Strain effects on optical properties of tetrapod-shaped CdTe/CdS core–shell nanocrystalsстатья
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Дата последнего поиска статьи во внешних источниках: 2 апреля 2015 г.
Аннотация:The exciton states of strained CdTe/CdS core–shell tetrapod-shaped
nanocrystals were theoretically investigated by the numerical
diagonalization of a configuration interaction Hamiltonian based
on the single-band effective mass approximation. We found that
the inclusion of strain promotes the type-II nature by confining
the electrons and holes in nonadjacent regions. This carrier separation
is more efficient than that with type-II spherical nanocrystals.
The strain leads to a small blue shift of the lowest exciton energy.
Its magnitude is smaller than the red shift induced by increasing
the shell thickness. Moreover, the larger arm diameter reduces
the influence of both shell thickness and strain on the exciton
energy. Considering the broken symmetry, a randomness induced
carrier separation was revealed which is unique to a branched
core–shell structure. The calculated shell thickness dependence
of the emission energy agrees well with available experimental
data.