Electron-phonon coupling (EPC) is a key factor for thermoelectric properties of materials. In this paper, the thermoelectric properties of zinc-blende chalcogenides (p-type) ZnS and ZnSe have been studied through full evaluation of EPC from first-principles, including the influences on both electrical and thermal transport. We find that the polar longitudinal optical phonon scattering is the dominant mechanism for electrical transport. Due to the triple degeneracy near the valence band maximum, the inter-band scattering also has detrimental contributions to the electrical conductivities. For phonon transport, it shows that the lattice thermal conductivity can be reduced by the electron-phonon scattering significantly at high carrier concentrations (e.g., at 300 K with 10²¹ cm⁻³ of hole, the reduction is ∼24.9% for ZnS and ∼28.4% for ZnSe, respectively). Finally, the p-type thermoelectric figure of merit (ZT) of two systems have been obtained, which are 0.129 for ZnS and 0.141 for ZnSe, at 700 K with their respective optimal hole concentrations. Our work provides a complete and in-depth study of thermoelectric properties in chalcogenides ZnX from the role of EPC. The results suggest EPC plays an important role on the thermoelectric properties and thus full evaluation of EPC is necessary especially for polar materials.

电子-声子耦合（EPC）是材料热电性能的关键因素。本文通过对第一性原理的EPC进行了全面评估，研究了混合锌硫属元素化物（p型）ZnS和ZnSe的热电性质，包括对电和热传输的影响。我们发现，极性纵向光学声子散射是电传输的主要机制。由于在价带最大值附近出现三次简并，带间散射也对电导率产生有害影响。对于声子传输，表明在高载流子浓度下（例如，在300 K时10 ²¹  cm孔的^-3处，ZnS的减少量约为24.9％，ZnSe的减少量约为28.4％。最终，获得了两个系统的p型热电品质因数（ZT），分别为700 K和ZnS，ZnS为0.129，ZnSe为0.141。我们的工作从EPC的作用出发，对硫族化物ZnX中的热电性质进行了全面而深入的研究。结果表明，EPC在热电性能中起着重要作用，因此对EPC进行全面评估是必要的，尤其是对于极性材料。