(457a) Semiconductor Nanowire Fabric

Solution-based synthetic routes have been developed to make significant quantities of nanowires of various semiconductors, including Si, Ge, InP and CuInSe₂.   The nanowires are threadlike crystals with nanometer-scale widths and lengths that can extend for millimeters.  Their remarkably high surface area-to-volume ratios and nanoscale dimensions give rise to range of unique material properties that might be useful in a variety of new technologies, including printable electronics, solar cells, batteries and sensors with unprecedented functionality.  We have been developing and exploring the use of these nanowires to make a new class of semiconductor “fabrics.”  The fabrics are essentially tangled, non-woven mats of nanowires.  Of course, underlying these efforts is the ability to generate sufficient quantities of nanowires, which must be long enough, and free of particulates, to be extensively intertwined into mechanically stable layers.  The nanowires can also be combined with intervening polymer to make composites.  Since the nanowires are semiconducting and mechanically flexible, but also have very high strength-to-weight ratio (far exceeding steel for example) because of their lack of extended defects, they have the potential to provide an unprecedented range of new properties in a fabric-like material.  This presentation will explain the nanowire synthesis, the approach to forming the fabric, and a summary of their properties.  For example, non-woven fabric of Si nanowires can be formed with extremely high optical densities; Si nanowires can be combined with polymer and elastomeric hosts to create new semiconductor-based materials with unique combinations of optical, electronic and mechanical properties; and Si and Ge nanowires in  lithium ion batteries can increase the storage capacity of the anode by more than five times its current capacity.