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 342 for “"Light emitting diodes."”.
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Liquid crystals for light emitting diodes
… crystals (LCs), which are applicable for organic light emitting diodes (OLEDs), were investigated. Semiempirical calculations were carried out on monomers and anti-cofacial dimers built from our molecules, representing molecules in solution and thin film respectively. Compared to the monomer a …
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High power superluminescent light-emitting diodes
Superluminescent light-emitting diodes (SLEDs) are optoelectronic devices which combine different aspects of laser diode and LED performance. The device utilises a ridge waveguide structure to amplify spontaneously emitted light. Steps are taken to suppress feedback by minimising facet …
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Thermal pumping of light-emitting diodes
… is a study of thermally enhanced injection in light-emitting diodes (LEDs). This effect, which we refer to as "thermal pumping", results from Peltier energy exchange from the lattice to charge carriers when current is injected into an LED. For an applied voltage V such that qV < (hw), where q …
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Packaging designs for ultraviolet light emitting diodes
… Nitride (GaN) based deep ultraviolet (DUV) light emitting didoes (LEDs) with emission wavelengths between 200-280 nm enable key emerging technologies such as water/air purification and sterilization, covert communications and portable bio-agent detection/identification systems for homeland …
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Perovskite Light-emitting Diodes with Tunable Emission
Solid-state lightings are becoming the popular choice for lightings due to its higher efficiency, improved colour rendering index and the flexibility of various size and shape. Halide perovskite has tunable colour emission, low disorder and is solution processable making it one of a popular choice …
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Device physics of perovskite light-emitting diodes
… emerged as next-generation semiconductors for light emission, owing to their bright luminescence, excellent charge-transport properties, ease of processing and tunable bandgap. In less than a decade, the external quantum efficiency of perovskite light-emitting diodes (PeLEDs) has increased …
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Underwater photographic lighting using Light Emitting Diodes
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 2003.
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Thermo-electrically pumped semiconductor light emitting diodes
Thermo-electric heat exchange in semiconductor light emitting diodes (LEDs) allows these devices to emit optical power in excess of the electrical power used to drive them, with the remaining power drawn from ambient heat. In the language of semiclassical electron transport, the electrons and holes …
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Fused-Molecular Systems for Organic Light Emitting Diodes
<p>Organic light emitting diodes (OLEDs) are electronic devices made by sandwitching organic light emissive materials between two electrodes. When voltage is applied across the two conductors, a bright light is generated. The color of the emitting light depends on the band gap of the semiconducting …
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Transfer printing of nitride based light emitting diodes
… heterogeneous integration of III-nitride based light emitting diodes (LEDs) onto a wide range of substrates, whether flexible or rigid in their nature. The initial steps towards a functioning prototype are described with the successful transfer printing of 2 µm-thick micron-size LEDs. The thin …
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The Optical Outcoupling of Organic Light Emitting Diodes
… in recent years, however up to 80% of emitted light may be lost within the OLED stack and in the substrate layers. This thesis investigates the effects of the layer stack on the OLED properties and also studies a number of approaches to substrate structuring and treatment in order to couple …
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Alternative transparent electrodes for organic light emitting diodes
Solid state lighting is a new environmentally friendly light source. So far, light emitting diodes (LEDs) and organic LEDs (OLEDs) have been presented as candidates with potentially high efficiency. Recent advances of OLEDs in device architecture, light-out coupling, and materials have ensured high …
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Prognostics and health management of light emitting diodes
… of various engineering systems and products. Light Emitting Diodes (LEDs) are optoelectronic micro-devices that are now replacing traditional incandescent and fluorescent lighting, as they have many advantages including higher reliability, greater energy efficiency, long life time and faster …
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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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Wide band-gap nanowires for light emitting diodes
… designs and potential efficiency improvement of light emitting diodes (LEDs) for solid state lighting. The large surface-to-volume ratio of nanowires provides facile strain-relaxation such that nanowires can be grown on substrates with a large lattice mismatch and remain free of threading …
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Photon Generation and Dissipation in Organic Light-Emitting Diodes
… 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 refractive indices. This thesis comprises …
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III-nitride nanowire light-emitting diodes: design and characterization
… III-nitride semiconductors can absorb or emit light efficiently over a broad spectrum, ranging from 0.65 eV (InN) to 6.4 eV (AlN), which encompasses from deep ultraviolet to near infrared spectrum. However, due to the lack of native substrates, conventional III-nitride planar heterostructures …
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Stability study in lead-halide perovskite light-emitting diodes
… but also have shown great potential in light emitting applications. Other than energy efficiency and brightness, perovskite emitters have advantages such as high colour saturation and low processing temperatures to compete with present inorganic and organic light emitting diode (LED) …
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Defect characterization of erbium doped silicon light emitting diodes
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1994.
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