TY - JOUR
T1 - CdSe/CdS/CdTe Core/Barrier/Crown Nanoplatelets
T2 - Synthesis, Optoelectronic Properties, and Multiphoton Fluorescence Upconversion
AU - Khan, Ali Hossain
AU - Bertrand, Guillaume H.V.
AU - Teitelboim, Ayelet
AU - Sekhar M, Chandra
AU - Polovitsyn, Anatolii
AU - Brescia, Rosaria
AU - Planelles, Josep
AU - Climente, Juan Ignacio
AU - Oron, Dan
AU - Moreels, Iwan
PY - 2020/4/28
Y1 - 2020/4/28
N2 - Colloidal two-dimensional (2D) nanoplatelet heterostructures are particularly interesting as they combine strong confinement of excitons in 2D materials with a wide range of possible semiconductor junctions due to a template-free, solution-based growth. Here, we present the synthesis of a ternary 2D architecture consisting of a core of CdSe, laterally encapsulated by a type-I barrier of CdS, and finally a type-II outer layer of CdTe as so-called crown. The CdS acts as a tunneling barrier between CdSe- and CdTe-localized hole states, and through strain at the CdS/CdTe interface, it can induce a shallow electron barrier for CdTe-localized electrons as well. Consequently, next to an extended fluorescence lifetime, the barrier also yields emission from CdSe and CdTe direct transitions. The core/barrier/crown configuration further enables two-photon fluorescence upconversion and, due to a high nonlinear absorption cross section, even allows to upconvert three near-infrared photons into a single green photon. These results demonstrate the capability of 2D heterostructured nanoplatelets to combine weak and strong confinement regimes to engineer their optoelectronic properties.
AB - Colloidal two-dimensional (2D) nanoplatelet heterostructures are particularly interesting as they combine strong confinement of excitons in 2D materials with a wide range of possible semiconductor junctions due to a template-free, solution-based growth. Here, we present the synthesis of a ternary 2D architecture consisting of a core of CdSe, laterally encapsulated by a type-I barrier of CdS, and finally a type-II outer layer of CdTe as so-called crown. The CdS acts as a tunneling barrier between CdSe- and CdTe-localized hole states, and through strain at the CdS/CdTe interface, it can induce a shallow electron barrier for CdTe-localized electrons as well. Consequently, next to an extended fluorescence lifetime, the barrier also yields emission from CdSe and CdTe direct transitions. The core/barrier/crown configuration further enables two-photon fluorescence upconversion and, due to a high nonlinear absorption cross section, even allows to upconvert three near-infrared photons into a single green photon. These results demonstrate the capability of 2D heterostructured nanoplatelets to combine weak and strong confinement regimes to engineer their optoelectronic properties.
KW - fluorescence upconversion
KW - k·p calculations
KW - nanoplatelets
KW - photoluminescence
KW - ternary architecture
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U2 - 10.1021/acsnano.9b09147
DO - 10.1021/acsnano.9b09147
M3 - Article
C2 - 32275814
AN - SCOPUS:85084167896
VL - 14
SP - 4206
EP - 4215
JO - ACS Nano
JF - ACS Nano
SN - 1936-0851
IS - 4
ER -