First-Principles Study on Thermoelectric Properties of Bi2O2Se

Compared with traditional thermoelectric (TE) materials, bismuth oxyselenide (Bi2O2Se) consists of nontoxic and lower-cost elements and has better chemical and thermal stability. The highest ZT value of Bi2O2Se ever obtained experimentally was recently reported at 0.69. To further improve its TE performance, the electron and phonon transport properties of intrinsic n-type Bi2O2Se are evaluated by first-principles calculations. Due to the density of states at the conduction band minimum being too small resulting in a low intrinsic carrier concentration, the reported TE properties of Bi2O2Se are not ideal. The TE parameters we calculated are in good agreement with the experimental values. The average optimal ZT values at 800 K for the p-type and n-type Bi2O2Se are 1.83 and 1.81, respectively, indicating that Bi2O2Se is a promising TE material. It is an innovative approach to improve the TE performance by regulating the vacancy defects in Bi2O2Se, which could achieve the cooperative optimization of electrons and phonons through the energy filtering effect and enhanced phonon scattering. Our results could provide a theoretical basis for further improving the TE properties of Bi2O2Se in experiments.