SrFBiS₂ is a quaternary n-type semiconductor with rock-salt-type BiS₂ and fluorite-type SrF layers alternately stacked along the c axis. The tunability of the crystal and electronic structures as well as the intrinsically low thermal conductivity make this compound a promising parent material for thermoelectric applications. In the current work, we show that alloying of Se and S in SrFBiS₂ reduces the optical band gap with the second conduction band serving as an electron-transport medium, simultaneously increasing the electron concentration and effective mass. In addition, the raw material Bi₂Se₃ is shown to act as liquid adjuvant during the annealing process, favoring preferred-orientation grain growth and forming strengthen microstructural texturing in bulk samples after hot-pressed sintering. Highly ordered lamellar grains are stacked perpendicular to the pressure direction, leading to enhanced mobility along this direction. The synthetic effect results in a maximum power factor of 5.58 μW cm⁻¹ K⁻² at 523 K for SrFBiSSe and a peak zT = 0.34 at 773 K, enhancements of 180% compared with those of pristine SrFBiS₂.

SrFBiS ₂是一种四元n型半导体，岩盐型BiS ₂和萤石型SrF层沿c轴交替堆叠。晶体和电子结构的可调性以及固有的低导热性使这种化合物成为热电应用的有前途的母体材料。在目前的工作中，我们表明 SrFBiS ₂中 Se 和 S 的合金化降低了光学带隙，第二导带用作电子传输介质，同时增加了电子浓度和有效质量。此外，原料Bi ₂ Se ₃显示在退火过程中充当液体辅助剂，有利于优先取向的晶粒生长并在热压烧结后的块状样品中形成强化的微观结构织构。高度有序的层状晶粒垂直于压力方向堆叠，导致沿该方向的流动性增强。合成效应导致 SrFBiSSe 在 523 K 时的最大功率因数为 5.58 μW cm ^-1  K ^-2 ，在 773 K 时峰值zT = 0.34，与原始 SrFBiS ₂ 相比提高了 180% 。