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 62 for “"External Quantum Efficiency"”.
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Implementing Solvothermally Synthesized Carbon Nanodots into Dye-Sensitized Solar Cells to Enhance External Quantum Efficiency in the Ultraviolet
… suitable 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 …
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Precise Characterization and Investigation of Laser Cooling in III-V Compound Semiconductors
… This 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 …
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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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Triplet Exciton Management in Organic Electronic Devices
… devices are reported with maximum external quantum efficiency of 27%, which indicates effective triplet utilisation. Emission colour can be selected through both molecular design and host environment allowing the demonstration of blue-emitting devices with 19% external quantum …
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Investigation of CZTSe Solar Cell with ZnS, ZnSe and In2S3 as Buffer Layers
… the optical properties of given cell like external quantum efficiency, reflectance, transmittance and maximum short circuit current. Among today’s thin film technologies CIGS and CdTe are profound but the toxic nature of Cd, and hard to mine elements used in CIGS, like In, Ga make the …
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Semiconductor quantum dot lasers.
Stimulated emission in semiconductor quantum dot (QD) laser structures is demonstrated. Red-emitting, self-assembled QDs of highly strained InAlAs were grown by molecular beam epitaxy on GaAs substrates. Carriers injected electrically from the doped regions of separate confinement heterostructures …
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All inorganic colloidal quantum dot LEDs
This thesis presents the first colloidal quantum dot light emitting devices (QD-LEDs) with metal oxide charge transport layers. Colloidally synthesized quantum dots (QDs) have shown promise as the active material in optoelectronic devices because of their tunable, narrow band emission. To date, the …
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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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Organische p-i-n Solarzellen
… morphology. The solar cells exhibit a maximum external quantum efficiency of 40% between 630nm and 700nm wavelength. With the help of an optical multilayer model, the optical properties of the solar cells are optimized by placing the active region at the maximum of the optical field …
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Towards quantum information processing with diamond color centers
… requirements summarize the key properties that quantum systems should have to be useful for quantum computing. The work in this thesis focuses on one of the leading solid-state quantum systems, the nitrogen vacancy (NV) center in diamond. The NV has emerged as an excellent quantum sensor, in …
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Measurement of Thermal Impedance of Deep Ultraviolet Light Emitting Diodes
… low injection currents and degrades their external quantum efficiency. Furthermore, this high heat dissipation also decreases the reliability of these devices and shorten their life span. Consequently, thermal management of high power LEDs is a crucial area of research and development. …
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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 photovoltaics
The efficiency of a solar cell is restricted by the "single junction limit," whereby photons with energy higher than the bandgap lose energy by thermalization. Singlet exciton fission splits a high-energy molecular excitation ("singlet" exciton) into a pair of lowenergy ones ("triplet" excitons). …
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Demonstrating visibly transparent solar cells and photodetectors
… by measuring the current-voltage behavior, external quantum efficiency and visible transparency. Our devices demonstrate an average visible transparency of around 56%, power conversion efficiencies between 0.53% and 1.36% and specific detectivities on the order of 1011 to 1012 Jones. These …
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Principles of quantum dot photophysics and applications to luminescent downshifting
Colloidal quantum dots (QDs) exhibit remarkable size-tunable optical properties including broad absorbance and bright, narrow emission. This thesis presents efforts to utilize, manipulate, and expand these properties. Despite the wide range of applications that benefit from multiband spectral …
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Device physics of perovskite light-emitting diodes
… and tunable bandgap. In less than a decade, the external quantum efficiency of perovskite light-emitting diodes (PeLEDs) has increased rapidly to over 25%, which is comparable with that of organic LEDs. The behaviour of PeLEDs is determined by the device processes including charge injection and …
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High efficiency thin film silicon solar cells with novel light trapping : principle, design and processing
One major efficiency limiting factor in thin film solar cells is weak absorption of long wavelength photons due to the limited optical path length imposed by the thin film thickness. This is especially severe in Si because of its indirect bandgap. This thesis invents a novel light trapping scheme, …
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Photoluminescent quantum-dot light emitting devices controlled by electric field induced quenching
Colloidal quantum dots (QDs) have been promising luminophores due to their bright, pure, and tunable colors. The ability to control the emission properties of QDs has far-reaching potential applications for a new generation of display and lighting technologies. The emission control of QDs in a QD …
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Visible light emission from Eu-containing Si-based materials
… the SiOC matrix and Eu2+ ions increases the efficiency of photon absorption for excitation wavelengths shorter than 300 nm. Due to this properties Eu-doped SiOC offers great potentialities for the fabrication of light sources. In this thesis a continuous redshift of the emission peak from 400 …
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Charge and exciton dynamics in quantum dot light-emitting diodes
Colloidal 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 …
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