As humans, we are constantly generating heat. Whether it’s from our appliances, transportation, factories, or even our electrical grid, a significant amount of the energy we produce is lost as heat. But what if we could harness that waste heat and turn it into a sustainable energy source?
“Waste heat is everywhere,” said UC Santa Barbara mechanical engineering professor Bolin Liao. “Our power plants, our car exhaust pipes – there are so many places where we create excess heat waste.”
Liao and his team, in collaboration with researchers from Ohio State University and University of Hong Kong, are working on a groundbreaking project to make use of this excess heat. Their research, recently published in the journal Advanced Materials, focuses on cadmium arsenide thin films as a potential solution for harvesting waste heat.
According to Liao, the key to efficient thermoelectric energy conversion lies in a material’s ability to conduct electricity well, conduct heat poorly, and generate a high voltage for a given temperature difference. Cadmium arsenide, a Dirac semimetal, exhibits promising transport properties with low thermal conductivity and high electron mobility.
However, there was one major obstacle – the material needed to generate enough voltage under a temperature gradient. Cadmium arsenide, while excellent at conducting electricity, lacked the necessary band gap to create a useful voltage. Through the use of high-quality thin films grown by UCSB materials scientist Susanne Stemmer’s lab, the team discovered that quantum effects at near-zero temperatures could enhance the material’s thermoelectric properties.
These findings have significant implications for cryogenic applications, such as in aerospace, medicine, and quantum computing. While Cd3As2 thin films may not be suitable for room-temperature or high-heat efficiency applications at the moment, they hold immense potential for solid-state cooling in low-temperature environments.
Ultimately, this research not only offers a practical solution for waste heat utilization but also demonstrates the remarkable effects of quantum confinement on thermoelectric properties. By isolating the contribution from surface states in cadmium arsenide thin films, the team has paved the way for a more sustainable and energy-efficient future.