Preparation and Enhanced Thermoelectric Performance of Cu2Se–SnSe Composite Materials

High‐Performance Thermoelectric SnSe: Aqueous Synthesis, Innovations, and Challenges

“…Among the state‐of‐the‐art thermoelectric materials, tin selenide (SnSe) is one of the most promising candidates to apply to thermoelectric devices due to its environmentally friendly feature, high cost‐effectiveness, and outstanding thermoelectric performance derived from its appropriate bandgap of ≈0.9 eV and intrinsic low κ l 9,10 . Figure a shows the development timeline for all SnSe‐based bulk thermoelectric materials,11–124 from which a record high ZT of ≈2.8 at 773 K was found in the n‐type SnSe single crystal,11 derived from its ultralow κ l of ≈0.18 W m −1 K −1 and high S 2 σ of ≈9.0 µW cm −1 K −2 at this temperature 125. Such a high ZT is also very competitive to other state‐of‐the‐art thermoelectric systems which possess ZTs > 2, such as PbTe,126–134 GeTe,135–147 Cu 2 Se/Cu 2 S,148–157 and AgSbTe 2 158.…”

“…A summary of ZTs for SnSe‐based thermoelectric materials. a) The timeline for state‐of‐the‐art SnSe bulks thermoelectric materials,11–124,169–182 the performance achieved by solution route are circled by yellow. b) Temperature‐dependent ZT and c) corresponding peak and average ZT values for polycrystalline SnSe through different fabrication techniques 13,16,22,46,58,62,95,99,101.…”

Ag-Nanoinclusion-Induced Enhanced Thermoelectric Properties of Ag2S

“…For this, the best emerging materials are semiconductors in which one can reduce the value of κ by several ways such as nanostructuring, point defect introduction, and selecting highly anisotropic layered materials that contain constituent heavy elements in large unit cells. Among these, nanostructuring is known as a promising way that can be done in three ways: (i) reduction of the grain size down to nanoscale, ,, (ii) introduction of nanocrystals into nanomaterial hosts, − and (iii) introduction of nanoparticles (NPs) into bulk hosts. ,, …”

“…A good ZT value (∼300 K) can be achieved by nanostructuring alone, ,, but the formation of nanocomposites by introducing nanocrystals in nanomaterials/bulk host is a unique strategy for simultaneous reduction of κ through combined grain boundary scattering of heat carriers, together with the enhancement of a power factor (α 2 /ρ) induced by low-energy charge-carrier filtering. ,− Mehta et al demonstrated a readily scalable bottom-up approach to create bulk TE nanomaterials of both n- and p-type pnictogen chalcogenides with ZT > 1 at 300 K. Li et al . demonstrated the synthesis of Bi 2 Te 2.7 Se 0.3 /SnS 2 nanocomposites through the polyol method and reported an enhanced ZT ∼ 0.93 at 450 K for this nanocomposite with 1.47 vol % of SnS 2 , which is 2.3 times higher than that of pristine Bi 2 Te 2.7 Se 0.3 .…”

“…Thus, introduction of a small fraction of resistive nanocrystals into a relatively less resistive/conducting host ,,− or conducting nanocrystals into a resistive/semiconducting host ,,, normally provides a well-stabilized strategy for optimization of charge concentration and hence enhancement of ZT. Moreover, inhomogeneous distribution and/agglomeration of incorporated nanoparticles in the TE matrix is of significant importance and a challenge to get an enhancement in the TE performance .…”