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 21 for “"charge carrier dynamics"”.
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Charge carrier dynamics in lead sulfide quantum dot solids
… In many of these applications, understanding charge transport in quantum dot solids is crucial to optimizing efficient devices. We examine charge transport in monodisperse, coupled quantum dot solids using spectroscopic techniques explained by hopping transport models that provide a …
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Charge Carrier Dynamics of Lead Halide Perovskites Probed with Ultrafast Spectroscopy
In this thesis, we investigate the nature of charge carrier generation, relaxation and recombination in a range of lead halide perovskites. We focus on understanding whether the photophysical behaviour of these perovskite materials is like that of highly-ordered inorganic crystalline semiconductors …
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Improving charge carrier dynamics in tin (II) sulfide through targeted defect engineering
… for commercial production. Low minority carrier lifetimes of <100 ps have been shown to be the root cause of this low performance, and carrier lifetimes >1 ns are predicted to enable >10%-efficient devices. In this thesis work, I employed defect modeling to identify the most …
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Exploring charge carrier dynamics in quantum dot and double heterojunction nanorod light emitting devices using transient electroluminesence measurements
… the location and concentration of the different charge carriers residing in the emitting layer. There are still open debates in the quantum dot light emitting diode (QD-LED) community regarding the details of the charge carrier populations which are expected to influence efficiency droop at …
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Spectroscopic Studies on the Impact of Defects in Hybrid Organic-Inorganic Perovskites on Charge Carrier Dynamics and Photovoltaic Device Performance
… includes the spectroscopic characterization of charge carriers in methylammonium lead iodide and the use of this characterization, along with time-resolved spectroscopy, to better understand the influence of carrier dynamics on solar cell device performance. We observed that a decrease in device …
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Charge carrier transport and recombination in semiconductors: Insights from statistical analysis and machine learning techniques
This thesis pioneers techniques to understand charge carrier dynamics in semiconductor materials, with the goal of advancing next–generation optoelectronic devices, with three main thrusts explored. In Chapter 4, efficient exciton energy transport in thin Ruddlesden-Popper perovskite flakes is …
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Femtosecond Time-Resolved Laser Spectroscopic Studies on the Electron Dynamics in Heterostructured Nanomaterials
… has been focused on the photoinduced charge carrier dynamics in heterostructured nanomaterials. Of particular interest are type-II heterostructures, where the relative band alignment of their constituent semiconductor materials promotes a spatial separation of the electron and hole …
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Singlet exciton fission-enhanced silicon photovoltaics: Interfacial engineering, device design and spectroscopic technique development
… not much is understood regarding the exciton and charge carrier dynamics at this interface. Finally, the silicon solar cell architecture should also be considered to extract transferred carriers effectively. This thesis tackles these three parts from an interfacial materials, device architecture …
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Advances in Phenyl-Modified Carbon Nitride: Towards Sustainable Environmental Applications
… composition. However, limitations such as poor charge separation and limited light absorption have hindered its practical use. To address these challenges, recently researchers have introduced phenyl groups into the carbon nitride framework, which enhanced its optoelectronic properties and …
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Steady State and Time-Resolved Cathodoluminescence Analysis of III-Nitride Semiconductors
… cathodoluminescence, the difference in charge carrier dynamics at these exposed crystallographic facets will be investigated. This is carried out to assess the effect of polarity on the degree of carrier recombination. Secondly, cathodoluminescence will be used as a novel quantification …
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Tracking and Exploiting Charge Carrier Movement and Photochemical Processes in Light-Harvesting Energy Materials
… efficiencies. In this thesis, the change in photocarrier recombination behaviour caused by cation alloying is explored. Time-resolved optical spectroscopy and microscopy are used to reveal local charge accumulation in mixed cation perovskites, creating p- and n-type photodoped regions, unearthing …
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Understanding the Influence of Interfacial Chemistry in Core, Core/Shell and Core/Shell/Shell Quantum Dots on their Fluorescence Properties
… groups play significant roles in determining the charge carrier dynamics that results on the various quantum yields and quality of the quantum dots. The experimental results also contradicted the trivial belief that starting with a high quality core material should result into high quality …
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Charge Carrier Localisation in Metal Halide Perovskites for Optoelectronic Applications
This dissertation is concerned with the charge carrier dynamics in semiconductors based on metal-halide perovskites. These materials have shown remarkable performance in optoelectronic applications like solar cells or light-emitting devices. They are solution-processable at low temperature using …
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Developing microwave probes for investigating opto-electronic processes in photovoltaic materials
… Microwave Conductivity (TRMC) as a probe for charge carrier dynamics, and shaped pulse Electron Paramagnetic Resonance (pEPR) as a coherent probe for spin-dependent processes, such as Singlet-Fission, Triplet-Triplet annihilation, and spin-dependent recombination in organic semiconductors. We …
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Contact-free Electrical Characterisation of Novel Materials Using Terahertz Spectroscopy
… a remarkable, long-term improvement in the charge carrier lifetime and charge carrier dynamics was demonstrated while retaining the charge carrier mobility. In addition, a demonstrated three-fold order of magnitude decrease in the surface recombination velocity was achieved by the ultra-thin …
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Generation, recombination and extraction of charges in polymer
… organic materials systems, the yield of charge generation can be very efficient. However, a detailed understanding of the free charge carrier generation mechanisms at the donor acceptor interface and the energy loss associated with it needs to be established. Moreover, organic solar cells …
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Spin dynamics of bulk and quasi-two-dimensional metal halide based perovskite semiconductors
… between Dr Ravichandran Shivanna and me. For carrier densities above ~10<sup>15</sup> cm<sup>-3</sup>, the room temperature exciton depolarisation rate increases with exciton density, showing that many-body interactions outcompete the precessional motional narrowing spin relaxation that was …
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Charge carrier recombination and open circuit voltage in organic solar cells
… open circuit voltage losses the recombination of charges in organic solar cells is also a prevailing research topic, especially with respect to the influence of trap states. The exploratory focus of this work is therefore set, on the one hand, on the development of hybrid organic/inorganic …
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DESIGN OF NOVEL MATERIALS FOR PHOTO-THERMO-CATALYTIC SOLAR FUELS PRODUCTION
… like platinum (Pt), which are known to enhance charge carrier separation and improve catalytic activity. The study revealed that TiO2, both in its pure form and decorated with Pt nanoparticles, exhibited significant photocatalytic activity at room temperature. However, the introduction of heat …
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