Enhanced Thermoelectric Properties of Cu3SbSe4 Compounds by Isovalent Bismuth Doping

Abstract

Cu 3 SbSe 4 , featuring its earth-abundant, cheap, nontoxic and environmentally-friendly constituent elements, can be considered as a promising intermediate temperature thermoelectric (TE) material.Herein, a series of p-type Bi-doped Cu 3 Sb 1 − x Bi x Se 4 (x = 0-0.04) samples were fabricated through melting and hot pressing (HP) process, and the effects of isovalent Bi-doping on their TE properties were comparatively investigated by experimental and computational methods. TEM analysis indicates that Bidoped samples consist of Cu 3 SbSe 4 and Cu 2 − x Se impurity phases, which is in good agreement with the results of XRD, SEM and XPS. For Bi-doped samples, the reduced electrical resistivity (ρ) caused by the optimized carrier concentrations and enhanced Seebeck coe cient derived from the densities of states near the Fermi level give rise to a high power factor of ~ 1000 µWcm − 1 K − 2 at 673 K for the Cu 3 Sb 0.985 Bi 0.015 Se 4 sample. Additionally, the multiscale defects of Cu 3 SbSe 4 -based materials involving point defects, nanoprecipitates, amorphous phases and grain boundaries can strongly scatter phonons to depress lattice thermal conductivity (κ lat ), resulting in a low κ lat of ~ 0.53 Wm − 1 K − 1 and thermal conductivity (κ tot ) of ~ 0.62 Wm − 1 K − 1 at 673 K for the Cu 3 Sb 0.98 Bi 0.02 Se 4 sample. As a consequence, a maximum ZT value ~ 0.95 at 673 K is obtained for the Cu 3 Sb 0.985 Bi 0.015 Se 4 sample, which is ~ 1.9 times more than that of pristine Cu 3 SbSe 4 . This work shows that isovalent heavy-element doping is an effective strategy to optimize thermoelectric properties of copper-based chalcogenides.

2D Self-Assembly of Large-Sized Inorganic Nanosheets Leading to Enhanced Power Factors in Earth-Abundant Cu3SbSe4-Based Flexible Hybrid Films

“…To overcome this limitation, many investigations have been made to optimize its carrier concentration by doping at Cu sites with elements such as Zn 16 and Ag 17 and substitution of Sb by elements like Pb, 18 Sn, 19,20 and Bi. 17,21,22 Other strategies include Sn and Zr or Hf codoping, 23 Sn and Bi double doping, 24 and Sn and La codoping. 25 However, doping of impurity atoms may also result in dislocations and the formation of the secondary-phase precipitates, and these dislocations and precipitates inevitably serve as scattering centers for carriers and diminish the carrier mobility and PF.…”

“…Many studies investigate Cu 3 SbSe 4 for thermoelectrics due to its low thermal conductivity and high Seebeck coefficient, − whereas its thermoelectric conversion efficiency is restricted by its relatively low PF and electrical conductivity resulting from its low carrier concentration and low carrier mobility. To overcome this limitation, many investigations have been made to optimize its carrier concentration by doping at Cu sites with elements such as Zn and Ag and substitution of Sb by elements like Pb, Sn, , and Bi. ,, Other strategies include Sn and Zr or Hf codoping, Sn and Bi double doping, and Sn and La codoping . However, doping of impurity atoms may also result in dislocations and the formation of the secondary-phase precipitates, and these dislocations and precipitates inevitably serve as scattering centers for carriers and diminish the carrier mobility and PF.…”