Preparation And Thermoelectric Properties Of Low Thermal Conductivity Nanostructured Tin Selenide Materials

Thermoelectric material is a kind of semiconductor functional material that can realize direct conversion between electric energy and thermal energy,and has great application prospect in power generation and refrigeration.SnSe is considered to be a promising thermoelectric material because of its excellent thermoelectric properties and the advantages of being cheaper and non-toxic.In this paper,the properties of SnSe polycrystalline bulk thermoelectric materials were optimized,and the low thermal conductivity polycrystalline SnSe nanostructures were prepared by hydrothermal synthesis.The nanostructured SnSe polycrystalline SnSe polycrystalline materials with high electrical conductivity Carrying on the new ideas of coordinated control,the thermoelectric properties of SnSe polycrystalline bulk materials have been greatly improved.Obtain the research results as follows:1.Prepared by hydrothermal synthesis of SnSe polycrystalline material,grain size through the regulation of the material induced cubic rock salt phase,designed to obtain a new type of cubic rock salt structure SnSe nanomaterials,cubic rock salt due to its excellent electrical properties,making the material Of the conductivity and power factor significantly increased,in addition to having SnSe material with medium-sized grains,but also found in the grain of many nano-precipitated phase,this structure greatly increased the number of phonon scattering,which aggravate phonon scattering,Reducing the lattice thermal conductivity.The power factor and the lattice thermal conductivity of the polycrystalline SnSe thermoelectric material are synergistically optimized so that the material achieves a ZT of 1.3 along the parallel pressure direction at a temperature of 850K as compared to the reported undoped polycrystalline SnSe sample The performance has been improved more than 2 times.2.The SnSe-PbSe phase-separated material prepared by hydrothermal synthesis method,due to the electronegativity difference between Pb and Sn,Pb doping increases the carrier concentration,and PbSe has a narrower bandgap and higher conductance than SnSe Therefore,the second phase of PbSe effectively improves the conductivity and power factor of the SnSe matrix,and through the hierarchical structure design of the microstructure of the material,the phonon transport process of the material is controlled,greatly reducing the thermal conductivity of the material.Finally,by optimizing the electroacoustic transport properties of materials,the thermoelectric figure of merit(ZT)of the material is increased to 1.7.3.Cu-doped SnSe samples CuxSnl-xSe materials were prepared by hydrothermal method.At high doping levels,the Cu-doped SnSe samples showed a very large inhibition of electrical properties.However,due to the existence of nano-precipitated phase on the substrate,the prepared CuSe doped SnSe sample formed a full-scale structure,greatly reducing its thermal conductivity and increasing the thermoelectric figure of merit ZT to 1.2.