Session: 03-03: Micro/Nanoscale Interfacial Transport Phenomena

Paper Number: 132793

132793 - Interfacial Thermal Resistance Between Bi2te3 and Cssni3 

Abstract: 

We have developed printed thermoelectric thin films using inorganic materials such as Bismuth Telluride to reduce the production costs of thermoelectric generators. The process involved crushing the material into fine powders and mixing it with polyamic acid in an organic solvent. The resulting viscous solution was screen printed onto a substrate and annealed in an Argon with 5% Hydrogen atmosphere. The heated polyamic acid transformed into polyamide at 400°C, acting as an adhesive between the thermoelectric powders.  However, we found that the electrical conductivity of the printed film was very low due to the low packing density. To solve this issue, we made a composite material by incorporating printable thermoelectric materials. We chose the lead-free halide perovskite, CsSnI3, which displayed relatively good thermoelectric properties. We carried out plasma treatment on the porous Bismuth Telluride film to enhance its wettability and then immersed it in the halide perovskite solution. After heating the film on a hotplate, at 140°C the halide perovskite precipitated in the pores, resulting in a composite film of Bi₂Te₃/CsSnI₃. This composite film displayed improved electrical conductivity and low thermal conductivity, while the Seebeck coefficient slightly lower than that of Bismuth telluride.  We also found that the thermal conductivities of Bismuth telluride and Halide perovskite composites were very low by Bi-directional 3 omega method measurements.  The thermoelectric composite film was printed on the strip wire for Bi-directional 3 omega method, and the film was covered by epoxy to avoid the deterioration of Halide perovskite in the air.  The measured thermal conductivity was 0.3W/(m·K).  The measured low thermal conductivity of the printed film cannot be understood by a conventional thermal conductivity model for composite.  The high interfacial thermal resistance between them was evaluated to be in the order of 10^-7K/(m²·W) using the differential 3omega method with the multi-layered films of Bismuth telluride and Halide perovskite. We controlled the film thickness of Bismuth Telluride and Halide perovskite in the multi-layered films to elucidate the interfacial thermal resistance.  The Bismuth telluride films were deposited by an arc plasma deposition, and the Halide perovskite films were made by spin coating. The low thermal conductivity can be explained by high interfacial thermal resistance, although the measured composite thermal conductivity was still lower than the evaluated value with interfacial thermal resistance. This high interfacial thermal resistance was explained by the low phonon group velocities of both consisting of materials, following a full spectral DMM model with Ab-initio calculations. We believe that our printing process can be applied to other thermoelectric materials, allowing us to create film-shaped thermoelectric generators.

Presenting Author: Koji Miyazaki Kyushu University

Presenting Author Biography: Professor at Kyushu University from Oct. 2022.

Authors:

Koji Miyazaki Kyushu University
Kosuke Watanabe Kyushu university
Asuka Miura Kyushu Institute of Technology
Tomohide Yabuki Kyushu Institute of Technology
Satoshi Iikubo Kyushu Univerisity