Search results for "Photoluminescence"

showing 10 items of 811 documents

Dynamic carrier distribution in quantum wells modulated by surface acoustic waves

2001

We have investigated the dynamics of photogenerated carriers under surface acoustic wave (SAW) fields in GaAs quantum wells using spatially and time-resolved photoluminescence (PL). The frequency and phase of the PL oscillations under a SAW yield information about the carrier distribution and the band-gap modulation induced by the SAW. We directly prove that the transport properties of the carriers ultimately control their distribution, storage and, subsequent recombination in the modulated potential.

Surface (mathematics)PhysicsYield (engineering)Photoluminescencebusiness.industrySurface acoustic wavePhase (waves)Acoustic waveCondensed Matter::Mesoscopic Systems and Quantum Hall EffectCondensed Matter::Materials ScienceModulationOptoelectronicsbusinessQuantum well
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Effect of donor substituents on thermally activated delayed fluorescence of diphenylsulfone derivatives

2019

This research was funded by the European Social Fund according to the activity ‘Improvement of researchers’ qualification by implementing world-class R&D projects’ of Measure No. 09.3.3-LMT-K-712. DG acknowledges to the ERDF PostDoc project No. 1.1.1.2/VIAA/1/16/177;

TADFMaterials sciencePhotoluminescenceBiophysicsQuantum yield02 engineering and technologyDiphenylsulphone010402 general chemistryPhotochemistry01 natural sciencesBiochemistrychemistry.chemical_compoundBathochromic shift:NATURAL SCIENCES:Physics [Research Subject Categories]CarbazoleSolvatochromismGeneral Chemistry021001 nanoscience & nanotechnologyCondensed Matter PhysicsAtomic and Molecular Physics and Optics0104 chemical sciencesOLEDchemistryExcited stateDensity functional theoryEmitter0210 nano-technologyPhenoxazineJournal of Luminescence
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Diphenylsulfone-based hosts for electroluminescent devices: Effect of donor substituents

2020

DG acknowledges to the ERDF PostDoc project No. 1.1.1.2/VIAA/1/16/177. This work was supported by the project of scientific co-operation program between Latvia, Lithuania and Taiwan ?Polymeric Emitters with Controllable Thermally Activated Delayed Fluorescence for Solution-processable OLEDs? (grant No. S-LLT-19-4). Support of the Lithuanian Academy of Sciences is gratefully acknowledged; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

TADFMaterials sciencePhotoluminescenceGeneral Chemical EngineeringCarbazoleQuantum yield02 engineering and technologyElectroluminescence010402 general chemistry01 natural scienceschemistry.chemical_compoundOLED:NATURAL SCIENCES:Physics [Research Subject Categories]TrifluoromethylCarbazoleProcess Chemistry and TechnologyHost021001 nanoscience & nanotechnologyDiphenylsulfone0104 chemical sciencesCrystallographyOLEDchemistryQuantum efficiency0210 nano-technologyGlass transitionDyes and Pigments
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Shedding Light on Graphene Quantum Dots: Key Synthetic Strategies, Characterization Tools, and Cutting-Edge Applications

2021

During the last 20 years, the scientific community has shown growing interest towards carbonaceous nanomaterials due to their appealing mechanical, thermal, and optical features, depending on the specific nanoforms. Among these, graphene quantum dots (GQDs) recently emerged as one of the most promising nanomaterials due to their outstanding electrical properties, chemical stability, and intense and tunable photoluminescence, as it is witnessed by a booming number of reported applications, ranging from the biological field to the photovoltaic market. To date, a plethora of synthetic protocols have been investigated to modulate the portfolio of features that GQDs possess and to facilitate the…

TechnologysynthesisComputer scienceNanotechnologyReview02 engineering and technology010402 general chemistry01 natural sciencesNanomaterialslaw.inventionlawhybrid materialsGeneral Materials Sciencedye-sensitized solar cellsMicroscopyQC120-168.85graphene quantum dotsGrapheneTunable photoluminescenceenergy storageTQH201-278.5021001 nanoscience & nanotechnologyEngineering (General). Civil engineering (General)0104 chemical sciencesCharacterization (materials science)TK1-9971Descriptive and experimental mechanicsQuantum dotKey (cryptography)Enhanced Data Rates for GSM EvolutionElectrical engineering. Electronics. Nuclear engineeringTA1-20400210 nano-technologyMaterials
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Transition metal ions luminescence in neutron irradiated magnesium oxide

2010

The results of investigation of the photoluminescence (PL), its excitation and optical absorption of MgO crystals doped with different concentrations of transition metals exposed to fast neutron irradiation and after annealing are presented. It is suggested that the 440 nm photoluminescence band belongs to the complex V−OH-Fe3+ center with tetragonal symmetry, the ~730 nm PL band observed in the irradiated MgO crystals is connected with defects, generated as a result of decay of the complex V−OH-Fe3+ centers. The near infrared luminescence bands in MgO crystals are connected with Fe3+-Fe3+ exchange coupled pairs.

Tetragonal crystal systemPhotoluminescenceMaterials scienceTransition metalAnnealing (metallurgy)DopingAnalytical chemistryNeutronIrradiationLuminescencePhotochemistryIOP Conference Series: Materials Science and Engineering
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Luminescence of oxygen related defects in zirconia nanocrystals

2007

The luminescence of undoped tetragonal structure ZrO2 nanocrystals was studied. The luminescence intensity depends on oxygen content in gases mixture in which the nanocrystals were annealed. The distorted Zr-O bond is suggested to be the recombination center for band carriers. The oxygen deficient defect is proposed to be responsible for photoluminescence. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Tetragonal crystal systemPhotoluminescenceOxygen deficientNanocrystalChemistrychemistry.chemical_elementCubic zirconiaCondensed Matter PhysicsLuminescencePhotochemistryOxygen contentOxygenphysica status solidi c
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Rapid and eco-friendly synthesis of graphene oxide-silica nanohybrids

2014

The increasing interest in Graphene oxide (GO) is due to many issues: the presence of both sp2-conjugated atoms and oxygen-containing functional groups provides a strong hydrophilicity and the possibility to further functionalize it with other molecules (i.e. π-π interactions covalent attachment etc.) [1]. Furthermore since the GO is biocompatible and noncytotoxic many studies have been recently focused on the development of GO-based nanodevices for bioimaging DNA detection drug delivery. Due to their low cytotoxicity and large internal surface area silica nanoparticles have been taken into account as promising material for biolabeling and drug loading/delivery. Particular consideration has recently been demonstrated for GO-silica composites because of the potentialities for electrical applications their chemical inertia and stability toward ions exposure. The possibility to combine the extraordinary properties of GO and silica offers several advantages for the realization of nanoprobes for biological applications and of biosensor [12]. The strategy for the fabrication of GO-nanosilica nanohybrids can be schematized as follows: (i) synthesis of GO by oxidizing graphite powder with the method described by Marcano et al. [3] (ii) Preparation of oxygen-loaded silica nanoparticles by thermal treatments in controlled atmosphere in order to induce high NIR emission at 1272 nm from high purity silica nanoparticles. (iii) preparation of GrO-silica nanohybrid films via rapid solvent casting in water. The nanohybrids were tested by XPS FTIR Raman analysis UV photoluminescence analysis TGA Zeta potential measurements electrical tests AFM and SEM. Several nanohybrids were prepared by combining two different typologies of GO and two different samples of silica.
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Chalcopyrite Semiconductors for Quantum Well Solar Cells

2011

We explore here the possibilities of using highly absorbing chalcopyrite semiconductors of the type Cu(In,Ga)Se2 in a quantum well solar cell structure. Thin alternating layers of 50 nm CuInSe2 and CuGaSe2 were grown epitaxially on a GaAs(100) substrate employing metalorganic vapor phase epitaxy. The optical properties of a resulting structure of three layers were investigated by photoluminescence and photoreflectance, indicating charge carrier confinement ∗To whom correspondence should be addressed †Helmholtz-Zentrum Berlin ‡Universidad Politecnica de Madrid ¶University of Illinois §University of Jyvaskyla ‖Current address: Universitat des Saarlandes, Uni Campus, Gebaude A5.1, 66123 Saarbr…

Theory of solar cellsPhotoluminescenceMaterials scienceta114Renewable Energy Sustainability and the Environmentbusiness.industryHybrid solar cellQuantum dot solar cellEpitaxylaw.inventionlawSolar cellOptoelectronicsGeneral Materials ScienceCharge carrierbusinessQuantum wellAdvanced Energy Materials
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Study on the thermotropic properties of highly fluorinated 1,2,4-oxadiazolylpyridinium salts and their perspective applications as ionic liquid cryst…

2007

A new series of fluorinated salts, iodides and trifluoromethanesulfonates, was synthesized from perfluoroalkylated 1,2,4-oxadiazolylpyridines. Their thermotropic properties were investigated by combined temperature resolved small angle and wide angle X-ray scattering, differential scanning calorimetry and polarised optical microscopy. The UV–visible and photoluminescence properties were studied for all compounds. The results showed for two compounds the existence of an enantiotropic mesomorphic smectic liquid crystal phase. All iodides showed thermochromism phenomena suggesting prospective applications in optoelectronics.

ThermochromismPhotoluminescenceChemistryOrganic salts ionic liquid crystals perfluoroalkyl oxadiazolylpyridiniumGeneral ChemistryThermotropic crystallaw.inventionCrystallographychemistry.chemical_compoundDifferential scanning calorimetryOptical microscopelawLiquid crystalPhase (matter)Ionic liquidMaterials ChemistryJournal of Materials Chemistry
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Toward development of optical biosensors based on photoluminescence of TiO2 nanoparticles for the detection of Salmonella

2017

Quality control of food and agriculture production is an inseparable part of human safety and wellbeing. Salmonella infections belong to one of the most monitored pathogens in the world, therefore advanced determination of this pathogen can decrease the risks of human diseases caused by this microorganism. In this research we introduce a novel optical immunosensor for determination of Salmonella typhimurium. The immunosensor is based on Titanium dioxide (TiO2) nanoparticles deposited on glass substrates (glass/TiO2)center dot TiO2 nanoparticles exhibit an intense photoluminescence (PL) in the visible range of spectrum at room temperature. The direct immobilization of antibodies (anti-S-Ab) …

TiO2 nanoparticles; Photoluminescence based biosensor; Immunosensor; Salmonella infection; AntibodySalmonellaPhotoluminescenceMaterials scienceNanoparticleNanotechnology02 engineering and technology010402 general chemistrymedicine.disease_cause01 natural sciencesAnalytical Chemistrychemistry.chemical_compoundAnalytisk kemiMaterials ChemistrymedicineHuman safetyElectrical and Electronic EngineeringInstrumentationTio2 nanoparticlesMetals and Alloys021001 nanoscience & nanotechnologyCondensed Matter Physics0104 chemical sciencesSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialschemistryTitanium dioxideVisible range0210 nano-technologyBiosensorSensors and Actuators B: Chemical
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