Chemical Pressure‐Induced Unconventional Band Convergence Leads to High Thermoelectric Performance in SnTe
Hongwei Ming, Zhong‐Zhen Luo, Zhigang Zou
Abstract
Abstract Band convergence is considered a net benefit to thermoelectric performance as it decouples the density of states effective mass () and carrier mobility ( µ ) by increasing valley degeneracy. Unlike conventional methods that typically prioritize at the expense of µ , this study theoretically demonstrates an unconventional band convergence strategy to enhance both and µ in SnTe under pressure. Density functional theory calculations reveal that increasing pressure from 0 to 5 GPa moves the Σ‐band of SnTe upward, reducing the energy offset between L‐ and Σ‐band from 0.35 to 0.2 eV while preserving the light band feature of the L‐band. Consequently, a high power factor ( PF ) of 119.2 µW cm −1 K −2 at 300 K is achieved for p‐type SnTe under 5 GPa. Chemical pressure also induces conduction band convergence, significantly enhancing the PF of n‐type SnTe. Additionally, the interplay between pressure‐induced phonon modes leads to a moderate increase in lattice thermal conductivity of SnTe below 3 GPa, which combined with the significantly enhanced PF , contributes to a large enhancement in ZT . Consequently, predicted ZT values of 2.12 at 650 K and 2.55 at 850 K are obtained for p‐ and n‐type SnTe, respectively, showcasing substantial performance enhancements.