Thermoelectric (TE) materials have ability to effectively convert waste heat into
ctrical power, making them a promising candidate for addressing current energy
sis and climate change. Pb-free chalcogenide SnTe-based compounds have received nificant interest as possible substitutes for the conventional medium-temperature E material PbTe because of their similar crystalline and electronic band structure. ppropriately manipulating Sn vacancies (VSn) in SnTe-based materials is of great nificance to balance various transport properties for optimizing TE performance. In view of ultra-low carrier mobility resulted from strong vacancy-electron attering in SnTe-Sb2Te3 alloy, an appropriate weakening of vacancy scattering to rsue ideal compromise among carrier mobility (μ), concentration (n), and density state effective mass (m*) is of great significance for more effective performance omotion. We, for the first time in the SnTe community, contrastively investigated
verse cation-site fillers (Sn, Pb, Cd, Mn) for maintaining high μ with a large m*,
hich indicated that Mn compensation exhibits the most appealing effect on finely
anipulating electron and phonon transports and optimizing TE performance.
Balancing electron and phonon scattering is crucial for enhancing the TE
rformance of an alloy. Formation of VSn in Mg-alloyed SnTe was suppressed via
-compensation, leading to high electrical transport performance. While high VSn
ncentration promotes the formation of dense dislocation arrays, resulting in an ultra
w lattice thermal conductivity in Sn0.88Bi0.03Mg0.09. A combination of Sn
mpensation and Bi-doping in Sn0.90Bi0.03Mg0.09Te resulted in high PF and low κlat,
multaneously, owing to the balanced scatterings of electron and phonon.
Finally, the promising cocktail effect generated by vacancies participated entropy
gineering was explored in SnTe-based TE material for decoupling the electronic and thermal transport properties. The introduction of VSn effectively reduced carrier
concentration and optimized the Femi level position. Pb and Ge were further
introduced into cation site for increasing the configurational entropy in the system,
leading to significant electronic band convergence and flattening in
AgSb3Pb2Ge2Sn8Te15. Combining with abundant nanostructures being responsible for full-frequency phonon scattering, a record TE performance at low-medium
temperatures was achieved. A single-stage TE module based on AgSb3Pb2Ge2Sn8Te15 was assembled with competitive conversion efficiency of 9.3%, demonstrating huge
application potential.