Progress in thermal rectification due to heat conduction in micro/nano solids

As one of the most important energy sources, the efficient utilization and management of thermal energy have attracted much attention. Thermal rectification can be used for directional thermal management, and has great potential in micro/nano scale heat dissipation, improvement of thermoelectric performance, thermal switch and thermal transistor, etc. With the continuous development of micro/nano materials and technology, some thermal rectification mechanisms have been found, which are different from the macro-solid material thermal rectification mechanisms and show good performance. Thermal rectification at micro/nano scale has attracted more and more attention. The methods of thermal rectification include simulation and experiment. Various rectification mechanisms and microscopic action principles of thermal rectification are expounded through simulation research, which provides theoretical guidance for the development of thermal rectification. Limited by research methods and material preparation, there are few experimental studies on thermal rectification at micro/nano scale, mainly focusing on asymmetric structure, which also restricts the further development of thermal rectification devices. This letter reviews the simulation and experimental researches on thermal rectification due to heat conduction at micro/nano scale. The applicability of different method is summarized, also the physical mechanism and action mechanism of thermal rectification are explained. Finally, the current problems and future development trend of thermal rectification at micro/nano scale are discussed.