Nonleaded Perovskite-Related Ferroelectric Semiconductor (IYA)SbBr5: High Thermal Stability, Narrow Bandgap, and Optoelectronic Potential

Molecular-based ferroelectrics refer to materials composed of organic molecules that form ordered structures through intermolecular interactions (such as hydrogen bonding and π–π interactions) and exhibit ferroelectricity under certain conditions. Molecular-based ferroelectrics are pivotal for next-generation flexible and sustainable devices, yet the lack of eco-friendly lead-free alternatives with robust thermal stability remains a critical bottleneck. Here, we present the synthesis of a novel one-dimensional perovskite-related ferroelectric semiconductor material of (1-(2-aminoethyl) imidazole)SbBr 5 ((IYA)SbBr 5 ), which uniquely integrates high thermal resilience, strong polarization, and a narrow bandgap. Unlike conventional toxic lead-based systems, this Sb 3+ -Br – hybrid features a zigzag [SbBr 5 ] 2– chain and disordered organic cations, enabling a record-high phase transition temperature of 392 K (surpassing most molecular ferroelectrics) with symmetry-breaking (nonpolar Pnma → polar Cc ) and thermal stability up to 500 K. Remarkably, the material exhibits a spontaneous polarization of 2.3 μ C/cm 2 and a relatively low indirect bandgap of 2.41 eV, attributed to synergistic order–disorder transitions and Sb–Br framework distortion. These properties position (IYA)SbBr 5 as a promising candidate for energy-efficient solar cells, photodetectors, and multifunctional optoelectronic devices. Our work pioneers a sustainable design strategy for high-performance ferroelectrics, addressing both environmental concerns and industrial scalability.