UBC Theses and Dissertations
Electrospun carbon model system for a nanofiber transparent conductor Ritchie, William Justin
Though absolute quantities of fossil fuels are abundant, the costs of drilling additional oil wells have increased more than 500% since 2000. Building a future that is less reliant on increasingly costly non-renewable energy resources will require the exploration of electricity generation from readily available solar power. Installed photovoltaic (PV) capacity has increased from 700 MW in 1996 to more than 69 GW in 2011. PV is contributing a rapidly growing share of electricity from a renewable source to the global energy picture but the manufacturing process of solar cells require many non-renewable resources and large amounts of energy. Performance of photovoltaic modules and cells are highly dependent on the properties of the transparent conductors. Indium tin oxide (ITO) is widely used in thin film and organic solar cell structures but recent projections for indium supplies show that only a few decades of this material may remain. Materials used in the manufacturing process of photovoltaics will need to use readily abundant resources if they are to become a significant portion of the electricity generation profile over the next century. This study explores the process of electrospinning and its ability to produce a transparent conductor layer for solar cells by using carbon instead of the scarce materials that constitute many transparent conductors. Thin layers of multi-walled carbon nanotube composites are electrospun, carbonized at temperatures of 700-1000˚C and characterized as a transparent conductor (TC) model system. This first iteration of the nanofiber TC system achieves transparencies of greater than 85% and a sheet resistance as low as 700 Ω/☐. Polyacrylonitrile (PAN) is evaluated as a carbon fiber precursor against PAN-co-methyl acrylate (PAN-co-MA) for electrical applications. PAN-co-MA is found to have as much as a 700% increase in conductivity compared to homopolymer PAN. The nanofiber transparent conductor model is evaluated in the context of an ITO replacement for solar cells and touch screen devices.
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