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 213 for “"charge carrier"”.
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Charge carrier transport in amorphous organic semiconductors
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.
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Charge-carrier transport in amorphous organic semiconductors
… the small bandwidth leads to localization of charge carriers and electron-hole pairs, called excitons. Thus, the charge-carrier mobility in organic semiconductors is generally much smaller than in their covalently-bonded, highly-ordered crystalline semiconductor counterparts. Indeed, one major …
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Charge carrier relaxation in fluorite-structured oxygen ion conductors /
… of electrical properties, attributed to charge carrier relaxation in electrical field, were observed in the obtained spectra. These data in complex plane plots resulted to depressed semicircles, which was assumed as consequence of existence of a distribution of relaxation times of charge …
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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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Field effect investigations of charge carrier transport in organic semiconductors
… conventional technologies. The understanding of charge transport in these materials and minimizing electrical losses in organic devices is essential to improve device output. In this thesis the transport properties of charge carriers in solution processed organic semiconductors were investigated …
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Modeling of Charge Carrier Transport in Photoetching of Gallium Arsenide
The process of wet photoelectrochemical etching of GaAs was investigated with a numerical model that calculated the potential, electron, and hole distributions in a selectively illuminated semiconductor. The transport mechanisms associated with the etching process were studied. The model used the …
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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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Charge Carrier Relaxation in Halide Perovskite Semiconductors for Optoelectronic Applications
… In this thesis, we study the 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 …
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Charge Carrier Balance in Lead Halide Perovskite Light Emitting Diodes
Charge balance in light emitting diodes (LEDs) is a critical determinant of their performance. Charge balance is directly related to the External Quantum Efficiency (EQE), and is thought to have additional effects on device endurance and stability. In this thesis I present a series of experiments …
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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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Designing Nanomaterials For Electronic And Optoelectronic Devices Through Charge Carrier Control
… of available methods to: 1) accurately control charge carrier statistics, such as majority carrier type and concentration, and carrier mobilities, and 2) efficiently passivate surface defects inherent in NC materials arising from their high surface-volume ratio. In this thesis, we study the …
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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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Quantum dynamics in condensed phases : charge carrier mobility, decoherence, and excitation energy transfer
… processes in condensed phases. First, we study charge-carrier mobilities in organic molecular crystals, and develop a microscopic theory that describes both the coherent band-like and incoherent hopping transport observed in organic crystals. We investigate the structures of polaron states using …
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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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Defects and charge-carrier lifetime in early-stage photovoltaic materials : relating experiment to theory
… which degrade solar cell efficiency due to short charge-carrier lifetimes. In this thesis, such defects and their impact on lifetime in early-stage PV materials are investigated, focusing on experimental methods to assess lifetime connected to theoretical concepts about both defects and lifetime …
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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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Defect energies, band alignments, and charge carrier recombination in polycrystalline Cu(In,Ga)(Se,S)2 alloys
… the defect energies, band alignments, and charge carrier recombination in polycrystalline Cu(In1-xGax)(Se1-ySy)2 chalcopyrite thin films and the interrelationship with the alloy composition. Photoluminescence spectroscopy of investigated Cu-poor Cu(In,Ga)(Se,S)2 layers generally shows broad …
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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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