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

Abstract Bismuth telluride (Bi 2 Te 3 ) has been the only commercialized material in thermoelectric cooling and waste heat recovery. However, the inferior performance for n‐type Bi 2 (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, Bi 2 Te 2.79 Se 0.21 I 0.004 +0.3%Ag achieves an excellent room‐temperature ZT of ≈1.1, while Bi 2 Te2 .79 Se 0.21 I 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 Bi 2 Te 2.79 Se 0.21 I 0.004 +0.3%Ag combined with commercial p‐type Bi 0.5 Sb 1.5 Te 3 has achieved a maximum cooling temperature difference (Δ T max ) of ≈68.3 K at 300 K and a larger Δ T max of ≈84.8 K at 343 K. Additionally, the Bi 2 Te 2.79 Se 0.21 I 0.004 + 0.4%Ag/Bi 0.5 Sb 1.5 Te 3 ‐based power generator realizes a conversion efficiency of ≈6.0% under a Δ T of ≈240 K. These results outperform commercial Bi 2 Te 3 ‐based devices, illustrating the effectiveness of lattice plainification for Bi 2 Te 3 ‐based thermoelectrics.