Boosting the thermoelectric performance of Bi2O2Se by isovalent doping

• Published in: Journal of the American Ceramic Society 2018-10, Vol.101 (10), p.4634-4644
• Main Authors: Tan, Xing, Lan, Jin‐Le, Hu, Kerong, Xu, Ben, Liu, Yaochun, Zhang, Peng, Cao, Xing‐Zhong, Zhu, Yingcai, Xu, Wei, Lin, Yuan‐Hua, Nan, Ce‐Wen
• Format: Article
• Language: English
• Subjects: Atomic structure; Carrier density; dopants/doping; electrical conductivity; Electrical resistivity; Heat conductivity; Heat transfer; Oxygen atoms; Point defects; Thermal conductivity; Thermodynamic properties; Thermoelectric materials; thermoelectric properties
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.15720

N‐type Bi2O2Se has a bright prospect for mid‐temperature thermoelectric applications on account of the intrinsically low thermal conductivity. However, the low carrier concentration of Bi2O2Se (~1015 cm−3) severely limits its thermoelectric performance. Herein, the boosting of the carrier concentration to ~1019 cm−3 can be realized in our La‐doped Bi2O2Se ceramic samples, which could be ascribed to the formation of isoelectronic traps and the narrowing of band gap, and contribute to a marked increase in the electrical conductivity (from 0.03 S cm−1 to 182 S cm−1). Our X‐ray absorption near‐edge structure spectra results reveal that a local disordering of oxygen atoms could be an important reason for the intrinsically low thermal conductivity of Bi2O2Se, and the point defects can also suppress the lattice thermal conductivity in La‐doped Bi2O2Se. The ZT value can be enhanced by a factor of ~4.5 to 0.35 at 823 K for Bi1.98La0.02O2Se as compared to the pristine Bi2O2Se. The coordinated optimization of electrical and thermal properties demonstrates an effective method for the rational design of high‐performance thermoelectric materials.