Characterization of a New Hybrid Perovskite Material for Renewable Energy (C₇H₁₁N₂)₂[FeCl₄]: Synthesis, IR Spectroscopy, and Optical Properties

The mild evaporation method at room temperature allows us to prepare a new iron hybrid perovskite (C₇H₁₁N₂)₂[FeCl₄] by replacing lead with metallic iron. The structural and optical characteristics of the produced perovskite are investigated. The identified crystalline structure of (C₇H₁₁N₂)₂[FeCl₄] falls within the monoclinic system (space group P2₁/c), characterized as zero-dimensional (0D), comprised of tetrahedral anions [FeCl₄]²⁻. The simulation of crystal morphologies is conducted by employing the unit cell parameters and Laue symmetries, utilizing the BFDH (Bravais–Fridel, Donnay–Harker) method. FTIR spectroscopy identifies the functional groups present in the crystal structure. This study investigates the optical properties of the synthesized compound, revealing absorption bands in the UV region, particularly at 225, 291, and 351 nm, associated with π-π* transitions. The optical bandgap of the compound is estimated as 1.9 eV for the indirect bandgap and 2.86 eV for the direct bandgap using the Tauc method. The indirect bandgap is further confirmed through a linear fit analysis, where the linear fitting of each curve uncovers a significant correlation: n = 0.46 for E_g^d = 1.9 eV and n = 0.47 for E_g^id = 2.86 eV. This confirmation solidifies understanding of the compound characteristics, providing valuable insights into its properties, making it a strong candidate for energy storage.