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Abstract The strong coupling between carrier and phonon transport in thermoelectric (TE) materials severely limits improvements to the figure of merit ( ZT ). In this work, an approach is proposed to weaken electron‐phonon coupling, effectively enhancing the TE performance of GeTe. Alloying with Zn 4 Sb 3 reduces excessive carrier concentration ( n H ), widens the bandgap, and promotes band convergence, synergistically improving charge carrier transport and ensuring a high power factor. Additional Pb doping further optimizes n H , boosting the power factor even more. Moreover, phonon transport is suppressed through Pb doping, as reflected in enhanced acoustic‐optical interactions due to the crossing of optical and acoustic modes, and a reduction in sound group velocity. This reinforced strong phonon scattering, combined with multi‐scale hierarchical nano/microstructures in the matrix, significantly reduces lattice thermal conductivity. As a result, a high ZT of 2.1 is achieved at 753 K in Ge 0.9 Pb 0.1 Te+0.9%Zn 4 Sb 3 . Alongside optimized mechanical performance, a high power density of 1.46 W cm −2 is realized at a temperature difference of 350 K in the fabricated 7‐pair TE module. The findings demonstrate the effectiveness of a stepwise optimization strategy for developing high‐performance TE materials.
Zhu et al. (Sat,) studied this question.