Controllable Synthesis Of PbSe-based Thermoelectric Nanomaterials And Their Thermoelectric Transportation Properties

Thermoelectric energy conversion is an environment clean, sustainabledevelopment technology that can achieve environmentally friendly refrigeration andeffectively convert waste heat into electricity. Lead chalcogenides have attractedmuch attention due to their outstanding thermoelectric performance, and as oneimportant part of the family, PbSe is not so widely studied yet despite its potentialfor massive application. The research shows that the performance can be enhancedthrough building complicated hierarchical structures, while the binary compoundcan achieve the same result in an effective way as well. Thus this research chosePbSe-based material as the object and tried to obtain various structures of PbSe bysolvothermol synthesis, and employing X-ray diffraction, scanning electronmicroscope, transmission electron microscope and thermoelectrical testingequipment to study the growth mechanism and thermoelectrical properties.By using solvothermol synthesis and choosing the right surfactant, theflower-like PbSe hierarchical structure is obtained. Based on the time-dependentexperiments, the growth process turns out to be a combined effect ofdissolution-recrystallization and self-assembly. Different parameters on themorphology have been studied such as temperature, the solvent ratio, the amount ofsurfactant and pH value.In the formamide and tetrahydrofuran solvents system, the flower-like,bundle-like and starfish-like hierarchitectures are achieved at different temperatures,and the dendritic crystals are fabricated in the mix-solvents of pyridine and water.In the presence of sublimed sulphur as sulfur source, binary PbSe/PbSconstructed by nanosheets were produced using one-step solvothermol method. theHRTEM result shows that the single polycrystal nanosheet is composed of manynanoparticles. After changing the sulfur sources, no sheet like morphology occurredany more but two-steps solvothermol synthesis solves the problem effectively.After thermoelectric properties characterization of PbSe and binary PbSe/PbSnanocomposites, it implies that the introduction of PbS brings a significantimprovement of both the electrical conductivity and Seebeck coefficient, whichmakes the binary strategy successful.