Simple correlated wave-function for excitons in 0D, quasi-1D and quasi-2D quantum dots

Planelles, Josep

doi:10.1007/s00214-017-2107-x

Cited by 18 publications

(29 citation statements)

References 40 publications

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“…3 of Ref. [25]. For illustration purposes and convenience for the analysis of results, here we only discuss the normalization factor N .…”

Section: Theoretical Modelmentioning

confidence: 99%

“…After trigonometric transformations, the integral over ξ + becomes analytical and one obtains [25,27] …”

Section: Theoretical Modelmentioning

confidence: 99%

“…Previous theoretical studies of NPLs with finite lateral size missed this requirement, as Coulomb interaction was either overlooked [23] or dealt with using a mean-field (Hartree) model [24]. The latter has been tested in analytically solvable 2D systems and found to be insufficient, especially in the weak confinement regime [25].…”

Section: Introductionmentioning

confidence: 99%

“…The Schrödinger equation, including dielectric mismatch effects, is solved with a simple yet reliable variational wave function [25], which provides clear insight into the influence of correlation and lateral confinement. We find large area CdSe NPLs lie in the weak confinement regime, where dielectric mismatch induces a nearly strict two-dimensional (2D) behavior, but current available sizes also reach an intermediate confinement regime, where the lateral walls of the NPL increase binding energies, emission energies, and radiative recombination rates as compared to quantum wells.…”

Section: Introductionmentioning

confidence: 99%

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Excitons in core-only, core-shell and core-crown CdSe nanoplatelets: Interplay between in-plane electron-hole correlation, spatial confinement, and dielectric confinement

2017

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Using semianalytical models we calculate the energy, effective Bohr radius, and radiative lifetime of neutral excitons confined in CdSe colloidal nanoplatelets (NPLs). The excitonic properties are largely governed by the electron-hole in-plane correlation, which in NPLs is enhanced by the quasi-two-dimensional motion and the dielectric mismatch with the organic environment. In NPLs with lateral size L 20 nm the exciton behavior is essentially that in a quantum well, with super-radiance leading to exciton lifetimes of 1 ps or less, only limited by the NPL area. However, for L < 20 nm excitons enter an intermediate confinement regime, hence departing from the quantum well behavior. In heterostructured NPLs, a different response is observed for core-shell and core-crown configurations. In the former, the strong vertical confinement limits separation of electrons and holes even for type-II band alignment. The exciton behavior is then similar to that in core-only NPL, albeit with weakened dielectric effects. In the latter, charge separation is also inefficient if band alignment is quasi-type-II (e.g., in CdSe/CdS), because electron-hole interaction drives both carriers into the core. However, it becomes very efficient for type-II alignment, for which we predict exciton lifetimes reaching microseconds.

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“…3 of Ref. [25]. For illustration purposes and convenience for the analysis of results, here we only discuss the normalization factor N .…”

Section: Theoretical Modelmentioning

confidence: 99%

“…After trigonometric transformations, the integral over ξ + becomes analytical and one obtains [25,27] …”

Section: Theoretical Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Excitons in core-only, core-shell and core-crown CdSe nanoplatelets: Interplay between in-plane electron-hole correlation, spatial confinement, and dielectric confinement

2017

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“…36 Such a short-range interaction makes CI calculations based on envelope wave functions miss correlation energy. 37,38 By contrast, the electron-electron (or hole-hole) repulsions in trions, which are also enhanced by the quasi-2D geometry and the dielectric confinement, are longerranged interactions and hence better captured by CI models. Conclusions about the balance between attractive and repulsive forces in these systems must be revisited using methods which account for both of them on equal footing.…”

Section: Introductionmentioning

confidence: 99%

Comparison between trion and exciton electronic properties in CdSe and PbS nanoplatelets

Macías-Pinilla¹,

Planelles²,

Mora‐Seró³

et al. 2021

Preprint

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The optoelectronic properties of metal chalcogenide colloidal nanoplatelets are often interpreted in terms of excitonic states. However, recent spectroscopic experiments evidence the presence of trion states, enabled by the slow Auger recombination in these structures. We analyze how the presence of an additional charge in trions modifies the emission energy and oscillator strength as compared to neutral excitons. These properties are very sensitive to dielectric confinement and electronic correlations, which we describe accurately using image-charge and variational Quantum Monte Carlo methods in effective mass Hamiltonians. We observe that the giant oscillator strength of neutral excitons is largely suppressed in trions. Both negative and positive trions are redshifted with respect to the exciton, and their emission energy increases with increasing dielectric mismatch between the platelet and its surroundings, which is a consequence of the self-energy potential. Our results are consistent with experiments in the literature, and assess on the validity of previous theoretical approximations.

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Effects of Quantum and Dielectric Confinement on the Emission of Cs‐Pb‐Br Composites

Caicedo‐Dávila

Caprioglio

Lehmann

et al. 2023

Adv Funct Materials

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The halide perovskite CsPbBr3 belongs to the Cs‐Pb‐Br material system, which features two additional thermodynamically stable ternary phases, Cs4PbBr6 and CsPb2Br5. The coexistence of these phases and their reportedly similar photoluminescence (PL) have resulted in a debate on the nature of the emission in these systems. Herein, optical and microscopic characterizations are combined with an effective mass, correlated electron–hole model of excitons in confined systems, to investigate the emission properties of the ternary phases in the Cs‐Pb‐Br system. It is found that all Cs‐Pb‐Br phases exhibit green emission and the non‐perovskite phases exhibit PL quantum yields orders of magnitude larger than CsPbBr3. In particular, blue‐ and red‐shifted emission for the Cs‐ and Pb‐rich phases, respectively, are measured, stemming from embedded CsPbBr3 nanocrystals (NCs). This model reveals that the difference in emission shift is caused by the combined effects of NC size and different band mismatch. Furthermore, the importance of including the dielectric mismatch in the calculation of the emission energy for Cs‐Pb‐Br composites is demonstrated. The results explain the reportedly limited blue shift in CsPbBr3@Cs4PbBr6 composites and rationalize some of its differences with CsPb2Br5.

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Simple correlated wave-function for excitons in 0D, quasi-1D and quasi-2D quantum dots

Cited by 18 publications

References 40 publications

Excitons in core-only, core-shell and core-crown CdSe nanoplatelets: Interplay between in-plane electron-hole correlation, spatial confinement, and dielectric confinement

Excitons in core-only, core-shell and core-crown CdSe nanoplatelets: Interplay between in-plane electron-hole correlation, spatial confinement, and dielectric confinement

Comparison between trion and exciton electronic properties in CdSe and PbS nanoplatelets

Effects of Quantum and Dielectric Confinement on the Emission of Cs‐Pb‐Br Composites

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