“Partnerships for International Research and Education (PIRE): JUNCTION Japan-US Network for Clean Energy Technologies Involving Oriented Nanotubes”

The goal of this project is to build international collaborations (JUNCTIONs) between Japanese and US researchers leveraging the unique properties of macroscopic materials made from oriented carbon nanotubes (CNTs). The transformative thermal, optical, electrical, and mechanical properties of these CNT macromaterials make them promising candidates for clean energy technologies, but further large-scale international fundamental research elucidating transport across the junctions between CNTs is required to reach the ultimate potential of energy technologies based on CNT films and fibers. The outstanding properties of individual CNTs have been extensively studied for >25 years; however, scaling up these nanoscale properties for technologically relevant macroscale systems requires answering fundamental questions regarding carrier transport at the junctions between individual nanotubes: at junctions between bundles of nanotubes; and p-n junctions. The use-inspired basic research in highly relevant for future applications in thermophotovoltaic and solid-state radiative refrigeration devices, thermal management of batteries and electronics, and lightweight overhead electrical conductors for next generation power transmission.

The first objective of this project is to demonstrate chiral thermophotovoltaic and solid-state radiative cooling devices using thermal emission from oriented CNT films. The second objective is demonstrating clean energy thermal management strategies using aligned CNTs with high thermal conductivity and high thermoelectric power factor, and high thermoelectric performance. The third objective is to leverage improved fundamental understanding of transport across junctions to achieve room-temperature electrical conductivities >25 MS/m in CNT fibers.

This work will be accomplished by leveraging collaborations with US- and Japan-based researchers working on nanotube macromaterial synthesis, solid-state theory, characterization, and energy devices using oriented nanotubes. Answering fundamental questions regarding carrier and heat transport at the junctions between individual nanotubes; at junctions between bundles of nanotubes; and at p-n junctions between doped regions of CNTs is crucial. The efforts of the Japan-US research team will address these open questions regarding the mechanisms of photon, exciton, phonon, and electron transport in aligned CNT materials, and leverage these mechanisms to demonstrate innovative device-level capabilities. If successful, the knowledge generated in this work will allow engineers and scientists to develop and scale up these aligned nanotube technologies to build an energy sector with improved efficiency, lifetime, and reliability. These efforts build upon existing productive collaborations within the JUNCTION team.

To train the next generation of CNT energy technology researchers, our educational efforts will include international research experiences for graduate and undergraduate students. The desired long-term outcome of the research and educational work is to establish an international network of excellent for aligned CNT energy technology research.

The broader impacts of this work include the development of clean energy technologies such as thermophotovoltaics, radiative cooling devices, thermoelectrics for heat switching and active cooling, and lightweight high-strength power transmission cables. These technologies will assist in reducing greenhouse gas emissions and improving energy conversion efficiency. In addition to the technological impact, the international educational efforts will be transformational. The visiting students from the US and the research opportunities will allow deep technical and cultural engagement for the students in Japan. Overall, the international network built in this program will serve as a launching pad for sustained global research and education to enable nanotube technologies for the clean energy transformation.