Final Report Summary - NINA (Nitride-based nanostructured novel thermoelectric thin-film materials)
This project aims to gain a basic understanding of an exciting class of materials for efficient energy harvesting in society, and ultimately to produce functional components. These so-called thermoelectric materials convert heat, like waste heat from engines or solar heat, into usable electricity. For this, a temperature difference is needed between the two ends of the material, which requires a material to be a poor conductor of heat, but conversely a good electrical conductor to yield any output power. The opposite exists (diamond is an electrical insulator but an excellent thermal conductor), but normally electrical conduction implies good thermal conductivity. Because of this profound limitation of existing materials, thermoelectrics are today restricted to some niche markets. For thermoelectric components to achieve widespread application in society, genuinely groundbreaking advances are needed. We have explored strategies for the dramatic reduction of thermal conductivity while improving – or at least not adversely affecting – electrical conduction, using state-of-the-art thin-film technology supported by integrated computational methods. As model system for these general strategies, thermoelectric materials based on nitrides of transition metals were used. The results have demonstrated that metal-alloying and nanostructuring of materials (nanocrystalline or nanolaminated) can indeed be used as a mean to achieve these purposes.