Investigations of modulation effect of co-metal ions on the optical properties of the hybrid double perovskites (MA)₂AgBi_1−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 AgBi 1−x Sb x Br 6 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 AgBi 1−x Sb x Br 6 systems, the Goldschmidt tolerance factor t and the octahedral factor μ indicate that all samples are in a standard double perovskite structure with alternating AgBr 6 and Bi/SbBr 6 octahedra. The calculated electronic structures show that the band gap of (MA) 2 AgBi 1−x Sb x Br 6 decreases with the increase of Sb content, but the indirect band gaps are maintained for all samples. By analyses of the imaginary part ε 2 (ω) of dielectric function and the absorption spectra, we find that all (MA) 2 AgBi 1−x Sb x Br 6 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 AgBi 1−x Sb x Br 6 systems and may open a new way to put it into applications in the fields of solar cells and other optoelectronic devices.

Antimony Doping of CsBi3I10 for Tailoring the Film Morphology and Defects toward Efficient Lead-Free Thin-Film Solar Cells

“…Notably, the typical peak for (003) planes was slightly shifted to a higher degree from 12.8 to 13.1°(Figure 1e) after Sb incorporation. This is probably due to the smaller ion radius of Sb (90 pm) than that of Bi (117 pm), 22 which induces the decrease of the crystal lattice constant and crystal plane spacing. However, there are no greater peak shifts for samples with higher Sb doping, which may result from the limited Sb incorporation in the CBI crystal lattice due to a large difference of the ionic radius between Sb and Bi.…”

“…In addition, Sb-based precursors have higher solubility in organic solvents than Bi-based counterparts, which could help tune the crystallization kinetics of the CBI thin film. 22 We found that Sb doping in CsBi…”

“…Metal alloying represents one of the most effective strategies to modulate the photoelectric properties of perovskite materials. A small amount of covalent or isovalent cations is usually doped to adjust the material properties . For example, the doping of Sn 2+ into Pb-based perovskites can effectively reduce the band gap and promote the light harvesting efficiency .…”

“…In addition, Sb is also an element with low toxicity. In addition, Sb-based precursors have higher solubility in organic solvents than Bi-based counterparts, which could help tune the crystallization kinetics of the CBI thin film . We found that Sb doping in CsBi 3– x Sb x I 10 significantly alters the crystallization kinetics and enables the formation of a polycrystalline thin film with high density, good uniformity, and few defects.…”

“…A small amount of covalent or isovalent cations is usually doped to adjust the material properties. 22 For example, the doping of Sn 2+ into Pb-based perovskites can effectively reduce the band gap and promote the light harvesting efficiency. 23 The doping of Ca 2+ on the Pb site in CsPbI 3 can increase the output voltage by passivating the crystal surface and improving the morphology of the film.…”