Regular Article

Enhanced thermoelectric properties of Bi₂O₂Se ceramics by Bi deficiencies

¹ Henan University of Engineering, Computer College, Zhengzhou Henan 451191, P.R. China
² National Digital Switching System Engineering & Technological R&D Center, Zhengzhou Henan 450002, P.R. China
³ North China University of Water Resources and Electric Power, Zhengzhou 450046, P.R. China

^a e-mail: hnsqxubin@163.com

Received: 9 April 2018
Received in final form: 21 October 2018
Published online: 23 January 2019

Abstract

The electronic structure and the thermoelectric properties of Bi_2−xO₂Se (x = 0, 1/4, 1/8, 1/16, 1/32, 1/36, 1/54 and 1/64) are studied by the first principles and the semiclassical BoltzTraP theory. It is found that the energy band gaps increase with increasing x. The calculated total density of states (TDOS) near the Fermi level and bandwidth are influenced by the applied defect. The S values of Bi_2−xO₂Se are much larger than Bi₂O₂Se at the same n, due to the much larger TDOS of Bi_2−xO₂Se. σ∕τ of p-type Bi_2−xO₂Se are larger than that of the n-type ones, due to the larger TDOS on the top of the valence band (VB). κ⁰of p-type doping is higher than that of n-type doping. Z_eT can be increased by Bi deficiency.