Matching Items (3)
Filtering by
- Resource Type: Text
Description
As global population and demand for electrical power increase, humanity is faced with the growing challenge of harnessing and distributing enough energy to sustain the developing world. Currently, fossil fuels (coal
atural gas) are our main sources of electricity. However, their cost is increasing, they are nonrenewable, and they are very harmful to the environment. Thus, capacity expansion in the renewable energy sector must be realized to offset higher energy demand and reduce dependence on fossil fuels. Solar energy represents a practical solution, as installed global solar capacity has been increasing exponentially over the past 2 decades. However, even with government incentives, solar energy price ($/kWh) continues to be highly dependent on political climate and raw material (silicon and silver) cost. To realistically and cost effectively meet the projected expansions within the solar industry, silver must be replaced with less costly and more abundant metals (such as copper) in the front-grid metallization process of photovoltaic cells. Copper, while offering both higher achievable efficiencies and a raw material cost nearly 100 times cheaper than silver, has inherent disadvantages. Specifically, copper diffuses rapidly into the silicon substrate, requires more complex and error-prone processing steps, and tends to have less adhesive strength, reducing panel robustness. In this study, nickel deposition via sputtering was analyzed, as well as overall potential of nickel as a seed layer for copper plating, which also provides a barrier layer to copper diffusion in silicon. Thermally-formed nickel silicide also reduces contact resistivity, increasing cell efficiency. It was found that at 400 \u00B0C, ideal nickel silicide formation occurred. By computer modeling, contact resistivity was found to have a significant impact on cell efficiency (up to 1.8%). Finally, sputtering proved useful to analyze nickel silicide formation, but costs and time requirements prevent it from being a practical industrial-scale metallization method.
atural gas) are our main sources of electricity. However, their cost is increasing, they are nonrenewable, and they are very harmful to the environment. Thus, capacity expansion in the renewable energy sector must be realized to offset higher energy demand and reduce dependence on fossil fuels. Solar energy represents a practical solution, as installed global solar capacity has been increasing exponentially over the past 2 decades. However, even with government incentives, solar energy price ($/kWh) continues to be highly dependent on political climate and raw material (silicon and silver) cost. To realistically and cost effectively meet the projected expansions within the solar industry, silver must be replaced with less costly and more abundant metals (such as copper) in the front-grid metallization process of photovoltaic cells. Copper, while offering both higher achievable efficiencies and a raw material cost nearly 100 times cheaper than silver, has inherent disadvantages. Specifically, copper diffuses rapidly into the silicon substrate, requires more complex and error-prone processing steps, and tends to have less adhesive strength, reducing panel robustness. In this study, nickel deposition via sputtering was analyzed, as well as overall potential of nickel as a seed layer for copper plating, which also provides a barrier layer to copper diffusion in silicon. Thermally-formed nickel silicide also reduces contact resistivity, increasing cell efficiency. It was found that at 400 \u00B0C, ideal nickel silicide formation occurred. By computer modeling, contact resistivity was found to have a significant impact on cell efficiency (up to 1.8%). Finally, sputtering proved useful to analyze nickel silicide formation, but costs and time requirements prevent it from being a practical industrial-scale metallization method.
ContributorsBliss, Lyle Brewster (Author) / Bowden, Stuart (Thesis director) / Karas, Joseph (Committee member) / Chemical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
One of the grand challenges of engineering is to provide access to clean water because it is predicted that by 2025 more than two thirds of the world’s population will face severe water shortages. To combat this global issue, our lab focuses on creating a novel composite membrane to recover potable water from waste. For use as the water-selective component in this membrane design Linde Type A zeolites were synthesized for optimal size without the use of a template. Current template-free synthesis of zeolite LTA produces particles that are too large for our application therefore the particle size was reduced in this study to reduce fouling of the membrane while also investigating the nanoparticle synthesis mechanisms. The time and temperature of the reaction and the aging of the precursor gel were systematically modified and observed to determine the optimal conditions for producing the particles. Scanning electron microscopy, x-ray diffraction, and energy dispersive x-ray analysis were used for characterization. Sub-micron sized particles were synthesized at 2 weeks aging time at -8°C with an average size of 0.6 micrometers, a size suitable for our membrane. There is a limit to the posterity and uniformity of particles produced from modifying the reaction time and temperature. All results follow general crystallization theory. Longer aging produced smaller particles, consistent with nucleation theory. Spinodal decomposition is predicted to affect nucleation clustering during aging due to the temperature scheme. Efforts will be made to shorten the effective aging time and these particles will eventually be incorporated into our mixed matrix osmosis membrane.
ContributorsKing, Julia Ann (Author) / Lind, Mary Laura (Thesis director) / Durgun, Pinar Cay (Committee member) / Chemical Engineering Program (Contributor) / Materials Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
The possibility of creating inorganic/organic hybrid materials has yet to be fully explored within geopolymer research. Using PDMS as an organic precursor, the surface of sodium and potassium geopolymers of varying precursor composition were functionalized with degraded PDMS oligomers. Both types of geopolymer yielded hydrophobic materials with BET surface area of 0.6475 m2/g and 4.342 m2/g for sodium and potassium geopolymer, respectively. Each respective material also had an oil capacity of 74.75 ± 4.06 weight% and 134.19 ± 4.89 weight%. X-ray diffraction analysis demonstrated that the PDMS functionalized sodium geopolymers had similar crystal structures that matched references for zeolite A and sodalite. The potassium geopolymers were amorphous, but showed consistency in diffraction patterns across different compositions.
ContributorsMaurer, Matthew (Author) / Seo, Don (Thesis director) / Ciota, David (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2022-05