Realizing enhanced thermoelectric properties in Cu_(2)S-alloyed Sn Se based composites produced via solution synthesis and sintering

摘要

Sn Se emerges as one of the most promising Te-free thermoelectric materials due to its strong anharmonicity and multiple valence bands structure.Recently,compositing has been proven effective in optimizing thermoelectric performance of various metal chalcogenides.Herein,a series of Sn Se-x Cu_(2)S(x=0,0.5%,1%,3%,5%)materials have been fabricated via solution synthesis,particle blending,and spark plasma sintering in sequence.After incorporating Cu_(2)S,the materials become Sn Se based composites with Cu doping,S substitution and Cu_(2)Sn Se_(3)secondary phase.We elucidate that the power factor of polycrystalline Sn Se can be tuned and enhanced at varied temperature ranges through adjusting the addition amount of Cu_(2)S.Additionally,the composites achieve suppressed lattice thermal conductivity when compared to Sn Se itself,as the introduced point defects and Sn Se/Cu_(2)Sn Se_(3)interfaces intensify phonon scattering.Consequently,Sn Se-0.5%Cu_(2)S and Sn Se-3%Cu_(2)S achieve a peak z T of 0.70 at 830 K(intermediate temperature range)and a highly increased z T of 0.28 at 473 K(low temperature range),respectively,which are~130%and 200%of values reached by Sn Se at the corresponding temperatures.The study demonstrates that our approach,which combines compositing with elemental doping and substitution,is effective in optimizing the thermoelectric performance of Sn Se at varied temperature ranges.