Enhanced thermoelectric performance of Cu${}_2$Se alloys by simultaneous engineering of thermal and electrical transport properties through S and Te co-doping

Cu${}_2$Se-based binary compounds have recently fetched the attention of researchers due to their remarkable electrical and extremely low thermal properties. In addition, Cu${}_2$Se-based quaternary chalcogenides are expected to present exceptional thermoelectric performance. Cu${}_2$Se${}_{1-x-y}$S${}_x$Te${}_y$-like compounds are synthesized via microwave-assisted hydrothermal method and their respective thermal and electrical transport properties are studied in this research work. The phase purity and homogeneity are examined by X-ray diffraction and energy-dispersive X-ray spectrometry analysis. The introduction of S and Te elements into Cu${}_2$Se matrix enhances Seebeck coefficient resulting in improved electrical performance illustrating a maximum power factor of 989.4 µWK${}^{-2}$ m${}^{-1}$ at 673 K. Furthermore, S- and Te-co-doped samples exhibit reduced total thermal conductivity values with lowest value of 0.808 WK${}^{-1}$ m${}^{-1}$ for Cu${}_2$Se${}_{0.96}$S${}_{0.02}$Te${}_{0.02}$ sample in comparison to 1.18 WK${}^{-1}$ m${}^{-1}$ for the pristine sample. The simultaneous improvement in electrical and thermal properties results in enhanced figure of merit of 0.82 for Cu${}_2$Se${}_{0.96}$S${}_{0.02}$Te${}_{0.02}$ sample at 673 K. (© 2024 Wiley‐VCH GmbH)