The mission of this program is to advance the science of low-dimensional semiconductor nanostructures through an approach combining atomically-precise nanowire synthesis with state-of-the-art characterization, theory and simulation approaches, and to understand size-dependent, coupled structural and electronic phenomena in emerging new classes of semiconductors and their nanostructures. The focus is on the technologically interesting and structurally diverse class of ionic semiconductors, including but not limited to halide perovskite derivative materials that have been found to display unique combinations of thermophysical and optoelectronic phenomena relevant to future energy and microelectronics technologies, including smart thermochromic solar windows and ferroelectric photovoltaics. Balancing ionic and covalent bonding in complex nanostructure motifs creates new opportunities to advance the science of semiconductor nanowires with properties and processing pathways unattainable in conventional covalent solids.