Effect of Dot Size on Exciton Binding Energy and Electron–Hole Recombination Probability in CdSe Quantum Dots

Elward, Jennifer M.; Chakraborty, Arindam

doi:10.1021/ct400485s

Cited by 87 publications

(95 citation statements)

References 117 publications

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“…Moreover, computational studies have shown that the electron-hole recombination probability increases with an increase in !/! and decrease in NC size 93 that effectively hinders the interfacial charge transfer as well. In this context, perhaps, it is also not surprising that the 1.6 nm diameter CuInSe 2 NCs displayed the highest photocatalytic activity.…”

Section: Size Dependent Electrochemical Properties Of Fully Diffused mentioning

confidence: 99%

Investigating the Control by Quantum Confinement and Surface Ligand Coating of Photocatalytic Efficiency in Chalcopyrite Copper Indium Diselenide Nanocrystals

et al. 2016

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ABSTRACT:In the past few years, there has been an immense interest in the preparation of sustainable photocatalysts composed of semiconductor nanocrystals (NCs) as one of their component. We report here, for the first time, the effects of structural parameters of copper indium diselenide (CuInSe 2 ) NCs on visible light driven photocatalytic degradation of pollutants under homogeneous conditions. Ligand exchange reactions were performed replacing insulating, oleylamine capping with poly(ethylene glycol) thiols to prepare PEG-thiolate-capped, 1.8 to 5.3 nm diameter CuInSe 2 NCs to enhance their solubility in water. This unique solubility property caused inner-sphere electron transfer reactions (O 2 to O 2 −) to occur at the NCs surface allowing for sustainable photocatalytic reactions. Electrochemical characterization of our dissolved CuInSe 2 NCs showed that the thermodynamic driving force (-ΔG) for oxygen reduction, which increased with decreased NCs size, was the dominant contributor to the overall process when compared to the contribution light absorption and the coulombic interaction energies of electronhole pair (J e/h ). A two-fold increase in phenol degradation efficiency (from 30 to ~60%) was achieved by controlled variation of the diameter of CuInSe 2 NCs from 5.3 to 1.8 nm. The surface ligand dependency of photocatalytic efficiency was also investigated and a profound effect on phenol degradation was observed. Our PEG-thiolate-capped CuInSe 2 NCs showed photocatalytic activity towards other organic compounds, such as N, N-dimethyl-4-phenylenediamine, methylene blue, and thiourea, which showed decomposition under visible light.3

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Section: Size Dependent Electrochemical Properties Of Fully Diffused mentioning

confidence: 99%

Investigating the Control by Quantum Confinement and Surface Ligand Coating of Photocatalytic Efficiency in Chalcopyrite Copper Indium Diselenide Nanocrystals

et al. 2016

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“…A parabolic potential was chosen because they have been used extensively 23,25,26,[100][101][102][103][104][105][106][107][108][109] to represent the confinement potential experienced by excitons in nanoparticles. The values of the force constant parameter, k, were selected such that the confining potential spanned from weakly confining region (k = 1.0 × 10 −4 a.u.)…”

Section: Physical System and Computational Detailsmentioning

confidence: 99%

Development of the Multicomponent Coupled-Cluster Theory for Investigation of Multiexcitonic Interactions

Ellis

Aggarwal²,

Chakraborty

2015

J. Chem. Theory Comput.

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Multicomponent systems are defined as chemical systems that require a quantum mechanical description of two or more different types of particles. Non-Born-Oppenheimer electron-nuclear interactions in molecules, electron-hole interactions in electronically excited nanoparticles, and electron-positron interactions are examples of physical systems that require a multicomponent quantum mechanical formalism. The central challenge in the theoretical treatment of multicomponent systems is capturing the many-body correlation effects that exist not only between particles of identical types (electron-electron) but also between particles of different types (electron-nuclear and electron-hole). In this work, the development and implementation of multicomponent coupled-cluster (mcCC) theory for treating particle-particle correlation in multicomponent systems are presented. This method provides a balanced treatment of many-particle correlation effects in a general multicomponent system while maintaining a size-consistent and size-extensive formalism. The coupled-cluster ansatz presented here is an extension of the electronic structure CCSD formulation for multicomponent systems and is defined as |ΨmcCC⟩ = eT1I+T2I+T1II+T2II+T11I,II+T12I,II+T21I,II+T22I,II|0I0II⟩. The cluster amplitudes in the mcCC wave function were obtained by projecting the mcCC Schrödinger equation onto a direct product space of singly and doubly excited states of type I and II particles and then solving the resulting mcCC equations iteratively. These equations were derived using an automated application of the generalized Wick’s theorem and were implemented using a computer-assisted source code generation approach. The applicability of the mcCC method was demonstrated by calculating ground state energies of multicomponent Hooke's atom and positronium hydride systems as well as by calculating exciton and biexciton binding energies in multiexcitonic systems. For each case, the mcCC results were benchmarked against full configuration interaction (FCI) calculations and were found to be in excellent agreement with the FCI results. The effect of neglecting certain classes of multicomponent connected excitation terms from the mcCC wave function was also investigated. The results from this study demonstrate that connected cluster operators that generate simultaneous excitation in type I and type II space are critical for capturing electron-hole correlation in multiexcitonic systems.

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“…The PL intensity

I_{k}

from the k ‐th state versus applied electric field is proportional to the electron–hole pair recombination probability. The recombination probability can be estimated as a probability that an electron and a hole are located at the same point anywhere inside the considered volume, so:

I_{k} \propto \int_{V} {normald}^{3} boldr {| Ψ}_{k}^{true(L true)} true(r, r true) true|^{2}

…”

Section: The Modelmentioning

confidence: 99%

Excitonic States and Photoluminescence Spectra of a Quantum Dot Molecule Exposed to the External Static Electric Field

Schillak

2018

Physica Status Solidi (b)

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The influence of a static electric field on the energy levels, wave functions, and optical properties of excitons in a quantum dot molecule is analyzed. Taking into account the cylindrical symmetry of the molecule, the wave functions and excitonic energies are calculated when the external constant electric field is applied along the symmetry axis. Two dots separated by a narrow barrier are considered as one system of three‐dimensional potential wells for an electron and a hole. The six‐dimensional Schrödinger equation is transformed into the equivalent eigenvalue problem given by the system of the coupled two‐dimensional second order differential equations as the separation of the relative‐ and center‐of‐mass motion of an electron and a hole is not possible in this case. The differential equations are solved numerically using finite differences method. Having the eigenfunctions and eigenvalues, the excitonic photoluminescence intensity is calculated and analyzed. As an example, the configuration indicating on the possibility of non‐monotonic behavior of the photoluminescence intensity versus electric field is discussed. The comparison of numerical results with experimental data for the GaInAs quantum dot molecule is presented. Satisfactory agreement with the available experimental data is obtained.

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Effect of Dot Size on Exciton Binding Energy and Electron–Hole Recombination Probability in CdSe Quantum Dots

Cited by 87 publications

References 117 publications

Investigating the Control by Quantum Confinement and Surface Ligand Coating of Photocatalytic Efficiency in Chalcopyrite Copper Indium Diselenide Nanocrystals

Investigating the Control by Quantum Confinement and Surface Ligand Coating of Photocatalytic Efficiency in Chalcopyrite Copper Indium Diselenide Nanocrystals

Development of the Multicomponent Coupled-Cluster Theory for Investigation of Multiexcitonic Interactions

Excitonic States and Photoluminescence Spectra of a Quantum Dot Molecule Exposed to the External Static Electric Field

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