Thermionic Energy Conversion:Fundamentals and Recent Progress Enabled by Nanotechnology

Thermionic energy conversion represents a simple and elegant approach for harvesting heat to generate electricity. This conversion mechanism has been known for over a century and has experienced several waves of interest in research and development. However, significant challenges related to materials properties and fabrication technologies have prevented the creation of efficient and practical devices, hindering broad adoption of this concept.In this presentation, the fundamentals of thermionic energy conversion will be reviewed and the parameters affecting converter performance discussed. Some of the past device examples will be briefly looked at and their challenges highlighted. Over the last two decades, interest in thermionic energy conversion has gradually resurfaced due to the advances in materials and fabrication processes, which have provided opportunities for addressing the long -standing challenges in this field. Several of the key recent developments will be described and the current status and future outlook discussed. It will be seen that new effects and nanomaterials sometimes necessitate a more sophisticated experimental approach to the study of their fundamental properties for thermionic emission and conversion than commonly used in the past.