Effects of the thermal rectification phenomenon induced by structural regulation on the thermoelectric performance of two-dimensional Bi2Se3 films†

The direct conversion of heat and electric energy through thermoelectric effects is one of the effective ways to improve energy efficiency and reduce carbon emissions. Thermoelectric parameters are the basis to evaluate the thermoelectric conversion efficiency of thermoelectric materials. Accurate and rapid characterization of thermoelectric parameters is the foundation and key of the optimization design and application of thermoelectric materials. Small-scale and micro-nanostructure of materials can not only effectively change their thermal conductivity but also affect their electrical conductivity and Seebeck coefficient, thus significantly improving thermoelectric conversion efficiency. Note that the thermal rectification effect caused by structural regulation can effectively change thermal conductivity, further affecting thermoelectric performance. Therefore, it is urgent to study the coupling mechanism between micro-/nano-scale structural regulation and thermoelectric properties. In this work, an in situ characterization technique is used to study the integration of structural regulation and thermoelectric properties of micro-/nanomaterials, and the coupling mechanism is experimentally investigated. The relation between thermoelectric properties and thermal rectification caused by structural regulation is also discovered. Results demonstrated that structural regulation could effectively improve the ZT value with a maximum improvement of nearly 1.7 times and further to 2.4 times because of the thermal rectification effect, which indicates that micro-nanostructural regulation is an effective approach to improve thermoelectric performance.