Thermal conductivity variation of Bi2Te3 nanofilm with interfacial defects using molecular dynamics

In this study, the thermal conductivity and thermal boundary resistance (TBR) of Bi2Te3 nanofilms with different interfacial defects were investigated using nonequilibrium molecular dynamics simulations, and the effects of temperature, defects (step junctions and grooves), and interfaces (amorphous and telluride) were assessed. The results show a strong temperature dependence of the thermal conductivity for Bi2Te3 nanofilms with an ideal structure; moreover, as the height of step-junction defects increased, the thermal conductivity decreased, exhibiting a linear dependency. In addition, the thermal conductivity gradually decreased by 36%–40% as the width of the interface defects increased. We also verified the self-assembly mechanism for nanoscale Bi2Te3 and found that the Bi2Te3–Te interface induces strong phonon scattering. In addition, the TBR decreased as the width of the amorphous or Te interface increased. Thus, interfacial defects in Bi2Te3 nanofilms affect the thermal conductivity and TBR. The results of this study may be useful for optimizing Bi2Te3 thermoelectric devices in the future.