Electronic structure and optical absorption property of BaTiO3/BiCoO3

Abstract

In this paper, we calculated the different forms of BaTiO3/BiCoO3 composite structure, predicting their visible light absorption performance based on the electronic structure using the first principles calculations. Firstly, six possible compounds that come from BaTiO3 and BiCoO3 were constructed. By calculating the different antiferromagnetic (AFM) structures of strip, columnar, and layered composite structures, it is found that the ground state of the composite structure changes to G‐type AFM structure from C‐type AFM structure of pure BiCoO3 under the influence of BaTiO3. Energy band calculations show that band gaps of three composite structures are smaller than those of pure BaTiO3 and pure BiCoO3. Furthermore, density of states analysis shows that the conduction band minimum (CBM) and valence band maximum (VBM) of three composite structures are mainly from the contribution of Co 3d and O 2p. For the characteristic that CBM and VBM of materials come from different atoms, it would reduce the recombination opportunities of electrons and holes and is conducive to the increase of photoelectric conversion efficiency under visible light irradiation. The calculation of optical properties shows that optical absorption coefficients of three composite structures are much larger than that of BaTiO3, especially the layered composite structure. There is a high absorption peak near 500 nm of the solar spectral irradiation maximum, which is significantly important to improve the optical energy conversion efficiency of the composite materials. The work provides an effective way for the application of wide band gap ferroelectric materials in ferroelectric photovoltaic.