Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 244 for “"Quantum efficiency"”.
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Quantum efficiency and fission rate in tetracene
… cell, the theoretical energy conversion efficiency limit is larger than the Shockley-Queisser limit due to two excitons produced with one incident photon. In a singlet fission material, an absorbed photon excites a singlet exciton and then split into two triplet excitons with energy …
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Efficiency droop mitigation and quantum efficiency enhancement for nitride Light-Emitting Diodes
… state-of-the art InGaN-based LEDs, including ‘efficiency droop’ issues that cause output power quenching at high current injection levels (> 100 A/cm2). In this dissertation, approaches were investigated to address the major issues related to state-of-the-art nitride LEDs, in particular related …
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Effect of temperature on tunneling and quantum efficiency in cigs solar cells
… as the Fowler-Nordheim formulation. The quantum efficiency model, for CIGS solar cells, is discussed. Device modeling and simulation studies of a Cu(In_{1-x},Gax)Se_2 (CIGS) thin film solar cell are carried out. A variety of graded band-gap structures, including space charge region (SCR) …
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Absolute internal quantum efficiency of indium-gallium nitride based light-emitting diodes
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2024-12-01
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HIGH TEMPERATURE ZnSe:Mn/ZnS NANOPHOSPHORS WITH VERY HIGH QUANTUM EFFICIENCY FOR WHITE LEDs
… of view of both human perception and energy efficiency. Currently, the most efficient and common LED design consists of a blue LED and a yellow phosphor, which in conjunction produce white light. The LED phosphor is a yellow phosphor made of yttrium aluminum garnet doped with cerium (YAG:Ce). …
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Implementing Solvothermally Synthesized Carbon Nanodots into Dye-Sensitized Solar Cells to Enhance External Quantum Efficiency in the Ultraviolet
… photon energy in order to increase the external quantum efficiency (EQE) of dye-sensitized solar cells (DSSCs) in the ultraviolet. In the first part of this study, the CND core-shell model and a reflux synthesis time-dependent evolving carbogenic core size are confirmed by optical measurements …
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The maximum quantum efficiency of CO2 assimilation declines with depth in the canopies of the C4 crops Miscanthus x giganteus and Zea mays
… This should reduce photosynthetic light use efficiency (PLUE) in the lower canopy. Zea mays (Z. mays), a close relative, may share this problem. Measurements were taken on healthy upper and lower canopy leaves of M. x giganteus and Z. mays, and isolated aging leaves of M. x giganteus. The …
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Precise Characterization and Investigation of Laser Cooling in III-V Compound Semiconductors
… research addresses the key concepts of external quantum efficiency (EQE) and parasitic background absorption in a semiconductor laser cooler. The external quantum efficiency describes how well recombination radiation is removed from the cooling device and is precisely measured by All-optical …
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Development and Characterization of Intermediate-Band Quantum Wire Solar Cells
<p>The effects of a quantum wire intermediate band, grown by molecular beam epitaxy, on the optical and electrical properties of solar cells are reported. To investigate the behavior of the intermediate band, the quantum wires were remotely doped at three different doping concentrations, the number …
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Singlet Fission Organic Solar Cell with Long-Wavelength Absorption Using Non-fullerene Acceptors
… materials enable solar cells that exhibit the quantum efficiency benefits of a multi-junction solar cell, with the simplicity of a single-junction structure. We investigated bilayer solar cells using tetracene, a singlet fission material, and Y6, a long-wavelength non-fullerene acceptor …
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Characteristics and applications of the enhanced HRP-catalyzed oxidation of luminol
… extent of luminol oxidation, $\phi\sb{\rm CL}$ (quantum efficiency of chemiluminescence), $\phi\sb{\rm fl}$ (quantum efficiency of fluorescence) and $\phi\sb{\rm ex}$ (quantum efficiency of excitation) were determined for this reaction under a variety of conditions. In addition, compounds with …
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A quantum dot heterojunction photodetector
… for photodetectors utilizing colloidally grown quantum dots as the principle photo-active component. We implement a thin film of cadmium selenide (CdSe) quantum dot sensitizers, sandwiched between an electron-transporting titanium dioxide (TiO2) layer and a hole-transporting N,N' diphenyl-N,N' …
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SOLAR ENERGY HARVESTING WITH PHOTOSYNTHETIC PIGMENT-PROTEIN COMPLEXES
… a photochemical charge separation that has a quantum efficiency close to 100%. Integrating these natural pigment-protein complexes in bio-hybrid architectures for solar energy harvesting is attractive due to their global abundance and environmental compatibility. Despite the ability of the …
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Toward the photo-induced reductive elimination of halogens
… on energy-poor substrates and must possess high quantum efficiency. The controlling aspect of this quantum efficiency is not hydrogen evolution, but rather activation of stable M-X bonds that are generated from the reaction of catalyst with the low energy substrate. This thesis examines the …
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Improving the efficiency and threshold current of photonic crystal vertical-cavity surface-emitting lasers
… to achieve high power, low threshold, and high efficiency single mode VCSELs. Various mechanisms that affect the differential quantum efficiency and threshold current of the proton-implanted and oxide-confined photonic crystal vertical-cavity surface-emitting lasers (VCSELs) are studied. Three …
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Structure Design and Luminescence Control of Eu⁺²-doped Orthorhombic Phosphors for Solid-State Lighting Applications
… Most of the current phosphors either have low quantum efficiencies (internal and external, IQE/EQE) or have poor luminescence thermal stability, significantly affecting the performance of phosphor-converted white light emitting diodes (pc-WLEDs). This work focuses on the exploration of novel …
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The U center in potassium bromide crystals
… hydride ion. The spectral distribution of quantum efficiency for conversion of U centers to negative ion vacancies at 78°K was measured and found to decrease by 4~ on the high energy side of the U band. The U band has a high energy shoulder and it is suggested that this high energy shoulder …
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Organic multilayer photoconductor utilizing a spacer layer
… can produce an order of magnitude enhancement in quantum efficiency over the of a spacer layer can produce an order of magnitude enhancement in quantum efficiency over the The work reported here provides encouraging results in the fields of chemosensors and organic optoelectronics.
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High efficiency photodetection below the quantum noise limit
Two low-noise, high quantum efficiency, high bandwidth photodetectors have constructed to form a balanced homodyne detector to detect squeezed light. The detectors have quantum efficiencies of 85% and 90%, a bandwidth of 1MHz, and a dark noise of ... at 1MHz.
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Multispectral Metamaterial Detectors for Smart Imaging
… to realize multicolor detectors with enhanced quantum efficiency for similar function to a human retina. The key idea is to engineer the pixel such that it not only has the ability to sense multimodal data such as color, polarization, dynamic range and phase but also the intelligence to …
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