Researchers from Hanyang University in South Korea, along with collaborators from institutions in Japan and the United States, have published a study in the journal Nature Communications that explores ways to enhance the thermoelectric properties of oxide superlattices. The team, led by Professor Woo Seok Choi, focused on improving the two-dimensional (2D) characteristics of these materials to boost their thermopower, a key metric for their efficiency in converting heat into electricity.
The researchers investigated a new platform using EuTiO3, an alternative perovskite material, to create artificial superlattices. By doping these superlattices with lanthanum (La), they were able to improve the 2D confinement of charge carriers. This enhancement led to a significant increase in thermopower, reaching a quasi-2D value of -950 microvolts per Kelvin, which is about 20 times higher than the three-dimensional (3D) value. The improved performance is attributed to the confinement of Ti 3dxy-states within the doped layers and the associated increase in the 2D density of states.
The study combined experimental measurements with theoretical calculations using hybrid density functional theory. The results showed that the enhanced thermopower originates from the smaller effective Bohr radius of EuTiO3 compared to SrTiO3, as well as the presence of Eu 4f-states. These factors modify the electronic band structure and strengthen the spatial confinement of Ti 3d-states, leading to improved thermoelectric properties.
For the energy industry, this research offers valuable insights into designing high-performance thermoelectric materials. By understanding and controlling the dimensional confinement of charge carriers, it may be possible to develop more efficient thermoelectric devices for waste heat recovery and other applications. This could contribute to improving energy efficiency and reducing greenhouse gas emissions in various industrial processes.
The research was published in the journal Nature Communications, providing a foundation for further exploration and development of advanced thermoelectric materials.
This article is based on research available at arXiv.