A two-step synthesis process of thermoelectric alloys for the separate control of carrier density and mobility

Thermoelectric polymer composite yarns and an energy harvesting wearable textile

“…First strategies of designing thermoelectric materials with high Z factor started with electrically conductive materials of high Seebeck coefficient, in which defects or vacancies were created to lower their thermal conductivity, as in alloys or doped semiconductors, with semiconductors generally displaying higher values of Seebeck coefficient than metals due to the respective band structures [19]. Bismuth telluride alloys may be p-or n-type semiconductors [20], such as p-type (Bi 1-x Sb x ) 2 Te 3 and n-type (Bi 1−x Sb x ) 2 (Te 1−y Se y ) 3 that may reach a maximum Z of 3-3.3×10 −3 K −1 at room temperature, [8,19,21,22]. Investigations to reduce the thermal conductivity of these materials include alloying to increase their entropy (Z= 1.4×10 −3 K −1 for BiSbTe 1.5 Se 1.5 with 0.9 at% Ag [23]), creating point defects (Z=3.4×10 −3 [24]), nanostructuring (Z=3.75×10 −3 K −1 [25][26][27], hierarchical nanostructuring (Z=3.59×10 −3 [28]) and introducing dense dislocation arrays at grain boundaries (Z=5.8×10 −3 [29]).…”