1
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Tiede D, Romero-Pérez C, Koch KA, Ucer KB, Calvo ME, Srimath Kandada AR, Galisteo-López JF, Míguez H. Effect of Connectivity on the Carrier Transport and Recombination Dynamics of Perovskite Quantum-Dot Networks. ACS NANO 2024; 18:2325-2334. [PMID: 38206821 PMCID: PMC10811662 DOI: 10.1021/acsnano.3c10239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 12/26/2023] [Accepted: 01/02/2024] [Indexed: 01/13/2024]
Abstract
Quantum-dot (QD) solids are being widely exploited as a solution-processable technology to develop photovoltaic, light-emission, and photodetection devices. Charge transport in these materials is the result of a compromise between confinement at the individual QD level and electronic coupling among the different nanocrystals in the ensemble. While this is commonly achieved by ligand engineering in colloidal-based systems, ligand-free QD assemblies have recently emerged as an exciting alternative where nanostructures can be directly grown into porous matrices with optical quality as well as control over their connectivity and, hence, charge transport properties. In this context, we present a complete photophysical study comprising fluence- and temperature-dependent time-resolved spectroscopy to study carrier dynamics in ligand-free QD networks with gradually varying degrees of interconnectivity, which we achieve by changing the average distance between the QDs. Analysis of the photoluminescence and absorption properties of the QD assemblies, involving both static and time-resolved measurements, allows us to identify the weight of the different recombination mechanisms, both radiative and nonradiative, as a function of QD connectivity. We propose a picture where carrier diffusion, which is needed for any optoelectronic application and implies interparticle transport, gives rise to the exposure of carriers to a larger defect landscape than in the case of isolated QDs. The use of a broad range of fluences permits extracting valuable information for applications demanding either low- or high-carrier-injection levels and highlighting the relevance of a judicious design to balance recombination and diffusion.
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Affiliation(s)
- David
O. Tiede
- Instituto
de Ciencias de Materiales de Sevilla (Consejo Superior de Investigaciones
Científicas-Universidad de Sevilla), C/Américo Vespucio, 49, Sevilla 41092, Spain
| | - Carlos Romero-Pérez
- Instituto
de Ciencias de Materiales de Sevilla (Consejo Superior de Investigaciones
Científicas-Universidad de Sevilla), C/Américo Vespucio, 49, Sevilla 41092, Spain
| | - Katherine A. Koch
- Department
of Physics and Center for Functional Materials, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, North Carolina 27109, United States
| | - K. Burak Ucer
- Department
of Physics and Center for Functional Materials, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, North Carolina 27109, United States
| | - Mauricio E. Calvo
- Instituto
de Ciencias de Materiales de Sevilla (Consejo Superior de Investigaciones
Científicas-Universidad de Sevilla), C/Américo Vespucio, 49, Sevilla 41092, Spain
| | - Ajay Ram Srimath Kandada
- Department
of Physics and Center for Functional Materials, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, North Carolina 27109, United States
| | - Juan F. Galisteo-López
- Instituto
de Ciencias de Materiales de Sevilla (Consejo Superior de Investigaciones
Científicas-Universidad de Sevilla), C/Américo Vespucio, 49, Sevilla 41092, Spain
| | - Hernán Míguez
- Instituto
de Ciencias de Materiales de Sevilla (Consejo Superior de Investigaciones
Científicas-Universidad de Sevilla), C/Américo Vespucio, 49, Sevilla 41092, Spain
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2
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Koga M, Masuoka K, Tsuneizumi S, Kameyama T, Ito S, Torimoto T, Miyasaka H. Direct Detection of Long-Range Interdomain Auger Recombination in Dumbbell-Shaped Quasi-Type-II Nanoparticle. J Phys Chem Lett 2022; 13:6845-6851. [PMID: 35861331 DOI: 10.1021/acs.jpclett.2c01077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Multicarrier dynamics in heterostructured ZnS-AgInS2 (ZAIS) dumbbell-like nanoparticle (nanodumbell), which consists of two visible-light absorptive domains (ellipsoidal tip domains) directly linked to each end of a 22 nm length rod domain of the ZAIS nanodumbell with a quasi-type-II heterostructure, was investigated by femtosecond transient absorption spectroscopy under variable excitation intensities. Quantitative analysis together with the numerical simulations for the excitation intensity dependence of the dynamics revealed that only one electron-hole pair survived in the overall dumbbell as a consequence of Auger recombination, even though multiple carriers were formed on both terminal tip domains. This result strongly suggested carrier-carrier interaction between the tip domains, leading to the long-range Auger recombination via tunneling across a rod potential barrier.
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Affiliation(s)
- Masafumi Koga
- Division of Frontier Materials Science and Center for Promotion of Advanced Interdisciplinary Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Ko Masuoka
- Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Shuhei Tsuneizumi
- Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Tatsuya Kameyama
- Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Syoji Ito
- Division of Frontier Materials Science and Center for Promotion of Advanced Interdisciplinary Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
- Research Institute for Light-Induced Acceleration System (RILACS), Osaka Prefecture University, 1-2, Sakai, Osaka 599-8570, Japan
| | - Tsukasa Torimoto
- Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan
| | - Hiroshi Miyasaka
- Division of Frontier Materials Science and Center for Promotion of Advanced Interdisciplinary Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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3
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Lee S, Kim S, Yoo H. Contribution of Polymers to Electronic Memory Devices and Applications. Polymers (Basel) 2021; 13:3774. [PMID: 34771332 PMCID: PMC8588209 DOI: 10.3390/polym13213774] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 10/26/2021] [Accepted: 10/29/2021] [Indexed: 11/23/2022] Open
Abstract
Electronic memory devices, such as memristors, charge trap memory, and floating-gate memory, have been developed over the last decade. The use of polymers in electronic memory devices enables new opportunities, including easy-to-fabricate processes, mechanical flexibility, and neuromorphic applications. This review revisits recent efforts on polymer-based electronic memory developments. The versatile contributions of polymers for emerging memory devices are classified, providing a timely overview of such unconventional functionalities with a strong emphasis on the merits of polymer utilization. Furthermore, this review discusses the opportunities and challenges of polymer-based memory devices with respect to their device performance and stability for practical applications.
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Affiliation(s)
| | | | - Hocheon Yoo
- Department of Electronic Engineering, Gachon University, Seongnam 1342, Korea; (S.L.); (S.K.)
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4
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Collini E. 2D Electronic Spectroscopic Techniques for Quantum Technology Applications. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2021; 125:13096-13108. [PMID: 34276867 PMCID: PMC8282191 DOI: 10.1021/acs.jpcc.1c02693] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/22/2021] [Indexed: 05/14/2023]
Abstract
2D electronic spectroscopy (2DES) techniques have gained particular interest given their capability of following ultrafast coherent and noncoherent processes in real-time. Although the fame of 2DES is still majorly linked to the investigation of energy and charge transport in biological light-harvesting complexes, 2DES is now starting to be recognized as a particularly valuable tool for studying transport processes in artificial nanomaterials and nanodevices. Particularly meaningful is the possibility of assessing coherent mechanisms active in the transport of excitation energy in these materials toward possible quantum technology applications. The diverse nature of these new target samples poses significant challenges and calls for a critical rethinking of the technique and its different realizations. With the confluence of promising new applications and rapidly developing technical capabilities, the enormous potential of 2DES techniques to impact the field of nanosystems, quantum technologies, and quantum devices is here delineated.
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Affiliation(s)
- Elisabetta Collini
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy
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5
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Geremew A, Qian C, Abelson A, Rumyantsev S, Kargar F, Law M, Balandin AA. Low-frequency electronic noise in superlattice and random-packed thin films of colloidal quantum dots. NANOSCALE 2019; 11:20171-20178. [PMID: 31616880 DOI: 10.1039/c9nr06899f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report measurements of low-frequency electronic noise in ordered superlattice, weakly-ordered and random-packed thin films of 6.5 nm PbSe quantum dots prepared using several different ligand chemistries. For all samples, the normalized noise spectral density of the dark current revealed a Lorentzian component, reminiscent of the generation-recombination noise, superimposed on the 1/f background (f is the frequency). An activation energy of ∼0.3 eV was extracted from the temperature dependence of the noise spectra in the ordered and random quantum dot films. The noise level in the ordered films was lower than that in the weakly-ordered and random-packed films. A large variation in the magnitude of the noise spectral density was also observed in samples with different ligand treatments. The obtained results are important for application of colloidal quantum dot films in photodetectors.
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Affiliation(s)
- Adane Geremew
- Nano-Device Laboratory (NDL), Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA.
| | - Caroline Qian
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, California 92697, USA
| | - Alex Abelson
- Department of Materials Science and Engineering, University of California, Irvine, California 92697, USA
| | - Sergey Rumyantsev
- Nano-Device Laboratory (NDL), Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA. and CENTERA Laboratories, Institute of High-Pressure Physics, Polish Academy of Sciences, Warsaw 01-142, Poland
| | - Fariborz Kargar
- Nano-Device Laboratory (NDL), Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA.
| | - Matt Law
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, California 92697, USA and Department of Materials Science and Engineering, University of California, Irvine, California 92697, USA and Department of Chemistry, University of California, Irvine, California 92697, USA
| | - Alexander A Balandin
- Nano-Device Laboratory (NDL), Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA. and Phonon Optimized Engineered Materials (POEM) Center, Materials Science and Engineering Program, University of California, Riverside, California 92521, USA
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6
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Sehrawat P, Islam SS. An ultrafast quantum thermometer from graphene quantum dots. NANOSCALE ADVANCES 2019; 1:1772-1783. [PMID: 36134218 PMCID: PMC9417143 DOI: 10.1039/c8na00361k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 02/15/2019] [Indexed: 06/11/2023]
Abstract
We report an ultra-sensitive temperature sensor derived from graphene quantum dots (GQDs) embedded in a self-standing reduced graphene oxide (RGO) film. The GQDs are obtained as a natural derivative during synthesis of GO to RGO. A fundamental study on low temperature transport mechanisms reveals the applicability of temperature zone specific 'variable range hopping (VRH)' conduction models, i.e. Mott-VRH, Efros-Shklovskii-VRH and activation energy supported VRH. On the basis of transport behavior and confirmed by characterization analyses, the RGO film is modeled as GQD arrays where graphitic (sp2) domains behave as QDs and oxygenated (sp3) domains between interdots act as tunneling barriers. Temperature dependent resistance and current-voltage (I-V) characteristics indicate high sensitivity where sensor resistance changes by almost six orders of magnitude as the temperature is varied between 300 and 12 K. In convection mode, the developed temperature sensor shows a temperature coefficient of resistance (TCR) of ∼-1999% K-1 in the 300-77 K temperature range, which is much higher than the TCR values reported so far. Additionally, the sensor exhibits an extremely fast response (∼0.3 s) and recovery (0.8 s) time; and such high TCR leads to ultra high resolution of ∼ μK. The sensor shows excellent repeatability with negligible drift over several cycles. These studies are crucial for modern day thermal management and sensitive cryogenic applications.
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Affiliation(s)
- Poonam Sehrawat
- Centre for Nanoscience and Nanotechnology, Jamia Millia Islamia (A Central University) New Delhi 110025 India +91 11 26987153
| | - S S Islam
- Centre for Nanoscience and Nanotechnology, Jamia Millia Islamia (A Central University) New Delhi 110025 India +91 11 26987153
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7
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Kurochkina MA, Konshina EA, Khmelevskaia D. Photoluminescence of CdSe/ZnS quantum dots in nematic liquid crystals in electric fields. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2018; 9:1544-1549. [PMID: 29977687 PMCID: PMC6009683 DOI: 10.3762/bjnano.9.145] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 04/27/2018] [Indexed: 06/08/2023]
Abstract
We have experimentally investigated the effect of the reorientation of a nematic liquid crystal (LC) in an electric field on the photoluminescence (PL) of CdSe/ZnS semiconductor quantum dots (QDs). To the LC with positive dielectric anisotropy, 1 wt % QDs with a core diameter of 5 nm was added. We compared the change of PL intensity and decay times of QDs in LC cells with initially planar or vertically orientated molecules, i.e., in active or passive LC matrices. The PL intensity of the QDs increases four-fold in the active LC matrix and only 1.6-fold in the passive LC matrix without reorientation of the LC molecules. With increasing electric field strength, the quenching of QDs luminescence occurred in the active LC matrix, while the PL intensity did not change in the passive LC matrix. The change in the decay time with increasing electric field strength was similar to the behavior of the PL intensity. The observed buildup in the QDs luminescence can be associated with the transfer of energy from LC molecules to QDs. In a confocal microscope, we observed the increase of particle size and the redistribution of particles in the active LC matrix with the change of the electric field strength. At the same time, no significant changes occurred in the passive LC matrix. With the reorientation of LC molecules from the planar in vertical position in the LC active matrix, quenching of QD luminescence and an increase of the ion current took place simultaneously. The obtained results are interesting for controlling the PL intensity of semiconductor QDs in liquid crystals by the application of electric fields.
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Affiliation(s)
- Margarita A Kurochkina
- Center of Information and Optical Technologies, ITMO University, Kronverksky pr. 49, Saint-Petersburg, 197101, Russia
| | - Elena A Konshina
- Department of Optical Physics and Modern Natural Science, ITMO University, Kronverksky pr. 49, Saint-Petersburg, 197101, Russia
| | - Daria Khmelevskaia
- Department of Optical Physics and Modern Natural Science, ITMO University, Kronverksky pr. 49, Saint-Petersburg, 197101, Russia
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8
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Photon antibunching in a cluster of giant CdSe/CdS nanocrystals. Nat Commun 2018; 9:1536. [PMID: 29670113 PMCID: PMC5906464 DOI: 10.1038/s41467-018-03971-w] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Accepted: 03/24/2018] [Indexed: 01/12/2023] Open
Abstract
When closely packed into a high-density film, semiconductor nanocrystals (NCs) can interact with each other to yield collective optical behaviours, which are normally difficult to characterize due to the ensemble average effect. Here we synthesized semiconductor NC clusters and performed single-particle spectroscopic measurements to probe the electronic couplings of several giant CdSe/CdS NCs contained in one cluster with nanometer-scale separations. Such a single cluster exhibits multiple emission peaks at the cryogenic temperature with nearly identical photoluminescence decay dynamics, suggesting that the Förster-type energy transfer does not occur among the composing NCs. Surprisingly, strong photon antibunching is still observed from a single cluster, which can be attributed to the Auger annihilation of photo-excited excitons from different NCs. The isolation of several nearby NCs interacting with the above novel mechanism has marked a solid progress towards a full understanding and an efficient control of the operation parameters in NC-based optoelectronic devices.
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9
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Chang IY, Kim D, Hyeon-Deuk K. Control of Electronic Structures and Phonon Dynamics in Quantum Dot Superlattices by Manipulation of Interior Nanospace. ACS APPLIED MATERIALS & INTERFACES 2016; 8:18321-18327. [PMID: 27385641 DOI: 10.1021/acsami.6b03219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Quantum dot (QD) superlattices, periodically ordered array structures of QDs, are expected to provide novel photo-optical functions due to their resonant couplings between adjacent QDs. Here, we computationally demonstrated that electronic structures and phonon dynamics of a QD superlattice can be effectively and selectively controlled by manipulating its interior nanospace, where quantum resonance between neighboring QDs appears, rather than by changing component QD size, shape, compositions, etc. A simple H-passivated Si QD was examined to constitute one-, two-, and three-dimensional QD superlattices, and thermally fluctuating band energies and phonon modes were simulated by finite-temperature ab initio molecular dynamics (MD) simulations. The QD superlattice exhibited a decrease in the band gap energy enhanced by thermal modulations and also exhibited selective extraction of charge carriers out of the component QD, indicating its advantage as a promising platform for implementation in solar cells. Our dynamical phonon analyses based on the ab initio MD simulations revealed that THz-frequency phonon modes were created by an inter-QD crystalline lattice formed in the QD superlattice, which can contribute to low energy thermoelectric conversion and will be useful for direct observation of the dimension-dependent superlattice. Further, we found that crystalline and ligand-originated phonon modes inside each component QD can be independently controlled by asymmetry of the superlattice and by restriction of the interior nanospace, respectively. Taking into account the thermal effects at the finite temperature, we proposed guiding principles for designing efficient and space-saving QD superlattices to develop functional photovoltaic and thermoelectric devices.
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Affiliation(s)
- I-Ya Chang
- Department of Chemistry, Kyoto University , Kyoto 606-8502, Japan
- PRESTO, Japan Science and Technology Agency , 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - DaeGwi Kim
- Department of Applied Physics, Osaka City University , Osaka 558-8585, Japan
| | - Kim Hyeon-Deuk
- Department of Chemistry, Kyoto University , Kyoto 606-8502, Japan
- PRESTO, Japan Science and Technology Agency , 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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10
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Madani A, Ma L, Miao S, Jorgensen MR, Schmidt OG. Luminescent nanoparticles embedded in TiO2 microtube cavities for the activation of whispering-gallery-modes extending from the visible to the near infrared. NANOSCALE 2016; 8:9498-9503. [PMID: 27102146 DOI: 10.1039/c5nr08979d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Luminescent nanoparticles (NPs) are deposited onto two dimensional (2D) pre-strained TiO2 nanomembranes by spin-coating. After rolling up the 2D differentially strained TiO2 nanomembranes into 3D microtube structures, the NPs are embedded within the tube windings. The embedded NPs serve as a light source for optical whispering-gallery-mode resonances under laser excitation, and therefore allow the TiO2 microtube to work as an active microcavity operating in emission mode. The spectral range of resonant modes can be tuned from the visible to the near infrared by embedding the proper NPs in the TiO2 tube wall. Rolled-up TiO2 microcavities combined with luminescent NPs could offer interesting opportunities in a variety of research fields, such as bio- and nanophotonics, optoelectronics, and optofluidics.
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Affiliation(s)
- Abbas Madani
- Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany.
| | - Libo Ma
- Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany.
| | - Shading Miao
- Anhui Key Lab of Controllable Chemical Reaction & Material Chemical Engineering, School of Chemical Engineering, Hefei University of Technology, Tunxi Road. 193, 230009, Hefei, Anhui Prov, China
| | - Matthew R Jorgensen
- Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany.
| | - Oliver G Schmidt
- Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany. and Material Systems for Nanoelectronics, Chemnitz University of Technology, Reichenhainer Str. 70, 09107 Chemnitz, Germany
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11
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Kim D, Tomita S, Ohshiro K, Watanabe T, Sakai T, Chang IY, Hyeon-Deuk K. Evidence of Quantum Resonance in Periodically-Ordered Three-Dimensional Superlattice of CdTe Quantum Dots. NANO LETTERS 2015; 15:4343-4347. [PMID: 26091186 DOI: 10.1021/acs.nanolett.5b00335] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Semiconductor quantum dot (QD) superlattices, which are periodically ordered three-dimensional (3D) array structures of QDs, are expected to exhibit novel photo-optical properties arising from the resonant interactions between adjacent QDs. Since the resonant interactions such as long-range dipole-dipole Coulomb coupling and short-range quantum resonance strongly depend on inter-QD nano space, precise control of the nano space is essential for physical understanding of the superlattice, which includes both of nano and bulk scales. Here, we study the pure quantum resonance in the 3D CdTe QD superlattice deposited by a layer-by-layer assembly of positively charged polyelectrolytes and negatively charged CdTe QDs. From XRD measurements, existence of the periodical ordering of QDs both in the lamination and in-plane directions, that is, the formation of the 3D periodic QD superlattice, was confirmed. The lowest excitation energy decreases exponentially with decreasing the nano space between the CdTe QD layers and also with decreasing the QD size, which is apparently indicative of the quantum resonance between the QDs rather than a dipole-dipole Coulomb coupling. The quantum resonance was also computationally demonstrated and rationalized by the orbital delocalization to neighboring CdTe QDs in the superlattice.
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Affiliation(s)
- DaeGwi Kim
- †Department of Applied Physics, Osaka City University, Osaka 558-8585, Japan
| | - Shougo Tomita
- †Department of Applied Physics, Osaka City University, Osaka 558-8585, Japan
| | - Kazuma Ohshiro
- †Department of Applied Physics, Osaka City University, Osaka 558-8585, Japan
| | - Taichi Watanabe
- †Department of Applied Physics, Osaka City University, Osaka 558-8585, Japan
| | - Takenobu Sakai
- ‡Green Mobility Collaborative Research Center, Nagoya University, Nagoya 464-8603, Japan
| | - I-Ya Chang
- §Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan
- ∥Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Kim Hyeon-Deuk
- §Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan
- ∥Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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12
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Cd/Hg cationic substitution in magic-sized CdSe clusters: Optical characterization and theoretical studies. Chem Phys 2015. [DOI: 10.1016/j.chemphys.2015.04.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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13
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Logar M, Xu S, Acharya S, Prinz FB. Variation of energy density of states in quantum dot arrays due to interparticle electronic coupling. NANO LETTERS 2015; 15:1855-1860. [PMID: 25670055 DOI: 10.1021/nl5046507] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Subnanometer-resolved local electron energy structure was measured in PbS quantum dot superlattice arrays using valence electron energy loss spectroscopy with scanning transmission electron microscopy. We found smaller values of the lowest available transition energies and an increased density of electronic states in the space between quantum dots with shorter interparticle spacing, indicating extension of carrier wave functions as a result of interparticle electronic coupling. A quantum simulation verified both trends and illustrated the wave function extension effect.
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Affiliation(s)
- Manca Logar
- Department of Mechanical Engineering and ‡Department of Material Science and Engineering, Stanford University , Stanford, California 94305, United States
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14
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Achtstein AW, Prudnikau AV, Ermolenko MV, Gurinovich LI, Gaponenko SV, Woggon U, Baranov AV, Leonov MY, Rukhlenko ID, Fedorov AV, Artemyev MV. Electroabsorption by 0D, 1D, and 2D nanocrystals: a comparative study of CdSe colloidal quantum dots, nanorods, and nanoplatelets. ACS NANO 2014; 8:7678-7686. [PMID: 25107475 DOI: 10.1021/nn503745u] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This work presents a comprehensive study of electroabsorption in CdSe colloidal quantum dots, nanorods, and nanoplatelets. We experimentally demonstrate that the exposure of the nanoplatelets to a dc electric field leads to strong broadening of their lowest-energy heavy-hole absorption band and drastically reduces the absorption efficiency within the band. These are results of the quantum-confined Stark and Franz–Keldysh effects. The field-induced change in the nanoplatelets’ absorption is found to be more than 10 times the change in the absorption by the quantum dots. We also demonstrate that the electroabsorption by the nanorods is weaker than that by the quantum dots and nanoplatelets and reveal an unusual dependence of the differential absorption changes on the nanoplatelet thickness: the thicker the nanoplatelet, the smaller the change.
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15
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Silva ACA, da Silva SW, Morais PC, Dantas NO. Shell thickness modulation in ultrasmall CdSe/CdS(x)Se(1-x)/CdS core/shell quantum dots via 1-thioglycerol. ACS NANO 2014; 8:1913-1922. [PMID: 24460449 DOI: 10.1021/nn406478f] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In this study, we report on the synthesis of CdSe/CdS core-shell ultrasmall quantum dots (CS-USQDs) using an aqueous-based wet chemistry protocol. The proposed chemical route uses increasing concentration of 1-thioglycerol to grow the CdS shell on top of the as-precipitated CdSe core in a controllable way. We found that lower concentration of 1-thioglycerol (3 mmol) added into the reaction medium limits the growth of the CdSe core, and higher and increasing concentration (5-11 mmol) of 1-thioglycerol promotes the growth of CdS shell on top of the CdSe core in a very controllable way, with an increase from 0.50 to 1.25 nm in shell thickness. The growth of CS-USQDs of CdSe/CdS was confirmed by using different experimental techniques, such as optical absorption (OA) spectroscopy, fluorescence spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. Data collected from OA were used to obtain the average values of the CdSe core diameter, whereas Raman data were used to assess the average values of the CdSe core diameter and CdS shell thicknesses.
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Affiliation(s)
- Anielle Christine A Silva
- Laboratório de Novos Materiais Isolantes e Semicondutores (LNMIS), Institute of Physics, Federal University of Uberlândia , CP 593, Uberlândia MG 38400-902, Brazil
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16
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Pejova B. Three-dimensional assemblies built up by quantum dots in size-quantization regime: Band gap shifts due to size-distribution of cadmium selenide nanoparticles. J SOLID STATE CHEM 2013. [DOI: 10.1016/j.jssc.2013.09.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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17
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Wang H, Shao Z, Bacher M, Liebner F, Rosenau T. Fluorescent cellulose aerogels containing covalently immobilized (ZnS) x(CuInS 2) 1-x/ZnS (core/shell) quantum dots. CELLULOSE (LONDON, ENGLAND) 2013; 20:3007-3024. [PMID: 26412950 PMCID: PMC4579861 DOI: 10.1007/s10570-013-0035-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 08/21/2013] [Indexed: 05/12/2023]
Abstract
Photoluminiscent (PL) cellulose aerogels of variable shape containing homogeneously dispersed and surface-immobilized alloyed (ZnS)x(CuInS2)1-x/ZnS (core/shell) quantum dots (QD) have been obtained by (1) dissolution of hardwood prehydrolysis kraft pulp in the ionic liquid 1-hexyl-3-methyl-1H-imidazolium chloride, (2) addition of a homogenous dispersion of quantum dots in the same solvent, (3) molding, (4) coagulation of cellulose using ethanol as antisolvent, and (5) scCO2 drying of the resulting composite aerogels. Both compatibilization with the cellulose solvent and covalent attachment of the quantum dots onto the cellulose surface was achieved through replacement of 1-mercaptododecyl ligands typically used in synthesis of (ZnS)x(CuInS2)1-x/ZnS (core-shell) QDs by 1-mercapto-3-(trimethoxysilyl)-propyl ligands. The obtained cellulose-quantum dot hybrid aerogels have apparent densities of 37.9-57.2 mg cm-3. Their BET surface areas range from 296 to 686 m2 g-1 comparable with non-luminiscent cellulose aerogels obtained via the NMMO, TBAF/DMSO or Ca(SCN)2 route. Depending mainly on the ratio of QD core constituents and to a minor extent on the cellulose/QD ratio, the emission wavelength of the novel aerogels can be controlled within a wide range of the visible light spectrum. Whereas higher QD contents lead to bathochromic PL shifts, hypsochromism is observed when increasing the amount of cellulose at constant QD content. Reinforcement of the cellulose aerogels and hence significantly reduced shrinkage during scCO2 drying is a beneficial side effect when using α-mercapto-ω-(trialkoxysilyl) alkyl ligands for QD capping and covalent QD immobilization onto the cellulose surface.
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Affiliation(s)
- Huiqing Wang
- Key Laboratory of Natural Polymeric Materials and Application Technology, Department of Materials Science and Engineering, Beijing Institute of Technology, Zhongguancun South Street 5, Beijing, 10081 People’s Republic of China
- Division of Chemistry of Renewables, Department of Chemistry, University of Natural Resources and Life Sciences, Konrad-Lorenz-Straße 24, 3430 Tulln, Austria
| | - Ziqiang Shao
- Key Laboratory of Natural Polymeric Materials and Application Technology, Department of Materials Science and Engineering, Beijing Institute of Technology, Zhongguancun South Street 5, Beijing, 10081 People’s Republic of China
| | - Markus Bacher
- Division of Chemistry of Renewables, Department of Chemistry, University of Natural Resources and Life Sciences, Konrad-Lorenz-Straße 24, 3430 Tulln, Austria
| | - Falk Liebner
- Division of Chemistry of Renewables, Department of Chemistry, University of Natural Resources and Life Sciences, Konrad-Lorenz-Straße 24, 3430 Tulln, Austria
| | - Thomas Rosenau
- Division of Chemistry of Renewables, Department of Chemistry, University of Natural Resources and Life Sciences, Konrad-Lorenz-Straße 24, 3430 Tulln, Austria
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18
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Pilla V, de Lima SR, Andrade AA, Silva AC, Dantas NO. Fluorescence quantum efficiency of CdSe/CdS magic-sized quantum dots functionalized with carboxyl or hydroxyl groups. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.07.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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19
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Korala L, Wang Z, Liu Y, Maldonado S, Brock SL. Uniform thin films of CdSe and CdSe(ZnS) core(shell) quantum dots by sol-gel assembly: enabling photoelectrochemical characterization and electronic applications. ACS NANO 2013; 7:1215-1223. [PMID: 23350924 PMCID: PMC3590068 DOI: 10.1021/nn304563j] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Optoelectronic properties of quantum dot (QD) films are limited by (1) poor interfacial chemistry and (2) nonradiative recombination due to surface traps. To address these performance issues, sol-gel methods are applied to fabricate thin films of CdSe and core(shell) CdSe(ZnS) QDs. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging with chemical analysis confirms that the surface of the QDs in the sol-gel thin films are chalcogen-rich, consistent with an oxidative-induced gelation mechanism in which connectivity is achieved by formation of dichalcogenide covalent linkages between particles. The ligand removal and assembly process is probed by thermogravimetric, spectroscopic, and microscopic studies. Further enhancement of interparticle coupling via mild thermal annealing, which removes residual ligands and reinforces QD connectivity, results in QD sol-gel thin films with superior charge transport properties, as shown by a dramatic enhancement of electrochemical photocurrent under white light illumination relative to thin films composed of ligand-capped QDs. A more than 2-fold enhancement in photocurrent, and a further increase in photovoltage can be achieved by passivation of surface defects via overcoating with a thin ZnS shell. The ability to tune interfacial and surface characteristics for the optimization of photophysical properties suggests that the sol-gel approach may enable formation of QD thin films suitable for a range of optoelectronic applications.
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Affiliation(s)
- Lasantha Korala
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
| | - Zhijie Wang
- Chemistry Department, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Yi Liu
- Electron Microscopy Facility, Oregon State University, Corvallis, Oregon 87331, USA
| | - Stephen Maldonado
- Chemistry Department, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Stephanie L. Brock
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA
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20
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Kwon BH, Lee KG, Park TJ, Kim H, Lee TJ, Lee SJ, Jeon DY. Continuous in situ synthesis of ZnSe/ZnS core/shell quantum dots in a microfluidic reaction system and its application for light-emitting diodes. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2012; 8:3257-3262. [PMID: 22888060 DOI: 10.1002/smll.201200773] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 06/28/2012] [Indexed: 06/01/2023]
Affiliation(s)
- Byoung-Hwa Kwon
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701, Republic of Korea
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21
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Enhanced dispersion of CdSe/MEH-CN-PPV hybrid nanocomposites by in situ polymerization using AEM as photopolymerizable precursor. Colloid Polym Sci 2012. [DOI: 10.1007/s00396-012-2672-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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22
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Yang Y, Rodríguez-Córdoba W, Xiang X, Lian T. Strong electronic coupling and ultrafast electron transfer between PbS quantum dots and TiO2 nanocrystalline films. NANO LETTERS 2012; 12:303-9. [PMID: 22182013 DOI: 10.1021/nl2035783] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Hot carrier and multiple exciton extractions from lead salt quantum dots (QDs) to TiO(2) single crystals have been reported. Implementing these ideas on practical solar cells likely requires the use of nanocrystalline TiO(2) thin films to enhance the light harvesting efficiency. Here, we report 6.4 ± 0.4 fs electron transfer time from PbS QDs to TiO(2) nanocrystalline thin films, suggesting the possibility of extracting hot carriers and multiple excitons in solar cells based on these materials.
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Affiliation(s)
- Ye Yang
- Department of Chemistry, Emory University, 1515 Dickey Drive NE, Atlanta, Georgia 30322, USA
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23
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Rakovich YP, Jäckel F, Donegan JF, Rogach AL. Semiconductor nanowires self-assembled from colloidal CdTe nanocrystal building blocks: optical properties and application perspectives. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm33566b] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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24
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Wang H, Shao Z, Chen B, Zhang T, Wang F, Zhong H. Transparent, flexible and luminescent composite films by incorporating CuInS2 based quantum dots into a cyanoethyl cellulose matrix. RSC Adv 2012. [DOI: 10.1039/c2ra01359b] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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25
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Zhang X, Sun D, Sue HJ, Nishimura R. Colloidal crystallization of surfactant-free ZnO quantum dots. Chemphyschem 2011; 12:3533-8. [PMID: 22069245 DOI: 10.1002/cphc.201100579] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Indexed: 01/26/2023]
Affiliation(s)
- Xi Zhang
- Materials Science and Engineering Program, Texas A&M University, College Station, Texas 77843, USA
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26
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Aerts M, Suchand Sandeep CS, Gao Y, Savenije TJ, Schins JM, Houtepen AJ, Kinge S, Siebbeles LDA. Free charges produced by carrier multiplication in strongly coupled PbSe quantum dot films. NANO LETTERS 2011; 11:4485-9. [PMID: 21939229 DOI: 10.1021/nl202915p] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We show that in films of strongly coupled PbSe quantum dots multiple electron-hole pairs can be efficiently produced by absorption of a single photon (carrier multiplication). Moreover, in these films carrier multiplication leads to the generation of free, highly mobile charge carriers rather than excitons. Using the time-resolved microwave conductivity technique, we observed the production of more than three electron-hole pairs upon absorption of a single highly energetic photon (5.7E(g)). Free charge carriers produced via carrier multiplication are readily available for use in optoelectronic devices even without employing any complex donor/acceptor architecture or electric fields.
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Affiliation(s)
- Michiel Aerts
- Optoeletronic Materials Section, Department of Chemical Engineering, Delft University of Technology , Julianalaan 136, 2628 BL Delft, The Netherlands.
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27
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Talgorn E, Gao Y, Aerts M, Kunneman LT, Schins JM, Savenije TJ, van Huis MA, van der Zant HSJ, Houtepen AJ, Siebbeles LDA. Unity quantum yield of photogenerated charges and band-like transport in quantum-dot solids. NATURE NANOTECHNOLOGY 2011; 6:733-9. [PMID: 21946709 DOI: 10.1038/nnano.2011.159] [Citation(s) in RCA: 110] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 08/18/2011] [Indexed: 05/07/2023]
Abstract
Solid films of colloidal quantum dots show promise in the manufacture of photodetectors and solar cells. These devices require high yields of photogenerated charges and high carrier mobilities, which are difficult to achieve in quantum-dot films owing to a strong electron-hole interaction and quantum confinement. Here, we show that the quantum yield of photogenerated charges in strongly coupled PbSe quantum-dot films is unity over a large temperature range. At high photoexcitation density, a transition takes place from hopping between localized states to band-like transport. These strongly coupled quantum-dot films have electrical properties that approach those of crystalline bulk semiconductors, while retaining the size tunability and cheap processing properties of colloidal quantum dots.
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Affiliation(s)
- Elise Talgorn
- Optoelectronic Materials Section, Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands
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28
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Talgorn E, de Vries MA, Siebbeles LDA, Houtepen AJ. Photoconductivity enhancement in multilayers of CdSe and CdTe quantum dots. ACS NANO 2011; 5:3552-8. [PMID: 21517097 DOI: 10.1021/nn2009134] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Charge separation at the interface between CdSe and CdTe quantum dots was investigated by comparing the photoconductivity of films consisting of only CdSe or CdTe quantum dots to that of films with alternating layers of CdSe and CdTe quantum dots. The photoconductivity for alternating layers is three times higher than for the single component layers. Different possible mechanisms are discussed, and it is concluded that the dissociation of photoexcited excitons into spatially separated mobile charge carriers at the CdSe/CdTe QD interfaces is the most likely explanation. Given that the yield of charge carrier photogeneration in the multilayer sample is at most one, and under the assumption that the mobility of QD layers in unchanged, we conclude that the yield of charge carrier photogeneration in the single component samples is at most one-third. The thickness of the individual CdSe and CdTe layers was varied, resulting in different distances between the CdSe/CdTe interfaces. The photoconductivity increased with respect to films of only CdSe or CdTe when these interfaces were separated by only one or two quantum dot layers, which implies that exciton diffusion is inefficient.
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Affiliation(s)
- Elise Talgorn
- Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands
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29
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Kong Y, Chen J, Gao F, Li W, Xu X, Pandoli O, Yang H, Ji J, Cui D. A multifunctional ribonuclease-A-conjugated CdTe quantum dot cluster nanosystem for synchronous cancer imaging and therapy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2010; 6:2367-73. [PMID: 20927799 DOI: 10.1002/smll.201001050] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- Yifei Kong
- Department of Bio-Nano Science and Engineering, Key Laboratory for Thin Film and Microfabrication Technology of Ministry of Education, National Key Laboratory of Micro/Nano Fabrication Technology, Research Institute of Micro/Nano Science and Technology, Shanghai Jiao Tong University, Shanghai, 200240, PR China
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30
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Talgorn E, Abellon RD, Kooyman PJ, Piris J, Savenije TJ, Goossens A, Houtepen AJ, Siebbeles LDA. Supercrystals of CdSe quantum dots with high charge mobility and efficient electron transfer to TiO2. ACS NANO 2010; 4:1723-31. [PMID: 20184385 DOI: 10.1021/nn901709a] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Thermal annealing of thin films of CdSe/CdS core/shell quantum dots induces superordering of the nanocrystals and a significant reduction of the interparticle spacing. This results in a drastic enhancement of the quantum yield for charge carrier photogeneration and the charge carrier mobility. The mobile electrons have a mobility as high as 0.1 cm(2)/(V x s), which represents an increase of 4 orders of magnitude over non-annealed QD films and exceeds existing literature data on the electron mobility in CdSe quantum dot films. The lifetime of mobile electrons is longer than that of the exciton. A fraction of the mobile electrons gets trapped at levels below the conduction band of the CdSe nanocrystals. These electrons slowly diffuse over 50-300 nm on longer times up to 20 micros and undergo transfer to a TiO2 substrate. The yield for electron injection in TiO2 from both mobile and trapped electrons is found to be >16%.
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Affiliation(s)
- Elise Talgorn
- Optoelectronic Materials Section, Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands
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31
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Ledo-Suárez A, Puig J, Zucchi IA, Hoppe CE, Gómez ML, Zysler R, Ramos C, Marchi MC, Bilmes SA, Lazzari M, López-Quintela MA, Williams RJJ. Functional nanocomposites based on the infusion or in situ generation of nanoparticles into amphiphilic epoxy gels. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/c0jm01421d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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32
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Talapin DV, Lee JS, Kovalenko MV, Shevchenko EV. Prospects of Colloidal Nanocrystals for Electronic and Optoelectronic Applications. Chem Rev 2009; 110:389-458. [PMID: 19958036 DOI: 10.1021/cr900137k] [Citation(s) in RCA: 2134] [Impact Index Per Article: 142.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dmitri V. Talapin
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, and Center for Nanoscale Materials, Argonne National Lab, Argonne, Illinois 60439
| | - Jong-Soo Lee
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, and Center for Nanoscale Materials, Argonne National Lab, Argonne, Illinois 60439
| | - Maksym V. Kovalenko
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, and Center for Nanoscale Materials, Argonne National Lab, Argonne, Illinois 60439
| | - Elena V. Shevchenko
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, and Center for Nanoscale Materials, Argonne National Lab, Argonne, Illinois 60439
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33
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Williams KJ, Tisdale WA, Leschkies KS, Haugstad G, Norris DJ, Aydil ES, Zhu XY. Strong electronic coupling in two-dimensional assemblies of colloidal PbSe quantum dots. ACS NANO 2009; 3:1532-8. [PMID: 19456114 DOI: 10.1021/nn9001819] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Thin films of colloidal PbSe quantum dots can exhibit very high carrier mobilities when the surface ligands are removed or replaced by small molecules, such as hydrazine. Charge transport in such films is governed by the electronic exchange coupling energy (beta) between quantum dots. Here we show that two-dimensional quantum dot arrays assembled on a surface provide a powerful system for studying this electronic coupling. We combine optical spectroscopy with atomic force microscopy to examine the chemical, structural, and electronic changes that occur when a submonolayer of PbSe QDs is exposed to hydrazine. We find that this treatment leads to strong and tunable electronic coupling, with the beta value as large as 13 meV, which is 1 order of magnitude greater than that previously achieved in 3D QD solids with the same chemical treatment. We attribute this much enhanced electronic coupling to reduced geometric frustration in 2D films. The strongly coupled quantum dot assemblies serve as both charge and energy sinks. The existence of such coupling has serious implications for electronic devices, such as photovoltaic cells, that utilize quantum dots.
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Affiliation(s)
- Kenrick J Williams
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455, USA
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34
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Affiliation(s)
- Amir Zabet-Khosousi
- Lash Miller Chemical Laboratories, University of Toronto, Ontario M5S 3H6, Canada
| | - Al-Amin Dhirani
- Lash Miller Chemical Laboratories, University of Toronto, Ontario M5S 3H6, Canada
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35
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The higher excited electronic states and spin–orbit splitting of the valence band in three-dimensional assemblies of close-packed ZnSe and CdSe quantum dots in thin film form. J SOLID STATE CHEM 2008. [DOI: 10.1016/j.jssc.2008.03.038] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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36
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Cadmium selenide nanowires within core–shell cylindrical polymer brushes: Synthesis, characterization and the double-loading process. POLYMER 2008. [DOI: 10.1016/j.polymer.2008.01.063] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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37
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Carbone L, Nobile C, De Giorgi M, Sala FD, Morello G, Pompa P, Hytch M, Snoeck E, Fiore A, Franchini IR, Nadasan M, Silvestre AF, Chiodo L, Kudera S, Cingolani R, Krahne R, Manna L. Synthesis and micrometer-scale assembly of colloidal CdSe/CdS nanorods prepared by a seeded growth approach. NANO LETTERS 2007; 7:2942-50. [PMID: 17845067 DOI: 10.1021/nl0717661] [Citation(s) in RCA: 627] [Impact Index Per Article: 36.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Key limitations of the colloidal semiconductor nanorods that have been reported so far are a significant distribution of lengths and diameters as well as the presence of irregular shapes produced by the current synthetic routes and, finally, the poor ability to fabricate large areas of oriented nanorod arrays. Here, we report a seeded-growth approach to the synthesis of asymmetric core-shell CdSe/CdS nanorods with regular shapes and narrow distributions of rod diameters and lengths, the latter being easily tunable up to 150 nm. These rods are highly fluorescent and show linearly polarized emission, whereby the emission energy depends mainly on the core diameter. We demonstrate their lateral alignment as well as their vertical self-alignment on substrates up to areas of several square micrometers.
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Affiliation(s)
- Luigi Carbone
- NNL-National Nanotechnology Laboratory of CNR-INFM and IIT Research Unit, via per Arnesano, km 5, 73100 Lecce, Italy
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38
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Hodes G. Semiconductor and ceramic nanoparticle films deposited by chemical bath deposition. Phys Chem Chem Phys 2007; 9:2181-96. [PMID: 17487315 DOI: 10.1039/b616684a] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chemical bath deposition (CBD) has been used to deposit films of metal sulfides, selenides and oxides, together with some miscellaneous compounds, beginning nearly 140 years ago. While it is a well-known technique in a few specific areas (notably photoconductive lead salt detectors, photoelectrodes and more recently, thin film solar cells), it is by and large an under-appreciated technique. The more recent interest in all things 'nano' has provided a boost for CBD: since it is a low temperature, solution (almost always aqueous) technique, crystal size is often very small. This is evidenced by the existence of size quantization commonly found in CBD semiconductor films. The intention of this review is to provide readers, many of whom may not even be aware of the CBD technique, with an overview of how the technique has been used to fabricate nanocrystalline semiconductor (this terminology also includes oxides often classified as ceramics) films and some properties of these films. The review begins, after a short introduction, with a general description of the CBD method, designed to give the reader a basic knowledge of the technique. The rest of the review then focuses on nanocrystalline (or, in the few cases of amorphous deposits, nanoparticle) films. The various factors which determine crystal size are first discussed. This is followed by some of the many examples of size quantization observed in the films. Since CBD films are usually porous, surface effects can be very important, and various surface-dependent properties (light emission and surface states) as well as surface modification, are treated: (although some properties, like emission, can be strongly dependent on both surface and 'bulk'). Because of the fact that many CBD films have been made specifically for use as photoelectrodes in photoelectrochemical cells, there is next a chapter on this topic with a few examples of such photoelectrodes. Film structure and morphology follows with examples of patterning, porosity and crystal shape. The review concludes with some of the author's opinions as to what the near future holds for CBD development in general.
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Affiliation(s)
- Gary Hodes
- Dept. of Materials and Interfaces Weizmann Institute of Science, Rehovot, 76100, Israel
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39
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Lee J, Yang B, Li R, Seery TAP, Papadimitrakopoulos F. Poly(allylamine)-Encapsulated Water-Soluble CdSe Nanocrystals. J Phys Chem B 2006; 111:81-7. [PMID: 17201431 DOI: 10.1021/jp0603841] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Water-soluble CdSe nanocrystal/poly(allylamine) clusters with sizes ranging between 50 and 200 nm were prepared using 3-amino-1-propanol as a compatibilizing agent. Photoluminescence (PL) quantum yields (QY) up to 20% were achieved in water without the need to clad these CdSe nanocrystals (NCs) with higher band gap inorganic layers. The polymer-to-nanocrystal ratio plays an important role in the internal structure and stability of these polymer/NC clusters, as determined by static and dynamic light scattering in conjunction with PL studies. These results were modeled by using an effective-mass approximation and perturbation theory on the change in dielectric constant of the immediate NC environment. The time evolution of the average cluster radius of gyration and hydrodynamic radius revealed that a higher polymer-to-NC ratio leads to increased PL stability and QY. This is a result of a denser cluster configuration, which affords improved NC passivation. Increasing the ionic strength results in greater nanocluster compaction and higher PL QYs. Decreasing the pH value below 12 resulted in dramatic reduction in PL brightness, despite cluster densification, due to partial ionization and dissolution of the amine-based NC surface-capping agents.
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Affiliation(s)
- Jeunghoon Lee
- Nanomaterials Optoelectronics Laboratory, Polymer Program, Institute of Material Science, Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3136, USA
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40
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Bao H, Wang E, Dong S. One-pot synthesis of CdTe nanocrystals and shape control of luminescent CdTe-cystine nanocomposites. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2006; 2:476-80. [PMID: 17193069 DOI: 10.1002/smll.200500346] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Affiliation(s)
- Haifeng Bao
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Graduate School of the Chinese Academy of Sciences, Changchun 130022, Jilin, PR China
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41
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Schöps O, Le Thomas N, Woggon U, Artemyev MV. Recombination Dynamics of CdTe/CdS Core−Shell Nanocrystals. J Phys Chem B 2006; 110:2074-9. [PMID: 16471785 DOI: 10.1021/jp0557013] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The recombination dynamics of zinc-blende-type, deep-red emitting CdTe/CdS core-shell nanocrystals is studied over a wide temperature range. Two characteristic decay regimes are found: a temperature-dependent decay component of a few nanoseconds and a long-living temperature-independent component of approximately 315 ns. The average decay time of the exciton states changes from 20 to 5ns when the temperature is increased from 15 to 295 K. At low temperatures, the observed decay behavior is assigned to thermally induced population and decay of the allowed exchange-split exciton states. At temperatures above T>100 K, nonradiative decay channels involving phonons start to contribute to the exciton recombination. The observed broad distribution in decay times, monitored by stretched exponential fitting functions, we explain by variations in the electron-hole overlap caused by a partly incomplete CdTe/CdS core-shell structure and the nearly energy-degenerated bright and dark state superposition.
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Affiliation(s)
- O Schöps
- Fachbereich Physik, Universität Dortmund, Otto-Hahn-Str. 4, 44227 Dortmund, Germany
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Talapin DV, Shevchenko EV, Gaponik N, Radtchenko IL, Kornowski A, Haase M, Rogach AL, Weller H. Reply: Self-Assembly of Monodisperse Nanocrystals Into Faceted Crystal Superlattices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2005; 17:1325-1329. [PMID: 34412417 DOI: 10.1002/adma.200500672] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Accepted: 03/21/2005] [Indexed: 06/13/2023]
Affiliation(s)
- D V Talapin
- IBM T. J. Watson Research Center, Yorktown Heights, NY 10598, USA
| | - E V Shevchenko
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027, USA
| | - N Gaponik
- Institute of Physical Chemistry, University of Hamburg, D-20146 Hamburg, Germany
| | - I L Radtchenko
- Max Planck Institute of Colloids and Interfaces, D-14424 Potsdam, Germany
| | - A Kornowski
- Institute of Physical Chemistry, University of Hamburg, D-20146 Hamburg, Germany
| | - M Haase
- Institute of Chemistry, University of Osnabrück, D-49076 Osnabrück, Germany
| | - A L Rogach
- Photonics and Optoelectronics Group, Physics Department & CeNS, Ludwig-Maximilians-Universtität München, D-80799 Munich, Germany
| | - H Weller
- Institute of Physical Chemistry, University of Hamburg, D-20146 Hamburg, Germany
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Sarkar SK, Hodes G. Charge Overlap Interaction in Quantum Dot Films: Time Dependence and Suppression by Cyanide Adsorption. J Phys Chem B 2005; 109:7214-9. [PMID: 16851824 DOI: 10.1021/jp044465d] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Chemical bath deposited films of CdSe nanocrystals (<4 nm) are shown to exhibit time-dependent spectral red shifts, caused by increasing overlap of the electron wave functions in adjacent nanocrystals. Treatment of these "aggregated" films with aqueous KCN solution results in repulsion of the wave functions due to the strongly adsorbed negatively charged cyanide and thus electronic decoupling of the physically connected nanocrystals. The previously reported band gap increase due to cyanide adsorption on nominally uncoupled nanocrystals is also described here in more detail.
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Affiliation(s)
- Shaibal K Sarkar
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
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Wuister SF, Koole R, de Mello Donega C, Meijerink A. Temperature-Dependent Energy Transfer in Cadmium Telluride Quantum Dot Solids. J Phys Chem B 2005; 109:5504-8. [PMID: 16851590 DOI: 10.1021/jp0447688] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Efficiently luminescing colloidal CdTe quantum dots (QDs) were used for the preparation of monodispersed and mixed size QD solids. Luminescence spectra and decay times of the QD emission were measured as a function of temperature to study energy transfer (ET) processes in the QD solids. In the luminescence decay curves of the emission of the largest QDs (acceptors), a rise time of the luminescence signal is observed due to energy transfer from smaller QDs. Both the rise time (a measure for the energy transfer rate) and the luminescence decay time lengthen upon cooling. This is explained by the decreased dipole strength of the excitonic emission of the QDs in the solid due to the presence of a singlet and a lower lying triplet level. Studies of energy transfer in heteronuclear QD solids reveal that single-step ET dominates.
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Affiliation(s)
- Sander F Wuister
- Condensed Matter and Interfaces, Debye Institute, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands.
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Lin CI, Joseph AK, Chang CK, Lee YD. Synthesis and photoluminescence study of molecularly imprinted polymers appended onto CdSe/ZnS core-shells. Biosens Bioelectron 2005; 20:127-31. [PMID: 15142585 DOI: 10.1016/j.bios.2003.10.017] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2003] [Accepted: 10/30/2003] [Indexed: 11/21/2022]
Abstract
The Photoluminescence of quantum dots have been found to be a useful tool for the detection of small to medium sized analyte molecules in a host-guest environment. By the incorporation of quantum dots into molecularly imprinted polymers, which can offer shape and selectivity, the former can respond by quenching the photoluminescence emission upon template binding. In this work host polymers were synthesized and cased into thin films using functional monomers such as methacrylic acid (MAA), CdSe/ZnS core-shell derivatized with 4-vinyl pyridine and ethylene glycol dimethacrylic acid (EGDMA) as a cross-linker. The intensity of photoluminescence emission is detected upon analyte binding.
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Affiliation(s)
- Chin I Lin
- Union Chemical Laboratories, Department of Polymer Technology, Industrial Technology Research Institute, 321 Kuang Fu Road, Section 2, Hsinchu 300, Taiwan, ROC.
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47
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Highly efficient Förster resonance energy transfer between CdTe nanocrystals and Rhodamine B in mixed solid films. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.02.080] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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48
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Kim DI, Islam MA, Avila L, Herman IP. Contribution of the Loss of Nanocrystal Ligands to Interdot Coupling in Films of Small CdSe/1-Thioglycerol Nanocrystals. J Phys Chem B 2003. [DOI: 10.1021/jp030168h] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Dae I. Kim
- Materials Research Science and Engineering Center, Department of Applied Physics and Applied Mathematics and Department of Chemistry, Columbia University, New York, New York 10027
| | - Mohammad A. Islam
- Materials Research Science and Engineering Center, Department of Applied Physics and Applied Mathematics and Department of Chemistry, Columbia University, New York, New York 10027
| | - Luis Avila
- Materials Research Science and Engineering Center, Department of Applied Physics and Applied Mathematics and Department of Chemistry, Columbia University, New York, New York 10027
| | - Irving P. Herman
- Materials Research Science and Engineering Center, Department of Applied Physics and Applied Mathematics and Department of Chemistry, Columbia University, New York, New York 10027
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Döllefeld H, Weller H, Eychmüller A. Semiconductor Nanocrystal Assemblies: Experimental Pitfalls and a Simple Model of Particle−Particle Interaction. J Phys Chem B 2002. [DOI: 10.1021/jp013234t] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Herwig Döllefeld
- Institute for Physical Chemistry, University of Hamburg, Bundesstrasse 45, D-20146 Hamburg, Germany
| | - Horst Weller
- Institute for Physical Chemistry, University of Hamburg, Bundesstrasse 45, D-20146 Hamburg, Germany
| | - Alexander Eychmüller
- Institute for Physical Chemistry, University of Hamburg, Bundesstrasse 45, D-20146 Hamburg, Germany
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50
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Abstract
Properties of materials determined by their size are indeed fascinating and form the basis of the emerging area of nanoscience. In this article, we examine the size dependent electronic structure and properties of nanocrystals of semiconductors and metals to illustrate this aspect. We then discuss the chemical reactivity of metal nanocrystals which is strongly dependent on the size not only because of the large surface area but also a result of the significantly different electronic structure of the small nanocrystals. Nanoscale catalysis of gold exemplifies this feature. Size also plays a role in the assembly of nanocrystals into crystalline arrays. While we owe the beginnings of size-dependent chemistry to the early studies of colloids, recent findings have added a new dimension to the subject.
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Affiliation(s)
- C N R Rao
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Bangalore, India.
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