报告题目：2D thermoelectric materials: Role of the lattice thermal conductivity
单位：沙特 阿卜杜拉国王科技大学 德籍
We study the role of the lattice thermal conductivity in 2D thermoelectric materials by first-principles calculations. Specific examples include a comparison of Ti2CO2, Zr2CO2, and Hf2CO2 in order to evaluate the role of the metal atom. The lattice thermal conductivity is demonstrated to grow along the series Ti-Zr-Hf in the temperature range 300-700 K, resulting in the highest figure of merit in the case of Ti2CO2. Flat conduction bands promote the thermopower in the case of n-doping. Functionalization effects are studied for Sc2C, which is semiconducting for various functional groups, including O, F, and OH. The lowest lattice thermal conductivity is found for OH functionalization. Despite a relatively low thermopower, Sc2C(OH)2 therefore and due to a high electrical conductivity can be interesting for intermediate-temperature thermoelectric applications. We also discuss results on heterostructures built of MXenes and transition metal dichalcogenide monolayers. Low frequency optical phonons are found to occur as a consequence of the van der Waals bonding. They contribute significantly to the thermal transport and compensate for reduced contributions of the acoustic phonons (strong scattering in heterostructures), such that the thermal conductivities become similar to those of the constituent MXenes.