Electronic structure and thermoelectric properties of Bi₂O₂Se with GGA and TB-mBJ potentials

Abstract

The electronic structure and thermoelectric (TE) properties of Bi 2 O 2 Se 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 [Bi 2 O 2 ] 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 σ/τ ratio shows the better TE performance for p-type Bi 2 O 2 Se. κ 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.

Surface electronic structure of bismuth oxychalcogenides

“…When the SOI and vdW corrections were properly accounted for, the lattice parameters were found to be very close to our values (e.g., a = 3.892 Å and c = 12.186 Å in Ref. [75]), and the mBJ gap (1.092 eV [75]) got close to our result (0.954 eV). The small difference can be apparently attributed to different z Bi (which was not reported in Ref.…”

“…The small difference can be apparently attributed to different z Bi (which was not reported in Ref. [75] and in many other works). The HSE06 results reported gaps of 0.89 eV [77] and 0.99 eV [78], where the larger value corresponds to the calculation without SOI.…”

“…The direct ( -) gap values, 1.307 eV (mBJ) and 1.340 eV (HSE06), are in reasonable agreement with the optical absorption band gap. Earlier calculations performed within the mBJ approach [51,53,75,76] demonstrated the gap varying from 0.85 eV [53] to 1.28 eV [51]. The larger value was obtained when the van der Waals (vdW) corrections were not taken into account during the structure optimization and hence the lattice parameters (especially c) were overestimated.…”

First-principles calculations to investigate mechanical, optoelectronic and thermoelectric properties of half-Heusler p-type semiconductor BaAgP

“…2. The GGA-PBE potential underestimate the experimental band gap by around 50% [48] and a lot of studies are available in literature that TB-mBJ potential can predict band gap comparable with experimental values [49][50][51][52][53][54]. In this study, we have calculated the electronic band structures using two different exchangecorrelation functionals GGA-PBE and TB-mBJ.…”

Bi2O2Se:Bi2O5Se High‐K Stack as a 2D Analog of Si:SiO2: A First‐Principles Study

“…However, the difference is normally around 0.1 eV. [ 47–49 ] This is small enough to guarantee that our results remain qualitatively unaffected. Norm‐conserving pseudopotentials are used.…”