Lattice Plainification and Intercalation Advances Power Generation and Thermoelectric Cooling in n‐type Bi2(Te, Se)3

This study employs the lattice plainification strategy to introduce extra Ag into commercial Bi₂Te_2.79Se_0.21I_0.004 thermoelectrics to regulate lattice defects and significantly enhance thermoelectric performance. Consequently, the competitive average ZT _ave of ≈1.1 and room-temperature ZT of ≈1.1 are attained in Bi₂Te_2.79Se_0.21I_0.004+Ag samples. Correspondingly, the Bi₂Te_2.79Se_0.21I_0.004+0.3%Ag and Bi₂Te_2.79Se_0.21I_0.004+0.4%Ag-based thermoelectric devices achieved better performance compared to commercial ones.

Abstract

Bismuth telluride (Bi₂Te₃) has been the only commercialized material in thermoelectric cooling and waste heat recovery. However, the inferior performance for n-type Bi₂(Te, Se)₃ largely restricts the practical applications. In this study, additional Ag atoms are introduced utilizing lattice plainification strategy to enhance electrical performance. Observations indicate that Ag atoms situate in the van der Waals layers, acting as n-type dopants to increase carrier concentration, bonding with adjacent Te as intercalating atoms to form electron transport channels, while also suppressing the formation of Te vacancies to boost carrier mobility, substantially favoring carrier transport. Consequently, Bi₂Te_2.79Se_0.21I_0.004+0.3%Ag achieves an excellent room-temperature ZT of ≈1.1, while Bi₂Te2_.79Se_0.21I_0.004 + 0.4%Ag demonstrates a higher average ZT of ≈1.1 at 300–523 K. Furthermore, a full-scale thermoelectric cooler using optimized Bi₂Te_2.79Se_0.21I_0.004+0.3%Ag combined with commercial p-type Bi_0.5Sb_1.5Te₃ has achieved a maximum cooling temperature difference (ΔT _max) of ≈68.3 K at 300 K and a larger ΔT _max of ≈84.8 K at 343 K. Additionally, the Bi₂Te_2.79Se_0.21I_0.004 + 0.4%Ag/Bi_0.5Sb_1.5Te₃-based power generator realizes a conversion efficiency of ≈6.0% under a ΔT of ≈240 K. These results outperform commercial Bi₂Te₃-based devices, illustrating the effectiveness of lattice plainification for Bi₂Te₃-based thermoelectrics.