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<p>Using first-principles density functional theory (DFT), this study explores the structural, electronic, optical, mechanical, magnetic, vibrational, charge distribution, and anisotropic properties of lead-free halide perovskites LiBX<sub>3</sub> (B = Ca, Ba; X = Cl, Br, I). All compounds crystallize in the cubic Pm3̅m phase, with lattice constants and unit cell volumes increasing as heavier halides are substituted. Tolerance factor analysis confirms the structural stability of these compounds, particularly for Ca-based systems. Electronic structure calculations reveal direct band gaps ranging from 3.75&#xa0;eV&#xa0;for LiCaCl<sub>3</sub>&#xa0;to 2.33&#xa0;eV for LiBaI<sub>3</sub>, with the gaps decreasing from Cl to I.&#xa0;The partial&#xa0;density of states (PDOS) shows significant&#xa0;hybridization between halide p-states and cation&#xa0;d-states, allowing for the tuning of band dispersions. Optical analyses reveal high absorption coefficients (&gt; 10<sup>5</sup>&#xa0;cm<sup>−1</sup>), with iodide compounds exhibiting enhanced dielectric constants, strong reflectivity, and broad optical conductivity spectra, making them suitable for light-harvesting and UV–visible optoelectronic applications. Mechanical stability is confirmed via elastic constants, with Ca-based systems showing higher stiffness and Ba-based iodides demonstrating improved ductility, flexibility, and machinability. Spin-polarized calculations indicate minimal magnetic splitting, confirming non-magnetic ground states. Charge density, Mulliken, and Hirshfeld analyses reveal an increasing covalent character and polarizability from&#xa0;Cl to I, which impacts bonding and charge transport. Anisotropy in elastic moduli further supports their use in flexible devices. Phonon dispersion indicates that Ba-based compounds are dynamically stable, while Ca-based materials exhibit soft modes, suggesting potential lattice instabilities.</p>

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Unveiling the Electronic, Optical, and Mechanical Properties of Lithium-Based Perovskites for Next-Generation Solar Cells

  • 期刊论文

  • 发表日期：

    2025年8月20日

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  • Imtiaz Ahamed Apon,
  • Md. Ratul Hasan,
  • Rifat Rafiu,
  • Riyad Kawsar,
  • Md. Sakib Hasan Saikot,
  • Md. Alamgir Hossain,
  • Md. Azizur Rahman,
  • Karim KRIAA,
  • Noureddine Elboughdiri,
  • Q. Mohsen,
  • Mohd Taukeer Khan,
  • Abdulaziz A. Alshihri

摘要

Using first-principles density functional theory (DFT), this study explores the structural, electronic, optical, mechanical, magnetic, vibrational, charge distribution, and anisotropic properties of lead-free halide perovskites LiBX3 (B = Ca, Ba; X = Cl, Br, I). All compounds crystallize in the cubic Pm3̅m phase, with lattice constants and unit cell volumes increasing as heavier halides are substituted. Tolerance factor analysis confirms the structural stability of these compounds, particularly for Ca-based systems. Electronic structure calculations reveal direct band gaps ranging from 3.75 eV for LiCaCl3 to 2.33 eV for LiBaI3, with the gaps decreasing from Cl to I. The partial density of states (PDOS) shows significant hybridization between halide p-states and cation d-states, allowing for the tuning of band dispersions. Optical analyses reveal high absorption coefficients (> 105 cm−1), with iodide compounds exhibiting enhanced dielectric constants, strong reflectivity, and broad optical conductivity spectra, making them suitable for light-harvesting and UV–visible optoelectronic applications. Mechanical stability is confirmed via elastic constants, with Ca-based systems showing higher stiffness and Ba-based iodides demonstrating improved ductility, flexibility, and machinability. Spin-polarized calculations indicate minimal magnetic splitting, confirming non-magnetic ground states. Charge density, Mulliken, and Hirshfeld analyses reveal an increasing covalent character and polarizability from Cl to I, which impacts bonding and charge transport. Anisotropy in elastic moduli further supports their use in flexible devices. Phonon dispersion indicates that Ba-based compounds are dynamically stable, while Ca-based materials exhibit soft modes, suggesting potential lattice instabilities.