Single walled carbon nanotubes (SWNT) and CdSe quantum dots (QDs) offer complementary characteristic and attractive properties for energy transport and charge collection. Interfacial engineering of the components of such nanostructure composites and the bonding mechanism between them strongly affects both electronic and optical properties, and hence allows the opportunity to significantly improve charge transfer between them and consequently to alter the efficiency of the solar cell devices. We use a combined experimental and theoretical approach to understand the mechanism of binding. Experimentally monitored transient absorption of CdSe QDs before and after attachment to (12,10) SWNTs reveal considerably shorter lifetimes upon direct covalent binding of the CdSe to SWNTs. The shorter lifetimes may indicate either faster deactivation of charge-separated states in CdSe QDs via ultrafast electron transfer from CdSe QD to the SWNTs or formation of strongly coupled nanocomposites. UV-visible spectroscopy, TEM, EXAFS, and photoluminescence experiments confirm the presence of a strongly bound nanocomposite. The latter explanation is supported by quantum dynamics simulations of interfacial electron transfer in a fully atomistic model of the molecular assembly, as determined by QM/MM calculations that match both the experimental EXAFS spectra and the transient absorption measurements.

Strong binding of CdSe quantum dots to single-walled carbon nanotubes

253rd National Meeting (2017)

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