RANDOM NETWORKS OF ONE-DIMENSIONAL CONDUCTIVE NANOMATERIALS: FABRICATION, PROPERTIES, AND APPLICATIONS
RANDOM NETWORKS OF ONE-DIMENSIONAL CONDUCTIVE NANOMATERIALS: FABRICATION, PROPERTIES, AND APPLICATIONS
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Date
2014
Authors
Preston, Colin
Advisor
Hu, Liangbing
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Abstract
Random networks of one-dimensional conductive nanomaterials are unique structures that exhibit nominal properties useful in flexible thin-film electronics; however, a greater understanding of these properties is necessary to enable high performance device functionality. This thesis presents a comprehensive investigation into the various mechanisms that determine certain characteristics of random networks composed of either carbon nanotubes or silver nanowires. In Chapter 1 we outline the motivation and structure of the dissertation. In Chapter 2, we explore the properties of carbon nanotube spray-coatings, and their application as conductive electrodes for various devices. In this chapter, an ink composed of originally grown nanotubes with a tailored wall number is demonstrated to enable spray-coatings with conductivities reaching 2100 S/cm, which is the highest conductivity for spray-coated carbon nanotube random networks from surfactant-free inks. In Chapter 3, we introduce a synthesis technique to form a new nanostructure of boron-doped few walled carbon nanotubes directed at lowering the bulk resistivity of the nanotube growth yield. An investigation into the structure, morphology, and composition of the boron-doped nanotubes is conducted and compared to undoped few walled nanotubes from the previous chapter. In Chapter 4, we explore the properties of random networks of originally grown Ag NWs and their application towards transparent conducting electrodes for thin-film solar cells. The impact of transmission haze in transparent conducting electrodes is investigated, which provides evidence that the current performance metric of transparent conducting electrodes is insufficient at evaluating their performance in thin-film solar cell devices. In Chapter 5, we expound upon our evidence that transmission haze is a beneficial property for transparent conducting electrodes in thin-film solar cells by introducing a novel Ag NW paper hybrid network that form a transparent conducting electrode with exceptional properties. The combined high transmittance, low sheet resistance, and high transmission haze measured and studied in this new Ag NW paper structure suggests that is the highest performing transparent conducting electrode for thin-film solar cells. In Chapter 6, we consider the impact of this dissertation on the current thin-film technology. Future experiments that may supplement the results in this thesis were also suggested in this chapter.