PbS/CdS Core-Shell Quantum Dots Suppress Charge Transfer and Enhance Triplet Transfer.
Angew Chem Int Ed Engl
; 56(52): 16583-16587, 2017 12 22.
Article
en En
| MEDLINE
| ID: mdl-29141118
ABSTRACT
A sub-monolayer CdS shell on PbS quantum dots (QDs) enhances triplet energy transfer (TET) by suppressing competitive charge transfer from QDs to molecules. The CdS shell increases the linear photon upconversion quantum yield (QY) from 3.5 % for PbS QDs to 5.0 % for PbS/CdS QDs when functionalized with a tetracene acceptor, 5-CT. While transient absorption spectroscopy reveals that both PbS and PbS/CdS QDs show the formation of the 5-CT triplet (with rates of 5.91±0.60â
ns-1 and 1.03±0.09â
ns-1 respectively), ultrafast hole transfer occurs only from PbS QDs to 5-CT. Although the CdS shell decreases the TET rate, it enhances TET efficiency from 60.3±6.1 % to 71.8±6.2 % by suppressing hole transfer. Furthermore, the CdS shell prolongs the lifetime of the 5-CT triplet and thus enhances TET from 5-CT to the rubrene emitter, further bolstering the upconverison QY.
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1
Colección:
01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
Angew Chem Int Ed Engl
Año:
2017
Tipo del documento:
Article
País de afiliación:
Estados Unidos