(Georgia Institute of Technology, 2010-05-20)
Weintraub, Benjamin A.
As humanly engineered materials systems approach the atomic scale, top-down manufacturing approaches breakdown and following nature's example, bottom-up or self-assembly methods have the potential to emerge as the dominant paradigm. Synthesis of one-dimensional nanomaterials takes advantage of such self-assembly manufacturing
techniques, but until now most efforts have relied on high temperature vapor phase schemes which are limited in scalability and compatibility with organic materials. The solution-phase approach is an attractive low temperature alternative to overcome these
shortcomings. To this end, this thesis is a study of the rationale solution-phase synthesis
of ZnO nanowires and applications in photovoltaics.
The following thesis goals have been achieved: rationale synthesis of a single
ZnO nanowire on a polymer substrate without seeding, design of a wafer-scale technique
to control ZnO nanowire array density using layer-by-layer polymers, determination of
optimal nanowire field emitter density to maximize the field enhancement factor, design
of bridged nanowires across metal electrodes to order to circumvent post-synthesis manipulation steps, electrical characterization of bridged nanowires, rationale solution-phase synthesis of long ZnO nanowires on optical fibers, fabrication of ZnO nanowire dye-sensitized solar cells on optical fibers, electrical and optical characterization of solar cell devices, comparison studies of 2-D versus 3-D nanowire dye-sensitized solar cell devices, and achievement of 6-fold solar cell power conversion efficiency enhancement using a 3-D approach. The thesis results have implications in nanomanufacturing scale-up and next generation photovoltaics.