Thermoelectric optimization of AgBiSe2 by defect engineering for room-temperature applications

Abstract

The hexagonal phase of AgBiSe2 has been discovered as a promising thermoelectric material for the room temperature applications. However, its basic conduction type is still ambiguous and its current ZT value is pretty low. To improve we predict several extrinsic dopants (Cu, Rh and Pd) that can be used to converge three valence band maxima. Our work provides methodologies to improve the room temperature thermoelectric applications of AgBiSe2 by tuning its band structures using intrinsic or extrinsic defects.

Valence Band Structure Degeneracy Enhanced Thermoelectric Performance in β-Cu2Se

“…Thus, in order to tune the VBM and VB 1 closer in energy for higher valence band degeneracy, we could reduce the anti-bonding strength, which would shift the VBM downward more compared to VB 1 . Such k -dependent orbital characters at the valence band edge of Cu 2 Se offer the possibility for band modification. , For example, the anti-bonding strength at Γ and L points could be tuned by varying the atomic orbital energy difference between Cu-d and Se-p or Cu–Se bond length …”

Enhanced thermoelectric performance in Sb–Br codoped Bi2Se3 with complex electronic structure and chemical bond softening

“…As is well known, a large N v is benecial to a large DOS effective mass ðm * DOS Þ without deterioration of the carrier mobility m. 4,39 N v is the effective total number of independent carrier pockets or valleys in the Brillouin zone, including both symmetry and orbital degeneracies. For Bi 2 Se 3 , it can be seen that alloying 50% Sb on Bi sites increases the valley number of effective energy from the degeneracy 2 to 10.…”

“…Such a good band feature may be associated with excellent thermoelectric properties, as found in other thermoelectric materials. 39,41 To clearly understand the states near the E F , we calculate the total density of states (TDOS) for Bi 2 Se 3 , BiSbSe 3 , and BiSb(Se 0.92 Br 0.08 ) 3 respectively, as shown in Fig. 4(a).…”

“…Such a good band feature may be associated with excellent thermoelectric properties, as found in other thermoelectric materials. 39,41 …”

Electronic structure and thermoelectric properties of full Heusler compounds Ca2YZ (Y = Au, Hg; Z = As, Sb, Bi, Sn and Pb)

“…Thermoelectric (TE) materials, which can generate electricity from waste heat or be used as solid-state Peltier coolers, are considered for a variety of energy harvesting and thermal management applications. [1][2][3] The efficiency of TE materials is described by the dimensionless gure of merit ZT, which is dened as ZT ¼ S 2 sT/(k e + k l ), where S is the Seebeck coefficient, s is the electrical conductivity (S 2 s also known as the power factor, PF), T is the absolute temperature, and k e and k l are the electronic and lattice contributions to the thermal conductivity, respectively. Therefore, high thermoelectric performance requires both a high PF and a low thermal conductivity (k ¼ k e + k l ).…”