Browsing by Subject "Well"

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    Observation of efficient transfer from Mott-Wannier to Frenkel excitons in a hybrid semiconductor quantum dot-polymer composite at room temperature
    (American Institute of Physics, 2010-12-29) Nizamoglu, S.; Sun, X. W.; Demir, Hilmi Volkan
    Efficient conversion from Mott-Wannier to Frenkel excitons is observed at room temperature. The time-resolved photoluminescence shows that the energy transfer rate and efficiency reach 0.262 ns-1 and 80.9%, respectively. The energy transfer is enabled by strong dipole-dipole coupling in a hybrid inorganic/organic system of CdSe/ZnS core/shell heteronanocrystal and poly[2-methoxy-5-(3,7-dimethyl-octyloxy)-1,4-phenylenevinylene] homopolymer composite, and the measured energy transfer efficiencies are consistent with the analytical model.
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    ItemOpen Access
    Resonant nonradiative energy transfer in CdSe/ZnS core/shell nanocrystal solids enhances hybrid white light emitting diodes
    (Optical Society of America, 2008) Nizamoglu, S.; Demir, Hilmi Volkan
    We propose and demonstrate hybrid white light emitting diodes enhanced with resonant nonradiative energy transfer in CdSe/ZnS core/shell nanocrystal solids integrated on near-UV InGaN/GaN LEDs. We observe a relative quantum efficiency enhancement of 13.2 percent for the acceptor nanocrystals in the energy gradient mixed assembly, compared to the monodisperse phase. This enhancement is attributed to the ability to recycle trapped excitons into nanocrystals using nonradiative energy transfer. We present the time-resolved photoluminescence of these nanocrystal solids to reveal the kinetics of their energy transfer and their steady-state photoluminescence to exhibit the resulting quantum efficiency enhancement.