TY - JOUR
T1 - Ultrafast exciton dynamics in 2D in-plane hetero-nanostructures
T2 - Delocalization and charge transfer
AU - Cassette, E.
AU - Pedetti, S.
AU - Mahler, B.
AU - Ithurria, S.
AU - Dubertret, B.
AU - Scholes, G. D.
N1 - Publisher Copyright:
© the Owner Societies 2017.
PY - 2017
Y1 - 2017
N2 - In this article we study the ultrafast dynamics of excitons and charge carriers photogenerated in two-dimensional in-plane heterostructures, namely, CdSe-CdTe nanoplatelets. We combine transient absorption and two-dimensional electronic spectroscopy to study charge transfer and delocalization from a few tens of femtoseconds to several nanoseconds. In contrast with spherical nanocrystals, the relative alignment of the electron and hole states of CdSe and CdTe in thin 2D nanoplatelets does not lead to a type-II heterostructure. Following the excitation in CdSe or CdTe materials, the electron preferentially delocalises instantaneously over the whole heterostructure. In addition, depending on the crown material (CdTe versus CdTeSe), the hole transfers either to trap states or to the crown, within a few hundreds of femtoseconds. We conclude that the photoluminescence band, at lower energy than the CdSe and CdTe first exciton transition, does not result from the recombination of the charge carriers at the charge transfer state but involves localised hole states.
AB - In this article we study the ultrafast dynamics of excitons and charge carriers photogenerated in two-dimensional in-plane heterostructures, namely, CdSe-CdTe nanoplatelets. We combine transient absorption and two-dimensional electronic spectroscopy to study charge transfer and delocalization from a few tens of femtoseconds to several nanoseconds. In contrast with spherical nanocrystals, the relative alignment of the electron and hole states of CdSe and CdTe in thin 2D nanoplatelets does not lead to a type-II heterostructure. Following the excitation in CdSe or CdTe materials, the electron preferentially delocalises instantaneously over the whole heterostructure. In addition, depending on the crown material (CdTe versus CdTeSe), the hole transfers either to trap states or to the crown, within a few hundreds of femtoseconds. We conclude that the photoluminescence band, at lower energy than the CdSe and CdTe first exciton transition, does not result from the recombination of the charge carriers at the charge transfer state but involves localised hole states.
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U2 - 10.1039/c6cp08689f
DO - 10.1039/c6cp08689f
M3 - Article
C2 - 28280802
AN - SCOPUS:85019111410
SN - 1463-9076
VL - 19
SP - 8373
EP - 8379
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 12
ER -