Effect of Substitutional Point Defect of Gold (Au) in Indium (In) Site of Double Halide Perovskite (Cs2InSbCl6)

Abstract

Lead (Pb) free (non-toxic) perovskite solar cells materials have attracted great interest in the commercialization of the photovoltaic devices. In this work, density functional theory (DFT) and linear response time-dependent within density functional theory (TDDFT) are used to simulate and investigate the effect of gold (Au) dopedPb-free double halide perovskite A₂BB'X₆(A = Cs; B = In, Au; B' = Sb; X = Cl) on the structural, electronic, and optical properties for perovskite solar cell application. On the structural properties, bond length and bulk modulus calculations show that the doped compound is more likely to resist deformation than the undoped compound. The calculated band structure for both materials (doped and undoped) reveals the presence of the Valence Band Maximum (VBM) and the Conduction Band Minimum (CBM) at around the same symmetry point which indicates a direct band gap nature (at Gamma point). The band gap value for the initial compound (E_g= 0.99 eV) agrees with published theoretical values. For the gold doped compound, the value of the band gap increased to a value of 1.25 eV. The result of the optical properties shows that the Au-doped material has higher absorption coefficient, lower reflectivity and higher optical conductivity when compared with the initial, as such demonstrates better properties as a candidate for solar cell applications and in other optoelectronic devices.