Deterministic conduction type switching and thermoelectric properties enhancement in Bi2Te3 via pressure-temperature engineered

Abstract

Bi2Te3-based alloys are cornerstones of commercial thermoelectric technology, yet their performance ceiling remains unexplored. Pressure loading can effectively enhance the dimensionless figure-of-merit (ZT) of Bi2Te3-based alloys; however, these gains disappear upon decompression, hindering practical applications. Here, a high-pressure and high-temperature (HPHT) treatment (1-5 GPa, 900-1,000 K) followed by quenching is proposed to preserve superior HP properties under ambient conditions. The results demonstrate that precise control over p-type and n-type conduction behaviors is achieved in a single material via HPHT tuning alone, attributed to a pressure-driven electronic topological transition (ETT). Furthermore, the recovered Bi2Te3-samples reinforce both thermoelectric and mechanical properties. Specifically, with respect to the pristine counterparts, the ZT values increase by factors of 6.75 at 3 GPa (p-type) and 3.88 at 5 GPa (n-type), while Vickers hardness rises by factors of 1.14 and 4.38, respectively. This proposed HPHT strategy challenges the conventional doping-dominated paradigm for semiconductor polarity, providing a novel approach that could redefine the design of future electronic materials. Bi₂Te₃-based alloys are pivotal in thermoelectric technology, yet their performance is limited by transient pressure-induced enhancements. Here, the authors employ a high-pressure and high-temperature treatment to achieve stable, enhanced thermoelectric and mechanical properties, significantly increasing ZT values and hardness, expanding semiconductor design beyond traditional doping methods.