Lattice plainification and band engineering lead to high thermoelectric cooling and power generation in n-type Bi₂Te₃ with mass production

Thermoelectrics can mutually convert between thermal and electrical energy, ensuring its utilization in both power generation and solid-state cooling. Bi₂Te₃ exhibits promising room-temperature performance, making it the sole commercially available thermoelectrics to date. Guided by the lattice plainification strategy, we introduce trace amounts of Cu into n-type Bi₂(Te, Se)₃ (BTS) to occupy Bi vacancies, thereby simultaneously weakening defect scattering and modulating the electronic bands. Meanwhile, the interstitial Cu can bond with the BTS matrix to form extra electron transport pathways. The multiple occupations of Cu substantially boost carrier mobility and electrical performance. Consequently, the BTS + 0.2%Cu achieves a room-temperature ZT of ∼1.3 with an average ZT_ave of ∼1.2 at 300–523 K. Moreover, the kilogram-scale ingot designed for mass production also exhibits high uniformity. Finally, we fabricate a full-scale device that achieves an excellent conversion efficiency of ∼6.4% and a high cooling ∆T_max of ∼70.1 K, both of which outperform commercial devices.