Unraveling electronic origins for boosting thermoelectric performance of p-type (Bi,Sb)2Te3 | Science Advances

P-type Bi _{2− x} Sb _x Te ₃ compounds are crucial for thermoelectric applications at room temperature, with Bi _0.5 Sb _1.5 Te ₃ demonstrating superior performance, attributed to its maximum density-of-states effective mass ( m *). However, the underlying electronic origin remains obscure, impeding further performance optimization. Herein, we synthesized high-quality Bi _{2− x} Sb _x Te ₃ (00 l ) films and performed comprehensive angle-resolved photoemission spectroscopy (ARPES) measurements and band structure calculations to shed light on the electronic structures. ARPES results directly evidenced that the band convergence along the

Please refer to original article for complete formulae.

- direction contributes to the maximum m * of Bi _0.5 Sb _1.5 Te ₃ . Moreover, strategic manipulation of intrinsic defects optimized the hole density of Bi _0.5 Sb _1.5 Te ₃ , allowing the extra valence band along - to contribute to the electrical transport. The synergy of the above two aspects documented the electronic origins of the Bi _0.5 Sb _1.5 Te ₃ ’s superior performance that resulted in an extraordinary power factor of ~5.5 milliwatts per meter per square kelvin. The study offers valuable guidance for further performance optimization of p-type Bi _{2− x} Sb _x Te ₃ .