Enhancement of thermoelectric performance across the topological phase transition in dense lead selenide

Towards temperature-induced topological phase transition in SnTe: A first-principles study

“…SnTe is an emerging thermoelectric material that reaches a maximal thermoelectric figure of merit between 0.6 and 1.4 at intermediate temperatures (600-1000 K) at relatively high intrinsic hole concentrations (∼ 10 20 cm −3 ) [15][16][17][18][19][20][21][22] . The values of the band gap and effective masses and the strength of electron-phonon coupling could change considerably near the topological phase transition, thus modifying the transport properties, as demonstrated recently for PbSe under external pressure 23 . A recent first principles study of thermoelectric transport in p-type SnTe argued that its almost linear bulk band dispersion could lead to a large enhancement of the Seebeck coefficient in nanostructures via energy filtering 24 .…”

Intrinsically Low Thermal Conductivity and High Carrier Mobility in Dual Topological Quantum Material, n‐Type BiTe

“…[21][22][23] Semiconducting crystalline solids with narrow band gap and heavy constituent elements are desired to facilitate strong spin orbit-coupling to realize the band inversion in topological materials. [22] Interestingly,s trong spin-orbit coupling in topological materials (TM) facilitates high band degeneracy( N V ), thus high carrier mobility (m) while heavy constituent elements cause slow acoustic waves needed to achieve low k lat .C onventional topological insulators (TI, where metallic surface states are protected by time reversal symmetry) [22][23][24] such as Bi 2 Te 3 and Bi 2 Se 3 and topological crystalline insulators (TCI, where metallic surface states are protected by crystal mirror symmetry) [25][26][27][28] such as SnTea re some of the best known TE materials.Aweak topological insulator (WTI, for example,B iSe) arises from stacking of 2D TI layers and exhibits even number of Dirac cones on the side surfaces;i ts layered hetero-structure is important to exhibit low k lat . [16,29] BiTe, au nique member of the (Bi 2 ) m (Bi 2 Te 3 ) n (where m:n = 1:2) homologous series, [30,31] possesses natural van der Waals hetero-structure (space group P " 3m1), where az igzag Bi-Bi bilayer is sandwiched between Te-Bi-Te-Bi-Teq uintuple layers (QL) via weak van der Waals interactions (Figure 1a).…”

Intrinsically Low Thermal Conductivity and High Carrier Mobility in Dual Topological Quantum Material, n‐Type BiTe

“…Interestingly, strong spin‐orbit coupling in topological materials (TM) facilitates high band degeneracy ( N V ), thus high carrier mobility ( μ ) while heavy constituent elements cause slow acoustic waves needed to achieve low κ lat . Conventional topological insulators (TI, where metallic surface states are protected by time reversal symmetry) such as Bi 2 Te 3 and Bi 2 Se 3 and topological crystalline insulators (TCI, where metallic surface states are protected by crystal mirror symmetry) such as SnTe are some of the best known TE materials. A weak topological insulator (WTI, for example, BiSe) arises from stacking of 2D TI layers and exhibits even number of Dirac cones on the side surfaces; its layered hetero‐structure is important to exhibit low κ lat …”