Browsing by Author "Cicek, N."

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    Highly efficient nonradiative energy transfer mediated light harvesting in water using aqueous CdTe quantum dot antennas
    (Optical Society of America, 2010) Mutlugun, E.; Samarskaya, O.; Ozel, T.; Cicek, N.; Gaponik, N.; Eychmuller, A.; Demir, Hilmi Volkan
    We present light harvesting of aqueous colloidal quantum dots to nonradiatively transfer their excitonic excitation energy efficiently to dye molecules in water, without requiring ligand exchange. These as-synthesized CdTe quantum dots that are used as donors to serve as light-harvesting antennas are carefully optimized to match the electronic structure of Rhodamine B molecules used as acceptors for light harvesting in aqueous medium. By varying the acceptor to donor concentration ratio, we measure the light harvesting factor, along with substantial lifetime modifications of these water-soluble quantum dots, from 25.3 ns to 7.2 ns as a result of their energy transfer with efficiency levels up to 86%. Such nonradiative energy transfer mediated light harvesting in aqueous medium holds great promise for future quantum dot multiplexed dye biodetection systems. (C) 2010 Optical Society of America.
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    Structural tuning of color chromaticity through nonradiative energy transfer by interspacing CdTe nanocrystal monolayers
    (American Institute of Physics, 2009-02-09) Cicek, N.; Nizamoglu, S.; Ozel, T.; Mutlugun, E.; Karatay, D. U.; Lesnyak, V.; Otto, T.; Gaponik N.; Eychmuller, A.; Demir, Hilmi Volkan
    We proposed and demonstrated architectural tuning of color chromaticity by controlling photoluminescence decay kinetics through nonradiative Forster resonance energy transfer in the heterostructure of layer-by-layer spaced CdTe nanocrystal (NC) solids. We achieved highly sensitive tuning by precisely adjusting the energy transfer efficiency from donor NCs to acceptor NCs via controlling interspacing between them at the nanoscale. By modifying decay lifetimes of donors from 12.05 to 2.96 ns and acceptors from 3.68 to 14.57 ns, we fine-tuned chromaticity coordinates from (x,y)=(0.575,0.424) to (0.632, 0.367). This structural adjustment enabled a postsynthesis color tuning capability, alternative or additive to using the size, shape, and composition of NCs.