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 36 for “"Internal Quantum Efficiency"”.
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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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Photon Generation and Dissipation in Organic Light-Emitting Diodes
… activated delayed fluorescence emitters, the internal quantum efficiency of organic light-emitting diodes (OLEDs) can now reach 100%. However, a major fraction of generated photons is trapped inside the device, because of the intrinsic multi-layer device structure and the mismatch of …
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Evaluation of potential applications for templated arrays of heterostructural semiconductor nanowires as light emitting devices
… on reliability and performance (both the internal quantum efficiency and the extraction efficiency) are evaluated. Business models for development of nanowire arrays for light emitting devices are discussed.
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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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Photodetectors based on colloidal quantum dots
… work demonstrating 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 …
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Interplay of Electrical, Mechanical and Thermal Fields in III-N Nanostructures for LED Applications
… at exploring the competing effects of various internal/built-in fields on the electronic structure and optical properties of III-N nanostructured (Quantum Dots and disk-in-a-wire) LEDs using a multiscale modeling approach. The objective is three-fold: (1) calculate the strain distribution, …
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Organische p-i-n Solarzellen
… 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 distribution. The …
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Simulation, Fabrication, and Characterization of Semiconductor Lasers
… 898 nm for all the lasers. External differential quantum efficiency is measured for different cavity lengths from which internal quantum efficiency is found 85.5% and also internal loss 5.85 cm−1. Finally, the characteristic temperature for the diode laser is found 208.3 0C. It is also shown that …
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Molekulinių spinduolių optimizacija naujos kartos organiniams šviestukams /
… intersystem crossing, leading to 100% of internal quantum efficiency. Efficiency of those TADF OLEDs is the same as of phosphorescent ones, however with much higher lifetime. Despite this, the molecular structure of TADF emitters is quite complex and even small changes of molecular …
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Optimization of molecular emitters for new generation OLEDs /
… intersystem crossing, leading to 100% of internal quantum efficiency. Efficiency of those TADF OLEDs is the same as of phosphorescent ones, however with much higher lifetime. Despite this, the molecular structure of TADF emitters is quite complex and even small changes of molecular …
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Development of Iii-Nitride Non-Polar Leds and Self-Aligned Laser Structure
… tied to the overall system power conversion efficiency as it dictates the number of light emitting diodes needed to produce a certain light output power. The system power conversion efficiency itself is dictated by the LED internal quantum efficiency (IQE), the light extraction and the …
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CRYSTAL STRUCTURE ENGINEERING FOR IMPROVED PERFORMANCE OF EMERGING NANOSCALE DEVICES
… near-field photolithography, free-space quantum cryptography, consumer displays, quantum computation, as well as diagnostic medicine and imaging. However, only few theoretical investigations have been performed on these structures due to the complex nature of the interplay of atomicity, …
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Singlet exciton fission, a multi-exciton generation process, in organic semiconductor solar cells
… and low manufacturing setup costs. The highest efficiency seen in research labs, ~10% today, is still too low for production. In this work we explore implementations of a multiple exciton generation process, singlet exciton fission, to work around the Shockley-Queisser limit, according to which, …
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Structural and optical properties of phase transition cubic phase gallium nitride for photonic devices
… that hinders performance. These include: internal polarization field (~MV/cm2), high acceptor activation energy (260 meV), low hole mobility (20 cm2/V), and expensive substrates (Al2O3, SiC). The metastable cubic-phase GaN offers interesting properties: no internal fields, lower acceptor …
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Modeling the effects of surface plasmon resonance on hot electron collection in a metallic-semiconductor photonic crystal device
… decay. However, how surface plasmon enhances the efficiency of hot electron collection is still debatable. This thesis studies the effects of surface plasmon resonance on hot electron collection in a metallic-semiconductor photonic crystal (MSPhC) designed by our group for efficient …
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Cubic phase gallium nitride photonics integrated on silicon(100) for next-generation solid state lighting
… cost that hinder market adoption. These include: internal polarization field ( MV/cm2), high acceptor activation energy (260 meV), low hole mobility (20 cm2/V), and expensive substrates (Al2O3, SiC). Gallium nitride also crystallizes in the cubic crystal that has a higher degree of symmetry. This …
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Halide Perovskites for Photovoltaics and Light-Emitting Diodes
Halide perovskite solar cells, with rapid efficiency improvements from ~10% to ~23% in 6 years, have attracted significant attention due to their remarkable performance, low processing cost and their potential to become a strong alternative candidate to silicon solar cells. Significant development …
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STUDY OF WURTZITE AND ZINCBLENDE GAN BASED GREEN LED HETEROSTRUCTURE
This thesis covers research on the efficiency of green light emitting diodes (LEDs). The work presented focusses on the characterisation of conventional wurtzite (wz)-GaN based LEDs and novel zincblende (zb)-GaN based LEDs. The investigated wz-GaN based multiple quantum well structures have been …
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Template-based control for bottom-up nanostructures - multilayer block copolymer graphoepitaxy and masked ZnO nanowire growth
… to investigate local charge collection and internal quantum efficiency for NW pitches of 100-1000 nm in research-scale solar cell devices.
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A study of efficiency droop of green light emitting diodes grown by metalorganic chemical vapor deposition
… Materials and Devices Group) to reduce the "efficiency droop" effect that occurs in III-Nitrides Light Emitting Diodes (LEDs) when driven at high injection current densities. The efficiency droop refers to a decrease of the LED light emission efficiency when increases the current density from …
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