Highly enhanced thermoelectric performance in (In, Pb) co-doped Bi Sb Te alloys via synergistic modulation of carrier concentration and band structure

The extensive utilization of thermoelectric (TE) conversion technology necessitates stricter performance requirements for bismuth telluride (Bi 2 Te 3 )-based commercial materials. Despite the numerous optimization methods available for Bi 2 Te 3 -based materials, each optimization method has a certain upper limitation, and combining multiple strategies can achieve the optimal thermoelectric figure of merit ( zT ). In this study, the thermoelectric properties of (Bi,Sb) 2 Te 3 materials are enhanced through the combined use of the heavy element Pb to regulate carrier concentration and the In element to optimize the band structure. Notably, indium (In) can suppress p-type antisite defects, which generate abundant Te vacancies, and help regulate the carrier concentration to its optimal level. This co-doping strategy achieves optimal carrier concentration, thereby enhancing the power factor (PF=4.57×10 3 μW⸱m –1 ⸱K –2 ), and generating abundant dislocations, the presence of the rich nano-second phase Sb 2 O 3 contributes to reduced lattice thermal conductivity. Consequently, a peak zT value of 1.41 at 323 K and a high average zT value of 1.23 between 300 K and 500 K are achieved. Additionally, two pairs of thermoelectric modules, composed of p-type (Bi 0.42 Sb 1.58 ) 0.994 (In, Pb) 0.006 Te 3 and zone-melted n-type Bi 2 Te 2.7 Se 0.3 , demonstrate a conversion efficiency of 7.3% at a temperature difference of 250 K. This underscores the promising potential of these thermoelectric modules in commercialization. Thus, this study demonstrates the feasibility of combining multiple strategies and is expected to provide a potential reference for other thermoelectric systems. • This work proposes a dual-engineering strategy to enhance the thermoelectric performance of bismuth telluride (Bi 2 Te 3 ) alloys • A high power factor (4571 μW·m –1 ·K –1 ) were obtained at 300 K. • A peak zT value of 1.41 at 323 K and a high average zT value of 1.23 between 300–500 K. • Conversion efficiency of the assembled two pairs of thermoelectric modules reaches a high level of 7.3% at Δ T = 250 K