Electronic structure and thermoelectric properties of Bi2O2 Se with GGA and TB-mBJ potentials

The electronic structure and thermoelectric (TE) properties of Bi2O2Se are studied by the first principles and the semiclassical BoltzTraP theory. The optimized equilibrium lattice parameters are very close to the experimental results. The band gap is enhanced significantly to 1.22 eV with Tran-Blaha modified Becke-Johnson (TB-mBJ). The hybridized densities of states (DOS) of Bi atoms p states and O atoms p states forms [Bi2O2](2+) cation. The peak value of S for TB-mBJ is about three times as high as the peak value of S for generalized gradient approximation (GGA) at 300 K due to the large band gap of TB-mBJ. The sigma/tau ratio shows the better TE performance for p-type Bi2O2Se. K-0 can be decreased by using TB-mBJ potential. TB-mBJ shows a larger value of Z(e)T as compared to GGA. The very broad peaks of Z(e)T for the TB-mBJ scheme show a broad doping range near the Fermi level for obtaining excellent TE materials. (C) 2018 The Japan Society of Applied Physics