Pressure-Induced Band Gap Engineering of Nontoxic Lead-Free Halide Perovskite CsMgI₃ for Optoelectronic Applications

Abstract

Recently, lead halide perovskites have gained considerable attention by dint of their predominant physiochemical features and potential use in various applications with an improved power conversion efficiency. Despite the incredible technological and research breakthroughs in this field, most of those compounds present an obstacle to future commercialization due to their instability and extreme poisonousness. Because of this, it is preferable to replace lead with alternative stable elements to produce eco-friendly perovskites with equivalent optoelectronic qualities similar to lead-based perovskites. However, Pb-free perovskite-based devices have relatively low power conversion efficiency. Pressure might be considered an effective way for modifying the physical characteristics of these materials to enhance their performance and reveal structure−property correlations. The present study has been done to investigate the structural, electronic, optical, elastic, mechanical, and thermodynamic properties of nontoxic perovskite CsMgI 3 under hydrostatic pressure by using density functional theory (DFT). At ambient pressure, the present findings are in excellent agreement with the available experimental data. Pressure causes the Mg−I and Cs−I bonds to shorten and become stronger. The absorption coefficient in the visible and ultraviolet (UV) zones grows up with the increase in pressure. Additionally, we have observed low reflectivity, a high-intensity conductivity peak, and a dielectric constant in the visible region of the electromagnetic spectrum. As pressure rises, the band gap keeps narrowing, facilitating an electron from the valence band to get excited easily at the conduction band. Furthermore, we analyze the mechanical, elastic, and thermodynamic properties under pressure, which suggests that this compound exhibit ductile behavior. The shrunk band gap and improved physical properties of CsMgI 3 under hydrostatic pressure suggest that this material may be used in solar cells (for photovoltaic applications) and optoelectronic devices more frequently than at ambient pressure. In addition, this paper emphasizes the feasibility of hydrostatic pressure in the systematic modification of the optoelectronic and mechanical characteristics of lead-free halide perovskites.

Hybrid-DFT study of halide perovskites, an energy-efficient material under compressive pressure for piezoelectric applications

“…The lattice constants under different pressures of these compounds are listed in table(T1). Thus, from our findings, we reported in table 1 and table(T1), we can say that substitution of halogen atoms down the group (Cl→Br→I) increases the lattice constants [42], while increasing pressure reduces the unit cell's lattice parameters [43].…”

Exploring the influence of pressure-induced semiconductor-to-metal transition on the physical properties of cubic perovskites FrXCl3 (X = Ge and Sn)

“…Another concern lies in the use of lead (Pb), a toxic material that poses potential harm to both human health and the environment [ 28 ]. Furthermore, lead-based perovskites, MAPbX 3 (X = Cl, Br, I), have comparatively small values of dielectric constants [ 33 ]. The fundamental obstacle to the widespread use of solar cell devices is the rate at which charge recombination occurs.…”

“…Most recently, there has been substantial research into the use of metal halide perovskite compounds due to their notable optoelectronic characteristics, such as their adaptable transparent bandgap, wide absorption spectrum, narrow emission width, high absorption and charge diffusion, and abundant mobile carriers with a light mass that is efficient [ 60 , 61 ]. Germanium-based, non-toxic, inorganic perovskite compounds, possessing superior conductivity and absorption capabilities compared to Pb-based perovskites, are showing great potential as an alternative to lead (Pb) [ 33 ]. Despite its brittleness, CsGeI 3 has been identified as the most promising Pb-free halide perovskite material, surpassing the ductile CsSnBr 3 , according to previous investigations [ 62 , 63 ].…”

Effect of Low to High Pressure on the Structural, Mechanical, Electrical, and Optical Properties of Inorganic Material Ca3AsBr3: An Ab Initio Investigation

“…Calculated and presented ratios such as the Poisson’s and Pugh’s ratios demonstrate a greater degree of ductility. Initially, these materials exhibit brittle behavior (about 0 GPa), but with increased pressure within the range mentioned, they become more ductile . The minimum and maximum values of Young’s modulus, compressibility, shear modulus, Poisson’s ratio, and the ratio A of Ca3AsBr3 are listed in Table .…”