Effect of selenium deficiency on the thermoelectric properties ofn-type In4Se

Thermoelectric properties of dense bulk polycrystalline In4Se3−x [In subscript 4 Se subscript 3-x] (x = 0, 0.25, 0.5, 0.65, and 0.8) compoundsare investigated. A peak dimensionless thermoelectric figure of merit (ZT) of about 1 is achieved for x = 0.65and 0.8. The peak ZT is about 50% higher than the previously reported highest value for polycrystalline In4Se3−x [In subscript 4 Se subscript 3-x]compounds. Our In4Se3−x [In subscript 4 Se subscript 3-x] samples were prepared by ball milling and hot pressing.We show that it is possible toeffectively control the electrical conductivity and thermal conductivity by controlling selenium (Se) deficiencyx. The ZT enhancement is mainly attributed to the thermal conductivity reduction due to the increased phononscattering by Se deficiency, defects, and nanoscale inclusions in the ball-milled and hot-pressed dense bulkIn4Se3−x [In subscript 4 Se subscript 3-x] samples.United States. Dept. of Energy (Contract no. DOE DE-FG02-00ER45805)Solid-State Solar-Thermal Energy Conversion CenterUnited States. Dept. of Energy. Office of Basic Energy Sciences (Award No. DE-SC0001299