The quality factor B involving carrier mobility, state density effective mass, and lattice thermal conductivity has always been regarded as the guidance for the thermoelectric materials design. However, the traditional quality factor considers a single band and neglects the influence of band gap and the sub-band, whose edge energy is 5 k_BT lower than valence band maximum for the p-type or higher than conduction band minimum for n-type semiconductor. In this work, we took into account the band gap and second band based on the three-parabolic-band model and derived an advanced quality factor $B_{\Delta E}^{\ast }$, which is better proportional to the peak ZT values of many compounds with multiple bands. A specific example is also validated based on this quality factor that a highest $B_{\Delta E}^{\ast }$ appears when x = 0.8 for (Yb_0.9Mg_0.1)Mg_xZn_2-xSb₂, leading to the highest ZT value at this composition.

涉及载流子迁移率，态密度有效质量和晶格热导率的品质因数B一直被视为热电材料设计的指南。然而，传统的品质因数只考虑单个频带，而忽略了带隙和子带的影响，其边沿能量比p型的价带最大价低5 k _B T或n-值的导带最小价高。型半导体。在这项工作中，我们基于三抛物带模型考虑了带隙和第二带，并推导了先进的品质因数${乙}_{\Delta Ë}^{\ast }$，它与许多具有多个谱带的化合物的ZT峰值成正比。还根据此品质因数验证了一个特定示例，该示例${乙}_{\Delta Ë}^{\ast }$当 （Yb _0.9 Mg _0.1）Mg _x Zn _{2- x} Sb _2的x = 0.8时出现，导致该组成下的ZT值最高。