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

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 Cu2ZnSnS4 (CZTS), Cu2ZnSnSe4 (CZTSe), Cu2.125Zn0.875SnS3Se (CZTSSe), and Cu2SnS3 (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/cm2, respectively, making CZTSe/AZO TEG the champion device.