Tin doped Cu3SbSe4: A stable thermoelectric analogue for the mid-temperature applications.

Graphical abstract Highlights • Pre-Screening of effective dopant for ZT enhancement in Cu 3 SbSe 4. • A maximum ZT˜1 at 623 K (∼3 times higher than pristine Cu 3 SbSe 4) in Cu 3 Sb 1-x Sn x Se 4. • Density functional theory (DFT) based formation energy calculations. • Sn doping at the Sb site results in thermal conductivity reduction of Cu 3 SbSe 4. Abstract Here, we report a thermoelectric material, Sn-doped Cu 3 SbSe 4 , with a figure-of-merit (ZT) of unity, which is stable up to 623 K. The Cu 3 SbSe 4 samples, individually doped with Bi, Pb and Sn, were synthesized using conventional vacuum melting followed by the spark plasma sintering. The first-principle density functional theory (DFT) based calculations suggest that these doped Cu 3 SbSe 4 compounds have negative formation energy throughout the temperature range, suggesting their chemical/thermal stability. The current study is to support the synchronization of theoretical and experimental study and pre-screening of the dopant which ensures stability and the TE performance. Among all the dopants studied, we realized a ZT max ∼1 at 623 K with Sn doping for the optimized composition Cu 3 Sb 0.985 Sn 0.015 Se 4 owing to the favourable optimization of the electrical and thermal transport properties. This is also supported by the DFT calculations, which suggests that Sn-doping leads to a decrease in lattice thermal conductivity. [ABSTRACT FROM AUTHOR]