PbS/CdS Core–Shell Quantum Dots Suppress Charge Transfer and Enhance Triplet Transfer
- Department of Chemistry University of California, Riverside 900 University Ave. Riverside CA 92507 USA
- Department of Chemistry Emory University Atlanta GA 30322 USA
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±0.60 ns −1 and 1.03±0.09 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.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1410701
- Journal Information:
- Angewandte Chemie (International Edition), Journal Name: Angewandte Chemie (International Edition) Vol. 56 Journal Issue: 52; ISSN 1433-7851
- Publisher:
- Wiley Blackwell (John Wiley & Sons)Copyright Statement
- Country of Publication:
- Germany
- Language:
- English
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