Novel Piezoelectric Organic–Inorganic Hybrid Perovskite Realized by H/Cl-Substitution: [(C₈H₁₁NOCl)(18-crown-6)][FeCl₄]

Organic–inorganic hybrid perovskites, known for their piezoelectric and ferroelectric properties, are widely used in data storage, solar cells, and molecular switches. This study introduces a novel hybrid perovskite, [(C8H11NOCl)(18-crown-6)][FeCl4], synthesized using an H/Cl-substitution strategy to enhance its functional properties. The physical properties of the perovskite such as phase transition, dielectricity, and piezoelectric properties, were investigated based on its single-crystal and thin-film morphologies. The compound undergoes a reversible phase transition and exhibits dielectric properties, demonstrating a high Curie temperature (Tc = 442 K). In addition, it crystallizes in the noncentrosymmetric P212121 space group with a unit-cell parameter of a = 11.8790(8) Å, b = 13.7901(9) Å, c = 18.1477(12) Å, α = β = γ = 90°, Z = 4, and V = 2972.8(3) Å3. According to the results of piezoresponse force microscopy, the compound exhibits piezoelectric properties with a maximum amplitude of 370 pm in the butterfly loop. The piezoelectric properties of the compound are related to the noncentrosymmetric structure realized by H/Cl-substitution. This study not only highlights the enhanced dielectric and piezoelectric performance of the novel perovskite but also proposes a potential piezoelectric mechanism, paving the way for future design and optimization of high-performance functional materials.