Entropy engineering in transition metal sulfides for thermoelectric application

Transition metal sulfides have emerged as highly promising materials in thermoelectrics owing to their economic viability and sustainable characteristics. Herein, we developed entropy-engineered sulfides based on TiS2. The process of equal doping at Ti sites resulted in a notable reduction in lattice thermal conductivity due to point defects and phase segregation induced by entropy engineering; however, it also had a substantial detrimental effect on the Seebeck coefficient. Finally, by incorporating minor doping at Ti sites with Zr, Nb and Ta, each at a concentration of 1 at%, an impressive figure of merit of 0.38 was achieved at 625 K because minor doping was able to maintain the large Seebeck coefficient while simultaneously reducing the lattice thermal conductivity. This study not only illuminates the significant role of entropy engineering in reducing lattice thermal conductivity but also sparks interest in the potential of equivalent doping at sulfur sites for future investigations.