Tuning Interstitials in Fully Dense β-Zn₄Sb₃ Doubles Single-Leg Thermoelectric Efficiency

Zinc antimonides, particularly the β-Zn 4 Sb 3 compound, act as prototypes in the early phases of thermoelectric generator (TEG) development. However, their potential applications are constrained by structural instability at elevated temperatures. In this study, introducing a low concentration of aluminum (Al) achieves a highly stable Al–Zn 4 Sb 3, exhibiting an improved peak zT value compared to undoped Zn 4 Sb 3 . Notably, a single-leg device utilizing a fully dense Al 0.01 Zn 3.99 Sb 3 demonstrates an impressive conversion efficiency (η) of 3% even at a temperature difference (Δ T ) of 225 K. This result represents an approximately 200% increase compared with the pristine one. The combination of dilute cationic doping and phase diagram engineering solidifies the potential of Zn 4 Sb 3 as an efficient and sustainable green energy device.