Improvement of Thermoelectric Performance of SnTe by Energy Band Optimization and Carrier Regulation

As groupⅣA tellurides,SnTe has the same crystal structure and similar bivalent band structure as PbTe,making it a promising thermoelectric material.However,the main concern of softening at elevated temperature and lower ZT at low temperatures has been hindering its application.Therefore,it is significant to expand the service temperature range of SnTe by improving its average ZT.It has been reported that the thermoelectric performance of SnTe is improved by regulating the power factor and lattice thermal conductivity based on band and lattice engineering In this study,MgSe alloying strategy was used to prepare a series of Sn1-yPbyTe-x%MgSe（0.01≤y≤0.05,0≤x≤6）samples by combining melting and Spark Plasma Sintering（SPS） techniques.The results show that alloying MgSe leads to an increase in the band gap,effectively suppressing the bipolar effect of intrinsic SnTe,improving the Seebeck coefficient in the high-temperature range,and reducing lattice thermal conductivity through phonon scattering as well.As a result,ZT at 873 K is improved by 100%.The incorporation of Pb effectively modulates the carrier concentration,successfully suppressing electronic thermal conductivity,and thereby improving average thermoelectric performance of SnTe.Among them,Sn0.96Pb0.04Te-4%MgSe possesses a ZT value of 1.5 at 873 K and an average ZT value of 0.8 at 423-873 K,displaying superior performance compared to literature.