Excellent Thermoelectric Performance Realized in SnSe Materials via Chemical Bond Tailoring Using GeTe as Molecule Scissors

ABSTRACT Tin selenide (SnSe) exhibits great potential in thermoelectrics, owing to the innocuity and intrinsic low thermal conductivity. However, the poor electrical transport properties seriously limit the performance improvement and practical application. Herein, we report that GeTe alloying in Ag‐doped SnSe acts as a “molecular scissor” to tailor chemical bond, inducing Ag 2 Se precipitation. This simultaneously enhances the Seebeck coefficient (632 µV K −1 at 523 K for the A‐SnSe + 0.5 wt.% GeTe sample) via controlling carrier concentration and suppresses the lattice thermal conductivity to an ultralow 0.25 W m −1 K −1 at 823 K through multi‐scale phonon scattering. This synergistic optimization yields a high ZT of 1.75 at 823 K and an impressive average ZT of 0.96 (623–823 K). This chemical bond tailoring strategy, validated by defect formation energy and DOS calculations, provides a general approach for improving thermoelectric performance.