Browsing by Author "Nizamoglu, S."
Now showing items 1-20 of 39
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Anisotropic Emission from Multilayered Plasmon Resonator Nanocomposites of Isotropic Semiconductor Quantum Dots
Ozel, T.; Nizamoglu, S.; Sefunc, M.A.; Samarskaya, O.; Ozel, I. O.; Mutlugun, E.; Lesnyak, V.; Gaponik N.; Eychmuller, A.; Gaponenko, S. V.; Demir, Hilmi Volkan (American Chemical Society, 2011-01-19)We propose and demonstrate a nanocomposite localized surface plasmon resonator embedded into an artificial three-dimensional construction. Colloidal semiconductor quantum dots are assembled between layers of metal nanoparticles ... -
Blue quantum electroabsorption modulators based on reversed quantum confined Stark effect with blueshift
Sari, E.; Nizamoglu, S.; Ozel, T.; Demir, Hilmi Volkan (AIP Publishing LLC, 2007-01-02)The authors present the design, growth, fabrication, experimental characterization, and theoretical analysis of blue quantum electroabsorption modulators that incorporate similar to 5 nm thick In0.35Ga0.65N/GaN quantum ... -
Color-converting combinations of nanocrystal emitters for warm-white light generation with high color rendering index
Nizamoglu, S.; Zengin, G.; Demir, Hilmi Volkan (American Institute of Physics, 2008-01-22)Warm-white light emitting diodes with high color rendering indices are required for the widespread use of solid state lighting especially indoors. To meet these requirements, we propose and demonstrate warm-white hybrid ... -
Computational study of power conversion and luminous efficiency performance for semiconductor quantum dot nanophosphors on light-emitting diodes
Erdem, T.; Nizamoglu, S.; Demir, Hilmi Volkan (Optical Society of America, 2012-01-30)We present power conversion efficiency (PCE) and luminous efficiency (LE) performance levels of high photometric quality white LEDs integrated with quantum dots (QDs) achieving an averaged color rendering index of >= 90 ... -
Dual-color emitting quantum-dot-quantum-well CdSe-ZnS heteronanocrystals hybridized on InGaN/GaN light emitting diodes for high-quality white light generation
Nizamoglu, S.; Mutlugun, E.; Özel, T.; Demir, Hilmi Volkan (AIP Publishing LLC, 2008-03)We report white light generation by hybridizing green-red emitting (CdSeZnS/CdSe (core) shell/ shell quantum-dot-quantum-well heteronanocrystals on blue InGaN/GaN light emitting diodes with the photometric properties of ... -
Efficient nonradiative energy transfer from InGaN/GaN nanopillars to CdSe/ZnS core/shell nanocrystals
Nizamoglu, S.; Guzelturk, B.; Jeon, D. W.; Lee, I. H.; Demir, Hilmi Volkan (AIP Publishing, 2011-04-20)In this study, we propose and demonstrate efficient electron-hole pair injection from InGaN/GaN multiple quantum well nanopillars (MQW-NPs) to CdSe/ZnS core/shell nanocrystal quantum dots (NQDs) via Forster-type nonradiative ... -
Electric field dependent radiative decay kinetics of polar InGaN/GaN quantum heterostructures at low fields
Sari, E.; Nizamoglu, S.; Lee, I. H.; Baek, J. H.; Demir, Hilmi Volkan (American Institute of Physics, 2009-05-29)Electric field dependent photoluminescence decay kinetics and its radiative component are studied in polar InGaN/GaN quantum heterostructures at low fields. Under externally applied electric field lower than polarization ... -
Excitation resolved color conversion of CdSe/ZnS core/shell quantum dot solids for hybrid white light emitting diodes
Nizamoglu, S.; Demir, Hilmi Volkan (American Institute of Physics, 2009-04-28)In this paper, for their use as nanoluminophors on color-conversion white light emitting diodes (LEDs), we present spectrally resolved relative quantum efficiency and relative color (photon) conversion efficiency of CdSe/ZnS ... -
Excitonic enhancement of nonradiative energy transfer from a quantum well in the optical near field of energy gradient quantum dots
Nizamoglu, S.; Hernandez-Martinez, P. L.; Mutlugun, E.; Karatay, D. U.; Demir, Hilmi Volkan (American Institute of Physics, 2012-06-13)We report strong exciton migration with an efficiency of 83.3% from a violet-emitting epitaxial quantum well (QW) to an energy gradient colloidal construct of layered green-and red-emitting nanocrystal quantum dots (NQDs) ... -
Förster resonance energy transfer enhanced color-conversion using colloidal semiconductor quantum dots for solid state lighting
Nizamoglu, S.; Demir, Hilmi Volkan (American Institute of Physics, 2009-10-15)In this paper, we present Förster resonance energy transfer (FRET)-enhanced color-conversion using colloidal semiconductor quantum dot nanocrystals (NCs) to make reddish-orange light-emitting diodes for use in ultraefficient ... -
Green/yellow solid state lighting via radiative and nonradiative energy transfer involving colloidal semiconductor nanocrystals
Nizamoglu, S.; Sari, E.; Baek, J. H.; Lee, I. H; Demir, Hilmi Volkan (IEEE, 2009-08-05)LEDs made of In(x)Ga(1-x)N and (Al(x)Ga(1-x))(1-y)In(y)P suffer from significantly reduced quantum efficiency and luminous efficiency in the green/yellow spectral ranges. To address these problems, we present the design, ... -
High scotopic/photopic ratio white-light-emitting diodes integrated with semiconductor nanophosphors of colloidal quantum dots
Nizamoglu, S.; Erdem, T.; Demir, Hilmi Volkan (Optical Society of America, 2011)We propose and demonstrate single-chip white-light-emitting diodes (WLEDs) integrated with semiconductor nanophosphors of colloidal quantum dots for high scotopic/photopic (S/P) ratio. These color conversion WLEDs achieve ... -
Hybrid white light sources based on layer-by-layer assembly of nanocrystals on near-UV emitting diodes
Nizamoglu, S.; Demir, Hilmi Volkan (Institute of Physics Publishing Ltd., 2007-09-17)We present the design, growth, fabrication, integration and characterization of alternative hybrid white light sources based on the controlled layer-by-layer assembly of nanocrystals on UV-emitting nitride diodes for ... -
Localized plasmon-engineered spontaneous emission of CdSe/ZnS nanocrystals closely-packed in the proximity of Ag nanoisland films for controlling emission linewidth, peak, and intensity
Soganci, I. M.; Nizamoglu, S.; Mutlugun, E.; Akin, O.; Demir, Hilmi Volkan (Optical Society of America, 2007)Using metallic nanoislands, we demonstrate the localized plasmonic control and modification of the spontaneous emission from closely-packed nanocrystal emitters, leading to significant changes in their collective emission ... -
Nanocrystal-based hybrid white light generation with tunable colour parameters
Nizamoglu, S.; Demir, Hilmi Volkan (Institute of Physics Publishing Ltd., 2007)We present the hybridization of CdSe/ZnS core-shell nanocrystals (NCs) on InGaN/GaN based blue/near-UV LEDs to generate light widely tunable across the visible spectral range and especially within the white region of the ... -
Nonradiative resonance energy transfer directed from colloidal CdSe/ZnS quantum dots to epitaxial InGaN/GaN quantum wells for solar cells
Nizamoglu, S.; Sari, E.; Baek, J. H.; Lee, I. H.; Demir, Hilmi Volkan (Wiley, 2010-06-04)We report on Förster-type nonradiative resonance energy transfer (NRET) directed from colloidal quantum dots (QDs) to epitaxial quantum wells (QWs) with an efficiency of 69.6% at a rate of 1.527 ns-1 for potential application ... -
Observation of efficient transfer from Mott-Wannier to Frenkel excitons in a hybrid semiconductor quantum dot-polymer composite at room temperature
Nizamoglu, S.; Sun, X. W.; Demir, Hilmi Volkan (American Institute of Physics, 2010-12-29)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. ... -
Observation of selective plasmon-exciton coupling in nonradiative energy transfer: donor-selective versus acceptor-selective plexcitons
Ozel, T.; Hernandez-Martinez, P. L.; Mutlugun, E.; Akin, O.; Nizamoglu, S.; Ozel, I. O.; Zhang, Q.; Xiong, Q.; Demir, Hilmi Volkan (American Chemical Society, 2013-06)We report selectively plasmon-mediated nonradiative energy transfer between quantum dot (QD) emitters interacting with each other via Forster-type resonance energy transfer (FRET) under controlled plasmon coupling either ... -
Onion-Like (CdSe)ZnS/CdSe/ZnS quantum-dot-quantum-well heteronanocrystals for investigation of multi-color emission
Nizamoglu, S.; Demir, Hilmi Volkan (Optical Society of America, 2008)We investigate multi-color spontaneous emission from quantum-dot-quantum-well heteronanocrystals made of onion-like (CdSe) ZnS/CdSe/ZnS ( core) shell/shell/shell structures, with our theoretical results explaining experimental ... -
Opposite carrier dynamics and optical absorption characteristics under external electric field in nonpolar vs. polar InGaN/GaN based quantum heterostructures
Sari, E.; Nizamoglu, S.; Choi, J H.; Lee, S J.; Baik, K H.; Lee, I. H.; Baek, J. H.; Hwang, S M.; Demir, Hilmi Volkan (Optical Society of America, 2011)We report on the electric field dependent carrier dynamics and optical absorption in nonpolar a-plane GaN-based quantum heterostructures grown on r-plane sapphire, which are surprisingly observed to be opposite to those ...