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 38 for “"Exciton dynamics"”.
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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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Simulating exciton dynamics in organic semiconductors
… organic semiconductors: the transport of Frenkel exciton and dissociation of charge-transfer (CT) exciton. Frenkel excitons are tightly bound electron-hole pairs created upon photo-excitation of molecules and they carry the excess energy imparted by photons.
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Correlated exciton dynamics in semiconductor nanostructures
… are often determined by excited electron dynamics. In semiconductors, one fundamentally important electronic state is an exciton, an excited electron bound to a positively charged vacancy. Excitons can become correlated with other excitons, mutually influencing one another and exhibiting …
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Fluctuations and exciton dynamics in molecular semiconductors
… structure of molecular semiconductors and of the exciton dynamics in the same materials. The method employed in this thesis is time- and angle-resolved photoemission spectroscopy. In the first part, the electronic structure of molecular semiconductors at equilibrium is considered. We show that the …
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Triplet exciton dynamics in conjugated polymer films
A thorough knowledge of the excited state dynamics in conjugated polymers is necessary for efficient use of these novel materials. Triplet excitons are believed to play an important role in conjugated polymer-based device operation. Triplet excitons are also believed to play a primary role in …
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Probing Exciton Dynamics in Metal–Organic Frameworks
Bound electron–hole pairs, known as excitons, are key carriers of energy during a material’s interaction with light. Therefore extending understanding and control over exciton dynamics can potentially break the bottlenecks that currently limit solar energy harvesting technologies. However, design …
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Exciton Dynamics in Perovskite CsPbBr₃ Semiconductor Nanocrystals
… different edge lengths (L = 4.9 - 13.2 nm). The excitonic transitions observed in the absorption spectra can be explained with an effective mass model considering the quasicubic NC shape and non-parabolicity of the electronic bands. We observe a temperature-dependent Stokes shift; while the trend …
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Exciton Dynamics in Organic and Inorganic Nanoscale Materials
… properties. In this thesis I investigate the dynamics of optically excited excitons in these materials and the available pathways for their recombination. I first study the interaction between excitons and the supramolecular lattice found in nanotubular molecular aggregates. The mechanism of …
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Single and multi-exciton dynamics in nanoscale semiconductors
… tunneling electron microscopy to correlate the excitonic and structural properties of J-aggregate nanotubes in solution. We observe weak coupling between inner and outer wall excitons in both isolated and bundled nanotubes. We also use two-dimensional rephasing spectroscopy to measure the …
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Exciton dynamics in organic semiconductors for efficient electroluminescent devices
… (EL) devices are explored by controlling exciton energy transfer and charge transport in organic semiconductors. In the first part of the thesis, ‘hyperfluorescence’, which is the concept that thermally activated delayed fluorescence (TADF) materials are exploited as an exciton sensitiser …
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Exciton Dynamics and Anisotropy in 2D Metal Organochalcogenolate Semiconductors
… (MOCs). Since its blue-emitting excitonic properties were discovered in 2018, AgSePh has attracted attention from the scientific community. From a fundamental science perspective, AgSePh provides an excellent platform for exploring many-body interactions among quasiparticles (such …
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Harnessing Vibrations for Efficient Exciton Dynamics in Semiconducting Energy Materials
… role vibrations play in the excited-state dynamics of semiconducting energy materials. We examine these effects in self-assembled organic semiconducting nanostructures and small molecules, focussing on the implications for exciton transport, energy transfer, and light emission. Special use …
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Charge and exciton dynamics in quantum dot light-emitting diodes
… we study how the interplay of charges and excitons in a QD-LED affect its operational behavior. In order to construct a physical model of a QD-LED, we start by developing quantitative characterization methods that directly measure charge accumulation and electric field in an operating …
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Spectroscopic Study of Triplet Exciton Dynamics at the Hybrid Organic-Inorganic Interface
The control and utilisation of spin-triplet excitons in organic semiconductors is highly sought after for the next generation of Optoelectronic applications. Of particular interest is the utilisation of these photoexcited states in the singlet-fission photon-multiplier and triplet-triplet …
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Ultrafast Investigations of Exciton Dynamics in 0D and 2D Hybrid Semiconductor Nanomaterials
… technique allows the electronic and vibrational dynamics of these materials to be investigated with femtosecond time resolution, providing new insights into their underlying physics. I first employ impulsive vibrational spectroscopy to study exciton-phonon interactions in silver phenyl selenolate …
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Investigation of exciton dynamics and electronic band structure of InP and GaAs nanowires
… sample. PL emission from single NWs exhibit an exciton peak at ~1.515eV. PL and TRPL spectroscopies exhibit high quantum efficiency and exciton lifetimes of ~1ns, which is equivalent to high quality two-dimensional heterostructures. State filling and many-body interaction effects were observed …
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Coherent multi-exciton dynamics in semiconductor nanostructures via two-dimensional Fourier transform optical spectroscopy
… of collective electronic excitations (i.e. excitons, biexcitons, etc.) which may be harnessed for applications in quantum optics, light-harvesting, or quantum information technologies. These excitations represent correlations among successively greater numbers of electrons and holes, and …
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Exciton Dynamics and Optical Properties of Lead Halide Perovskite Nanocrystals: From Nanorods to Nanocubes
… a wide temperature range in order to pinpoint exciton-phonon coupling mechanisms, structural and surface effects, and spin mixing in these novel materials. In the second part of the thesis, I focus on the opposite size regime, where collective behaviour dominates the optical properties. I …
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Study of Triplet Exciton Dynamics in Small Organic Molecule Films Using Time Resolved Optical Spectroscopy
… This thesis reports an investigation of triplet exciton dynamics in small organic molecule single and multilayer layer films using optical time resolved nanosecond spectroscopy. A diligent step by step approach, leading towards the investigation of complex donor/spacer/acceptor multilayer …
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The role of spatial size and orientation of electronic wavefunction in exciton dissociation at van der Waals interfaces
… are generated directly by the light absorption, excitons, Coulombic bound electron-hole pairs, are created upon light absorption in OPV materials. The performance of OPVs depends on how effective the bound charge transfer (CT) exciton, an exciton with its electron and hole spatially separated by …
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