Interface‐Enhanced High‐Temperature Thermoelectricity in Cu1.99Se/B4C Composites with Synergistically Improved Mechanical Strength

• Published in: Advanced energy materials Vol. 14; no. 14
• Main Authors: Yu, Jincheng, Hu, Haihua, Jiang, Yilin, Hua‐Lu Zhuang, Hao‐Cheng Thong, Su, Bin, Jing‐Wei Li, Han, Zhanran, Li, Hezhang, Pei, Jun, Jing‐Feng Li
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.04.2024
• Subjects: Anharmonicity; Boron carbide; Carrier density; Carrier mobility; Composite materials; Copper selenides; Electrical resistivity; Electrons; Figure of merit; High temperature; Ion migration; Lattice vibration; Power factor; Thermal conductivity; Thermoelectric materials
• DOI: 10.1002/aenm.202303942
• ISSN: 1614-6832

Degenerate semiconductors usually demonstrate a metallic‐like conduction behavior, showing limited carrier mobility at high temperatures. Herein, by incorporating B4C nanoparticles into the Cu1.99Se system, an unusual switch from the “degenerate” to “non‐degenerate” semiconducting behavior is revealed as a result of the engineered interfaces. Heterogeneous interfaces and disordered Cu2Se amorphous phases are introduced in the Cu1.99Se/B4C composites, which generate a trapping effect against the mobile Cu ions, leading to a distinctive “hump” signature for electrical conductivity. Benefiting from this rare high‐temperature thermoelectric response, a high power factor is obtained due to reduced carrier concentration and enhanced mobility, and low lattice thermal conductivity is retained because of relatively stronger anharmonic lattice vibrations. Consequently, the Cu1.99Se + 0.9 vol.% B4C sample at least achieves a maximum thermoelectric figure of merit (ZT) of 2.6 at 1025 K with synergistically enhanced mechanical robustness. The present interface engineering strategy may be applicable to other thermoelectric materials with ionic migration characteristics.