Strategies to enhance polycrystal SnSe thermoelectrics: Structure control offers a novel direction

Abstract

Thermoelectric materials can directly convert between thermal energy and electrical energy, and their efficiency is determined by the average dimensionless figure of merit ZT. The crystal SnSe has been discovered with unique transport features and ultra-high ZT values. Considering the high production cost, long processing time, and poor mechanical properties of crystal SnSe, it is important to achieve mass production and commercial applications in polycrystal SnSe with good processability and low cost. This perspective summarizes the strategies to improve the thermoelectric properties of polycrystal SnSe, including composition control to tune the carrier concentration and modify the band structure, and process control to texture the grains and remove oxides, which all mainly focused on enhancing the peak ZT values of polycrystal SnSe. Recently, a novel structure control strategy was implemented to modulate the crystal structure of SnSe. By alloying proper ternary compounds, the cubic-structure polycrystal SnSe was obtained with completely different thermoelectric transports and high-ranged overall ZT values. This structure control strategy offers an effective way to enhance the wide-range thermoelectric performance of polycrystal SnSe and provides a new research idea for the development of highly efficient thermoelectric materials, especially for those with low-dimensional structures.