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<p>Halide perovskites have become promising lead-free candidates for sustainable optoelectronics; nevertheless, beryllium-based systems remain relatively unexplored. First-principles density functional theory (DFT) calculations using a cluster approach provide insights into the structural, electronic, optical, and thermodynamic properties of crystalline InBeX<sub>3</sub> (X = F, Cl, Br, I) perovskites, interpreted within a solid-state framework. The cubic Pm3m phase is structurally proven to be a stable form with tolerance factors (0.97–1.05) and negative formation energies (−5.45&#xa0;eV to −3.40&#xa0;eV). The electronic energy gaps are between 2.30&#xa0;eV (InBeF<sub>3</sub>) and 1.03&#xa0;eV (InBeI<sub>3</sub>) (close to the optimum window of 0.9–1.6&#xa0;eV) of high-efficiency solar cells. Conceptual DFT (CDFT) descriptors indicate that halide mass decreases chemical hardness and increases softness and polarizability, which are signs of enhanced characteristics of charge transport. A small reduction in the dipole moment is seen, and optical electronegativity is reduced; the refractive index and dielectric constant increase monotonically. Results of time-dependent functional theory (TD-DFT) indicate that excitation energy decreases with a decrease in F (3.25&#xa0;eV) to I (2.03&#xa0;eV), and the emission changes from UV (approximately at 380&#xa0;nm) to the red region (approximately at 608&#xa0;nm). Vibrational analysis of infrared (IR) and Raman spectra shows halide-dependent red shifts, which give clear spectral fingerprints. According to thermodynamic parameters, heavier halides result in higher heat capacity, entropy, and Gibbs free energy, with InBeI<sub>3</sub> being the most stable at standard conditions. Generally, halide substitution enables accurate control of optoelectronic properties; these materials are good candidates for device applications in the UV, visible, and near-infrared.</p>

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Tuning Electronic and Optical Properties of InBeX3 (X = F, Cl, Br, I) Perovskites Through Halide Substitution: A First-Principles Study

  • 期刊论文

  • 发表日期：

    2026年7月6日

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  • Pooja Sharma

摘要

Halide perovskites have become promising lead-free candidates for sustainable optoelectronics; nevertheless, beryllium-based systems remain relatively unexplored. First-principles density functional theory (DFT) calculations using a cluster approach provide insights into the structural, electronic, optical, and thermodynamic properties of crystalline InBeX3 (X = F, Cl, Br, I) perovskites, interpreted within a solid-state framework. The cubic Pm3m phase is structurally proven to be a stable form with tolerance factors (0.97–1.05) and negative formation energies (−5.45 eV to −3.40 eV). The electronic energy gaps are between 2.30 eV (InBeF3) and 1.03 eV (InBeI3) (close to the optimum window of 0.9–1.6 eV) of high-efficiency solar cells. Conceptual DFT (CDFT) descriptors indicate that halide mass decreases chemical hardness and increases softness and polarizability, which are signs of enhanced characteristics of charge transport. A small reduction in the dipole moment is seen, and optical electronegativity is reduced; the refractive index and dielectric constant increase monotonically. Results of time-dependent functional theory (TD-DFT) indicate that excitation energy decreases with a decrease in F (3.25 eV) to I (2.03 eV), and the emission changes from UV (approximately at 380 nm) to the red region (approximately at 608 nm). Vibrational analysis of infrared (IR) and Raman spectra shows halide-dependent red shifts, which give clear spectral fingerprints. According to thermodynamic parameters, heavier halides result in higher heat capacity, entropy, and Gibbs free energy, with InBeI3 being the most stable at standard conditions. Generally, halide substitution enables accurate control of optoelectronic properties; these materials are good candidates for device applications in the UV, visible, and near-infrared.