Thermoelectric performance of multiphase GeSe‐CuSe composites prepared by hydrogen decrepitation method

Abstract

Recently, lead and tellurium-free GeSe chalcogenide-based thermoelectric materials have been considered as an alternative for PbTe and GeTe because of their nontoxic and attractive properties. However, the reports on thermoelectric properties of GeSe are very limited with low power factor values. Herein, we report the effect of Cu substitution on mixed phase formation and thermoelectric performance of Ge 1Àx Cu x Se (0.0 ≤ x ≤ 0.4) samples. In the prepared samples, the multiphases of orthorhombic/Imm2 Cu 2 GeSe 3 , cubic/Fm3m Cu 2 Se, hexagonal/P63mc CuSe, hexagonal/P63/mmc Cu 8 GeSe 6 , and orthorhombic/Pnnm CuSe 2 were observed, due to incorporation of Cu in GeSe as confirmed by X-ray diffraction analysis. The electrical resistivity of the samples decreased with x values due to the formation of Cu-rich phases. Moreover, the mobility of GeSe increased by one order through Cu substitution resulting from the percolation effect in the sample with multiphases. A high-power factor of 720 μW/K 2 m was achieved at 500 K for the Ge 0.6 Cu 0.4 Se samples with thermal conductivity (κ L ) of 1.47 Wm À1 κ À1 at the same temperature which resulted in a high figure of merit (ZT) $ 0.26, due to Cu-rich multiphases in the sample.

Enhanced Thermoelectric Properties of p-Type Bi0.5Sb1.5Te3-Cu8GeSe6 Composite Materials

“…As reported previously, the argyrodite-type compound Cu 8 GeSe 6 is a potential TE candidate material with a band gap of about 1.12 eV . At an increased temperature, Ag + and Cu + cations are mobile and distributed in the lattice without order, − which can reinforce phonon scattering and result in an intrinsically low κ l at room temperature. ,− Inspired by the recent works of bismuth-telluride-based composites, ,, we prepared Bi 0.5 Sb 1.5 Te 3 - x wt % Cu 8 GeSe 6 samples by the hot pressing method and symmetrically investigated the thermoelectric performance. Since the Cu + cations may migrate easily and distribute evenly to enter the sites of Bi 3+ /Sb 3+ , the carrier concentration is obviously enhanced, accounting for the optimization of power factor ( S 2 σ) from room temperature to an intermediate temperature.…”

Achieving Superior Thermoelectric Performance in Ge4Se3Te via Symmetry Manipulation with I–V–VI2 Alloying

“…[ 23 ] Up to now, the maximum ZT value of orthorhombic GeSe is only ≈0.2 due to the lower n H ≈ 10 18 cm −3 via Ag‐Sn codoping or Cu‐doping. [ 24,25 ] Nevertheless, through the crystal structure modulation by alloying with MnCdTe 2 , [ 26 ] AgSbTe 2 , [ 27 ] or InTe 3/2 , [ 28 ] GeSe transformed from the orthorhombic phase to the rhombohedral phase, which exhibits a significantly enhanced thermoelectric performance.…”