T2.5 Effects of Nanoparticle Dimensionality on the Optoelectronic Properties of CdSe Nanoplatelets

Alexandra Brumberg (Northwestern University), Richard Schaller (Northwestern University)

Recent advances in nanoparticle synthesis have presented scientists with the opportunity to control not only nanoparticle size and composition, but also morphology and dimensionality. Among these advances, colloidal, two-dimensional nanocrystals known as nanoplatelets have emerged, which display exceptionally narrow photoluminescence linewidth and large absorption cross-sections that arise specifically as a result of their dimensionality. However, while extensive studies have led to an understanding of how electron transfer rates scale with nanoparticle size, analogous studies relating rates of electron transfer to nanoparticle dimensionality are lacking. Here, we study electronic interactions in films containing mixtures of zero- or two-dimensional nanostructures (quantum dots or nanoplatelets, respectively) with constant driving force and nanoparticle separation, achieved via the use of isoenergetic nanoparticles and identical capping ligands. Electron transfer is observed in all of the examined mixtures, regardless of the particle dimensionality, and characterized via static and time-resolved photoluminescence, as well as transient absorption spectroscopy. Rates of electron transfer for different combinations of dimensionalities in dilute and concentrated films reveal that dimensionality does, in fact, impact rates of electron transfer, with films containing nanoplatelets exhibiting faster charge separation rates. This novel insight into how dimensionality affects exciton dynamics has implications in the design of photocatalysts and optoelectronic devices such as photovoltaics, as the appropriate selection of nanoparticle dimension can potentially boost device efficiencies.

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Alexandra Brumberg
Location: Technological Institute M177