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 15 of 15 for “"charge carrier recombination"”.
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Charge carrier recombination and open circuit voltage in organic solar cells
… Besides 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 …
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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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Three Grains, Two Photons and a Colourful Diamond
… entirely suppress it. We then unveil buried charge-carrier recombination pathways in both thin film and micro-crystal methylammonium lead halide perovskite structures through 3D photoluminescence tomography acquired using two-photon confocal microscopy. These measurements reveal that …
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Electrical impact assessment of dislocations in silicon materials for solar cells
… dislocations, results in a greater density of charge-carrier recombination centers, which reduce a solar cell's efficiency. Interestingly, the recombination activity of individual dislocations and dislocation clusters can vary by orders of magnitude, even within the same device and a separation …
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Charge transfer engineering in Phenyl-modified Carbon Nitride-based hybrid systems: from powder Photocatalysts to Thin films
… however, its performance is limited by rapid charge carrier recombination, low mobility, and inefficient charge utilization. To overcome these intrinsic drawbacks, this thesis adopts charge transfer engineering as a central design strategy, focusing on controlling charge generation, …
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Optoelectronic applications of solution-processable sulfide semiconductors
… absorber layer is investigated. A reduction in charge carrier recombination is the reason for the improved efficiency, caused by the oxidation process. Further, a new chemical bath deposition method for antimony sulfide is developed. Carried out at room temperature, this technique eliminates the …
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Composition, structure, and performance of nanocrystal bulk heterojunction photovoltaics
… our bulk heterojunction devices, such that charge carriers generated anywhere within the blend are well within a carrier collection length of the charge separating driving force required to separate them and enable their collection. Of the compositions we studied, we found that devices with …
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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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Sustainable photocatalysis using carbon-based materials through interfacial and solvent engineering
… arises from intrinsic drawbacks such as rapid charge-carrier recombination, restricted charge transport, limited density of catalytically active sites, and poor electrical conductivity. To overcome these limitations, this thesis explores interfacial and solvent engineering strategies aimed at …
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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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Titania Nanowires: synthesis, characterization and properties.
… by Ti-Au interdiffusion, Ti migration, gas carrier transport and oxygen gas reaction. We demonstrared that the same method of TiO2 NWs growth can be applied to different type of Ti substrates, opening new possibilities for different kind of applications. Fe+ implantation-induced defects …
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Mixed Lead-Tin Halide Perovskites for Optoelectronic Applications
… then extend the above work to probe the lateral charge transport mechanism in mixed Pb-Sn perovskite FETs in Chapter 5. Through temperature-dependent field-effect mobility measurements, aided further with photoluminescence microscopy under bias, we show that ionic screening effects are greatly …
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Nonlinear optical studies of dye-doped nematic liquid crystals
… experiments resides in the process of photo-charge generation. The photorefractive gain coefficients were found to be in the range of 100 – 400 cm-1. The values of the nonlinear optical Kerr index (~ 0.08 cm2/W) measured in samples with certain dye/liquid crystal combinations are higher than …
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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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Correlation between dynamic parameters and device performance of organic solar cells
… cells is determined by the generation of free charge carriers upon light absorption and their transport to the electrodes in competition to the loss of charge carriers due to recombination. The object of this thesis is to provide a comprehensive understanding of the dynamic processes and …