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)SbBr5 ((IYA)SbBr5), which uniquely integrates high thermal resilience, strong polarization, and a narrow bandgap. Unlike conventional toxic lead-based systems, this Sb3+-Br- hybrid features a zigzag [SbBr5]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 μC/cm2 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)SbBr5 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.