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 545 for “"QD"”.
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The Theory and Modeling of Solar Cells Based on Semiconducting Quantum Dots
<p>Quantum dots (QDs) are promising building block materials for many emerging energy-harvesting applications. We theoretically investigated the influences of the QD-QD (CdTe-CdSe) charge transfer rates and mechanisms on QD solar cells power conversion efficiencies using multi-level modeling …
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Fabrication and optimization of light emitting devices with core-shell quantum dots
Quantum dot light emitting devices (QD-LEDs) are promising options for the next generation of solid state lighting, color displays, and other optoelectronic applications. Overcoating quantum dots (QDs) -- semiconducting nanocrystals of CdSe, PbS, or another similar compound -- with a wide band-gap …
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Aluminum Gallium Arsenide-Gallium Arsenide-Indium Gallium Arsenide-Indium Arsenide Quantum Dot Coupled to Quantum Well Heterostructure Lasers by Low-Pressure Metalorganic Chemical Vapor Deposition
… tunneling distance of a single-quantum-dot (QD) layer of an AlGaAs-GaAs-InGaAs-InAs QD heterostructure laser to realize also smaller size QDs of greater density and uniformity. The QD density is changed from 2 x 1010/cm2 for a 50-A GaAs coupling barrier (QW to QD) to 3 x 1010/cm2 for a 5-A …
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Photodetectors based on colloidal quantum dots
… photocurrent enhancement in quantum-dot (QD) solids via post-deposition chemical annealing and by recent successes incorporating single monolayers of QDs in light-emitting devices (QD-LEDs), we set out to develop thin-film, layered photodetectors in which the active layer is a chemically …
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The Role of Quantum Dot Size on the Performance of Intermediate Band Solar Cells
… and solar cell efficiency in quantum dot (QD) intermediate band solar cells (IBSCs). More specifically, the effect of indium arsenide (InAs) QD height on the open circuit voltage and solar cell efficiency was studied in a systematic way. To explore this effect in QD solar cells, several …
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Efficiency loss mechanisms in colloidal quantum-dot light-emitting diodes
… colloidal quantum-dot light-emitting diodes (QD-LEDs) interesting for the next generation of display and lighting technologies. However, there still remain various hurdles to the commercialization of QD-LEDs, including their relatively low external quantum efficiencies (EQE). In this thesis, …
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Enhancing quantum-dot luminescence in visible and infrared light emitting devices
… of colloidal quantum-dot light emitting devices (QD-LEDs) can be enhanced by addressing in situ QD photoluminescence (PL) quenching mechanisms occurring with and without applied bias. QD-LEDs promise efficient, high colour-quality solid-state lighting and displays, and our cost analysis of …
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The Stability of PbS Quantum Dot Solar Cells
Solution-based lead sulfide (PbS) quantum dots (QDs) may enable lightweight solar cells that facilitate high-throughput module manufacturing, simplify module installation, and bring light-harvesting functionality to unconventional or weight-restricted surfaces. Proven long-term stability is …
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Physical properties and design of light-emitting devices based on organic materials and nanoparticles
… semiconductors and colloidal quantum dots (QDs). This hybrid material system has several advantages over crystalline semiconductor technology; first, it is compatible with inexpensive fabrication methods such as solution processing and roll-to-roll deposition; second, hybrid devices can be …
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Physical properties and design of light-emitting devices based on organic materials and nanoparticles
… semiconductors and colloidal quantum dots (QDs). This hybrid material system has several advantages over crystalline semiconductor technology; first, it is compatible with inexpensive fabrication methods such as solution processing and roll-to-roll deposition; second, hybrid devices can be …
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Studies on the next-generation quantum dots light-emitting diodes for full-colour display and smart lighting application by printing technology
… candidates, a quantum dot light-emitting device (QD-LED) is strongly recommended for the next-generation display and lighting application. Herein, this thesis touches the studies on the science and technologies of QD-LEDs from the material, the process technology, the device design and …
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Investigating transport of charged nanoparticles by multiphoton fluorescence correlation spectroscopy (MPFCS)
… of charge on the diffusion of quantum dot (QD) nanocrystals in collagen and collagen-hyaluronan (HA) composite gel models of human colon adenocarcinoma (LS174T). The MPFCS system was integrated with a multiphoton laser-scanning microscope (MPLSM) to enable visualization of QD distribution …
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Charge and exciton dynamics in quantum dot light-emitting diodes
… quantum dot based light-emitting diodes (QD-LEDs) offer the possibility of bright, saturated, and tunable emission for the next generation of display and solid state lighting technologies. In this thesis, we study how the interplay of charges and excitons in a QD-LED affect its operational …
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Energy level engineering in colloidal quantum dot solar cells
Lead sulfide colloidal quantum dots (PbS QDs) possess a uniquely tunable set of electronic properties that has generated considerable interest in their use as active materials in lightweight, flexible, solution-processed photovoltaics. The bandgap of PbS QDs can be tuned across the entire range …
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Surface trap passivation and characterization of lead sulfide quantum dots for optical and electrical applications
Quantum dots (QDs) are semiconductor nanocrystals having a size comparable to or smaller than its exciton Bohr radius. The small size of QDs leads to the quantum confinement effects in their electronic structures. Their unique optical properties, including a tunable emission from UV to IR, make QDs …
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Photonic crystal enhancement and tuning of quantum dot emission
… output emission and performance of quantum dots (QDs). We integrate visible wavelength emitting QDs within a polymer-based photonic crystal and excite them using an ultraviolet-emitting LED. The PC design incorporates two interleaved regions, each with distinct periods in orthogonal directions to …
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Ultra-High Resolution Environmentally-Friendly Full-Colour Quantum Dot Display Fabricated via Cracking Assisted Transfer Printing
… along with extended lifetimes. Quantum dots (QDs) have emerged as a leading emissive material in the in this application, with the properties of tuneable bandgap controlled by the QD size and composition, high photoluminescence quantum yield (PLQY), high colour purity with narrow emission …
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Development of indium arsenide quantum dot solar cells for high conversion efficiency
… solar cells. In this thesis InAs quantum dot (QD) solar cells are studied and investigated. The theory of using QDs as an intermediate band in GaAs-based solar cells is introduced. Three samples are grown for investigation, an MBE grown GaAs control cell, an MBE grown six-stack InAs QD solar …
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Theory of Operating Characteristics of Quantum Dot Lasers with Asymmetric Barrier Layers
… the operating characteristics of quantum dot (QD) lasers with asymmetric barrier layers (ABLs) are studied. Several different cases are examined, in particular: 1) Effect of excited states on static and dynamic operating characteristics Within QDs, in addition to the lasing ground state, …
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Translating semiconductor device physics into nanoparticle films for electronic applications
… of semiconductor nanocrystal quantum dot (QD) electronic devices, and photovoltaic devices in particular. This involves a variety of characterization techniques and their adaptations, as well as careful evaluation of their results to assure the validity of assumptions. Chapter 1 provides an …
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