| Abstract Scope |
Topological electronic transition is the very promising strategy for achieving high band degeneracy (NV) and for optimizing thermoelectric performances. Here, through comprehensive angle-resolved photoemission spectroscopy characterizations and band structure calculations, we propose and verify in p-type Mg3Sb2-xBix solid solution that topological electronic transition is the key mechanism responsible for elevating the NV of valence band edge from 1 to 6, leading to much improved thermoelectric performances. This is explained by the vanishing band gap and strengthened spin-orbital coupling with increasing the Bi content. The optimal p-type Mg3Sb0.5Bi1.5 simultaneously obtains a positive band gap and a high NV of 6, and thus acquires the largest thermoelectric power factor of 3.54 and 6.93 μWcm-1K-2 at 300 K and 575 K, significantly outperforming the values in other compositions. This work provides important guidance on improving thermoelectric performances of p-type Mg3Sb2-xBix utilizing the topological electronic transition. |