Mondulation Of Thermoelectric Transmission Performance Of Te By Doping And Interfance Barrier Construction

Thermoelectric conversion technology plays an important role in the field of green clean energy because it can realize the recycling of low-quality heat sources and thermoelectric refrigeration as a feasible solution to energy and environmental problems.Compared to composite thermoelectric materials,elemental semiconductors have been considered to be potential thermoelectric materials because of their unique advantages of no precipitation,separation or volatilization,and ease of purification.Its inherent nested valence band and anisotropic quasi-one-dimensional structure exhibit excellent electrical and thermal properties,and can further improve its performance by modifying the carrier concentration based on element doping and decorating grain boundaries based on energy filtering effect.In this paper,the elemental Te is used as the matrix.Based on the doping modification principle,Sb-doped composites were prepared by hot pressing method and thermoelectric properties of Te are controlled by carrier concentration optimization,besides,the intrinsic reason of its excellent thermoelectric properties is explored through experiments.At the same time,based on the energy band engineering theory,the Ag/Te and Ni/Te heterojunction barrier composite structures were constructed by electroless plating and spark plasma sintering?SPS?technology,and the thermoelectric properties of the materials were optimized by energy filtering effect;and through the study of the composite effect of its doping and interface barrier,the following research results were obtained:The lone pair of electrons in Tellurium's electronic structure is an intrinsic reason for its high Seebeck coefficient and low thermal conductivity,which provides a new idea for finding excellent thermoelectric materials.The carrier concentration of the material was increased effectively and the thermoelectric performance of Te was optimized by Sb doping.The heterojunction interface barrier is constructed in the Te matrix to exert energy filtering effect,and the Seebeck coefficient and resistivity were simultaneously optimized.At 600K,the power factor of 3wt%Ag/Te and18wt%Ni/Te was increased by 60%and 16%,respectively,compared to the Te sample.The Ag/Te and Ni/Te interface barriers can further reduce the thermal conductivity by 24%and 20%,which increases the zT value by 124%and57.3%,respectively.The combination of electroless Ni plating and Sb doping can synergistically improve the thermoelectric properties of the material.Electroless Ni plating mainly acts to improve the Seebeck coefficient by energy filtering effect,and Sb doping mainly acts to adjust the carrier concentration to reduce the resistivity,through the combined effect of the two effects,the power factor was greatly improved,the zT value of the 18wt%Ni/Sb_0.003Te_0.997 sample reached 0.96 at550K,which was about 50%higher than that of the Sb_0.003Te_0.997 sample.