Thermoelectric properties of quaternary chalcogenide Cu₂ZnSnS₄ synthesised by mechanical alloying

Abstract

The quaternary chalcogenide Cu 2 ZnSnS 4 has emerged as a potential thermoelectric (TE) material due to its low thermal conductivity (κ), high Seebeck coefficient (S) and composition including earth-abundant, low-cost and non-toxic elements. In this work, Cu 2 ZnSnS 4 was synthesised from a mixture of Cu, Zn, Sn and S powders using a mechanical alloying method. As a result, Cu 2 ZnSnS 4 powders were formed after 16 h of milling, without additional heat treatment. After milling, the powders were heat-treated at 723 K for 24 h and then sintered by spark plasma sintering under an applied pressure of 60 MPa at 873 K for 10 min. The heat-treated Cu 2 ZnSnS 4 sample showed a wide-band-gap of 1.49 eV. The sintered Cu 2 ZnSnS 4 sample exhibited S and κ values of 170 μV K −1 and 1.06 W m −1 K −1 , respectively with an electrical conductivity σ of 1240 S m −1 and a dimensionless figure of merit (ZT) of 0.022 at 663 K.

Static and dynamic components of Debye–Waller coefficients in the novel cubic polymorph of low-temperature disordered Cu2ZnSnS4

“…For the same reasons of sustainability and safety, CZTS has also been explored as a possible thermoelectric (TE) material (Liu et al, 2009;Yang et al, 2012;Kosuga et al, 2015;Kumar et al, 2018;Sharma & Neeleshwar, 2018;Zheng et al, 2018;Nagaoka et al, 2018;Isotta et al, 2019aIsotta et al, ,b, 2020aIsotta et al, ,b, 2021aSharma et al, 2019Sharma et al, , 2020Jiang et al, 2020;Long et al, 2020;Bala ´z ˇet al, 2021). Given the large energy gap, CZTS shows an increasing performance with temperature, thus potentially appropriate for applications in the mid to high temperature range (600-800 K) (Kosuga et al, 2015).…”

“…The highly disordered but low-temperature environment of high-energy mechanical alloying seems to favour a disordered arrangement of cations. Only a few reports on low-temperature cubic CZTS from ball milling can be found (Kapusta et al, 2019;Isotta et al, 2019bIsotta et al, , 2020b, although in several works where kesterite was synthesized by mechanical alloying, the XRD patterns of the as-milled powders were clearly missing the tetragonal superstructure reflections (Ritscher et al, 2016;Park et al, 2014;Yao et al, 2014;Pareek et al, 2017;Hegedu ¨s et al, 2018;Long et al, 2020;Bala ´z ˇet al, 2019). This was typically associated with disorder (Ritscher et al, 2016) and, in rather loose terms, with low crystallinity (Shyju et al, 2015;Zhou et al, 2016;Zhang et al, 2019;Alirezazadeh & Sheibani, 2020).…”

Exceptional Thermoelectric Performance of Cu2(Zn,Fe,Cd)SnS4 Thin Films

“…The PF of the CZFCTS-1 thin films was substantially improved by annealing (Figure c). Compared to the CZTS films (Figure ), the CZFCTS-1 thin films annealed for 24 h show significant enhancement in maximum PF, by a factor of ∼22, with a PF of ∼2.4 μW cm –1 K –2 at 575 K. Figure e provides a comparison of the maximum PF values obtained in this work to that of published data for analogous polycrystalline quaternary sulfide (Cu 2 BSnS 4 (CBTS), where B = Mn, Fe, Co, Ni) bulk materials and thin films. ,,,,,,− Our maximum PF values are significantly higher than all previous reports for single-phase CZTS-based thin films and most polycrystalline bulk materials. This outstanding result demonstrates that cosubstitution of high levels of Cd and Fe into CZTS is an effective approach to increasing the power factor of thin films, and, furthermore, that postdeposition annealing can both enhance film quality and significantly improve charge transport.…”

“…(d) Dependence of S , σ, and PF at 575 K on postdeposition annealing time. (e) Comparison of the maximum PF value obtained in this work and published data for single-phase polycrystalline quaternary sulfide (Cu 2 BSnS 4 (CBTS); B = Mn, Fe, Co, Ni) bulk and thin film materials. ,,,,,,− The uncertainty bars show uncertainties of 5, 3, and 10% in the S , σ, and PF values, respectively.…”

“…Long et al. synthesized bulk CZTS by mechanical alloying (MA) and spark plasma sintering (SPS), and obtained a maximum zT of ∼0.22 at 663 K . Hot-pressed CZTS bulk materials prepared by Sharma et al exhibited a peak zT of ∼0.024 at 623 K .…”