Investigations of modulation effect of co-metal ions on the optical properties of the hybrid double perovskites (MA)2AgBi1−x Sb x Br6

Abstract

Composition engineering plays an important role in generating novel properties and decreasing the lead (Pb) toxicity for halide perovskite materials. To find out the modulation effect introduced by the composition engineering, namely, B '-site co-metal ions, in (MA)(2)AgBi1-x Sb x Br6 systems with various Bi/Sb ratios of x = 0, 0.25, 0.75, 1.00, series of theoretical simulations and analyses are carried out. For the (MA)(2)AgBi1-x Sb x Br6 systems, the Goldschmidt tolerance factor t and the octahedral factor mu indicate that all samples are in a standard double perovskite structure with alternating AgBr6 and Bi/SbBr6 octahedra. The calculated electronic structures show that the band gap of (MA)(2)AgBi1-x Sb x Br6 decreases with the increase of Sb content, but the indirect band gaps are maintained for all samples. By analyses of the imaginary part e (2)(omega) of dielectric function and the absorption spectra, we find that all (MA)(2)AgBi1-x Sb x Br6 systems show absorption in the visible-light region. All these results indicate that the composition engineering adopted in this paper is an effective strategy to modulate the optical properties of (MA)(2)AgBi1-x Sb x Br6 systems and may open a new way to put it into applications in the fields of solar cells and other optoelectronic devices.