1
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Geiregat P, Erdem O, Samoli M, Chen K, Hodgkiss JM, Hens Z. The Impact of Partial Carrier Confinement on Stimulated Emission in Strongly Confined Perovskite Nanocrystals. ACS NANO 2024. [PMID: 38913946 DOI: 10.1021/acsnano.4c03441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Semiconductor lead halide perovskites are excellent candidates for realizing low threshold light amplification due to their tunable and highly efficient luminescence, ease of processing, and strong light-matter interactions. However, most studies on optical gain have addressed bulk films, nanowires, or nanocrystals that exhibit little or no size quantization. Here, we show by means of a multitude of optical spectroscopy methods that small CsPbBr3 nanocrystals (NCs) exhibit a progressive red shift of the band-edge transition upon addition of electron-hole pairs, at least one carrier of which occupies a 2-fold degenerate, delocalized state in agreement with strong confinement. We demonstrate that this combination results in a threshold for biexciton gain, well below the limit of one electron-hole pair on average per NC. On the other hand, both the luminescent lifetime and the optical Stark effect of 4.7 nm CsPbBr3 NCs indicate that the oscillator strength of the band-edge transition is considerably smaller than expected from the band-edge absorption. We assign this discrepancy to a mixed confinement regime, with one delocalized and one localized charge carrier, and show that the concomitant reduction of the oscillator strength for stimulated emission accounts for the surprisingly small material gain observed in small NCs. The conclusion of mixed confinement aligns with studies reporting small and large polarons for holes and electrons in lead halide perovskite nanocrystals, respectively, and creates opportunities for understanding multiexciton photophysics in confined perovskite materials.
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Affiliation(s)
- Pieter Geiregat
- Physics and Chemistry of Nanostructures group, Department of Chemistry, Ghent University, Gent 9000, Belgium
- NOLIMITS, Core Facility for Non-Linear Microscopy and Spectroscopy, Ghent University, Gent, 9000, Belgium
| | - Onur Erdem
- Physics and Chemistry of Nanostructures group, Department of Chemistry, Ghent University, Gent 9000, Belgium
| | - Margarita Samoli
- Physics and Chemistry of Nanostructures group, Department of Chemistry, Ghent University, Gent 9000, Belgium
| | - Kai Chen
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand
- The Dodd-Walls Centre for Photonic and Quantum Technologies, University of Otago, Dunedin 9016, New Zealand
- Robinson Research Institute, Faculty of Engineering, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Justin M Hodgkiss
- The MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6140, New Zealand
- School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington 6140, New Zealand
| | - Zeger Hens
- Physics and Chemistry of Nanostructures group, Department of Chemistry, Ghent University, Gent 9000, Belgium
- NOLIMITS, Core Facility for Non-Linear Microscopy and Spectroscopy, Ghent University, Gent, 9000, Belgium
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2
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Diroll BT, Dabard C, Hua M, Climente JI, Lhuillier E, Ithurria S. Hole Relaxation Bottlenecks in CdSe/CdTe/CdSe Lateral Heterostructures Lead to Bicolor Emission. NANO LETTERS 2024. [PMID: 38885197 DOI: 10.1021/acs.nanolett.4c01250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
Concentric lateral CdSe/CdTe/CdSe heterostructures show bicolor photoluminescence from both a red charge transfer band of the CdSe/CdTe interface and a green fluorescence from CdSe. This work uses visible and near-infrared transient spectroscopy measurements to demonstrate that the deviation from Kasha's rule arises from a hole relaxation bottleneck from CdSe to CdTe. Hole transfer can take up to 1 ns, which permits radiative relaxation of excitons remaining in CdSe. Simulations indicate that the hole relaxation bottleneck arises due to the sparse density of states and poor spatial overlap of hole states at energies near the CdSe band edge. The divergent kinetics of transfer for band edge and hot holes is exploited to vary the ratio of green and red photoluminescence with excitation wavelength, providing another knob to control emission color. These findings support the use of lateral heterojunctions as a method for slowing carrier relaxation in two-dimensional materials.
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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
| | - 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, Paris 75005, France
| | - Muchuan Hua
- Center for Nanoscale Materials, Argonne National Laboratory. 9700 S. Cass Avenue, Lemont, Illinois 60439, United States
| | - Juan I Climente
- Departament de Química Física i Analítica, Universitat Jaume I, Castelló de la Plana 12080, Spain
| | - Emmanuel Lhuillier
- Sorbonne Université, CNRS, Institut des NanoSciences de Paris, 4 Place Jussieu, Paris 75005, 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, Paris 75005, France
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3
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Li Q, Wu K, Zhu H, Yang Y, He S, Lian T. Charge Transfer from Quantum-Confined 0D, 1D, and 2D Nanocrystals. Chem Rev 2024; 124:5695-5763. [PMID: 38629390 PMCID: PMC11082908 DOI: 10.1021/acs.chemrev.3c00742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 03/29/2024] [Accepted: 04/02/2024] [Indexed: 05/09/2024]
Abstract
The properties of colloidal quantum-confined semiconductor nanocrystals (NCs), including zero-dimensional (0D) quantum dots, 1D nanorods, 2D nanoplatelets, and their heterostructures, can be tuned through their size, dimensionality, and material composition. In their photovoltaic and photocatalytic applications, a key step is to generate spatially separated and long-lived electrons and holes by interfacial charge transfer. These charge transfer properties have been extensively studied recently, which is the subject of this Review. The Review starts with a summary of the electronic structure and optical properties of 0D-2D nanocrystals, followed by the advances in wave function engineering, a novel way to control the spatial distribution of electrons and holes, through their size, dimension, and composition. It discusses the dependence of NC charge transfer on various parameters and the development of the Auger-assisted charge transfer model. Recent advances in understanding multiple exciton generation, decay, and dissociation are also discussed, with an emphasis on multiple carrier transfer. Finally, the applications of nanocrystal-based systems for photocatalysis are reviewed, focusing on the photodriven charge separation and recombination processes that dictate the function and performance of these materials. The Review ends with a summary and outlook of key remaining challenges and promising future directions in the field.
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Affiliation(s)
- Qiuyang Li
- Department
of Physics, University of Michigan, 450 Church St, Ann Arbor, Michigan 48109, United States
| | - Kaifeng Wu
- State
Key Laboratory of Molecular Reaction Dynamics and Collaborative Innovation
Center of Chemistry for Energy Materials (iChEM), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China
- University
of Chinese Academy of Sciences, Beijing 100049, China
| | - Haiming Zhu
- Department
of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Ye Yang
- The
State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM
(Collaborative Innovation Center of Chemistry for Energy Materials),
College of Chemistry & Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
| | - Sheng He
- Department
of Chemistry, Emory University, Atlanta, Georgia 30322, United States
| | - Tianquan Lian
- Department
of Chemistry, Emory University, Atlanta, Georgia 30322, United States
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4
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Wengler-Rust S, Staechelin YU, Lange H, Weller H. Electron Donor-Specific Surface Interactions Promote the Photocatalytic Activity of Metal-Semiconductor Nanohybrids. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024:e2401388. [PMID: 38634407 DOI: 10.1002/smll.202401388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Revised: 03/25/2024] [Indexed: 04/19/2024]
Abstract
In the past two decades, the application of colloidal semiconductor-metal nanoparticles (NPs) as photocatalysts for the hydrogen generation from water has been extensively studied. The present body of literature studies agrees that the photocatalytic yield strongly depends on the electron donating agent (EDA) added for scavenging the photogenerated holes. The highest reported hydrogen production rates are obtained in the presence of ionic EDAs and at high pH. The large hydrogen production rates are attributed to fast hole transfer from the NP onto the EDAs. However, the present discussions do not treat the influence of EDA-specific surface interactions. This systematic study focuses on that aspect by combining steady-state hydrogen production measurements with time-resolved and static optical spectroscopy, employing 11-mercaptoundecanoic acid-capped, Pt-tipped CdSe/CdS dot-in-rods in the presence of a large set of EDAs. Based on the experimental results, two distinct EDA groups are identified: surface-active and diffusion-limited EDAs. The largest photocatalytic efficiencies are obtained in the presence of surface-active EDAs that induce an agglomeration of the NPs. This demonstrates that the introduction of surface-active EDAs can significantly enhance the photocatalytic activity of the NPs, despite reducing their colloidal stability and inducing the formation of NP networks.
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Affiliation(s)
- Soenke Wengler-Rust
- Institut für Physikalische Chemie, Universität Hamburg, 20146, Hamburg, Germany
| | - Yannic U Staechelin
- Institut für Physikalische Chemie, Universität Hamburg, 20146, Hamburg, Germany
| | - Holger Lange
- The Hamburg Centre for Ultrafast Imaging, 22761, Hamburg, Germany
- Institut für Physik und Astronomie, Universität Potsdam, 14476, Potsdam, Germany
| | - Horst Weller
- Institut für Physikalische Chemie, Universität Hamburg, 20146, Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, 22761, Hamburg, Germany
- Fraunhofer IAP-CAN, 20146, Hamburg, Germany
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5
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Shulenberger KE, Sherman SJ, Jilek MR, Keller HR, Pellows LM, Dukovic G. Exciton and biexciton transient absorption spectra of CdSe quantum dots with varying diameters. J Chem Phys 2024; 160:014708. [PMID: 38174790 DOI: 10.1063/5.0179129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 12/04/2023] [Indexed: 01/05/2024] Open
Abstract
Transient absorption (TA) spectroscopy of semiconductor nanocrystals (NCs) is often used for excited state population analysis, but recent results suggest that TA bleach signals associated with multiexcitons in NCs do not scale linearly with exciton multiplicity. In this manuscript, we probe the factors that determine the intensities and spectral positions of exciton and biexciton components in the TA spectra of CdSe quantum dots (QDs) of five diameters. We find that, in all cases, the peak intensity of the biexciton TA spectrum is less than 1.5 times that of the single exciton TA spectrum, in stark contrast to a commonly made assumption that this ratio is 2. The relative intensities of the biexciton and exciton TA signals at each wavelength are determined by at least two factors: the TA spectral intensity and the spectral offset between the two signals. We do not observe correlations between either of these factors and the particle diameter, but we find that both are strongly impacted by replacing the native organic surface-capping ligands with a hole-trapping ligand. These results suggest that surface trapping plays an important role in determining the absolute intensities of TA features for CdSe QDs and not just their decay kinetics. Our work highlights the role of spectral offsets and the importance of surface trapping in governing absolute TA intensities. It also conclusively demonstrates that the biexciton TA spectra of CdSe QDs at the band gap energy are less than twice as intense as those of the exciton.
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Affiliation(s)
| | - Skylar J Sherman
- Department of Chemistry, University of Colorado Boulder, 215 UCB, Boulder, Colorado 80309, USA
| | - Madison R Jilek
- Department of Chemistry, University of Colorado Boulder, 215 UCB, Boulder, Colorado 80309, USA
| | - Helena R Keller
- Materials Science and Engineering, University of Colorado Boulder, 613 UCB, Boulder, Colorado 80303, USA
| | - Lauren M Pellows
- Department of Chemistry, University of Colorado Boulder, 215 UCB, Boulder, Colorado 80309, USA
| | - Gordana Dukovic
- Department of Chemistry, University of Colorado Boulder, 215 UCB, Boulder, Colorado 80309, USA
- Materials Science and Engineering, University of Colorado Boulder, 613 UCB, Boulder, Colorado 80303, USA
- Renewable and Sustainable Energy Institute (RASEI), University of Colorado Boulder, 027 UCB, Boulder, Colorado 80309, USA
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6
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Manoj B, Rajan D, Thomas KG. InP quantum dots: Stoichiometry regulates carrier dynamics. J Chem Phys 2023; 158:2887769. [PMID: 37129142 DOI: 10.1063/5.0146484] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 04/13/2023] [Indexed: 05/03/2023] Open
Abstract
The optical properties of non-toxic indium phosphide (InP) quantum dots (QDs) are impinged by the existence of characteristic deep trap states. Several surface engineering strategies have been adopted to improve their optical quality, which has promoted the use of InP QDs for various technological applications. An antithetical approach involves the effective utilization of the deep trap states in InP QDs to modulate back electron transfer rates. Here, we explore the influence of the core-size of InP on their In-to-P stoichiometry and charge transfer dynamics when bound to an acceptor molecule, decyl viologen (DV2+). The mechanism of interaction of InP and DV2+ based on the quenching sphere model established the presence of (i) a 1:1 complex of DV2+ bound on InP and (ii) immobile quenchers in the quenching sphere, depending on the concentration of DV2+. While the forward electron transfer rates from photoexcited InP to bound DV2+ does not substantially vary with an increase in core size, the back electron transfer rates are found to be retarded. Findings from inductively coupled plasma-optical emission spectroscopy (ICP-OES) and X-ray photoelectron spectroscopy (XPS) reveal that the In to P ratio is higher for QDs with larger core size, which further brings about increased carrier trapping and a decreased rate of charge recombination. Furthermore, long-lived charge-separated states in DV2+ bound to InP, extending to hundreds of milliseconds, are obtained by varying the number of DV2+ in the quenching sphere of the QDs.
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Affiliation(s)
- B Manoj
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER TVM), Vithura, Thiruvananthapuram 695551, India
| | - Devika Rajan
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER TVM), Vithura, Thiruvananthapuram 695551, India
| | - K George Thomas
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram (IISER TVM), Vithura, Thiruvananthapuram 695551, India
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7
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Bhati M, Ivanov SA, Senftle TP, Tretiak S, Ghosh D. How structural and vibrational features affect optoelectronic properties of non-stoichiometric quantum dots: computational insights. NANOSCALE 2023; 15:7176-7185. [PMID: 37013402 DOI: 10.1039/d2nr06785d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
While stoichiometric quantum dots (QDs) have been well studied, a significant knowledge gap remains in the atomistic understanding of the non-stoichiometric ones, which are predominantly present during the experimental synthesis. Here, we investigate the effect of thermal fluctuations on structural and vibrational properties of non-stoichiometric cadmium selenide (CdSe) nanoclusters: anion-rich (Se-rich) and cation-rich (Cd-rich) using ab initio molecular dynamics (AIMD) simulations. While the excess atoms on the surface fluctuate more for a given QD type, the optical phonon modes are mostly composed of Se atoms dynamics, irrespective of the composition. Moreover, Se-rich QDs have higher bandgap fluctuations compared to Cd-rich QDs, suggesting poor optical properties of Se-rich QDs. Additionally, non-adiabatic molecular dynamics (NAMD) suggests faster non-radiative recombination for Cd-rich QDs. Altogether, this work provides insights into the dynamic electronic properties of non-stoichiometric QDs and proposes a rationale for the observed optical stability and superiority of cation-rich candidates for light emission applications.
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Affiliation(s)
- Manav Bhati
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, TX 77005-1892, USA
| | - Sergei A Ivanov
- Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Thomas P Senftle
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, Houston, TX 77005-1892, USA
| | - Sergei Tretiak
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
| | - Dibyajyoti Ghosh
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA
- Department of Materials Science and Engineering and Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi 110016, India
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8
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Brosseau P, Seiler H, Palato S, Sonnichsen C, Baker H, Socie E, Strandell D, Kambhampati P. Perturbed free induction decay obscures early time dynamics in two-dimensional electronic spectroscopy: The case of semiconductor nanocrystals. J Chem Phys 2023; 158:084201. [PMID: 36859087 DOI: 10.1063/5.0138252] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Abstract
Two-dimensional electronic spectroscopy (2DES) has recently been gaining popularity as an alternative to the more common transient absorption spectroscopy due to the combination of high frequency and time resolution of 2DES. In order to advance the reliable analysis of population dynamics and to optimize the time resolution of the method, one has to understand the numerous field matter interactions that take place at an early and negative time. These interactions have historically been discussed in one-dimensional spectroscopy as coherent artifacts and have been assigned to both resonant and non-resonant system responses during or before the pulse overlap. These coherent artifacts have also been described in 2DES but remain less well-understood due to the complexity of 2DES and the relative novelty of the method. Here, we present 2DES results in two model nanocrystal samples, CdSe and CsPbI3. We demonstrate non-resonant signals due to solvent response during the pulse overlap and resonant signals, which we assign to perturbed free induction decay (PFID), both before and during the pulse overlap. The simulations of the 2DES response functions at early and negative time delays reinforce the assignment of the negative time delay signals to PFID. Modeling reveals that the PFID signals will severely distort the initial picture of the resonant population dynamics. By including these effects in models of 2DES spectra, one is able to push forward the extraction of early time dynamics in 2DES.
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Affiliation(s)
- Patrick Brosseau
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Hélène Seiler
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Samuel Palato
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Colin Sonnichsen
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Harry Baker
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Etienne Socie
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0G4, Canada
| | - Dallas Strandell
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0G4, Canada
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9
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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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10
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Ghosh S, Mukherjee S, Mandal S, De CK, Mardanya S, Saha A, Mandal PK. Beneficial Intrinsic Hole Trapping and Its Amplitude Variation in a Highly Photoluminescent Toxic-Metal-Free Quantum Dot. J Phys Chem Lett 2023; 14:260-266. [PMID: 36595225 DOI: 10.1021/acs.jpclett.2c03373] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Intrinsic hole trapping as well as hole detrapping have not been observed for any quantum dot (QD) or perovskite nanocrystal (PNC) system. Moreover, amplitude variation of intrinsic hole trapping (or detrapping) has not been reported at all for any QD or PNC system. However, for a CuInS2-based core/alloy-shell (CAS) QD system, (a) both intrinsic hole trapping and detrapping have been observed and (b) very significant amplitude variations of hole trapping (∼16 to ∼42%) and hole detrapping (∼44 to 23%) have been observed. Unlike detrimental electron trapping, hole trapping has been shown to be beneficial, having a direct correlation toward increasing PLQY to 96%. Simultaneous electron and hole trapping has been shown to be quite beneficial for the CuInS2-based CAS QD system leading to the longest ON time (∼130 s) for which a nontoxic metal-based QD remains only in the ON-state without blinking.
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11
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Ashokan A, Han J, Hutchison JA, Mulvaney P. Spectroelectrochemistry of CdSe/Cd xZn 1-xS Nanoplatelets. ACS NANO 2023; 17:1247-1254. [PMID: 36629376 DOI: 10.1021/acsnano.2c09298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
We report an unexpected enhancement of photoluminescence (PL) in CdSe-based core/shell nanoplatelets (NPLs) upon electrochemical hole injection. Moderate hole doping densities induce an enhancement of more than 50% in PL intensity. This is accompanied by a narrowing and blue-shift of the PL spectrum. Simultaneous, time-resolved PL experiments reveal a slower luminescence decay. Such hole-induced PL brightening in NPLs is in stark contrast to the usual observation of PL quenching of CdSe-based quantum dots following hole injection. We propose that hole injection removes surface traps responsible for the formation of negative trions, thereby blocking nonradiative Auger processes. Continuous photoexcitation causes the enhanced PL intensity to decrease back to its initial level, indicating that photocharging is a key step leading to loss of PL luminescence during normal aging. Modulating the potential can be used to reversibly enhance or quench the PL, which enables electro-optical switching.
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Affiliation(s)
- Arun Ashokan
- ARC Centre of Excellence in Exciton Science, School of Chemistry, University of Melbourne, Parkville, Victoria3010, Australia
| | - Jiho Han
- ARC Centre of Excellence in Exciton Science, School of Chemistry, University of Melbourne, Parkville, Victoria3010, Australia
| | - James A Hutchison
- ARC Centre of Excellence in Exciton Science, School of Chemistry, University of Melbourne, Parkville, Victoria3010, Australia
| | - Paul Mulvaney
- ARC Centre of Excellence in Exciton Science, School of Chemistry, University of Melbourne, Parkville, Victoria3010, Australia
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12
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Zeng S, Li Z, Tan W, Si J, Li Y, Hou X. Ultrafast Charge Carrier Dynamics in InP/ZnSe/ZnS Core/Shell/Shell Quantum Dots. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:3817. [PMID: 36364592 PMCID: PMC9657385 DOI: 10.3390/nano12213817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 10/25/2022] [Accepted: 10/27/2022] [Indexed: 06/16/2023]
Abstract
The excellent performance of InP/ZnSe/ZnS core/shell/shell quantum dots (CSS-QDs) in light-emitting diodes benefits from the introduction of a ZnSe midshell. Understanding the changes of ultrafast carrier dynamics caused by the ZnSe midshell is important for their optoelectronic applications. Herein, we have compared the ultrafast carrier dynamics in CSS-QDs and InP/ZnS core/shell QDs (CS-QDs) using femtosecond transient absorption spectroscopy. The results show that the ZnSe midshell intensifies the electron delocalization and prolongs the in-band relaxation time of electrons from 238 fs to 350 fs, and that of holes from hundreds of femtoseconds to 1.6 ps. We also found that the trapping time caused by deep defects increased from 25.6 ps to 76 ps, and there were significantly reduced defect emissions in CSS-QDs. Moreover, the ZnSe midshell leads to a significantly increased density of higher-energy hole states above the valence band-edge, which may reduce the probability of Auger recombination caused by the positive trion. This work enhances our understanding of the excellent performance of the CSS-QDs applied to light-emitting diodes, and is likely to be helpful for the further optimization and design of optoelectronic devices based on the CSS-QDs.
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13
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Prins PT, Spruijt DAW, Mangnus MJJ, Rabouw FT, Vanmaekelbergh D, de Mello Donega C, Geiregat P. Slow Hole Localization and Fast Electron Cooling in Cu-Doped InP/ZnSe Quantum Dots. J Phys Chem Lett 2022; 13:9950-9956. [PMID: 36260410 DOI: 10.1021/acs.jpclett.2c02764] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Impurity doping of low-dimensional semiconductors is an interesting route towards achieving control over carrier dynamics and energetics, e.g., to improve hot carrier extraction, or to obtain strongly Stokes shifted luminescence. Such studies remain, however, underexplored for the emerging family of III-V colloidal quantum dots (QDs). Here, we show through a detailed global analysis of multiresonant pump-probe spectroscopy that electron cooling in copper-doped InP quantum dot (QDs) proceeds on subpicosecond time scales. Conversely, hole localization on Cu dopants is remarkably slow (1.8 ps), yet still leads to very efficient subgap emission. Due to this slow hole localization, common Auger assisted pathways in electron cooling cannot be blocked by Cu doping III-V systems, in contrast with the case of II-VI QDs. Finally, we argue that the structural relaxation around the Cu dopants, estimated to impart a reorganization energy of 220 meV, most likely proceeds simultaneously with the localization itself leading to efficient luminescence.
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Affiliation(s)
- P Tim Prins
- Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584CC Utrecht, The Netherlands
| | - Dirk A W Spruijt
- Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584CC Utrecht, The Netherlands
| | - Mark J J Mangnus
- Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584CC Utrecht, The Netherlands
| | - Freddy T Rabouw
- Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584CC Utrecht, The Netherlands
| | - Daniel Vanmaekelbergh
- Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584CC Utrecht, The Netherlands
| | - Celso de Mello Donega
- Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584CC Utrecht, The Netherlands
| | - Pieter Geiregat
- Department of Chemistry, Ghent University, Krijgslaan 281, 9000 Gent, Belgium
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14
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Kaur G, Shukla A, Babu KJ, Bhatt H, Ghosh HN. Probing the charge transfer mechanisms in type-II Cs 2AgBiBr 6-CdSe composite system: ultrafast insights. NANOTECHNOLOGY 2022; 33:485406. [PMID: 35785756 DOI: 10.1088/1361-6528/ac7dee] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 07/04/2022] [Indexed: 06/15/2023]
Abstract
Lead-free halide-based double perovskites (DPs) have established themselves as the emerging nontoxic alternatives for photovoltaic (PV) applications thus substituting the long-standing lead halide perovskites. Among the prospective lead-free DPs, Cs2AgBiBr6has gained immense popularity owing to the fascinating properties demonstrated by them including low carrier effective mass and microsecond lifetime for electron-hole recombination. Nevertheless, the large, indirect bandgap remains the prime hurdle that restrains commercialization of the Cs2AgBiBr6DPs based PV devices. A rational solution could be designing its heterostructure with another suitable material that could mitigate the inadequacies of Cs2AgBiBr6DPs. With this line of thought, herein we synthesized a composite of Cs2AgBiBr6DPs with CdSe NCs and then performed transient absorption (TA) spectroscopic measurements to introspect its photophysical aspects. Executing excitation energy-dependent studies clearly reveal the carrier transfer efficiency to be strongly pump-dependent. Upon exciting with 350 nm pump, in compliance with the energy band alignment and tendency of both the constituents to be photoexcited across their bandgap, there is a bidirectional transfer of hot electrons anticipated in the composite system. Nevertheless, the TA outcomes indicate the transfer of hot electrons from CdSe to Cs2AgBiBr6to be more favorable out of the bidirectional pathways. Employing further lower pump energies (480 nm) when only CdSe NCs are capable of being excited, the transfer efficiency of the electrons from CdSe to Cs2AgBiBr6is noticed to be fairly low. Besides this, when the pump wavelength is tuned to 530 nm i.e. quite close to the CdSe band edge, no electron transfer is noticeable despite the anticipation from thermodynamic feasibility. Thus, as reflected by the TA kinetics, electron transfer is discerned to be more efficient from the hot states rather than the band edges. Most advantageously, charge separation is successfully achieved in this never explored composite architecture which eases the carrier extraction and minimizes the otherwise prevalent fast recombination processes.
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Affiliation(s)
- Gurpreet Kaur
- Institute of Nano Science and Technology, SAS Nagar, Sector 81, Mohali, Punjab-140306, India
| | - Ayushi Shukla
- Institute of Nano Science and Technology, SAS Nagar, Sector 81, Mohali, Punjab-140306, India
| | | | - Himanshu Bhatt
- Institute of Nano Science and Technology, SAS Nagar, Sector 81, Mohali, Punjab-140306, India
| | - Hirendra N Ghosh
- Institute of Nano Science and Technology, SAS Nagar, Sector 81, Mohali, Punjab-140306, India
- Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai-400085, India
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15
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Gogoi H, Pathak SS, Dasgupta S, Panchakarla LS, Nath S, Datta A. Exciton Dynamics in Colloidal CdS Quantum Dots with Intense and Stokes Shifted Photoluminescence in a Single Decay Channel. J Phys Chem Lett 2022; 13:6770-6776. [PMID: 35853205 DOI: 10.1021/acs.jpclett.2c01623] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
CdS quantum dots (QDs), synthesized by a sol-gel method, exhibit significantly Stokes shifted bright photoluminescence (PL), predominantly from the trap states. Surprisingly, the PL decay at the emission maximum is single-exponential. This is an unusual observation for as-prepared QDs and indicates a narrow distribution in the nature of trap states. A closer look reveals an additional fast component for the decays at shorter emission wavelengths, presumably due to the band edge emission, which remains elusive in the steady-state spectra. Indeed, a significantly narrower and blue-shifted emission band is observed in the decay-associated spectra. The contribution of this component to the steady-state PL intensity is shown to be overwhelmed by that of the significantly stronger trap emission. Exciton dynamics in the quantum dots is elucidated using transient absorption spectra, in which the stimulated emission is observed even at low pump power.
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Affiliation(s)
- Hemen Gogoi
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Sushil Swaroop Pathak
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Souradip Dasgupta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | | | - Sukhendu Nath
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
- Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400 094, India
| | - Anindya Datta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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16
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Staechelin YU, Deffner M, Krohn S, Castillo Delgadillo C, Niehaus JS, Lange H. Carrier localization in zero-dimensional and one-dimensional CdSe–CdS heterostructures. J Chem Phys 2022; 156:061102. [DOI: 10.1063/5.0079619] [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)
| | - Michael Deffner
- Institut für Anorganische und Angewandte Chemie, Universität Hamburg, Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Hamburg, Germany
| | | | | | | | - Holger Lange
- Institut für Physikalische Chemie, Universität Hamburg, Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Hamburg, Germany
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17
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He S, Li Q, Jin T, Lian TT. Contributions of exciton fine structure and hole trapping on the hole state filling effect in the transient absorption spectra of CdSe quantum dots. J Chem Phys 2022; 156:054704. [DOI: 10.1063/5.0081192] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Sheng He
- Chemistry, Emory University, United States of America
| | - Qiuyang Li
- Physics, University of Michigan, United States of America
| | - Tao Jin
- Chemistry Department, Emory University, United States of America
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18
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Žurauskas M, Alex A, Park J, Hood SR, Boppart SA. Fluorescent nanodiamonds for characterization of nonlinear microscopy systems. PHOTONICS RESEARCH 2021; 9:2309-2318. [PMID: 37181134 PMCID: PMC10174270 DOI: 10.1364/prj.434236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Characterizing the performance of fluorescence microscopy and nonlinear imaging systems is an essential step required for imaging system optimization and quality control during longitudinal experiments. Emerging multimodal nonlinear imaging techniques require a new generation of microscopy calibration targets that are not susceptible to bleaching and can provide a contrast across the multiple modalities. Here, we present a nanodiamond-based calibration target for microscopy, designed for facilitating reproducible measurements at the object plane. The target is designed to support day-to-day instrumentation development efforts in microscopy laboratories. The images of a phantom contain information about the imaging performance of a microscopy system across multiple spectral windows and modalities. Since fluorescent nanodiamonds are not prone to bleaching, the proposed imaging target can serve as a standard, shelf-stable sample to provide rapid reference measurements for ensuring consistent performance of microscopy systems in microscopy laboratories and imaging facilities.
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Affiliation(s)
- Mantas Žurauskas
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- GSK Center for Optical Molecular Imaging, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Aneesh Alex
- GSK Center for Optical Molecular Imaging, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- GlaxoSmithKline, Collegeville, Pennsylvania 19426, USA
| | - Jaena Park
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - Steve R. Hood
- GSK Center for Optical Molecular Imaging, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- GlaxoSmithKline, Stevenage, Hertfordshire SG1 2NY, UK
| | - Stephen A. Boppart
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- GSK Center for Optical Molecular Imaging, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Cancer Center at Illinois, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
- Corresponding author:
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19
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Baek W, Chang H, Bootharaju MS, Kim JH, Park S, Hyeon T. Recent Advances and Prospects in Colloidal Nanomaterials. JACS AU 2021; 1:1849-1859. [PMID: 34841404 PMCID: PMC8611664 DOI: 10.1021/jacsau.1c00339] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Indexed: 05/13/2023]
Abstract
Colloidal nanomaterials of metals, metal oxides, and metal chalcogenides have attracted great attention in the past decade owing to their potential applications in optoelectronics, catalysis, and energy conversion. Introduction of various synthetic routes has resulted in diverse colloidal nanostructured materials with well-controlled size, shape, and composition, enabling the systematic study of their intriguing physicochemical, optoelectronic, and chemical properties. Furthermore, developments in the instrumentation have offered valuable insights into the nucleation and growth mechanism of these nanomaterials, which are crucial in designing prospective materials with desired properties. In this perspective, recent advances in the colloidal synthesis and mechanism studies of nanomaterials of metal chalcogenides, metals, and metal oxides are discussed. In addition, challenges in the characterization and future direction of the colloidal nanomaterials are provided.
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Affiliation(s)
- Woonhyuk Baek
- Center
for Nanoparticle Research, Institute for
Basic Science (IBS), Seoul 08826, Republic of Korea
- School
of Chemical and Biological Engineering, and Institute of Chemical
Processes, Seoul National University, Seoul 08826, Republic of Korea
| | - Hogeun Chang
- Center
for Nanoparticle Research, Institute for
Basic Science (IBS), Seoul 08826, Republic of Korea
- School
of Chemical and Biological Engineering, and Institute of Chemical
Processes, Seoul National University, Seoul 08826, Republic of Korea
| | - Megalamane S. Bootharaju
- Center
for Nanoparticle Research, Institute for
Basic Science (IBS), Seoul 08826, Republic of Korea
- School
of Chemical and Biological Engineering, and Institute of Chemical
Processes, Seoul National University, Seoul 08826, Republic of Korea
| | - Jeong Hyun Kim
- Center
for Nanoparticle Research, Institute for
Basic Science (IBS), Seoul 08826, Republic of Korea
- School
of Chemical and Biological Engineering, and Institute of Chemical
Processes, Seoul National University, Seoul 08826, Republic of Korea
| | - Sungjun Park
- Center
for Nanoparticle Research, Institute for
Basic Science (IBS), Seoul 08826, Republic of Korea
- School
of Chemical and Biological Engineering, and Institute of Chemical
Processes, Seoul National University, Seoul 08826, Republic of Korea
| | - Taeghwan Hyeon
- Center
for Nanoparticle Research, Institute for
Basic Science (IBS), Seoul 08826, Republic of Korea
- School
of Chemical and Biological Engineering, and Institute of Chemical
Processes, Seoul National University, Seoul 08826, Republic of Korea
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20
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Li W, Zhang G, Liu L. Near-Infrared Inorganic Nanomaterials for Precise Diagnosis and Therapy. Front Bioeng Biotechnol 2021; 9:768927. [PMID: 34765596 PMCID: PMC8576183 DOI: 10.3389/fbioe.2021.768927] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 10/12/2021] [Indexed: 11/13/2022] Open
Abstract
Traditional wavelengths (400–700 nm) have made tremendous inroads in vivo fluorescence imaging. However, the ability of visible light photon penetration hampered the bio-applications. With reduced photon scattering, minimal tissue absorption and negligible autofluorescence properties, near-infrared light (NIR 700–1700 nm) demonstrates better resolution, high signal-to-background ratios, and deep tissue penetration capability, which will be of great significance for in-vivo determination in deep tissue. In this review, we summarized the latest novel NIR inorganic nanomaterials and the emission mechanism including single-walled carbon nanotubes, rare-earth nanoparticles, quantum dots, metal nanomaterials. Subsequently, the recent progress of precise noninvasive diagnosis in biomedicine and cancer therapy utilizing near-infrared inorganic nanomaterials are discussed. In addition, this review will highlight the concerns, challenges and future directions of near-infrared light utilization.
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Affiliation(s)
- Wenling Li
- Medicine and Pharmacy Research Center, School of Pharmacy, Binzhou Medical University, Yantai, China
| | - Guilong Zhang
- Medicine and Pharmacy Research Center, School of Pharmacy, Binzhou Medical University, Yantai, China
| | - Lu Liu
- Medicine and Pharmacy Research Center, School of Pharmacy, Binzhou Medical University, Yantai, China
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21
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Pattengale B, Ostresh S, Schmuttenmaer CA, Neu J. Interrogating Light-initiated Dynamics in Metal-Organic Frameworks with Time-resolved Spectroscopy. Chem Rev 2021; 122:132-166. [PMID: 34613710 DOI: 10.1021/acs.chemrev.1c00528] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Time-resolved spectroscopy is an essential part of both fundamental and applied chemical research. Such techniques access light-initiated dynamics on time scales ranging from femtosecond to microsecond. Many techniques falling under this description have been applied to gain significant insight into metal-organic frameworks (MOFs), a diverse class of porous coordination polymers. MOFs are highly tunable, both compositionally and structurally, and unique challenges are encountered in applying time-resolved spectroscopy to interrogate their light-initiated properties. These properties involve various excited state mechanisms such as crystallographically defined energy transfer, charge transfer, and localization within the framework, photoconductivity, and structural dynamics. The field of time-resolved MOF spectroscopic studies is quite nascent; each original report cited in this review was published within the past decade. As such, this review is a timely and comprehensive summary of the most significant contributions in this emerging field, with focuses on the overarching spectroscopic concepts applied and on identifying key challenges and future outlooks moving forward.
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Affiliation(s)
- Brian Pattengale
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
| | - Sarah Ostresh
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
| | | | - Jens Neu
- Department of Chemistry, Yale University, New Haven, Connecticut 06511, United States
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22
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Ruhman S. Solving Quantum-Dot Excitonic Riddles with Absolute Pump-Probe Spectroscopy. J Phys Chem Lett 2021; 12:9336-9343. [PMID: 34549584 DOI: 10.1021/acs.jpclett.1c02408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Absolute absorption changes in molecular flash photolysis experiments are routinely translated into molar extinction coefficients and oscillator strengths of reactive intermediates. These direct quantum chemical investigation and allow precise concentration readings in later experiments. In this Perspective we show how a similar approach can deliver crucial information for interpreting transient absorption spectra in colloidal semiconductor quantum dots. The intrinsic complexity of such samples stemming from the inhomogeneity of particle size, shape, and surface chemistry poses unique challenges to mechanistic assignment of ultrafast pump-probe measurements. We will describe applications of this approach to elucidate the photophysics of quantum confined nanocrystals made of various semiconducting materials. These case studies demonstrate how, faced with conflicting interpretations, it has pointed in the right direction in assessing single and multiple exciton generation and relaxation, in searches for ultrafast carrier trapping and scavenging, and in tests of band edge level structure and state degeneracies.
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Affiliation(s)
- Sanford Ruhman
- The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
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23
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Carulli F, Pinchetti V, Zaffalon ML, Camellini A, Rotta Loria S, Moro F, Fanciulli M, Zavelani-Rossi M, Meinardi F, Crooker SA, Brovelli S. Optical and Magneto-Optical Properties of Donor-Bound Excitons in Vacancy-Engineered Colloidal Nanocrystals. NANO LETTERS 2021; 21:6211-6219. [PMID: 34260252 PMCID: PMC8397387 DOI: 10.1021/acs.nanolett.1c01818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/30/2021] [Indexed: 06/13/2023]
Abstract
Controlled insertion of electronic states within the band gap of semiconductor nanocrystals (NCs) is a powerful tool for tuning their physical properties. One compelling example is II-VI NCs incorporating heterovalent coinage metals in which hole capture produces acceptor-bound excitons. To date, the opposite donor-bound exciton scheme has not been realized because of the unavailability of suitable donor dopants. Here, we produce a model system for donor-bound excitons in CdSeS NCs engineered with sulfur vacancies (VS) that introduce a donor state below the conduction band (CB), resulting in long-lived intragap luminescence. VS-localized electrons are almost unaffected by trapping, and suppression of thermal quenching boosts the emission efficiency to 85%. Magneto-optical measurements indicate that the VS are not magnetically coupled to the NC bands and that the polarization properties are determined by the spin of the valence-band photohole, whose spin flip is massively slowed down due to suppressed exchange interaction with the donor-localized electron.
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Affiliation(s)
- Francesco Carulli
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | - Valerio Pinchetti
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | - Matteo L. Zaffalon
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | - Andrea Camellini
- Dipartimento
di Energia, Politecnico di Milano, IT-20133 Milano, Italy
| | | | - Fabrizio Moro
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | - Marco Fanciulli
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | | | - Francesco Meinardi
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
| | - Scott A. Crooker
- National
High Magnetic Field Laboratory, Los Alamos
National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Sergio Brovelli
- Dipartimento
di Scienza dei Materiali, Università
degli Studi di Milano-Bicocca, via Cozzi 55, IT-20125 Milano, Italy
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24
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Mulder J, du Fossé I, Alimoradi Jazi M, Manna L, Houtepen AJ. Electrochemical p-Doping of CsPbBr 3 Perovskite Nanocrystals. ACS ENERGY LETTERS 2021; 6:2519-2525. [PMID: 34307881 PMCID: PMC8294022 DOI: 10.1021/acsenergylett.1c00970] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 06/15/2021] [Indexed: 05/21/2023]
Abstract
Lead halide perovskite nanocrystals have drawn attention as active light-absorbing or -emitting materials for opto-electronic applications due to their facile synthesis, intrinsic defect tolerance, and color-pure emission ranging over the entire visible spectrum. To optimize their application in, e.g., solar cells and light-emitting diodes, it is desirable to gain control over electronic doping of these materials. However, predominantly due to the intrinsic instability of perovskites, successful electronic doping has remained elusive. Using spectro-electrochemistry and electrochemical transistor measurements, we demonstrate here that CsPbBr3 nanocrystals can be successfully and reversibly p-doped via electrochemical hole injection. From an applied potential of ∼0.9 V vs NHE, the emission quenches, the band edge absorbance bleaches, and the electronic conductivity quickly increases, demonstrating the successful injection of holes into the valence band of the CsPbBr3 nanocrystals.
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Affiliation(s)
- Jence
T. Mulder
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629HZ Delft, The Netherlands
| | - Indy du Fossé
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629HZ Delft, The Netherlands
| | - Maryam Alimoradi Jazi
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629HZ Delft, The Netherlands
| | - Liberato Manna
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629HZ Delft, The Netherlands
- Department
of Nanochemistry, Istituto Italiano di Tecnologia
(IIT), Via Morego 30, 16163 Genova, Italy
| | - Arjan J. Houtepen
- Optoelectronic
Materials Section, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629HZ Delft, The Netherlands
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25
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Schleusener A, Micheel M, Benndorf S, Rettenmayr M, Weigand W, Wächtler M. Ultrafast Electron Transfer from CdSe Quantum Dots to an [FeFe]-Hydrogenase Mimic. J Phys Chem Lett 2021; 12:4385-4391. [PMID: 33939438 DOI: 10.1021/acs.jpclett.1c01028] [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 combination of CdSe nanoparticles as photosensitizers with [FeFe]-hydrogenase mimics is known to result in efficient systems for light-driven hydrogen generation with reported turnover numbers in the order of 104-106. Nevertheless, little is known about the details of the light-induced charge-transfer processes. Here, we investigate the time scale of light-induced electron transfer kinetics for a simple model system consisting of CdSe quantum dots (QDs) of 2.0 nm diameter and a simple [FeFe]-hydrogenase mimic adsorbed to the QD surface under noncatalytic conditions. Our (time-resolved) spectroscopic investigation shows that both hot electron transfer on a sub-ps time scale and band-edge electron transfer on a sub-10 ps time scale from photoexcited QDs to adsorbed [FeFe]-hydrogenase mimics occur. Fast recombination via back electron transfer is observed in the absence of a sacrificial agent or protons which, under real catalytic conditions, would quench remaining holes or could stabilize the charge separation, respectively.
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Affiliation(s)
- Alexander Schleusener
- Department Functional Interfaces, Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745 Jena, Germany
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
| | - Mathias Micheel
- Department Functional Interfaces, Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745 Jena, Germany
| | - Stefan Benndorf
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstraße 8, 07743 Jena, Germany
| | - Markus Rettenmayr
- Otto Schott Institute of Materials Research, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany
| | - Wolfgang Weigand
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Humboldtstraße 8, 07743 Jena, Germany
| | - Maria Wächtler
- Department Functional Interfaces, Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745 Jena, Germany
- Institute of Physical Chemistry, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena, Germany
- Abbe Center of Photonics, Friedrich Schiller University Jena, Albert-Einstein-Str. 6, 07745 Jena, Germany
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26
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Dana J, Haggag OS, Dehnel J, Mor M, Lifshitz E, Ruhman S. Testing the fate of nascent holes in CdSe nanocrystals with sub-10 fs pump-probe spectroscopy. NANOSCALE 2021; 13:1982-1987. [PMID: 33443522 DOI: 10.1039/d0nr07651a] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Numerous studies have reported that transient absorption spectra in core CdSe nanocrystals do not register state filling in 1Sh, an absence which has profound consequences in light-emitting applications. It has been assigned alternatively to rapid hole trapping, or to distribution over a dense degenerate valence band manifold which includes dark states. Here we attempt to observe early contributions of nascent holes to the bleaching of the band edge exciton transition by conducting 1Se1Sh pump-1Se1Sh probe spectroscopy with <10 fs laser pulses on organic ligand passivated CdSe crystals. The results show no rapidly hole-state filling effects in transient absorption measurements even at the earliest delay, despite the use of pulses which are capable of resolving all dissipation mechanisms reflected in the homogeneous 1Se1Sh bandwidth. This proves that neither hole trapping nor rapid redistribution of the nascent hole over energetically available valence band states can explain the absence of hole contributions to band edge bleaching, calling for a mechanistic review of this phenomenon.
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Affiliation(s)
- Jayanta Dana
- The Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
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27
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Geuchies JJ, Brynjarsson B, Grimaldi G, Gudjonsdottir S, van der Stam W, Evers WH, Houtepen AJ. Quantitative Electrochemical Control over Optical Gain in Quantum-Dot Solids. ACS NANO 2021; 15:377-386. [PMID: 33171052 PMCID: PMC7844817 DOI: 10.1021/acsnano.0c07365] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 11/02/2020] [Indexed: 05/03/2023]
Abstract
Solution-processed quantum dot (QD) lasers are one of the holy grails of nanoscience. They are not yet commercialized because the lasing threshold is too high: one needs >1 exciton per QD, which is difficult to achieve because of fast nonradiative Auger recombination. The threshold can, however, be reduced by electronic doping of the QDs, which decreases the absorption near the band-edge, such that the stimulated emission (SE) can easily outcompete absorption. Here, we show that by electrochemically doping films of CdSe/CdS/ZnS QDs, we achieve quantitative control over the gain threshold. We obtain stable and reversible doping of more than two electrons per QD. We quantify the gain threshold and the charge carrier dynamics using ultrafast spectroelectrochemistry and achieve quantitative agreement between experiments and theory, including a vanishingly low gain threshold for doubly doped QDs. Over a range of wavelengths with appreciable gain coefficients, the gain thresholds reach record-low values of ∼1 × 10-5 excitons per QD. These results demonstrate a high level of control over the gain threshold in doped QD solids, opening a new route for the creation of cheap, solution-processable, low-threshold QD lasers.
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Affiliation(s)
- Jaco J. Geuchies
- Optoelectronic Materials
Section, Faculty of Applied Sciences, Delft
University of Technology, Van der Maasweg 9, Delft 2629 HAZ, The Netherlands
| | - Baldur Brynjarsson
- Optoelectronic Materials
Section, Faculty of Applied Sciences, Delft
University of Technology, Van der Maasweg 9, Delft 2629 HAZ, The Netherlands
| | | | - Solrun Gudjonsdottir
- Optoelectronic Materials
Section, Faculty of Applied Sciences, Delft
University of Technology, Van der Maasweg 9, Delft 2629 HAZ, The Netherlands
| | | | - Wiel H. Evers
- Optoelectronic Materials
Section, Faculty of Applied Sciences, Delft
University of Technology, Van der Maasweg 9, Delft 2629 HAZ, The Netherlands
| | - Arjan J. Houtepen
- Optoelectronic Materials
Section, Faculty of Applied Sciences, Delft
University of Technology, Van der Maasweg 9, Delft 2629 HAZ, The Netherlands
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28
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Utterback JK, Cline RP, Shulenberger KE, Eaves JD, Dukovic G. The Motion of Trapped Holes on Nanocrystal Surfaces. J Phys Chem Lett 2020; 11:9876-9885. [PMID: 33170725 DOI: 10.1021/acs.jpclett.0c02618] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
This Perspective discusses the phenomenon of trapped-hole diffusion in colloidal semiconductor nanocrystals. Surface charge-carrier traps are ubiquitous in nanocrystals and often dictate the fate of photoexcited carriers. New measurements and calculations are unveiling the nature of the nanocrystal surface, but many challenges to understanding the dynamics of trapped carriers remain. In contrast to the view that trapped holes are stationary, we have put forward a series of reports demonstrating that trapped holes on the surfaces of CdS and CdSe nanocrystals are mobile and move between traps in a sequence of hops. We summarize how these findings advance the understanding of carrier dynamics in colloidal nanocrystals and how they may impact a broad set of excited-state behaviors in these materials.
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Affiliation(s)
- James K Utterback
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - R Peyton Cline
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | | | - Joel D Eaves
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Gordana Dukovic
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, United States
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29
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Li Q, He S, Lian T. How Exciton and Single Carriers Block the Excitonic Transition in Two-Dimensional Cadmium Chalcogenide Nanoplatelets. NANO LETTERS 2020; 20:6162-6169. [PMID: 32697589 DOI: 10.1021/acs.nanolett.0c02461] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Cadmium chalcogenide nanoplatelets (NPLs) possess unique properties and have shown great potential in lasing, light-emitting diodes, and photocatalytic applications. However, the exact natures of the band-edge exciton and single carrier (electron and hole) states remain unclear, even though they affect the key properties and applications of these materials. Herein, we study the contribution of a single carrier (electron or hole) state to phase space filling of single exciton states of cadmium chalcogenide NPLs. With pump fluence dependent TA study and selective electron removal, we determine that a single electron and hole states contribute 85% and 12%, respectively, to the blocking of the excitonic transition in CdSe/ZnS core/shell NPLs. These observations can be rationalized by a model of band-edge exciton and single carrier states of 2D NPLs that differs significantly from that of quantum dots.
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Affiliation(s)
- Qiuyang Li
- Department of Chemistry, Emory University, 1515 Dickey Drive, NE, Atlanta, Georgia 30322, United States
| | - Sheng He
- Department of Chemistry, Emory University, 1515 Dickey Drive, NE, Atlanta, Georgia 30322, United States
| | - Tianquan Lian
- Department of Chemistry, Emory University, 1515 Dickey Drive, NE, Atlanta, Georgia 30322, United States
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30
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Feng D, Yakovlev DR, Dubertret B, Bayer M. Charge Separation Dynamics in CdSe/CdS Core/Shell Nanoplatelets Addressed by Coherent Electron Spin Precession. ACS NANO 2020; 14:7237-7244. [PMID: 32453553 DOI: 10.1021/acsnano.0c02402] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We investigate the charge separation dynamics provided by carrier surface trapping in CdSe/CdS core/shell nanoplatelets by means of a three-laser-beam pump-orientation-probe technique, detecting the electron spin coherence at room temperature. Signals with two Larmor precession frequencies are found, which strongly differ in their dynamical characteristics and dependencies on pump power and shell thickness. The electron trapping process occurs on a time scale of about 10 ns, and the charge separation induced thereby has a long lifetime of up to hundreds of microseconds. On the other hand, the hole trapping requires times from subpicoseconds to hundreds of picoseconds, and the induced charge separation has a lifetime of a few nanoseconds. With increasing CdS shell thickness the hole trapping vanishes, while the electron trapping is still detectable. These findings have important implications for understanding the photophysical processes of nanoplatelets and other colloidal nanostructures.
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Affiliation(s)
- Donghai Feng
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
| | - Dmitri R Yakovlev
- Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
| | - Benoit Dubertret
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI, CNRS, 75231 Paris, France
| | - Manfred Bayer
- Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany
- Ioffe Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia
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31
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Yang W, Yang Y, Kaledin AL, He S, Jin T, McBride JR, Lian T. Surface passivation extends single and biexciton lifetimes of InP quantum dots. Chem Sci 2020; 11:5779-5789. [PMID: 32832054 PMCID: PMC7416692 DOI: 10.1039/d0sc01039a] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 05/15/2020] [Indexed: 01/18/2023] Open
Abstract
Indium phosphide quantum dots (InP QDs) are nontoxic nanomaterials with potential applications in photocatalytic and optoelectronic fields. Post-synthetic treatments of InP QDs are known to be essential for improving their photoluminescence quantum efficiencies (PLQEs) and device performances, but the mechanisms remain poorly understood. Herein, by applying ultrafast transient absorption and photoluminescence spectroscopies, we systematically investigate the dynamics of photogenerated carriers in InP QDs and how they are affected by two common passivation methods: HF treatment and the growth of a heterostructure shell (ZnS in this study). The HF treatment is found to improve the PLQE up to 16-20% by removing an intrinsic fast hole trapping channel (τ h,non = 3.4 ± 1 ns) in the untreated InP QDs while having little effect on the band-edge electron decay dynamics (τ e = 26-32 ns). The growth of the ZnS shell, on the other hand, is shown to improve the PLQE up to 35-40% by passivating both electron and hole traps in InP QDs, resulting in both a long-lived band-edge electron (τ e > 120 ns) and slower hole trapping lifetime (τ h,non > 45 ns). Furthermore, both the untreated and the HF-treated InP QDs have short biexciton lifetimes (τ xx ∼ 1.2 ± 0.2 ps). The growth of an ultra-thin ZnS shell (∼0.2 nm), on the other hand, can significantly extend the biexciton lifetime of InP QDs to 20 ± 2 ps, making it a passivation scheme that can improve both the single and multiple exciton lifetimes. Based on these results, we discuss the possible trap-assisted Auger processes in InP QDs, highlighting the particular importance of trap passivation for reducing the Auger recombination loss in InP QDs.
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Affiliation(s)
- Wenxing Yang
- Department of Chemistry , Emory University , 1515 Dickey Drive Northeast , Atlanta , Georgia 30322 , USA . ;
- Department of Chemistry - Ångström Laboratory , Physical Chemistry , Uppsala University , SE-75120 Uppsala , Sweden
| | - Yawei Yang
- Department of Chemistry , Emory University , 1515 Dickey Drive Northeast , Atlanta , Georgia 30322 , USA . ;
- Electronic Materials Research Laboratory , Key Laboratory of the Ministry of Education , International Center for Dielectric Research , Shaanxi Engineering Research Center of Advanced Energy Materials and Devices , School of Electronic Science and Engineering , Xi'an Jiaotong University , Xi'an 710049 , Shaanxi , P. R. China
| | - Alexey L Kaledin
- Cherry L. Emerson Center for Scientific Computation , Emory University , 1515 Dickey Drive , Atlanta , GA 30322 , USA
| | - Sheng He
- Department of Chemistry , Emory University , 1515 Dickey Drive Northeast , Atlanta , Georgia 30322 , USA . ;
| | - Tao Jin
- Department of Chemistry , Emory University , 1515 Dickey Drive Northeast , Atlanta , Georgia 30322 , USA . ;
| | - James R McBride
- Department of Chemistry , The Vanderbilt Institute of Nanoscale Science and Engineering , Vanderbilt University , Nashville , TN 37235 , USA
| | - Tianquan Lian
- Department of Chemistry , Emory University , 1515 Dickey Drive Northeast , Atlanta , Georgia 30322 , USA . ;
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32
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Abstract
The microscopic origin and timescale of the fluctuations of the energies of electronic states has a significant impact on the properties of interest of electronic materials, with implication in fields ranging from photovoltaic devices to quantum information processing. Spectroscopic investigations of coherent dynamics provide a direct measurement of electronic fluctuations. Modern multidimensional spectroscopy techniques allow the mapping of coherent processes along multiple time or frequency axes and thus allow unprecedented discrimination between different sources of electronic dephasing. Exploiting modern abilities in coherence mapping in both amplitude and phase, we unravel dissipative processes of electronic coherences in the model system of CdSe quantum dots (QDs). The method allows the assignment of the nature of the observed coherence as vibrational or electronic. The expected coherence maps are obtained for the coherent longitudinal optical (LO) phonon, which serves as an internal standard and confirms the sensitivity of the technique. Fast dephasing is observed between the first two exciton states, despite their shared electron state and common environment. This result is contrary to predictions of the standard effective mass model for these materials, in which the exciton levels are strongly correlated through a common size dependence. In contrast, the experiment is in agreement with ab initio molecular dynamics of a single QD. Electronic dephasing in these materials is thus dominated by the realistic electronic structure arising from fluctuations at the atomic level rather than static size distribution. The analysis of electronic dephasing thereby uniquely enables the study of electronic fluctuations in complex materials.
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33
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Gélvez-Rueda MC, Fridriksson MB, Dubey RK, Jager WF, van der Stam W, Grozema FC. Overcoming the exciton binding energy in two-dimensional perovskite nanoplatelets by attachment of conjugated organic chromophores. Nat Commun 2020; 11:1901. [PMID: 32312981 PMCID: PMC7171160 DOI: 10.1038/s41467-020-15869-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 03/26/2020] [Indexed: 11/08/2022] Open
Abstract
In this work we demonstrate a novel approach to achieve efficient charge separation in dimensionally and dielectrically confined two-dimensional perovskite materials. Two-dimensional perovskites generally exhibit large exciton binding energies that limit their application in optoelectronic devices that require charge separation such as solar cells, photo-detectors and in photo-catalysis. Here, we show that by incorporating a strongly electron accepting moiety, perylene diimide organic chromophores, on the surface of the two-dimensional perovskite nanoplatelets it is possible to achieve efficient formation of mobile free charge carriers. These free charge carriers are generated with ten times higher yield and lifetimes of tens of microseconds, which is two orders of magnitude longer than without the peryline diimide acceptor. This opens a novel synergistic approach, where the inorganic perovskite layers are combined with functional organic chromophores in the same material to tune the properties for specific applications.
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Affiliation(s)
- María C Gélvez-Rueda
- Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | - Magnus B Fridriksson
- Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | - Rajeev K Dubey
- Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
- POLYMAT, Basque Center for Macromolecular Design and Engineering, University of the Basque Country UPV/EHU, Avenida de Tolosa 72, 20018, Donostia-San Sebastian, Spain
| | - Wolter F Jager
- Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
| | - Ward van der Stam
- Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands
- Inorganic Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | - Ferdinand C Grozema
- Department of Chemical Engineering, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, The Netherlands.
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34
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Palato S, Seiler H, Baker H, Sonnichsen C, Brosseau P, Kambhampati P. Investigating the electronic structure of confined multiexcitons with nonlinear spectroscopies. J Chem Phys 2020; 152:104710. [DOI: 10.1063/1.5142180] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- S. Palato
- Department of Chemistry, McGill University, 801 Sherbrooke Street W, Montréal, Québec H3A 0B8, Canada
| | - H. Seiler
- Department of Chemistry, McGill University, 801 Sherbrooke Street W, Montréal, Québec H3A 0B8, Canada
| | - H. Baker
- Department of Chemistry, McGill University, 801 Sherbrooke Street W, Montréal, Québec H3A 0B8, Canada
| | - C. Sonnichsen
- Department of Chemistry, McGill University, 801 Sherbrooke Street W, Montréal, Québec H3A 0B8, Canada
| | - P. Brosseau
- Department of Chemistry, McGill University, 801 Sherbrooke Street W, Montréal, Québec H3A 0B8, Canada
| | - P. Kambhampati
- Department of Chemistry, McGill University, 801 Sherbrooke Street W, Montréal, Québec H3A 0B8, Canada
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35
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Utterback JK, Ruzicka JL, Keller HR, Pellows LM, Dukovic G. Electron Transfer from Semiconductor Nanocrystals to Redox Enzymes. Annu Rev Phys Chem 2020; 71:335-359. [PMID: 32074472 DOI: 10.1146/annurev-physchem-050317-014232] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This review summarizes progress in understanding electron transfer from photoexcited nanocrystals to redox enzymes. The combination of the light-harvesting properties of nanocrystals and the catalytic properties of redox enzymes has emerged as a versatile platform to drive a variety of enzyme-catalyzed reactions with light. Transfer of a photoexcited charge from a nanocrystal to an enzyme is a critical first step for these reactions. This process has been studied in depth in systems that combine Cd-chalcogenide nanocrystals with hydrogenases. The two components can be assembled in close proximity to enable direct interfacial electron transfer or integrated with redox mediators to transport charges. Time-resolved spectroscopy and kinetic modeling have been used to measure the rates and efficiencies of the electron transfer. Electron transfer has been described within the framework of Marcus theory, providing insights into the factors that can be used to control the photochemical activity of these biohybrid systems. The range of potential applications and reactions that can be achieved using nanocrystal-enzyme systems is expanding, and numerous fundamental and practical questions remain to be addressed.
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Affiliation(s)
- James K Utterback
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, USA; , , .,Current affiliation: Department of Chemistry, University of California, Berkeley, California 94720, USA;
| | - Jesse L Ruzicka
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, USA; , ,
| | - Helena R Keller
- Materials Science and Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, USA;
| | - Lauren M Pellows
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, USA; , ,
| | - Gordana Dukovic
- Department of Chemistry, University of Colorado Boulder, Boulder, Colorado 80309, USA; , ,
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36
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Wang J, Ding T, Nie C, Wang M, Zhou P, Wu K. Spin-Controlled Charge-Recombination Pathways across the Inorganic/Organic Interface. J Am Chem Soc 2020; 142:4723-4731. [DOI: 10.1021/jacs.9b12724] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Junhui Wang
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China
| | - Tao Ding
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China
| | - Chengming Nie
- State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, Dalian University of Technology, Dalian, Liaoning 116024, China
| | - Mei Wang
- State Key Laboratory of Fine Chemicals, Institute of Artificial Photosynthesis, Dalian University of Technology, Dalian, Liaoning 116024, China
| | - Panwang Zhou
- Institute of Molecular Sciences and Engineering, Institute of Frontier and Interdisciplinary Science, Shandong University, Qingdao, Shandong 266235, China
| | - Kaifeng Wu
- State Key Laboratory of Molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, China
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37
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Richter AF, Binder M, Bohn BJ, Grumbach N, Neyshtadt S, Urban AS, Feldmann J. Fast Electron and Slow Hole Relaxation in InP-Based Colloidal Quantum Dots. ACS NANO 2019; 13:14408-14415. [PMID: 31790203 DOI: 10.1021/acsnano.9b07969] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Colloidal InP-based quantum dots are a promising material for light-emitting applications as an environment friendly alternative to their Cd-containing counterparts. Especially for their use in optoelectronic devices, it is essential to understand how charge carriers relax to the emitting state after injection with excess energy and if all of them arrive at this desired state. Herein, we report time-resolved differential transmission measurements on colloidal InP/ZnS and InP/ZnSe core/shell quantum dots. By optically exciting and probing individual transitions, we are able to distinguish between electron and hole relaxation. This, in turn, allows us to determine how the initial excess energy of the charge carriers affects the relaxation processes. According to the electronic level scheme, one expects a strong phonon bottleneck for electrons, whereas holes should relax easier as their energy levels are more closely spaced. On the contrary, we find that electrons relax faster than holes. The fast electron relaxation occurs via an efficient Auger-like electron-hole scattering mechanism. On the other hand, a small wave function overlap between core and shell states slows the hole relaxation. Additionally, holes can be trapped at the core/shell interface, leading to either slow detrapping or nonradiative recombination. Overall, these results demonstrate that it is crucial to construct devices enabling the injection of charge carriers energetically close to their emitting states in order to maximize the radiative efficiency of the system.
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Affiliation(s)
- Alexander F Richter
- Chair for Photonics and Optoelectronics, Nano-Institute Munich, Physics Department , Ludwig-Maximilians-Universität (LMU) , Königinstr. 10 , 80539 Munich , Germany
| | - Michael Binder
- Chair for Photonics and Optoelectronics, Nano-Institute Munich, Physics Department , Ludwig-Maximilians-Universität (LMU) , Königinstr. 10 , 80539 Munich , Germany
| | - Bernhard J Bohn
- Chair for Photonics and Optoelectronics, Nano-Institute Munich, Physics Department , Ludwig-Maximilians-Universität (LMU) , Königinstr. 10 , 80539 Munich , Germany
| | - Nathan Grumbach
- Merck KGaA , Frankfurter Str. 250 , 64293 Darmstadt , Germany
| | - Shany Neyshtadt
- Merck KGaA , Frankfurter Str. 250 , 64293 Darmstadt , Germany
| | - Alexander S Urban
- Nanospectroscopy Group, Nano-Institute Munich, Physics Department , Ludwig-Maximilians-Universität (LMU) , Königinstr. 10 , 80539 Munich , Germany
| | - Jochen Feldmann
- Chair for Photonics and Optoelectronics, Nano-Institute Munich, Physics Department , Ludwig-Maximilians-Universität (LMU) , Königinstr. 10 , 80539 Munich , Germany
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38
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Azzaro MS, Le AK, Wang H, Roberts ST. Ligand-Enhanced Energy Transport in Nanocrystal Solids Viewed with Two-Dimensional Electronic Spectroscopy. J Phys Chem Lett 2019; 10:5602-5608. [PMID: 31475832 DOI: 10.1021/acs.jpclett.9b02040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We examine CdSe NCs functionalized with the exciton-delocalizing ligand phenyldithiocarbamate (PDTC) using two-dimensional electronic spectroscopy (2DES). PDTC forms hybrid molecular orbitals with CdSe's valence band that relax hole spatial confinement and create potential for enhanced exciton migration in NC solids. We find PDTC broadens the intrinsic line width of individual NCs in solution by ∼30 meV, which we ascribe to modulation of NC band edge states by ligand motion. In PDTC-exchanged solids, photoexcited excitons are mobile and rapidly move to low-energy NC sites over ∼30 ps. We also find placing excitons into high-energy states can accelerate their rate of migration by over an order of magnitude, which we attribute to enhanced spatial delocalization of these states that improves inter-NC wave function overlap. Our work demonstrates that NC surface ligands can actively facilitate inter-NC energy transfer and highlights principles to consider when designing ligands for this application.
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Affiliation(s)
- Michael S Azzaro
- Department of Chemistry , The University of Texas at Austin , Austin , Texas 78712 , United States
| | - Aaron K Le
- Department of Chemistry , The University of Texas at Austin , Austin , Texas 78712 , United States
| | - Honghao Wang
- Department of Chemistry , The University of Texas at Austin , Austin , Texas 78712 , United States
| | - Sean T Roberts
- Department of Chemistry , The University of Texas at Austin , Austin , Texas 78712 , United States
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39
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Utterback JK, Ruzicka JL, Hamby H, Eaves JD, Dukovic G. Temperature-Dependent Transient Absorption Spectroscopy Elucidates Trapped-Hole Dynamics in CdS and CdSe Nanorods. J Phys Chem Lett 2019; 10:2782-2787. [PMID: 31067408 DOI: 10.1021/acs.jpclett.9b00764] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Charge-carrier traps play a central role in the excited-state dynamics of semiconductor nanocrystals, but their influence is often difficult to measure directly. In CdS and CdSe nanorods of nonuniform width, spatially separated electrons and trapped holes display relaxation dynamics that follow a power-law function in time that is consistent with a recombination process limited by trapped-hole diffusion. However, power-law relaxation can originate from mechanisms other than diffusion. Here we report transient absorption spectroscopy measurements on CdS and CdSe nanorods recorded at temperatures ranging from 160 to 294 K. We find that the exponent of the power law is temperature-independent, which rules out several models based on stochastic activated processes and provides insights into the mechanism of diffusion-limited recombination in these structures. The data point to weak electronic coupling between trap states and suggest that surface-localized trapped holes couple strongly to phonons, leading to slow diffusion. Trap-to-trap hole hopping behaves classically near room temperature, while quantum aspects of phonon-assisted tunneling become observable at low temperatures.
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Affiliation(s)
- James K Utterback
- Department of Chemistry , University of Colorado Boulder , Boulder , Colorado 80309 , United States
| | - Jesse L Ruzicka
- Department of Chemistry , University of Colorado Boulder , Boulder , Colorado 80309 , United States
| | - Hayden Hamby
- Department of Chemistry , University of Colorado Boulder , Boulder , Colorado 80309 , United States
| | - Joel D Eaves
- Department of Chemistry , University of Colorado Boulder , Boulder , Colorado 80309 , United States
| | - Gordana Dukovic
- Department of Chemistry , University of Colorado Boulder , Boulder , Colorado 80309 , United States
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