Enargite Cu₃PS₄: A Cu–S‐Based Thermoelectric Material with a Wurtzite‐Derivative Structure

Abstract

(1 of 8)Compound semiconductors derived from ZnS (zincblende and wurtzite) with tetrahedral framework structures have functions for various applications. Examples of such materials include Cu-S-based materials with zincblendederivative structures, which have attracted attention as thermoelectric (TE) materials over the past decade. This study illuminates superior TE performance in polycrystalline samples of enargite Cu 3 P 1−x Ge x S 4 with a wurtzite-derivative structure. The substitution of Ge for P dopes holes into the top of the valence band composed of Cu-3d and S-3p, whereby its multiband characteristic leads to a high TE power factor. Furthermore, a reduction in the grain size to 50-300 nm can effectively decrease phonon mean free paths, leading to low thermal conductivity. These features result in a dimensionless TE figure of merit ZT of 0.5 at 673 K for the x = 0.2 sample. Environmentally benign and low-cost characteristics of the constituent elements of Cu 3 PS 4 , as well as its high-performance thermoelectricity, make it a promising candidate for large-scale TE applications. Furthermore, this finding extends the development field of Cu-S-based TE materials to those with wurtzite-derivative structures.

Crystal Structure Classification of Copper‐Based Sulfides as a Tool for the Design of Inorganic Functional Materials

“…In the wurtzite-type system, derivatives from the mineral enargite (Cu 3 PS 4 ) are attracting attention as potential candidates for both thermoelectric and photovoltaic applications. [83,103] Them ulti-band characteristics of the valence band, similar to what has been reported for sphaleritetype structures,y ields heavy effective masses of charge carriers and good electrical performances. Maximum power factor values of 0.4-0.8 mW m À1 K À2 at around 700 Khave been reported, depending on the concentration of the Ge dopant.…”

“…Maximum power factor values of 0.4-0.8 mW m À1 K À2 at around 700 Khave been reported, depending on the concentration of the Ge dopant. [83] Grain boundary scattering from the nano-sized crystallites result in the thermal conductivity remaining low,w ith ZT reaching 0.5 at 673 K. Although currently under-investigated, complex copper sulfide derivatives of the wurtzite-type system definitely offer some interesting prospects as cost-efficient thermoelectric materials.…”

Metallization and Superconductivity in the van der Waals Compound CuP2Se through Pressure-Tuning of the Interlayer Coupling

“…Recently, several Cu-bearing layered binary (e.g., CuP 2 Se) and ternary (e.g., Cu 0.32 In 1.74 Ga 0.84 S 4 ) metal chalcogenides have been synthesized. 29,30 Studies showed that some of the Cubearing materials exhibited good thermoelectric, 31 catalytic, 32,33 and superconductive properties. 34,35 Even though, as a new class of Cu-bearing vdW materials, many of their structural, physical, and chemical properties remain unknown.…”

Synergistic Effect of Chemical Substitution and Insertion on the Thermoelectric Performance of Cu26V2Ge6S32 Colusite

“…In addition to high performance (high ZT), natural abundance and nontoxic characteristics are desired for TE materials used in large-scale applications. Cu−S-based (degenerate) semiconductors have emerged as such TE materials in the recent decade, 4,5 for example, Cu 2 ZnSnS 4 , 6 CuFeS 2 , 7,8 Cu 1.8 S, 9 Cu 2 S, 10 Cu 12 Sb 4 S 13 , 11−13 Cu 3 SbS 4 , 14 Cu 5 FeS 4 , 15−18 Cu 2 SnS 3 , 19 Cu 4 Sn 7 S 16 , 20 Cu 8 Fe 3 Sn 2 S 12 , 21 CuFe 2 S 3 , 22 Cu 22 Fe 8 Ge 4 S 32 , 23 Cu 3 PS 4 , 24 and Cu 26 V 2 Ge 6 S 32 . 25,26 The last example is a synthetic member of the colusite family: Cu 26 T 2 M 6 S 32 (T = Ti, V, Nb, Ta, Cr, Mo, W; M = Ge, Sn, Sb).…”