Low-Cost, High-Reliability Thermoelectrics for Waste Heat Conversion

Thermoelectrics operating at high temperatures can cost-effectively convert waste heat and compete with other zero-carbon technologies. Among different high-temperature thermoelectric materials, silicon nanowires possess the combined attributes of cost effectiveness and mature manufacturing infrastructure. Despite significant breakthroughs in silicon nanowirebased thermoelectrics for waste heat conversion, the efficiency and operating temperature has remained low. This research project reports on the synthesis of large-area, wafer-scale arrays of porous silicon nanowires with ultra-thin silicon crystallite size of about 4 nanometers. Measurements show much higher efficiency than bulk silicon and higher efficiency than any nanostructured silicon-based thermoelectrics reported in the literature at 801°F (427°C). Towards device-level applications, the research team fabricated high-quality double-sided silicon nanowire arrays, with significantly improved performance. Therefore, this project demonstrates the potential of silicon nanowires for high-temperature waste heat recovery.