Synergistic Entropy Engineering with Vacancies: Unraveling the Cocktail Effect for Extraordinary Thermoelectric Performance in SnTe‐Based Materials

The pursuit of high‐power factor and low lattice thermal conductivity simultaneously in thermoelectric research is longstanding. Herein, great success has been achieved in SnTe‐based materials by employing a proposed strategy of entropy engineering involving vacancies, thus leveraging the promising cocktail effect. Significant band convergence and flatness effects have given rise to exceptionally high density of state carrier effective mass and Seebeck coefficients. These effects have also led to the theoretical optimal carrier concentration closely aligning with the actual carrier concentration. Furthermore, the entropy engineering involving vacancies has induced pronounced lattice disorder and a wealth of nanostructures, facilitating multi‐scale phonon scattering. Consequently, impressive thermoelectric performance is realized in AgSb3Pb2Ge2Sn6Te15: room‐temperature ZT of ≈0.4, peak ZT of ≈1.3 at 623 K, and average ZT of ≈1.0 (300–773 K). A thermoelectric module, comprising this p‐type material and the homemade n‐type PbTe, is assembled, demonstrating a competitive conversion efficiency of 9.3% at a temperature difference of 478 K. This work not only provides valuable insights into the modulation of electron/phonon transports but also establishes an effective paradigm of entropy engineering involving vacancies. Unlike the exclusive implementation of entropy engineering or vacancy engineering in SnTe‐based materials, a strategy of entropy engineering involving vacancies is proposed in this work to leverage a promising cocktail effect. The approach results in the simultaneous attainment of high power factor and low lattice thermal conductivity, culminating in extraordinary thermoelectric performance at low‐medium temperatures.