Intercalation: Building a Natural Superlattice for Better Thermoelectric Performance in Layered Chalcogenides

Abstract

A natural superlattice with composition (SnS) 1.2 (TiS 2 ) 2 , built by intercalating a SnS layer into the van der Waals gap of layered TiS 2 , has been directly observed by high-resolution transmission electron microscopy (HRTEM). The thermoelectric performance is improved in the direction parallel to the layers because the electron mobility is maintained while simultaneously suppressing phonon transport, which is attributed to softening of the transverse sound velocities due to weakened interlayer bonding. In the direction perpendicular to the layers, the lattice thermal conductivity of (SnS) 1.2 (TiS 2 ) 2 is even lower than the predicted minimum thermal conductivity, which may be caused by phonon localization due to the translational disorder of the SnS layers parallel to the layers. Moreover, we propose a large family of misfit-layer compounds (MX) 1+x (TX 2 ) n (M = Pb, Bi, Sn, Sb, rare-earth elements; T = Ti, V, Cr, Nb, Ta; X = S, Se; n = 1, 2, 3) with a natural superlattice structure as possible candidate high-performance thermoelectric materials.

Design and Numerical Evaluation of Cascade-Type Thermoelectric Modules

“…Table 1 shows the TE material combinations that our team intends to apply to practical TE modules [8,10,[14][15][16][17]. Cases 1 and 2 are recently obtained experimental data, and Case 3 is the ideal target data.…”

CdI2 structure type as potential thermoelectric materials: Synthesis and high temperature thermoelectric properties of the solid solution TiSxSe2−x

“…It is the case of certain Zintl phases such as Yb 14 MnSb 11 and its derivative for high temperature spatial applications [2][3][4][5][6], or some members of the CaAl 2 Si 2 structure type [7][8][9][10][11][12]. Other such new families are the molybdenum selenides based on Mo 9 Se 11 clusters [13], and layered sulfides [14,15], oxyselenides [16] or selenides [17]. The other route to reach efficient materials, also the object of many efforts worldwide, is by optimizing the properties of known good thermoelectric materials such as Bi 2 Te 3 , PbTe, or SiGe for example.…”

Topological Phase Diagrams of Bulk and MonolayerTiS2−xTex

“…The layered structure enables easy intercalation (removal) of impurity atoms into (from) the void between the layers. Therefore, TiS 2 is used in numerous applications, e.g., as cathode material in rechargeable batteries [42], as hydrogen storage material [43], and as a high-performance thermoelectric material [44]. The quasitwo-dimensional nature also enables the synthesis of various kinds of nanostructures, including stable monolayers as obtained by micromechanical cleavage and liquid exfoliation [45,46].…”