Realizing High Wide‐Temperature‐Range Thermoelectric Performance in Ga, I, and S co‐doped AgSbTe ₂

Abstract Herein, a peak ZT value of ≈2 at 625 K and an average ZT of 1.46 are achieved in the AgSbTe ₂ system through band engineering and multiscale phonon scattering. This demonstrates that Ga doping achieves band convergence and an additional impurity level between the valence and conduction bands. In contrast, I and S doping contribute profound band flattening. The collective effect of band engineering yields an improved Seebeck coefficient ( S ) and power factor ( PF ). The band manipulation strategy facilitated the attainment of peak PF of 17.9 µW cm ⁻¹ K ⁻² at 625 K, and an excellent average power factor ( PF _ave ) of 15.12 µW cm ⁻¹ K ⁻² is achieved for AgSb _0.97 Ga _0.03 Te _1.76 S _0.15 I _0.09 sample. In the meanwhile, the combined presence of coherent and incoherent nanoprecipitates introduces strong phonon scattering in AgSbTe ₂ matrix, leading to a significantly suppressed lattice thermal conductivity. The lowest lattice thermal conductivity as low as 0.31 W m ⁻¹ K ⁻¹ is achieved in AgSb _0.98 Ga _0.02 Te _1.84 S _0.10 I _0.06 sample. The vast increase of peak ZT and average ZT promotes AgSbTe ₂ as a promising candidate for widespread applications for waste heat recovery and power generation near room‐temperature range (300–625 K).