Facile and Low-Cost Fabrication of Cu/Zn/Sn-Based Ternary and Quaternary Chalcogenides Thermoelectric Generators

Abstract

In this work, Cu/Zn/Sn-based ternary and quaternary chalcogenides inks were synthesized via hot injection and/or from ball-milled powders. The synthesized inks were used to fabricate thermoelectric generators (TEGs) based on p-type chalcogenide and n-type aluminum-doped zinc oxide (AZO) thin films via spin-coating and magnetron sputtering, respectively. This work highlights the first-ever attempt in a facile and scalable method to fabricate thin-film TEGs using safe, low-cost, and abundant materials. Four different TEGs were fabricated using Cu 2 ZnSnS 4 (CZTS), Cu 2 ZnSnSe 4 (CZTSe), Cu 2.125 Zn 0.875 SnS 3 Se (CZTSSe), and Cu 2 SnS 3 (CTS) chalcogenides. Thermoelectric transport analysis confirmed the respective p-and n-type natures of the chalcogenides and AZO, with their Seebeck coefficients compatible to be coupled in a p−n device. In addition, a full-device analysis has been carried out, and several factors affecting the performance of TEGs were investigated, including the composition, density, and presence of secondary phases in chalcogenide thin films. The maximum power per unit active planar area obtained for CZTS, CZTSe, CZTSSe, and CTS TEGs at a temperature difference (ΔT) of 160 K was ∼43, ∼188, ∼23, and ∼59 nW/cm 2 , respectively, making CZTSe/AZO TEG the champion device. KEYWORDS: thermoelectric generator (TEG), thin film, Cu 2 ZnSn(S/Se) 4 (CZTS/Se), Cu 2 SnS 3 (CTS), aluminium-doped zinc oxide (AZO)

High-Performance Paper-Based Thermoelectric Generator from Cu2SnS3 Nanocubes and Bulk-Traced Bismuth

“…65 Previously, Syafiq et al also constructed a TEG with CTS (synthesized via a ball milling process) and AZO (aluminumdoped zinc oxide) on soda-lime glass that produced an output power of 75 nW at ΔT = 160 K with an output power density of 0.3 nW cm −2 K −1 , although the TEG device was not flexible or environmentally safe paper-based due to the rigidity of the substrate. 28 The output power measured from our flexible 20pair CTS NC film-pressed Bi film PTEG assembled by Kapton as reported in this work (Table S2) thus generates significantly high output power and power density as compared to any recent related PTEG work and is also comparable to other contemporary thin film TEGs as shown graphically 62−74 in Figure 6d and as tabulated in Table S3 in the Supporting Information. It clearly indicates the excellent performance of our reported PTEG with added advantages of economic and easier fabrication methods on stationery emery paper and chemically synthesized pure phase earth-abundant elementsbased nanocrystalline CTS, which was not studied before for flexible TE applications.…”

“…The emergence of sustainable and affordable TE materials is another unstoppable trend and a number of Sn-based compounds with outstanding TE performance have been reported progressively such as SnSe, 23 SnS, 24 Cu 2 ZnSnS 4 , 25,26 and Cu 2 SnS 3 . 27,28 Among the aforementioned compounds, Cu 2 SnS 3 (CTS) is a promising, earthabundant elements-based p-type material with decent TE performance. 29−31 Alongside, CTS has a low semiconducting band gap (0.8−1.35 eV), high absorption coefficient (10 4 cm −1 ), and ultralow thermal conductivity (0.26 W/m K) resulting from the phono-glass-electron-crystal scattering and good electrical conductivity that makes it a strong candidate as a TE material.…”

“…The emergence of sustainable and affordable TE materials is another unstoppable trend and a number of Sn-based compounds with outstanding TE performance have been reported progressively such as SnSe, SnS, Cu 2 ZnSnS 4 , , and Cu 2 SnS 3 . , Among the aforementioned compounds, Cu 2 SnS 3 (CTS) is a promising, earth-abundant elements-based p-type material with decent TE performance. − Alongside, CTS has a low semiconducting band gap (0.8–1.35 eV), high absorption coefficient (10 4 cm –1 ), and ultralow thermal conductivity (0.26 W/m K) resulting from the phono-glass-electron-crystal scattering and good electrical conductivity that makes it a strong candidate as a TE material . A few reports are there where CTS has been synthesized in bulk as well as on a nanoscale and the electrical properties have been tuned by doping with different transition metals for TE applications. − ,− Moreover, its crystal symmetry-dependent electronic properties (crystallizes in monoclinic, cubic, and tetragonal systems with corner-sharing tetrahedron of Cu and Sn atoms with 4S atoms at the corner) are potentially explored for a wide range of other applications in photovoltaics, transistors, and photodetectors, with cubic phase material being in more focus for TEs . CTS has been synthesized previously in bulk, film, and in nanocrystalline form by both physical − and chemical methods. , Physical methods are costly as they involve high-temperature and high-pressure processes, including expensive and complex laser and high vacuum operation, while chemical methods are much simpler, comparatively inexpensive, cost-effective, can be synthesized in different crystal sizes, and can be cast onto a variety of substrates using industrially viable deposition techniques .…”

Mechanochemical Synthesis of Sustainable Ternary and Quaternary Nanostructured Cu2SnS3, Cu2ZnSnS4, and Cu2ZnSnSe4 Chalcogenides for Thermoelectric Applications

“…Cu-based sulfides/selenides have recently attracted much attention in TE research, in part because of their earth abundance. Devices employing these materials showed power output per unit cost comparable to high-performance thermoelectric devices, underlining the relevance of obtaining a thorough understanding of the transport mechanism in these materials [ 13 , 14 ]. Mechanochemical syntheses via high-energy reactive milling offer the unique advantage of producing various disordered polymorphs of these compounds.…”

Enhanced Thermoelectric Performance of Nanostructured Cu2SnS3 (CTS) via Ag Doping

“…These systems are safe to use in the medium temperature range due to the high melting temperature (∼1000 K). Recent work on CTS and similar chalcogenides-based in-plane thermoelectric generators (TEGs) shows promising power output per unit active planar area …”