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Articles 1 - 6 of 6
Full-Text Articles in Engineering
Market-Conscious Strategies To Improve The Performance And Stability Of Planar, P-I-N Hybrid Organic-Inorganic Metal Halide Perovskite Solar Cells, Brandon Dunham
Doctoral Dissertations
Planar, p-i-n (inverted) hybrid organic-inorganic perovskite solar cells that use low-temperature, solution-processable charge-transport layers have garnered much attention due to their direct compatibility with flexible substrates and cost-effective roll-to-roll manufacturing. Nevertheless, this architecture has failed to repeatedly achieve the superior power conversion efficiencies frequently attained by its n-i-p counterpart. Additionally, the perovskite active layer has poor stability in the presence of prolonged light exposure, high temperatures, and moisture. In this study, we propose commercially viable strategies to improve the performance and stability of inverted methylammonium lead iodide perovskite solar cells. First, we show that a simple two-step method comprising evaporation-induced …
Computational Studies Of Structure–Function Relationships Of Supported And Unsupported Metal Nanoclusters, Hongbo Shi
Computational Studies Of Structure–Function Relationships Of Supported And Unsupported Metal Nanoclusters, Hongbo Shi
Doctoral Dissertations
Fuel cells have been demonstrated to be promising power generation devices to address the current global energy and environmental challenges. One of the many barriers to commercialization is the cost of precious catalysts needed to achieve sufficient power output. Platinum-based materials play an important role as electrocatalysts in energy conversion technologies. In order to improve catalytic efficiency and facilitate rational design and development of new catalysts, structure–function relationships that underpin catalytic activity must be understood at a fundamental level. First, we present a systematic analysis of CO adsorption on Pt nanoclusters in the 0.2-1.5 nm size range with the aim …
Solution-Based Assembly Of Conjugated Polymers Into Nanofibers For Organic Electronics, Daniel E. Acevedo Cartagena
Solution-Based Assembly Of Conjugated Polymers Into Nanofibers For Organic Electronics, Daniel E. Acevedo Cartagena
Doctoral Dissertations
Solution-based crystallization of conjugated polymers offers a scalable and attractive route to develop hierarchical structures for electronic devices. The introduction of well-defined nucleation sites into metastable solutions provides a way to regulate the crystallization behavior, and therefore the morphology of the material. A crystallization method for generating metastable solutions of poly(3-hexylthiophene) (P3HT) was established. These metastable solutions allow P3HT to selectively crystallize into nanofibers (NFs) on graphene-coated surfaces. It was found that the crystallization kinetics is faster with increasing P3HT molecular weight and concentration. Through in situ atomic force microscopy, it was confirmed that NFs grow vertically in a face-on …
Interactions At The Aqueous Interface Of Large-Area Graphene: Colloidal-Scale And Protein Adsorption, Aaron Chen
Interactions At The Aqueous Interface Of Large-Area Graphene: Colloidal-Scale And Protein Adsorption, Aaron Chen
Doctoral Dissertations
This thesis addresses the interactive interfacial character of large-area supported graphene in an aqueous environment near neutral pH. Studies of molecular bio-interactions with proteins and colloidal interactions with microparticles probe the role of hydrophobicity, van der Waals, and electrostatic contributions with varied ionic strength. The respective roles of the silica support and the graphene itself are identified. Results are benchmarked against other systems directly in experiments, and against published behavior with other materials, especially self-assembled monolayers. The adhesive and adsorption behavior of supported graphene is also put into context by calculations of surface and interaction potentials. Interest in graphene is …
Structural, Electronic And Catalytic Properties Of Graphene-Supported Platinum Nanoclusters, Ioanna Fampiou
Structural, Electronic And Catalytic Properties Of Graphene-Supported Platinum Nanoclusters, Ioanna Fampiou
Doctoral Dissertations
Carbon materials are predominantly used as catalytic supports due to their high surface area, excellent electrical conductivity, resistance to corrosion and structural stability. Graphene, a 2D monolayer of graphite, with its excellent thermal, electronic and mechanical features, has been considered a promising support material for next generation metal-graphene nanocatalysts. The main focus of this dissertation is to investigate the properties of such metal-graphene nanocomposites using computational methods, and to develop a comprehensive understanding of the experimentally observed enhanced catalytic activity of graphene-supported Platinum (Pt) clusters. In particular, we seek to understand the role of graphene supports on the ground-state morphology …
Computational Analysis Of Structural Transformations In Carbon Nanostructures Induced By Hydrogenation, Andre R. Muniz
Computational Analysis Of Structural Transformations In Carbon Nanostructures Induced By Hydrogenation, Andre R. Muniz
Open Access Dissertations
Carbon nanomaterials, such as carbon nanotubes and graphene, have attracted significant interest over the past several years due to their outstanding and unusual combination of physical properties. These properties can be modified in a controllable way by chemical functionalization in order to enable specific technological applications. One example is hydrogenation, achieved by the exposure of these materials to a source of atomic hydrogen. This process has been considered for hydrogen storage purposes and for the control of the band gap of these materials for applications in carbon-based electronics. Hydrogen atoms are chemisorbed onto the surface of these materials, introducing sp3-hybridized …