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 18 of 18 for “"Exciton transport"”.
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Exciton transport and thermodynamics in gallium arsenide quantum wells
… spectroscopy in understanding the spatial transport and energy relaxation of excitons in quantum well systems. I discuss the mechanism of carrier-induced changes in the absorption spectrum of a 210A GaAs multiple quantum well, and show that at moderate densities, the enhanced transmission …
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Exciton transport and coherence in molecular and nanostructured materials
… of molecular and nanostructured materials is the exciton, a bound electron hole pair. Excitons, which can be generated optically or electrically, are the nanoscale carriers of energy, acting as intermediates between photons and electronic excitations. The goal of this thesis is to add to the …
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An analysis of exciton transport, electron tunneling, and electromigration in nanotube and nanowire systems
… dominant mechanism of electromigration from bulk transport to surface transport. We then apply the model to design a process controller to guide gradual electromigration. We then turn to investigating the tunnel junctions themselves. Diverse physical insights have been gained from electron …
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Harnessing Vibrations for Efficient Exciton Dynamics in Semiconducting Energy Materials
… molecules, focussing on the implications for exciton transport, energy transfer, and light emission. Special use of ultrafast laser spectroscopy techniques such as impulsive vibrational spectroscopy and transient absorption microscopy is made to directly observe vibronic couplings and exciton …
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Electronic Excitation Energy Transport and Trapping in Dispersions of Dye Molecules in Rigid Media
… research involves electronic excitation energy (exciton) transport and trapping in dispersions of dye molecules in films of polymer and protein. Excitonic diffusion coefficients and effective concentrations of self-traps were evaluated by comparing luminescence decay curves to theoretical curves …
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Exciton Dynamics in Perovskite CsPbBr₃ Semiconductor Nanocrystals
… photophysical properties, as well as energy transport properties within the NC solids, are still under active debate. Here, I measure both the temperature-dependent (35 K - 300 K) absorption and PL spectra of zwitterionic ligand-capped CsPbBr₃ NCs with four different edge lengths (L = 4.9 - …
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Controlling the architectures and optical properties of conjugated polymer aggregates and films
… materials. We discuss how aggregation enhances exciton transport properties in fluorescent polymers, thereby increasing the probability of excitons reaching low-energy sites in the polymer. A consequence of this aggregation-enhanced exciton migration is that low-energy defect sites in a …
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Biologically engineering nanostructures to maximize energy, electron, and ion transport
… The main ideas in the thesis focus on maximizing transport phenomena in the systems, resulting in performance improvements. Genetic engineering of M13 bacteriophage enables nano-scale multi-component assemblies to create tunable, artificial photosystems for solar energy utilization. Artificial …
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Optoelectronic properties and energy transport processes in cylindrical J-aggregates
… energy by efficient light capture and subsequent transport of the light’s energy to a chemical reaction center. Man-made optical devices could benefit by mimicking these naturally occurring light harvesting processes. Supramolecular organic nanostructures, composed of the amphiphilic carbocyanine …
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Computational investigation of light harvesting in purple photosynthetic bacteria
… first step in photosynthesis is the capture and transport of light energy in the form of short-lived electronic excitation called excitons. Rapid long-range exciton transport is key to the high light harvesting efficiency associated with purple bacteria. The light harvesting system of purple …
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Exciton Dynamics in DNA-Chromophore Assemblies
Excitonic systems have the potential to provide new materials for light harvesting, computing, and imaging. Such applications require control over the spatiotemporal evolution of excited states. Natural light harvesting systems achieve the required control through precise molecular placement; …
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Exploring Structure Function Relationship using Bio-Inspired DNA-Chromophore Complexes
… delivers absorbed energy via a series of exciton transport steps with an efficiency higher than that predicted by a classical random walk in a process that is not yet fully understood. The function of these natural complexes are controlled through carefully arranging electronically active …
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Electrostatic effects of inhomogeneous strain in monolayer transition metal dichalcogenides
… have potential implications for luminescence and exciton transport behavior in monolayer transition metal dichalcogenides with spatially varying strain. We then characterize monolayer MoS₂ which is inhomogeneously strained via a nanopatterned substrate. Kelvin probe force microscopy and …
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Modification of exciton energies and dynamics for thin film optoelectronics
… and sensors. Mediating photons and charges, excitons are responsible for electrical and optical properties in these energetically disordered media. To improve current technology and develop novel applications, a thorough understanding of exciton dynamics is crucial. This thesis focuses on …
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Engineering the optical properties of luminescent solar concentrators at the molecular scale
… two main energy loss mechanisms in LSCs, namely transport losses and trapping losses. We used phycobilisomes, a biological light-harvesting complex, as dyes in the LSC collector to circumvent transport losses caused by photon re-absorption. The selfassembled structure of phycobilisomes couples …
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Spectral properties of the random conductance model
Charge and exciton transport in disordered media plays an essential role in modern technologies. Classical examples are amorphous and organic semiconductors where the disorder can give rise to localized electron states. These localized electrons effectively behave like discrete particles hopping …
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Superradiant Emission from Delocalized Frenkel Excitons in Molecular J-Aggregates
… J-aggregates leads to delocalized Frenkel excitons that span multiple molecules in the aggregate. Delocalized Frenkel excitons in molecular J-aggregates provide an avenue to access high-speed fluorescent materials with unique optical properties such as strong absorption, long-range exciton …
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Charge and energy transport in 0D/2D systems probed using linear and nonlinear spectroscopy
… it is crucial to understand the dynamics and transport of energy and charge in these materials and hybrid structures built from them. The first Chapter of this thesis briefly motivates the technological importance of QDs and TMDs. The remainder explores exciton dynamics and transport in these …