Dr. Svetlana Kilina from North Dakota State University will present a seminar.

Impact of Covalent Functionalization of Nanostructures on Their Optical Properties: Computational Insights

Abstract:

“I will present current research of my group focused on computations of photo-excited processes at organic-inorganic interfaces in covalently functionalized nanomaterials, such as quantum dots (QD) and carbon nanotubes (CNTs). Recent focus on assemblies of the QDs functionalized by various organic and metal-organic dyes is dictated by their promise to serve as a key element for both solar-to-electrical and solar-to-chemical energy conversion processes. Our simulations of QD/dye composites have led us to predictions of conditions that govern the direction and rates of the charge transfer from the QD to the dye and interpretation of transit-spectroscopy data. These results provide important insights into the photo-physics and charge transfer processes in QDs, which understanding is critical for realization of these nanomaterials for photovoltaic, sensor, and photocatalytic applications. Simulations of covalently functionalized CNTs have complimented and advanced recent experimental efforts in spectroscopy and chemistry of CNTs. A covalent binding of molecular adduct to the CNT, introducing sp3-hybridized defects into the sp2-lattice of the nanotube, results in redshifted optically active transitions providing defect-originated emission at the near infrared (NIR) range. Also, the sp3-defect in CNTs creates required conditions for single photon emission tunable from NIR to telecom wavelengths and achievable at room temperature. Collaborations with scientists from Los Alamos National Lab have allowed us to directly compare calculated and experimental results from pump-dependent low-temperature photoluminescence spectroscopy and identify the role of tube’s chirality, tube’s mode, adduct polarity, and defect-defect interactions in selective control of defect-associated emission of CNTs. Our results demonstrate that manipulation of the tube chirality together with the polarity and bond character of molecular adducts is a practical strategy for precise tuning of light emission in functionalized CNTs. Overall, our research outcomes establish fundamentals for the novel material design for solar energy conversion, sensing, and quantum technologies.”

Host: Dr. Wenfang Sun