PbS/CdS 核壳量子点抑制电荷转移并增强三重态转移。
PbS/CdS Core-Shell Quantum Dots Suppress Charge Transfer and Enhance Triplet Transfer.
机构信息
Department of Chemistry, University of California, Riverside, 900 University Ave., Riverside, CA, 92507, USA.
Department of Chemistry, Emory University, Atlanta, GA, 30322, USA.
出版信息
Angew Chem Int Ed Engl. 2017 Dec 22;56(52):16583-16587. doi: 10.1002/anie.201710224. Epub 2017 Nov 30.
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 and 1.03±0.09 ns 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.
在 PbS 量子点 (QD) 上覆盖亚单层 CdS 壳可以抑制 QD 与分子之间的竞争电荷转移，从而增强三重态能量转移 (TET)。当用苝受体 5-CT 功能化时，CdS 壳将 PbS QD 的线性光上转换量子产率 (QY) 从 3.5%提高到 PbS/CdS QD 的 5.0%。虽然瞬态吸收光谱表明 PbS 和 PbS/CdS QD 均形成了 5-CT 三重态（形成速率分别为 5.91±0.60 ns 和 1.03±0.09 ns），但超快空穴转移仅发生在 PbS QD 到 5-CT。尽管 CdS 壳降低了 TET 速率，但通过抑制空穴转移，将 TET 效率从 60.3±6.1%提高到 71.8±6.2%。此外，CdS 壳延长了 5-CT 三重态的寿命，从而增强了从 5-CT 到 rubrene 发射体的 TET，进一步提高了上转换 QY。
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