Investigation of electronic and optical properties of PbxSn1-xO2 for optoelectronic applications: A TB-mBJ DFT approach

A comprehensive study of electronic and optical properties of PbxSn1-xO2 (x = 0.125, 0.25 and 0.375) have been performed utilizing PBE-GGA + TB-mBJ scheme employing WIEN2K package under DFT formalism. The lattice constant parameters obtained for PbxSn1-xO2 are observed to be invariant with rutile SnO2. The DoS (Density of States) profile of PbxSn1-xO2 states a dominant impact of partial states of Pb along the conduction band. A red shift of conduction band edge has been observed with increasing Pb incorporation in PbxSn1-xO2 supercells. The contribution due to partial states of O is supreme as compared to Pb along the valence band, as also encountered in SnO2. The nature of bandstructure is in parity with DoS profile. With increased incorporation of Pb atoms in PbxSn1-xO2 supercells, a significant lowering of conduction band minimum occurs thereby resulting in reduced band gap. The nature of reduction of optical band gap values is in parity with the electronic band structure. The optical parameter characteristic curves undergo redshift due to increased Pb incorporation in PbxSn1-xO2 supercells. Distinct peak values in absorption characteristic curve claims the material to have direct band gap. Higher value of static refractive index causes dispersion in the material. The real (imaginary) part of dielectric constant is consistent with the refractive index (extinction coefficient) characteristic curves. The reflection coefficient curve indicates lossy nature of the material. The reflection coefficient curve contradicts the loss coefficient characteristic curve. Hence, the consequences of this investigation claim the competency of PbxSn1-xO2 material for optoelectronic applications.