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Movilla JL, Planelles J, Climente JI. Correction: Excitons in metal halide perovskite nanoplatelets: an effective mass description of polaronic, dielectric and quantum confinement effects. Nanoscale Adv 2024; 6:2527. [PMID: 38694457 PMCID: PMC11059561 DOI: 10.1039/d4na90041c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 03/21/2024] [Indexed: 05/04/2024]
Abstract
[This corrects the article DOI: 10.1039/D3NA00592E.].
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Affiliation(s)
- Jose L Movilla
- Departament d'Educació i Didàctiques Específiques, Universitat Jaume I Av. Sos Baynat, s/n 12071 Castelló Spain
| | - Josep Planelles
- Departament de Química Física i Analítica, Universitat Jaume I Av. Sos Baynat, s/n 12071 Castelló Spain
| | - Juan I Climente
- Departament de Química Física i Analítica, Universitat Jaume I Av. Sos Baynat, s/n 12071 Castelló Spain
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Movilla JL, Planelles J, Climente JI. Excitons in metal halide perovskite nanoplatelets: an effective mass description of polaronic, dielectric and quantum confinement effects. Nanoscale Adv 2023; 5:6093-6101. [PMID: 37941960 PMCID: PMC10628976 DOI: 10.1039/d3na00592e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 10/05/2023] [Indexed: 11/10/2023]
Abstract
A theoretical model for excitons confined in metal halide perovskite nanoplatelets is presented. The model accounts for quantum confinement, dielectric confinement, short and long range polaron interactions by means of effective mass theory, image charges and Haken potentials. We use it to describe the band edge exciton of MAPbI3 structures surrounded by organic ligands. It is shown that the quasi-2D quantum and dielectric confinement squeezes the exciton radius, and this in turn enhances short-range polaron effects as compared to 3D structures. Dielectric screening is then weaker than expected from the static dielectric constant. This boosts the binding energies and radiative recombination probabilities, which is a requisite to match experimental data in related systems. The thickness dependence of Coulomb polarization and self-energy potentials is in fair agreement with sophisticated atomistic models.
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Affiliation(s)
- Jose L Movilla
- Departament d'Educació i Didàctiques Específiques, Universitat Jaume I Av. Sos Baynat, s/n 12071 Castelló Spain
| | - Josep Planelles
- Departament de Química Física i Analítica, Universitat Jaume I Av. Sos Baynat, s/n 12071 Castelló Spain
| | - Juan I Climente
- Departament de Química Física i Analítica, Universitat Jaume I Av. Sos Baynat, s/n 12071 Castelló Spain
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Alo A, Barros LWT, Nagamine G, Lemus JC, Planelles J, Movilla JL, Climente JI, Lee HJ, Bae WK, Padilha LA. Beyond Universal Volume Scaling: Tailoring Two-Photon Absorption in Nanomaterials by Heterostructure Design. Nano Lett 2023; 23:7180-7187. [PMID: 37506366 DOI: 10.1021/acs.nanolett.3c02131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/30/2023]
Abstract
Colloidal semiconductor nanomaterials present broadband, with large cross-section, two-photon absorption (2PA) spectra, which turn them into an important platform for applications that benefit from a high nonlinear optical response. Despite that, to date, the only means to control the magnitude of the 2PA cross-section is by changing the nanoparticle volume, as it follows a universal volume scale, independent of the material composition. As the emission spectrum is connected utterly to the nanomaterial dimensions, for a given material, the magnitude of the nonlinear optical response is also coupled to the emission spectra. Here, we demonstrate a means to decouple both effects by exploring the 2PA response of different types of heterostructures, tailoring the volume dependence of the 2PA cross-section due to the different dependence of the density of final states on the nanoparticle volume. By heterostructure engineering, one can obtain 1 order of magnitude enhancement of the 2PA cross-section with minimum emission spectra shift.
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Affiliation(s)
- Arthur Alo
- Instituto de Fisica "Gleb Wataghin", Universidade Estadual de Campinas, UNICAMP, P.O. Box 6165, 13083-859 Campinas, Sao Paulo, Brazil
| | - Leonardo W T Barros
- Instituto de Fisica "Gleb Wataghin", Universidade Estadual de Campinas, UNICAMP, P.O. Box 6165, 13083-859 Campinas, Sao Paulo, Brazil
| | - Gabriel Nagamine
- Instituto de Fisica "Gleb Wataghin", Universidade Estadual de Campinas, UNICAMP, P.O. Box 6165, 13083-859 Campinas, Sao Paulo, Brazil
| | - Jonathan C Lemus
- Instituto de Fisica "Gleb Wataghin", Universidade Estadual de Campinas, UNICAMP, P.O. Box 6165, 13083-859 Campinas, Sao Paulo, Brazil
| | - Josep Planelles
- Departament de Química Física i Analítica, Universitat Jaume I, 12080, Castelló, Spain
| | - José L Movilla
- Departament d'Educació i Didàctiques Específiques, Universitat Jaume I, 12080, Castelló, Spain
| | - Juan I Climente
- Departament de Química Física i Analítica, Universitat Jaume I, 12080, Castelló, Spain
| | - Hak June Lee
- School of Chemical and Biological Engineering, Seoul National University, Seoul 08826, Republic of Korea
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| | - Wan Ki Bae
- SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea
| | - Lazaro A Padilha
- Instituto de Fisica "Gleb Wataghin", Universidade Estadual de Campinas, UNICAMP, P.O. Box 6165, 13083-859 Campinas, Sao Paulo, Brazil
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Frenkel N, Scharf E, Lubin G, Levi A, Panfil YE, Ossia Y, Planelles J, Climente JI, Banin U, Oron D. Two Biexciton Types Coexisting in Coupled Quantum Dot Molecules. ACS Nano 2023; 17:14990-15000. [PMID: 37459645 PMCID: PMC10416571 DOI: 10.1021/acsnano.3c03921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 07/12/2023] [Indexed: 08/09/2023]
Abstract
Coupled colloidal quantum dot molecules (CQDMs) are an emerging class of nanomaterials, manifesting two coupled emission centers and thus introducing additional degrees of freedom for designing quantum-dot-based technologies. The properties of multiply excited states in these CQDMs are crucial to their performance as quantum light emitters, but they cannot be fully resolved by existing spectroscopic techniques. Here we study the characteristics of biexcitonic species, which represent a rich landscape of different configurations essentially categorized as either segregated or localized biexciton states. To this end, we introduce an extension of Heralded Spectroscopy to resolve the different biexciton species in the prototypical CdSe/CdS CQDM system. By comparing CQDMs with single quantum dots and with nonfused quantum dot pairs, we uncover the coexistence and interplay of two distinct biexciton species: A fast-decaying, strongly interacting biexciton species, analogous to biexcitons in single quantum dots, and a long-lived, weakly interacting species corresponding to two nearly independent excitons. The two biexciton types are consistent with numerical simulations, assigning the strongly interacting species to two excitons localized at one side of the quantum dot molecule and the weakly interacting species to excitons segregated to the two quantum dot molecule sides. This deeper understanding of multiply excited states in coupled quantum dot molecules can support the rational design of tunable single- or multiple-photon quantum emitters.
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Affiliation(s)
- Nadav Frenkel
- Department
of Physics of Complex Systems, Weizmann
Institute of Science, Rehovot 7610001, Israel
| | - Einav Scharf
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Gur Lubin
- Department
of Physics of Complex Systems, Weizmann
Institute of Science, Rehovot 7610001, Israel
| | - Adar Levi
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Yossef E. Panfil
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Yonatan Ossia
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Josep Planelles
- Departament
de Quimica Fisica i Analitica, Universitat
Jaume I, E-12080 Castello de la Plana, Spain
| | - Juan I. Climente
- Departament
de Quimica Fisica i Analitica, Universitat
Jaume I, E-12080 Castello de la Plana, Spain
| | - Uri Banin
- Institute
of Chemistry and the Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Dan Oron
- Department
of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot 76100, Israel
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Macias-Pinilla DF, Planelles J, Climente JI. Biexcitons in CdSe nanoplatelets: geometry, binding energy and radiative rate. Nanoscale 2022; 14:8493-8500. [PMID: 35662303 DOI: 10.1039/d2nr01354a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Biexciton properties in semiconductor nanostructures are highly sensitive to quantum confinement, relative electron-hole masses, dielectric environment and Coulomb correlations. Here we present a variational Quantum Monte Carlo model which, coupled to effective mass Hamiltonians, takes into account all of the above effects. The model is used to provide theoretical assessment on the biexciton ground state properties in colloidal CdSe nanoplatelets. A number of characteristic features is observed: (i) the finite thickness of these systems makes the biexciton geometry depart from the planar square expected in the two-dimensional (2D) limit, and form a distorted tetrahedron instead; (ii) the strong dielectric confinement enhances not only Coulomb attractions but also repulsions, which lowers the ratio of the biexciton-to-exciton binding energy down to EXXb/EXb = 0.07. (iii) EXXb is less sensitive than EXb to lateral confinement, and yet it can reach values above 30 meV, thus granting room temperature stability; (iv) the ratio of biexciton-to-exciton radiative rates, kradXX/kradX, decreases from 3.5 to ∼1 as the platelet area increases. These results pave the way for the rational design of biexciton properties in metal chalcogenide nanoplatelets.
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Affiliation(s)
- David F Macias-Pinilla
- Institute of Advanced Materials (INAM), Universitat Jaume I, Av. Sos Baynat, s/n, 12071 Castelló, Spain
- Departament de Química Física i Analítica, Universitat Jaume I, Av. Sos Baynat, s/n, 12071 Castelló, Spain.
| | - Josep Planelles
- Departament de Química Física i Analítica, Universitat Jaume I, Av. Sos Baynat, s/n, 12071 Castelló, Spain.
| | - Juan I Climente
- Departament de Química Física i Analítica, Universitat Jaume I, Av. Sos Baynat, s/n, 12071 Castelló, Spain.
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Abstract
We show theoretically that carriers confined in semiconductor colloidal nanoplatelets (NPLs) sense the presence of neighbor, cofacially stacked NPLs in their energy spectrum. When approaching identical NPLs, the otherwise degenerate energy levels red-shift and split, forming (for large stacks) minibands that are several millielectronvolts in width. Unlike in epitaxial structures, the molecular behavior does not result from quantum tunneling but from changes in the dielectric confinement. The associated excitonic absorption spectrum shows a rich structure of bright and dark states, whose optical activity and multiplicity can be understood from reflection symmetry and Coulomb tunneling. We predict spectroscopic signatures that should confirm the formation of molecular states, whose practical realization would pave the way for the development of nanocrystal chemistry based on NPLs.
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Affiliation(s)
- José L Movilla
- Departament d'Educació i Didàctiques Específiques, Universitat Jaume I, 12080 Castelló, Spain
| | - Josep Planelles
- Departament de Química Física i Analítica, Universitat Jaume I, E-12080 Castelló de la Plana, Spain
| | - Juan I Climente
- Departament de Química Física i Analítica, Universitat Jaume I, E-12080 Castelló de la Plana, Spain
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Khan AH, Bertrand GHV, Teitelboim A, Sekhar M. C, Polovitsyn A, Brescia R, Planelles J, Climente JI, Oron D, Moreels I. CdSe/CdS/CdTe Core/Barrier/Crown Nanoplatelets: Synthesis, Optoelectronic Properties, and Multiphoton Fluorescence Upconversion. ACS Nano 2020; 14:4206-4215. [PMID: 32275814 PMCID: PMC7199781 DOI: 10.1021/acsnano.9b09147] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Colloidal two-dimensional (2D) nanoplatelet heterostructures are particularly interesting as they combine strong confinement of excitons in 2D materials with a wide range of possible semiconductor junctions due to a template-free, solution-based growth. Here, we present the synthesis of a ternary 2D architecture consisting of a core of CdSe, laterally encapsulated by a type-I barrier of CdS, and finally a type-II outer layer of CdTe as so-called crown. The CdS acts as a tunneling barrier between CdSe- and CdTe-localized hole states, and through strain at the CdS/CdTe interface, it can induce a shallow electron barrier for CdTe-localized electrons as well. Consequently, next to an extended fluorescence lifetime, the barrier also yields emission from CdSe and CdTe direct transitions. The core/barrier/crown configuration further enables two-photon fluorescence upconversion and, due to a high nonlinear absorption cross section, even allows to upconvert three near-infrared photons into a single green photon. These results demonstrate the capability of 2D heterostructured nanoplatelets to combine weak and strong confinement regimes to engineer their optoelectronic properties.
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Affiliation(s)
- Ali Hossain Khan
- Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium
- Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | | | - Ayelet Teitelboim
- Department of Physics
of Complex Systems, Weizmann Institute of
Science, Rehovot 7610001, Israel
| | - Chandra Sekhar M.
- Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium
| | | | - Rosaria Brescia
- Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Josep Planelles
- Departament
de Química Física i Analítica, Universitat Jaume I, 12080 Castelló de la Plana, Spain
| | - Juan Ignacio Climente
- Departament
de Química Física i Analítica, Universitat Jaume I, 12080 Castelló de la Plana, Spain
| | - Dan Oron
- Department of Physics
of Complex Systems, Weizmann Institute of
Science, Rehovot 7610001, Israel
| | - Iwan Moreels
- Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium
- Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
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Christodoulou S, Climente JI, Planelles J, Brescia R, Prato M, Martín-García B, Khan AH, Moreels I. Chloride-Induced Thickness Control in CdSe Nanoplatelets. Nano Lett 2018; 18:6248-6254. [PMID: 30178676 PMCID: PMC6526959 DOI: 10.1021/acs.nanolett.8b02361] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 09/03/2018] [Indexed: 05/19/2023]
Abstract
Current colloidal synthesis methods for CdSe nanoplatelets (NPLs) routinely yield samples that emit, in discrete steps, from 460 to 550 nm. A significant challenge lies with obtaining thicker NPLs, to further widen the emission range. This is at present typically achieved via colloidal atomic layer deposition onto CdSe cores, or by synthesizing NPL core/shell structures. Here, we demonstrate a novel reaction scheme, where we start from 4.5 monolayer (ML) NPLs and increase the thickness in a two-step reaction that switches from 2D to 3D growth. The key feature is the enhancement of the growth rate of basal facets by the addition of CdCl2, resulting in a series of nearly monodisperse CdSe NPLs with thicknesses between 5.5 and 8.5 ML. Optical characterization yielded emission peaks from 554 nm up to 625 nm with a line width (fwhm) of 9-13 nm, making them one of the narrowest colloidal nanocrystal emitters currently available in this spectral range. The NPLs maintained a short emission lifetime of 5-11 ns. Finally, due to the increased red shift of the NPL band edge photoluminescence excitation spectra revealed several high-energy peaks. Calculation of the NPL band structure allowed us to identify these excited-state transitions, and spectral shifts are consistent with a significant mixing of light and split-off hole states. Clearly, chloride ions can add a new degree of freedom to the growth of 2D colloidal nanocrystals, yielding new insights into both the NPL synthesis as well as their optoelectronic properties.
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Affiliation(s)
- Sotirios Christodoulou
- Istituto
Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
- ICFO
- Institut de Ciencies Fotoniques, The Barcelona Institute of Science
and Technology, Castelldefels, 08860 Barcelona, Spain
| | - Juan I. Climente
- Departament
de Química Física i Analítica, Universitat Jaume I, 12080 Castelló de la Plana, Spain
| | - Josep Planelles
- Departament
de Química Física i Analítica, Universitat Jaume I, 12080 Castelló de la Plana, Spain
| | - Rosaria Brescia
- Istituto
Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | - Mirko Prato
- Istituto
Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
| | | | - Ali Hossain Khan
- Istituto
Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
- Department
of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Gent, Belgium
- E-mail:
| | - Iwan Moreels
- Istituto
Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy
- Department
of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Gent, Belgium
- E-mail:
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10
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Segarra C, Climente JI, Polovitsyn A, Rajadell F, Moreels I, Planelles J. Piezoelectric Control of the Exciton Wave Function in Colloidal CdSe/CdS Nanocrystals. J Phys Chem Lett 2016; 7:2182-2188. [PMID: 27225599 DOI: 10.1021/acs.jpclett.6b00622] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Using multiband k·p calculations, we show that strain-engineered piezoelectricity is a powerful tool to modulate the electron-hole spatial separation in a wide class of wurtzite CdSe/CdS nanocrystals. The inherent anisotropy of the hexagonal crystal structure leads to anisotropic strain and, consequently, to a pronounced piezoelectric field along the c axis, which can be amplified or quenched through a proper design of the core-shell structure. The use of large cores and thick shells promotes a gradual departure from quantum confined nanocrystals to a regime dominated by piezoelectric confinement. This allows excitons to evolve from the usual type-I and quasi-type-II behavior to a type-II behavior in dot-in-dots, dot-in-rods, rod-in-rods, and dot-in-plates. Piezoelectric fields explain experimental observations for giant-shell nanocrystals, whose time-resolved photoluminescence reveals long exciton lifetimes for large cores, contrary to the expectations of standard quantum confinement models. They also explain the large differences in exciton lifetimes reported for different classes of CdSe/CdS nanocrystals.
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Affiliation(s)
- Carlos Segarra
- Departament de Química Física i Analítica, Universitat Jaume I , E-12080 Castelló de la Plana, Spain
| | - Juan I Climente
- Departament de Química Física i Analítica, Universitat Jaume I , E-12080 Castelló de la Plana, Spain
| | | | - Fernando Rajadell
- Departament de Química Física i Analítica, Universitat Jaume I , E-12080 Castelló de la Plana, Spain
| | - Iwan Moreels
- Istituto Italiano di Tecnologia , Via Morego 30, IT-16163 Genova, Italy
| | - Josep Planelles
- Departament de Química Física i Analítica, Universitat Jaume I , E-12080 Castelló de la Plana, Spain
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Segarra C, Climente JI, Rajadell F, Planelles J. Hole spin relaxation in InAs/GaAs quantum dot molecules. J Phys Condens Matter 2015; 27:415301. [PMID: 26418483 DOI: 10.1088/0953-8984/27/41/415301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We calculate the spin-orbit induced hole spin relaxation between Zeeman sublevels of vertically stacked InAs quantum dots. The widely used Luttinger-Kohn Hamiltonian, which considers coupling of heavy- and light-holes, reveals that hole spin lifetimes (T1) of molecular states significantly exceed those of single quantum dot states. However, this effect can be overcome when cubic Dresselhaus spin-orbit interaction is strong. Misalignment of the dots along the stacking direction is also found to be an important source of spin relaxation.
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Affiliation(s)
- C Segarra
- Departament de Química Física i Analítica, Universitat Jaume I, Castelló de la Plana, Spain
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12
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Planelles J, Climente JI. Magnetic field implementation in multiband k⋅p Hamiltonians of holes in semiconductor heterostructures. J Phys Condens Matter 2013; 25:485801. [PMID: 24177289 DOI: 10.1088/0953-8984/25/48/485801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We propose an implementation of external homogeneous magnetic fields in k⋅p Hamiltonians for holes in heterostructures, in which we make use of the minimal coupling prior to introducing the envelope function approximation. Illustrative calculations for holes in InGaAs quantum dot molecules show that the proposed Hamiltonian outperforms the standard Luttinger model (Luttinger 1956 Phys. Rev. 102 1030) describing the experimentally observed magnetic response. The present implementation culminates our previous proposal (Planelles et al 2010 Phys. Rev. B 82 155307).
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Affiliation(s)
- J Planelles
- Departament de Quimica Fisica i Analitica, Universitat Jaume I, Box 224, E-12080 Castelló, Spain
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13
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Abstract
What is the optimum way of describing the age-specific fertility pattern by mathematical functions? We propose a parametric fitting model, based on a mixture of Weibull functions, which performs well for countries where the fertility curve shows a non-traditional pattern. We also consider a simplified version of this model with a reduced number of parameters that can be applied to fit fertility curves in countries where the fertility pattern exhibits a classical shape. To test the new model, fertility curves for a range of countries and years are fitted empirically. The results show that both versions of the new model outperform existing procedures in most cases.
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Affiliation(s)
- S Bermúdez
- Instituto de Estadística de Andalucía, Seville, Spain
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14
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Movilla JL, Planelles J. Magnetic modulation of the tunnelling between defect states in antidot superlattices. J Phys Condens Matter 2012; 24:275301. [PMID: 22713775 DOI: 10.1088/0953-8984/24/27/275301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We show theoretically that the tunnelling between properly designed defects in periodic antidot lattices can be strongly modulated by applied magnetic fields. Further, transport channels made up of linear arrangements of tunnel-coupled defects can accommodate Aharonov-Bohm cages, suggesting a magnetic control of the transport through the system. Evidence supporting an unusual robustness of the caging effect against electron-electron interactions is also provided.
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Affiliation(s)
- J L Movilla
- Departament de Química Física i Analítica, Universitat Jaume I, E-12080, Castelló, Spain
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15
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Segarra C, Climente JI, Planelles J. Valence band mixing of cubic GaN/AlN quantum dots. J Phys Condens Matter 2012; 24:115801. [PMID: 22353784 DOI: 10.1088/0953-8984/24/11/115801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We study the spin purity of the hole ground state in nearly axially symmetric GaN/AlN quantum dots (QDs). To this end, we develop a six-band Burt-Foreman Hamiltonian describing the valence band structure of zinc blende nanostructures with cylindrical symmetry and calculate the effects of eccentricity variationally. We show that the aspect ratio is a key factor for spin purity. In typical QDs with small aspect ratio the ground state is essentially a heavy hole (HH) whose spin purity is even higher than that of InGaAs QDs of similar sizes. When the aspect ratio increases, mixing with light-hole (LH) and split-off (SO) subbands becomes important and, additionally, the ground state becomes sensitive to QD anisotropy, which further enhances the mixing. We finally show that, despite the large GaN hole effective mass, an efficient magnetic modulation is feasible in QDs with aspect ratio ~1, which can be used to modify the ground state symmetry and hence the optical spectrum properties.
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Affiliation(s)
- C Segarra
- Departament de Química Física i Analítica, Universitat Jaume I, E-12080 Castelló, Spain
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16
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Climente JI, Movilla JL, Planelles J. Auger recombination suppression in nanocrystals with asymmetric electron-hole confinement. Small 2012; 8:754-759. [PMID: 22223514 DOI: 10.1002/smll.201101740] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Indexed: 05/31/2023]
Abstract
Type II and quasi-type II nanocrystals with thick shells exhibit reduced blinking. However, after a number of monolayers, the influence of the shell thickness is found to vanish. Using a two-band Kane Hamiltonian, it is shown that this behavior is a consequence of interband coupling and asymmetric confinement of electrons and holes. Interface alloying provides an additional, order-of-magnitude contribution to the Auger suppression, in agreement with recent experiments. The existence is predicted of critical shell thicknesses that strongly quench Auger processes for any core size.
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Affiliation(s)
- Juan I Climente
- Departament de Quimica Fisica i Analitica, Universitat Jaume I, Castelló de la Plana 12080, Spain
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Abstract
We theoretically study the effect of the dielectric environment on the exciton ground state of CdSe and CdTe/CdSe/CdTe nanorods. We show that insulating environments enhance the exciton recombination rate and blueshift the emission peak by tens of meV. These effects are particularly pronounced for type-II nanorods. In these structures, the dielectric confinement may even modify the spatial distribution of the electron and hole charges. A critical electric field is required to separate electrons from holes, whose value increases with the insulating strength of the surroundings.
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Affiliation(s)
- M Royo
- Departament de Química Física i Analítica, Universitat Jaume I, E-12080, Castelló, Spain
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Planelles J, Climente JI, Royo M, Movilla JL. Correlation in narrow nanorods: a variational potential-configuration interaction scheme. J Phys Condens Matter 2009; 21:215801. [PMID: 21825560 DOI: 10.1088/0953-8984/21/21/215801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Full configuration interaction calculations for two electrons in narrow semiconductor nanorods are carried out employing different orbital basis sets. It is shown that the usual configurations built from single-particle states cannot yield a correct singlet-triplet energetic order regardless of the basis size, as they miss the correlation energy. Mean-field optimized orbitals partially correct this drawback. A new approach is introduced, based on a simple variational procedure, which yields robust results.
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Affiliation(s)
- J Planelles
- Departament de Química-Física i Analítica, UJI, Box 224, E-12080 Castelló, Spain
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Abstract
We provide theoretical modeling of the optical spectrum of recently synthesized triangular CdS nanocrystals by means of atomistic tight-binding theory. Both zinc blende and wurtzite structures are considered. Optical properties predicted for triangular prisms are very different from the ones obtained for tetrahedral quantum dots when z-polarized light is employed. In particular, the ground transition is dim for triangular prisms, whereas it is bright and highly intense for tetrahedra. The high sensitivity of the fine optical properties on the quantum dot shape allows us to discriminate between truncated tetrahedra and triangular prisms and also to estimate the thickness of the nanocrystals.
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Affiliation(s)
- J G Díaz
- Departament de Ciències Experimentals, UJI, Box 224, E-12080 Castelló, Spain
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Díaz JG, Planelles J, Bryant GW, Aizpurua J. Tight-Binding Method and Multiband Effective Mass Theory Applied to CdS Nanocrystals: Single-Particle Effects and Optical Spectra Fine Structure. J Phys Chem B 2004. [DOI: 10.1021/jp047658+] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Planelles J, Movilla JL. Tunneling in Chains of Quantum Dots. J Phys Chem B 2004. [DOI: 10.1021/jp048007g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J. Planelles
- Departament de Ciències Experimentals, Universitat Jaume I, 12080 Castelló, Spain
| | - J. L. Movilla
- Departament de Ciències Experimentals, Universitat Jaume I, 12080 Castelló, Spain
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Affiliation(s)
- J. G. Díaz
- Departament de Ciències Experimentals, UJI, Box 224, E-12080 Castelló, Spain
| | - J. Planelles
- Departament de Ciències Experimentals, UJI, Box 224, E-12080 Castelló, Spain
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Planelles J, Merchan M, Nebot-Gil I, Tomas F. A MO-CI study on the interaction of copper(I) with methylene: the (CuCH2)+ carbene-like ground state. ACTA ACUST UNITED AC 2002. [DOI: 10.1021/j100355a006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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García-Granero E, Esclápez P, García-Armengol J, Espí A, Planelles J, Millán M, Lledó S. Simple technique for the intraoperative detection of Crohn's strictures with a calibration sphere. Dis Colon Rectum 2000; 43:1168-70. [PMID: 10950019 DOI: 10.1007/bf02236569] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Several methods have been used to detect and evaluate small-bowel strictures in Crohn's disease. We describe a simple technique for the calibration of strictures using a 2.5-cm medical plastic sphere. This method provides an aseptic, safe, and effective calibration of the entire small bowel.
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Affiliation(s)
- E García-Granero
- Department of General Surgery, Hospital Clínico Universitario, University of Valencia, Spain
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Peris G, Planelles J, Malrieu JP, Paldus J. Perturbatively selected CI as an optimal source for externally corrected CCSD. J Chem Phys 1999. [DOI: 10.1063/1.479116] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Li X, Peris G, Planelles J, Rajadall F, Paldus J. Externally corrected singles and doubles coupled cluster methods for open-shell systems. J Chem Phys 1997. [DOI: 10.1063/1.474355] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Grinberg M, Jaskólski W, Koepke C, Planelles J, Janowicz M. Spectroscopic manifestation of a confinement-type lattice anharmonicity. Phys Rev B Condens Matter 1994; 50:6504-6507. [PMID: 9977041 DOI: 10.1103/physrevb.50.6504] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Rajadell F, Planelles J, Tomás F, Asensio G, Miranda MA, Sabater MJ. Competition between decarboxylation and isomerization in the C 3H 5O 2+ energy surface. Justification of the experimental results by molecular orbital calculations on the solvated ions. J PHYS ORG CHEM 1994. [DOI: 10.1002/poc.610070502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Planelles J, Valdemoro C, Karwowski J. Symmetric-group approach to the study of the traces of p-order reduced-density operators and of products of these operators. Phys Rev A 1990; 41:2391-2397. [PMID: 9903369 DOI: 10.1103/physreva.41.2391] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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Viruela-Martín PM, Nebot I, Viruela-Martín R, Planelles J. A proposal for a branching mechanism in medium-sized cycloalkanes: MINDO/3 study of the hypersurface for isomerization of cyclohexylium to 1-methylcyclopentylium ion. ACTA ACUST UNITED AC 1986. [DOI: 10.1039/p29860000049] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Planelles J, Sánchez-Marin J, Tomás F, Corma A. A molecular orbital approach to a comprehensive cracking mechanism for linear long chain alkanes in heterogeneous acid catalytic conditions through carbenium ion β-cleavage. ACTA ACUST UNITED AC 1985. [DOI: 10.1039/p29850000333] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Planelles J, Werner FF. Druckpuls der Arteria carotis und Elektrokardiogramm bei langsamer intravenöser Infusion von Digitalisstoffen. Naunyn Schmiedebergs Arch Pharmacol 1923. [DOI: 10.1007/bf01863927] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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