Thermoelectric materials are defined as materials which can directly convert heat into electrical energy; they are often used for applications such as power generation, energy harvesting, or refrigeration. Because of their applications, it is important to understand the electrical-to-thermal coupling behavior of such materials. One of the more recent types of materials to gain traction in the researching of thermoelectric materials is that of 2D materials. 2D materials have been shown to have applications in the fields of ultra thin photovoltaics and nanoelectronics; these applications often relate to the thermoelectric applications of thermoelectric materials . Because of these applications, it is important to understand the transient electrical to thermal coupling behavior of these materials on a nanoscale level. The thermoelectric materials simulated are 2D film configurations of Tin Selenide (SnSe). level. The SnSe is approximated using a diatomic chain in a cubic crystal lattice structure, with switching between “railroad” and “zig zag” bond configurations. Obtaining properties of a 2D lattice ab initio can encounter challenges such as high demand computational resources and variability in interatomic dynamics. This work will use the derivations for non-equilibrium electron-phonon dynamics as well as obtaining the phonon dispersions, second-order and third-order elastic constants, the thermoelectric properties can be calculated using what is known as the three-phonon method in order to obtain the properties of SnSe as a 2D thin film. The main thermoelectric properties observed are the thermopwer, thermal conductivity, and thermoelectric figure of merit. The thermal conductivity is measured over the characteristic length of the 2D sheet while the thermoelectric figure of merit and thermopower are measured over the applied voltage of each 2D sheet; the applied voltages are generated by an electrical field strength of 10,000 V/m. Furthermore, an analysis on the effect of strain on the thermoelectric properties of SnSe is conducted and compared with the results of the non-strain cases in order to determine the optimal thermoelectric properties. Strain is shown to primarily affect the electrical properties of a material due to the electron distributions changing in a material when strain is applied. The desired thermoelectric parameter results with the strain and without the strain are compared in order to observe the variations of the material properties. Overall, understanding of the ultra fast lattice jellium dynamics of a 2D material such as SnSe can provide insight into reversible temperature phase transition solids for flexible and minimal power consumption electronic switching devices.


Calculation and Variation of Thermoelectric Properties of Phase Transition Materials

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Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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