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 20 for “"photoluminescence quantum yield"”.
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Controlling structure and composition in double-heterojunction nanorods for high quantum yield and tunable color
… nanorods reported thus far are low photoluminescence quantum yield, low color purity owing to wide size distribution, and emission over a narrow range of energies in the visible spectrum. Here we report alterations to the synthetic route which result in a narrow size and …
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Organometallic Synthesis Kinetics of CdSe Quantum Dots
CdSe quantum dots produced by organometallic synthesis are useful as tunable emitters for photonic devices and as multi-colored protein markers for biomedical imaging, applications requiring bright and narrow emission. A diffusion-limited model helped monitor growth rates via photoluminescence and …
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Colloidal CdSe/CdS nanostructures : synthesis, optical characterization and applications
… particular, we discuss the synthesis of CdSe/CdS quantum dots and seeded CdSe/CdS nanorods that have a near unity photoluminescence quantum yield and complete energy transfer from the shell to the core. Next, we discuss the fabrication of luminescent solar concentrators using these materials and …
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Biopolymer-mediated analyte detection via photoluminescence modulation of single-walled carbon nanotubes
… the modulation of SWNT optical properties—both photoluminescence and resonance Raman scattering—demonstrate their tunable nature. Solution dispersed SWNT are sorted by length and the photoluminescence quantum yield is shown to increase nonlinearly with length, suggesting that SWNT ends quench …
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Novel type-II nanocrystal quantum dots and versatile oligomeric phosphine ligands
… and applications of novel type-II quantum dots and versatile oligomeric phosphine ligands. Type-II band engineered quantum dots (CdTe/CdSe(core/shell) and CdSe/ZnTe(core/shell) heterostructures) are synthesized by chemical means. The optical properties of these type-II quantum dots …
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Charge Carrier Relaxation in Halide Perovskite Semiconductors for Optoelectronic Applications
… early-time carrier relaxation and its impact on photoluminescence emission. We first study ultrafast carrier thermalization processes using 2D electronic spectroscopy and extract characteristic carrier thermalization times from below 10 fs to 85 fs. We then investigate the early-time …
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Experimental investigations of excited-state dynamics in conjugated polymers using time-resolved laser spectroscopy
… in the conjugated copolymer Super Yellow. The photoluminescence quantum yield of the copolymer was measured and its relatively high value was attributed to the effect of the aforementioned energy transfer. Femtosecond pump-probe spectroscopy has been used to identify and characterise the …
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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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Enhancing Stability in Quantum-Dot and Perovskite Optoelectronic Devices through Compositional Engineering and Surface Treatment
Solution-processed quantum dots (QDs) and metal-halide perovskites are of interest inoptoelectronics because of their sharp color, high absorption, and bright emission. However, their further progress is hampered today by limited operating stability. In this thesis, I study how compositional …
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Chemical Modifications and Passivation Approaches in Metal Halide Perovskite Solar Cells
… potassium halides. This leads to luminescence quantum yields approaching unity while maintaining high charge mobilities along with the inhibition of transient photo-induced ion migration processes even in mixed halide perovskites that otherwise show bandgap instabilities. We demonstrate a wide …
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Design and Characterisation of Hybrid Organic-Inorganic Materials for Luminescence Downshifting Devices
… lumophore, as this can directly impact the final photoluminescence properties and material structure. Hence, understanding these interactions is crucial for the design of highly efficient downshifting devices. Firstly, composites of a polyethylene-co-glycidyl methacrylate organic polymer and …
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Heavy-metal-free colloidal nanocrystal heterostructures – synthetic chemistry and growth mechanisms
… the heterostructures, as well as to improve the photoluminescence quantum yield (PL QY) of nanocrystals. We first examine how different Cu precursors in the synthesis of colloidal copper sulfide (Cu2-xS) nanocrystals affect the resulting shape and phase. Decreasing aspect ratio in 1D nanorods …
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Ultra-High Resolution Environmentally-Friendly Full-Colour Quantum Dot Display Fabricated via Cracking Assisted Transfer Printing
… colour gamut, 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 …
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Molecular Encapsulation of Conjugated Polymers for Organic Electronics
… chains. However, it is noteworthy that the photoluminescence quantum yield (PLQY) in the solid state is unexpectedly lower (1%) compared to previous studies. Nevertheless, when assessing the performance of devices in comparison to the record breaker PM6:Y6 system, our materials demonstrate …
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Energetics and Dynamics in Quantum Confined Semiconductor Nanostructures
… to tune the band-gap energies of semiconductor quantum dots, nanoplatelets, and quantum wires, their significant absorption cross sections, and high photoluminescence quantum yields make these nanostructures promising moieties for use in optoelectronic devices, solar concentrators, chemical …
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Surface and interface engineering in quantum dot and double-heterojunction nanorod light-emitting diodes
Colloidal quantum dots (QDs) have shown to be a promising class of materials for the next generation displays. State-of-the-art QD-LEDs that utilize CdSe-based spherical core/shell (C/S) QDs as the electroluminescent layer have shown efficiencies and brightness that rival the best organic LEDs. One …
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Incorporating double-heterojunction in anisotropic semiconductor nanocrystals for novel optoelectronic applications
… enable the use of solution processable colloidal quantum dots (QDs) in future devices. Such heterojunctions incorporated into colloidal nanorods may be especially promising since the inherent shape anisotropy can provide additional benefits of directionality and accessibility in band structure …
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Quantum dot - molecularly imprinted polymer nanomaterials for the fluorescence sensing of selected pharmaceutical and personal care products
… and applying cadmium based core/shell quantum dots (QDs) as fluorescence probes for the detection in aquatic compartments of triclosan (TCS) and acetaminophen (AC) which fall within the pharmaceutical and personal care products (PPCPs) subclass of emerging chemical pollutants (ECPs). …
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Micro-photovoltaic materials and systems for solar energy harvesting and light management
… The polyhydrofuran exhibits blue emission with a quantum yield of ca. 14%, and the fluorescence is largely quenched with precise addition of an acidic dopant. Notably, dopant addition reversibly extends absorption to wavelengths throughout the entire visible regime, and absorption intensity …
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Strategies to Optimize Photophysical Properties in Cyclometalated Iridium Complexes
In the past 50 years, iridium has become an indispensable material that supports various technologies that power our modern world. Recently, there has been a growing interest in iridium(III) organometallic complexes for their optoelectronic applications. This thesis delves into the synthesis, …