2020/11/12 by Kevin Octavian, Octavian, Kevin, Hasdeo, Eddwi H.
Materials Science · #Advanced Thermoelectric Materials and Devices #FOS: Physical sciences #Machine Learning in Materials Science #Materials Science (cond-mat.mtrl-sci) #Thermal properties of materials
paper · pdf · doi:10.48550/arxiv.2011.06321
openalex publication_date 2020/11/12 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We performed the first-principles calculation on common thermoelectric\nsemiconductors rm Bi2Te3, rm Bi2Se3, rm SiGe, and rm PbTe in\nbulk three-dimension (3D) and two-dimension (2D). We found that miniaturization\nof materials does not generally increase the thermoelectric figure of merit\n(ZT) according to the Hicks and Dresselhaus (HD) theory. For example, ZT\nvalues of 2D rm PbTe (0.32) and 2D rm SiGe (0.04) are smaller than\ntheir 3D counterparts (0.49 and 0.09, respectively). Meanwhile, the ZT values\nof 2D rm Bi2Te3 (0.57) and 2D rm Bi2Se3 (0.43) are larger than the\nbulks (0.54 and 0.18, respectively), which agree with HD theory. The HD theory\nbreakdown occurs because the band gap and band flatness of the materials change\nupon dimensional reduction. We found that flat bands give a larger electrical\nconductivity (\σ) and electronic thermal conductivity (\κel) in\n3D materials, and smaller values in 2D materials. In all cases, maximum ZT\nvalues increase proportionally with the band gap and saturate for the band gap\nabove 10 kBT. The 2D Bi2Te3 and Bi2Se3 obtain a higher ZT due to\nthe flat corrugated bands and narrow peaks in their DOS. Meanwhile, the 2D PbTe\nviolates HD theory due to the flatter bands it exhibits, while 2D SiGe\npossesses a small gap Dirac-cone band.\n