Beverly Sackler Center of Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
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8
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Morcillo-Arencibia MF, Alcaraz-Pelegrina JM, Sarsa AJ, Randazzo JM. An off-center endohedrally confined hydrogen molecule. Phys Chem Chem Phys 2022; 24:22971-22977. [PMID: 36125249 DOI: 10.1039/d2cp03456e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this study, we address the problem of a C60 endohedrally confined hydrogen molecule through a configuration-interaction approach to electronic dynamics. Modeling the confinement by means of a combination of two Woods-Saxon potentials, we analyze the stability of the system as a function of the nuclei position through the behavior of the electronic spectrum. After studying the convergence of two different partial wave expansions, one related to the molecular Coulomb centers and the other related to the off-centering of the C60 well, we found that the second approach provides a more accurate description of the system. Furthermore, we observed that the inter-atomic distance changes based on the position of the atoms inside the cavity. Thus, to obtain the most favourable energetic configuration for the molecule, it should be positioned inside the cavity next to the structure, where its size decreases.
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Affiliation(s)
- Milagros F Morcillo-Arencibia
- Departamento de Física, Campus de Rabanales, Edif. C2. Universidad de Córdoba, E-14071 Córdoba, Spain. .,Centro Atómico Bariloche, CNEA and CONICET, S. C. de Bariloche, Río Negro, Argentina
| | | | - Antonio J Sarsa
- Departamento de Física, Campus de Rabanales, Edif. C2. Universidad de Córdoba, E-14071 Córdoba, Spain.
| | - Juan M Randazzo
- Centro Atómico Bariloche, CNEA and CONICET, S. C. de Bariloche, Río Negro, Argentina
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9
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Wang CW, Liu X, Qiao T, Khurana M, Akimov AV, Son DH. Photoemission of the Upconverted Hot Electrons in Mn-Doped CsPbBr 3 Nanocrystals. NANO LETTERS 2022; 22:6753-6759. [PMID: 35939549 DOI: 10.1021/acs.nanolett.2c02342] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Hot electrons play a crucial role in enhancing the efficiency of photon-to-current conversion or photocatalytic reactions. In semiconductor nanocrystals, energetic hot electrons capable of photoemission can be generated via the upconversion process involving the dopant-originated intermediate state, currently known only in Mn-doped cadmium chalcogenide quantum dots. Here, we report that Mn-doped CsPbBr3 nanocrystals are an excellent platform for generating hot electrons via upconversion that can benefit from various desirable exciton properties and the structural diversity of metal halide perovskites (MHPs). Two-dimensional Mn-doped CsPbBr3 nanoplatelets are particularly advantageous for hot electron upconversion due to the strong exciton-dopant interaction mediating the upconversion process. Furthermore, nanoplatelets reveal evidence for the hot electron upconversion via long-lived dark excitons in addition to bright excitons that may enhance the upconversion efficiency. This study establishes the feasibility of hot electron upconversion in MHP hosts and demonstrates the potential merits of two-dimensional MHP nanocrystals in the upconversion process.
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Affiliation(s)
- Chih-Wei Wang
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Xiaohan Liu
- Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, United States
| | - Tian Qiao
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Mohit Khurana
- Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, United States
| | - Alexey V Akimov
- Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, United States
| | - Dong Hee Son
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
- Center for Nanomedicine, Institute for Basic Science and Graduate Program of Nano Biomedical Engineering, Advanced Science Institute, Yonsei University, Seoul 03722, Republic of Korea
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10
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Zhao C, Zhang X, Huang H, Yuan J. Highly Efficient A-Site Cation Exchange in Perovskite Quantum Dot for Solar Cells. J Chem Phys 2022; 157:031101. [DOI: 10.1063/5.0100258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The mixed cation colloidal Cs1-XFAXPbI3 perovskite quantum dots (PQDs) obtained by cation exchange between CsPbI3 and FAPbI3 PQDs has been reported to exhibit enhanced photovoltaic performance. However, the cation exchange mechanism requires further in-depth investigation in terms of both material properties and device application. In this work, the impact of PQDs weight ratio, PQDs concentration and host solvent polarity during cation exchange is comprehensively investigated for the first time. In addition, the whole exchange process under varying conditions is monitored by photoluminescence spectroscopy. As a result, we observe extremely fast cation exchange (approximately 20 minutes) under a condition of CsPbI3/FAPbI3 PQD weight ratio=1:1, a concentration of 70 mg/mL and host solvent using toluene. Moreover, we directly fabricate PQDs solar cell device using these obtained mixed cation Cs0.5FA0.5PbI3 PQDs and achieved an enhanced power conversion efficiency of 14.58%. We believe these results would provide more insights into the cation exchange in emerging PQDs towards efficient photovoltaic fabrication and application.
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Affiliation(s)
- Chenyu Zhao
- Soochow University - Dushu Lake Campus, China
| | | | - Hehe Huang
- Soochow University - Dushu Lake Campus, China
| | - Jianyu Yuan
- Institute of Functional Nano& Soft Materials (FUNSOM), Soochow University - Dushu Lake Campus, China
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11
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Kim YH, Park J, Kim S, Kim JS, Xu H, Jeong SH, Hu B, Lee TW. Exploiting the full advantages of colloidal perovskite nanocrystals for large-area efficient light-emitting diodes. NATURE NANOTECHNOLOGY 2022; 17:590-597. [PMID: 35577974 DOI: 10.1038/s41565-022-01113-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 03/02/2022] [Indexed: 06/15/2023]
Abstract
Cost-effective, high-throughput industrial applications of metal halide perovskites in large-area displays are hampered by the fundamental difficulty of controlling the process of polycrystalline film formation from precursors, which results in the random growth of crystals, leading to non-uniform large grains and thus low electroluminescence efficiency in large-area perovskite light-emitting diodes (PeLEDs). Here we report that highly efficient large-area PeLEDs with high uniformity can be realized through the use of colloidal perovskite nanocrystals (PNCs), decoupling the crystallization of perovskites from film formation. PNCs were precrystallized and surrounded by organic ligands, and thus they were not affected by the film formation process, in which a simple modified bar-coating method facilitated the evaporation of residual solvent to provide uniform large-area films. PeLEDs incorporating the uniform bar-coated PNC films achieved an external quantum efficiency (EQE) of 23.26% for a pixel size of 4 mm2 and an EQE of 22.5% for a large pixel area of 102 mm2 with high reproducibility. This method provides a promising approach towards the development of large-scale industrial displays and solid-state lighting using perovskite emitters.
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Affiliation(s)
- Young-Hoon Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul, Republic of Korea
- Department of Energy Engineering, Hanyang University, Seoul, Republic of Korea
| | - Jinwoo Park
- Department of Materials Science and Engineering, Seoul National University, Seoul, Republic of Korea
| | - Sungjin Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul, Republic of Korea
| | - Joo Sung Kim
- Department of Materials Science and Engineering, Seoul National University, Seoul, Republic of Korea
| | - Hengxing Xu
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN, USA
| | - Su-Hun Jeong
- Department of Materials Science and Engineering, Seoul National University, Seoul, Republic of Korea
| | - Bin Hu
- Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN, USA
| | - Tae-Woo Lee
- Department of Materials Science and Engineering, Seoul National University, Seoul, Republic of Korea.
- School of Chemical and Biological Engineering, Institute of Engineering Research, Research Institute of Advanced Materials, Soft Foundry, Seoul National University, Seoul, Republic of Korea.
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12
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Gramlich M, Swift MW, Lampe C, Lyons JL, Döblinger M, Efros AL, Sercel PC, Urban AS. Dark and Bright Excitons in Halide Perovskite Nanoplatelets. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2103013. [PMID: 34939751 PMCID: PMC8844578 DOI: 10.1002/advs.202103013] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 10/13/2021] [Indexed: 05/22/2023]
Abstract
Semiconductor nanoplatelets (NPLs), with their large exciton binding energy, narrow photoluminescence (PL), and absence of dielectric screening for photons emitted normal to the NPL surface, could be expected to become the fastest luminophores amongst all colloidal nanostructures. However, super-fast emission is suppressed by a dark (optically passive) exciton ground state, substantially split from a higher-lying bright (optically active) state. Here, the exciton fine structure in 2-8 monolayer (ML) thick Csn - 1 Pbn Br3n + 1 NPLs is revealed by merging temperature-resolved PL spectra and time-resolved PL decay with an effective mass model taking quantum confinement and dielectric confinement anisotropy into account. This approach exposes a thickness-dependent bright-dark exciton splitting reaching 32.3 meV for the 2 ML NPLs. The model also reveals a 5-16 meV splitting of the bright exciton states with transition dipoles polarized parallel and perpendicular to the NPL surfaces, the order of which is reversed for the thinnest NPLs, as confirmed by TR-PL measurements. Accordingly, the individual bright states must be taken into account, while the dark exciton state strongly affects the optical properties of the thinnest NPLs even at room temperature. Significantly, the derived model can be generalized for any isotropically or anisotropically confined nanostructure.
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Affiliation(s)
- Moritz Gramlich
- Nanospectroscopy GroupNano‐Institute MunichDepartment of PhysicsLudwig‐Maximilians‐Universität München (LMU)Munich80539Germany
| | - Michael W. Swift
- Center for Computational Materials ScienceU.S. Naval Research LaboratoryWashington D.C.20375USA
| | - Carola Lampe
- Nanospectroscopy GroupNano‐Institute MunichDepartment of PhysicsLudwig‐Maximilians‐Universität München (LMU)Munich80539Germany
| | - John L. Lyons
- Center for Computational Materials ScienceU.S. Naval Research LaboratoryWashington D.C.20375USA
| | - Markus Döblinger
- Department of ChemistryLudwig‐Maximilians‐Universität München (LMU) & Center for NanoScience (CeNS)Munich81377Germany
| | - Alexander L. Efros
- Center for Computational Materials ScienceU.S. Naval Research LaboratoryWashington D.C.20375USA
| | - Peter C. Sercel
- Center for Hybrid Organic Inorganic Semiconductors for EnergyGoldenCO80401USA
| | - Alexander S. Urban
- Nanospectroscopy GroupNano‐Institute MunichDepartment of PhysicsLudwig‐Maximilians‐Universität München (LMU)Munich80539Germany
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Jang SJ, Burghardt I, Hsu CP, Bardeen CJ. Excitons: Energetics and spatiotemporal dynamics. J Chem Phys 2021; 155:200401. [PMID: 34852498 DOI: 10.1063/5.0075292] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Seogjoo J Jang
- Department of Chemistry and Biochemistry, Queens College, City University of New York, 65-30 Kissena Boulevard, Queens, New York 11367, USA and PhD Programs in Chemistry and Physics, and Initiative for the Theoretical Sciences, Graduate Center, City University of New York, 365 Fifth Avenue, New York, New York 10016, USA
| | - Irene Burghardt
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Frankfurt, Germany
| | - Chao-Ping Hsu
- Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan and Physics Division, National Center for Theoretical Sciences, Taipei 106, Taiwan
| | - Christopher J Bardeen
- Department of Chemistry, University of California, Riverside, Riverside, California 92521, USA
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14
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Qiao T, Liu X, Rossi D, Khurana M, Lin Y, Wen J, Cheon J, Akimov AV, Son DH. Magnetic Effect of Dopants on Bright and Dark Excitons in Strongly Confined Mn-Doped CsPbI 3 Quantum Dots. NANO LETTERS 2021; 21:9543-9550. [PMID: 34762431 DOI: 10.1021/acs.nanolett.1c03114] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We investigated the magnetic effect of Mn2+ ions on an exciton of Mn-doped CsPbI3 quantum dots (QDs), where we looked for the signatures of an exciton magnetic polaron known to produce a large effective magnetic field in Mn-doped CdSe QDs. In contrast to Mn-doped CdSe QDs that can produce ∼100 T of magnetic field upon photoexcitation, manifested as a large change in the energy and relaxation dynamics of a bright exciton, Mn-doped CsPbI3 QDs exhibited little influence of a magnetic dopant on the behavior of a bright exciton. However, a μs-lived dark exciton in CsPbI3 QDs showed 40% faster decay in the presence of Mn2+, equivalent to the effect of ∼3 T of an external magnetic field. While further study is necessary to fully understand the origin of the large difference in the magneto-optic property of an exciton in two systems, we consider that the difference in antiferromagnetic coupling of the dopants is an important contributing factor.
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Affiliation(s)
- Tian Qiao
- Department of Chemistry, Texas A&M University, College Station, Texas 777843, United States
| | - Xiaohan Liu
- Department of Physics, Texas A&M University, College Station, Texas 777843, United States
| | - Daniel Rossi
- Center for Nanomedicine, Institute for Basic Science and Graduate Program of Nano Biomedical Engineering, Advanced Science Institute, Yonsei University, Seoul 03722, Republic of Korea
| | - Mohit Khurana
- Department of Physics, Texas A&M University, College Station, Texas 777843, United States
| | - Yulin Lin
- Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Jianguo Wen
- Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Jinwoo Cheon
- Center for Nanomedicine, Institute for Basic Science and Graduate Program of Nano Biomedical Engineering, Advanced Science Institute, Yonsei University, Seoul 03722, Republic of Korea
| | - Alexey V Akimov
- Department of Physics, Texas A&M University, College Station, Texas 777843, United States
| | - Dong Hee Son
- Department of Chemistry, Texas A&M University, College Station, Texas 777843, United States
- Center for Nanomedicine, Institute for Basic Science and Graduate Program of Nano Biomedical Engineering, Advanced Science Institute, Yonsei University, Seoul 03722, Republic of Korea
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15
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Kambhampati P. Nanoparticles, Nanocrystals, and Quantum Dots: What are the Implications of Size in Colloidal Nanoscale Materials? J Phys Chem Lett 2021; 12:4769-4779. [PMID: 33984241 DOI: 10.1021/acs.jpclett.1c00754] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Semiconductor nanoparticles (NP) or nanocrystals (NC) have been investigated for many decades, with particular acceleration in interest upon the discovery of quantum confinement effects thereby yielding quantum dots (QD) from certain well-grown NC. The term NP is commonly used in the case of metal and wide gap semiconductor nanocrystals. The term NC is commonly used in semiconductor nanocrystals, whether covalent II-VI or ionic perovskites, that are colloidally grown. The term QD applies to select semiconductor nanocrystals for whom their size is on the order of the excitonic Bohr radius. In the case of colloidal particles on the nanometer length scale, these terms are often used carelessly and interchangeably. The words have specific meaning in relationship to specific physical effects which give rise to specific key processes that can be measured. Here, we provide a Perspective on the ways in which size confers function across different families of NP. In this way, we aim to find ways to identify their similarities and differences by providing the correct semantics for discussion of the salient processes.
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Qiao T, Son DH. Synthesis and Properties of Strongly Quantum-Confined Cesium Lead Halide Perovskite Nanocrystals. Acc Chem Res 2021; 54:1399-1408. [PMID: 33566565 DOI: 10.1021/acs.accounts.0c00706] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
ConspectusSemiconducting metal halide perovskite (MHP) nanocrystals have emerged as an important new class of materials as the source of photons and charges for various applications that can outperform many other semiconductor nanocrystals utilized for the same purposes. However, the majority of the studies of MHP nanocrystals focused on weakly or nonconfined systems, where the quantum confinement giving rise to various size-dependent and confinement-enhanced photophysical properties cannot be explored readily. This was partially due to the challenge in producing strongly quantum-confined MHP nanocrystals, since the traditional kinetic control approach was less effective for the size control. Recent synthetic progress in MHP nanocrystals utilizing the equilibrium-based size control achieved the precise control of quantum confinement with high ensemble uniformity, enabling the exploration of the unique properties of MHP nanocrystals under strong quantum confinement. In this Account, we review the recent progress made in the synthesis of strongly quantum-confined cesium lead halide nanocrystals and investigation of the properties of exciton modified by strong quantum confinement. The main body of this Account discusses the key results of the research in this field in two separate sections. Section 2 describes the thermodynamic equilibrium-based synthesis method to control the size of cesium lead halide perovskite quantum dots in strongly confined regime. Size control in anisotropic nanocrystals with one- and two-dimensional quantum confinement is also discussed. Section 3 covers the following three topics that highlight the effects of quantum confinement on various spectroscopic properties of excitons in cesium lead halide perovskite nanocrystals: (1) Size-dependent absorption cross section of cesium lead halide quantum dots; (2) confinement effect on exciton fine structure and access to the dark exciton exhibiting intense and long-lived photoluminescence; (3) activation of forbidden exciton transition via dynamic lattice distortion by the photoexcited charge carriers enhanced by quantum confinement. The impact of strong quantum confinement goes beyond the properties of excitons covered in this Account and is expected to expand the functionality of MHP nanocrystals as the source of photons and charges. For instance, realization of the possible enhancement of photon down- and upconversion and hot carrier generation via quantum confinement will further increase the usefulness of strongly confined MHP nanocrystals in their applications.
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Affiliation(s)
- Tian Qiao
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Dong Hee Son
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
- Center for Nanomedicine, Institute for Basic Science (IBS) and Graduate Program of Nano Biomedical Engineering (BME), Advanced Science Institute, Yonsei University, Seoul 03722, Republic of Korea
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