Self-powered wearable electronics require thermoelectric materials simultaneously with a high dimensionless figure of merit(zT)and good flexibility to convert the heat discharged by the human body into electricity.Ag2(S,Se)-based semiconducting materials can well satisfy these requirements,and thus,they are attracting great attention in thermoelectric society recently.Ag2(S,Se)crystalizes in an orthorhombic structure or monoclinic structure,depending on the detailed S/Se atomic ratio,but the relationship between its crystalline structure and mechanical/thermoelectric performance is still unclear to date.In this study,a series of Ag2Se1-xSx(x=0,0.1,0.2,0.3,0.4,and 0.45)samples were prepared and their mechanical and thermoelectric performance dependence on the crystalline structure was systematically investigated.x = 0.3 in the Ag2Se,-xSx system was found to be the transition boundary between orthorhombic and monoclinic structures.Mechanical property measurement shows that the orthorhombic Ag2Se,.xSx samples are brittle while the monoclinic Ag2Se,-xSx samples are ductile and flexible.In addition,the orthorhombic Ag2Se1.xSx samples show better electrical transport performance and higher zT than the monoclinic samples under a comparable carrier concentration,most likely due to their weaker electron-phonon interactions.This study sheds light on the further development of flexible inorganic TE materials.
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