Mediating Point Defects Endows n‐Type Bi₂Te₃ with High Thermoelectric Performance and Superior Mechanical Robustness for Power Generation Application

Abstract

Bi2Te3‐related alloys dominate the commercial thermoelectric market, but the layered crystal structure leads to the dissociation and intrinsic brittle fracture, especially for single crystals that may worsen the practical efficiency. In this work, point defect configuration by S/Te/I defects engineering is engaged to boost thermoelectric and mechanical properties of n‐type Bi2Te3 alloy, which, coupled with p‐type BiSbTe, shows a competitive conversion efficiency for the fabricated module. First, as S alloying suppresses the intrinsic BiTe, antisite defects and forms a donor‐like effect, electronic transport properties are optimized, associated with the decreased thermal conductivity due to the point defect scattering. The periodide compound TeI4 is afterward adopted to further tune carrier concentration for the realization of an optimal ZT. Finally, an advanced average ZT of 1.05 with ultra‐high compressive strength of 230 MPa is achieved for Bi2Te2.9S0.1(TeI4)0.0012. Based on this optimum composition, a fabricated 17‐pair module demonstrates a maximum conversion efficiency of 5.37% under the temperature difference of 250 K, rivaling the current state‐of‐the‐art Bi2Te3 modules. This work reveals the novel mechanism of point defect reconfiguration in synergistic enhancement of thermoelectric and mechanical properties for durably commercial application, which may be applicable to other thermoelectric systems.

Tunable Electrical Conductivity and Simultaneously Enhanced Thermoelectric and Mechanical Properties in n‐type Bi2Te3

“…Lattice parameter c exhibited obvious expansion compared with the lattice parameters a and b . [ 31 ] It is well known that Bi 2 Te 3 consists of the quintuple‐layer unit ‐Te(1)‐Bi‐Te(2)‐Bi‐Te(1)‐, which interconnects by van der Waals forces. As explored by Hashibon et al., [ 32 ] the antisite defects Bi′ Te in Bi 2 Te 3 are more inclined to be generated at Te(1) sites.…”

Recent Advances in the Nanomaterials, Design, Fabrication Approaches of Thermoelectric Nanogenerators for Various Applications

“…crystal defects. [63] For example, Zhu et al [22] found that creating point defects by adding indium to a Bi 2 Te 3 alloy increased the zT by more than 10 times that of pristine Bi 2 Te 3 . Alloying Bi 2 Te 3 with sulfur increased the zT from 0.1 to 0.7, owing to an increased Seebeck coefficient, electrical conductivity and reduced thermal conductivity by the sulfur atoms reducing antisite defects.…”

High thermoelectric performance of two-dimensional layered AB2Te4 (A = Sn, Pb; B = Sb, Bi) ternary compounds

“…Thermoelectric (TE) materials have been intensely considered for cooling and power generation applications due to the ability to convert heat and electricity into each other. [1][2][3][4] The thermoelectric efficiency of a TE material can be measured by the thermoelectric figure of merit 5 zT = S 2 sT/k, where S is the Seebeck coefficient, s is the electrical conductivity, T is the absolute temperature, and k is the total thermal conductivity including phononic (k l ) and electronic (k e ) thermal conductivity, respectively. Apparently, increasing the power factor (PF = S 2 s) by tuning the band structure and/or reducing k by increasing phonon scattering are straightforward to enhance zT values.…”