Distance-Dependence of Interparticle Energy Transfer in the Near-Infrared within Electrostatic Assemblies of PbS Quantum Dots

作者：Kodaimati Mohamad S; Wang Chen; Chapman Craig; Schatz George C^*; Weisse Emily A^*

来源：ACS Nano, 2017, 11(5): 5041-5050.

DOI：10.1021/acsnano.7b01778

• near-infrared
• Forster theory
• energy transfer
• quantum dot assemblies
• cross-linking
• transition density cube method

This paper describes control of the rate constant for near-infrared excitonic energy transfer (EnT) within soluble aqueous assemblies of PbS quantum dots, cross-linked by Zn2+, by changing the length of the mercapto-alkanoic acid (MAA) that serves as the cross-linking ligand. Sequestration of Zn2+ by a chelating agent or zinc hydroxide species results in deaggregation of the assemblies with EnT turned "off". Upon decreasing the number of methylene groups in MAAs from 16 to 3, the interparticle separation decreases from 5.8 nut to 3.7 nm and the average observed EnT rate increases from similar to(150 ns)(-1) to similar to(2 ns)(-1). A master equation translates intrinsic (single-donor-single-acceptor) EnT rate constants predicted for each ligand length using Fiirster theory to observed average rate constants. For interparticle distances greater than similar to 4 nm, the point dipole approximation (PDA) implementation of Forster theory agrees with experimentally measured rates. At shorter interparticle distances, the PDA drastically underestimates the observed EnT rate. The prediction of the rates of these short-distance EnT processes is improved by similar to 20% by replacing the PDA with a transition density cube calculation of the interparticle Coulombic coupling.

• 出版日期2017-5
• 单位西北大学