Abstract
We present a general model for describing the properties of excess electrons in multiply charged quantum dots (QDs). Key factors governing Fermi-level energies and electron density distributions are investigated by treating carrier densities, charge compensation, and various material and dielectric medium properties as independently tunable parameters. Electronic interactions are described using a mean-field electrostatic potential calculable through Gauss's Law by treating the quantum dot as a sphere of uniform charge density. This classical approximation modifies the "Particle in a Sphere" Schrödinger equation for a square well potential and reproduces the broken degeneracy and Fermi-level energies expected from experiment and first-principles methods. Several important implications emerge from this model: (i) excess electron density drifts substantially toward the QD surfaces with high electron densities and large radii and when solvated by a high dielectric medium. (ii) The maximum density of the conduction-band electrons depends strongly on the dielectric strength of the solvent and the electron affinity and dielectric strength of the QD material. (iii) Fermi-level energies stabilize with charge-balancing cations in close proximity to the QD surface.
Original language | English |
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Pages (from-to) | 26086-26095 |
Number of pages | 10 |
Journal | Journal of Physical Chemistry C |
Volume | 121 |
Issue number | 46 |
DOIs | |
State | Published - Nov 22 2017 |
Externally published | Yes |
Funding
The development of the computational model is supported by the NSF (CHE-1464497 to X.L., CHE-1506014 to D.R.G., and DMR-1719797). The development of open-source computational code is supported by the NSF Office of Advanced Cyberinfrastructure (OAC-1663636 to X.L.). This work was facilitated though the use of advanced computational storage, and networking infrastructure provided by the Hyak supercomputer system and was funded by the STF at the University of Washington and the National Science Foundation (MRI-1624430). The development of the computational model is supported by the NSF (CHE-1464497 to X.L., CHE-1506014 to D.R.G., and DMR-1719797). The development of open-source computational code is supported by the NSF Office of Advanced Cyberinfrastructure (OAC-1663636 to X.L.). This work was facilitated though the use of advanced computational, storage, and networking infrastructure provided by the Hyak supercomputer system and was funded by the STF at the University of Washington and the National Science Foundation (MRI-1624430).
Funders | Funder number |
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National Science Foundation | 1663636, DMR-1719797, CHE-1506014, MRI-1624430, 1624430, CHE-1464497, 1464497 |
Office of Advanced Cyberinfrastructure | OAC-1663636 |
University of Washington | |
Norsk Sykepleierforbund | |
Sveriges Tandläkarförbund | |
National Science Foundation |