Investigations of structural, electronic and optical properties of YInO3 (Y = Rb, Cs, Fr) perovskite oxides using mBJ approximation for optoelectronic applications: A first principles study

The structural, electronic and optical properties of indium based novel combinations of ternary perovskite oxides YInO3 (Y = Rb, Cs, Fr) are investigated by first Principles DFT-based calculations scheme via Full Potential Linearly Augmented Plane Wave (FP-LAPW) technique. Comprehensive study is done among three cations (Rb, Cs, Fr) in the same order of symmetry in ABO(3) cubical phase. Electronic properties are improved through PBE plus Tran and Blaha modified Becke-Johnson (PBE + TB-mBJ) functional. Using PBE-GGA, indirect band gaps are calculated to be 2.38 eV, 1.92 eV for RbInO3 and CsInO3, respectively. Whereas, FrInO3 exhibits direct band gap of 1.82 eV. However, these band gap values show improvement in all cases by the use of PBE + TB-mBJ functional. The phonon dispersion curves exhibit no imaginary phonon frequencies indicating that the studied compounds are structurally and dynamically stable. TDOS and PDOS results show the highest contribution of Fr-7s and In-5p states of FrInO3 in increasing conductivity. The electronic charge density contours depict covalent character between In- O atoms. Whereas, spherical contours around the cations (Rb, Cs, Fr) show their ionic bonding. The optical analysis illustrates that the studied compounds possess conductivity and absorptivity in a wide range of the incident photon energies with their minimal reflectivity. The overall analyses depict that the considered compounds are potential candidates for applications in optoelectronic and other allied devices.