Excitons in core-only, core-shell and core-crown CdSe nanoplatelets: Interplay between in-plane electron-hole correlation, spatial confinement, and dielectric confinement
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Other documents of the author: Rajadell Viciano, Fernando; Climente, Juan I.; Planelles, Josep
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comunitat-uji-handle2:10234/7013
comunitat-uji-handle3:10234/8638
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Title
Excitons in core-only, core-shell and core-crown CdSe nanoplatelets: Interplay between in-plane electron-hole correlation, spatial confinement, and dielectric confinementDate
2017Publisher
American Physical SocietyISSN
2469-9950; 2469-9969Type
info:eu-repo/semantics/articlePublisher version
https://journals.aps.org/prb/abstract/10.1103/PhysRevB.96.035307Version
info:eu-repo/semantics/publishedVersionAbstract
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 ... [+]
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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PHYSICAL REVIEW B 96, 035307 (2017)Investigation project
CTQ2014-60178-P ; P1- 1B2014-24Rights
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info:eu-repo/semantics/openAccess
info:eu-repo/semantics/openAccess
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