Organic Ferroelectric Vortex-Antivortex Domain Structure

Organic ferroelectrics are attracting tremendous interest because of their mechanical flexibility, ease of fabrication, and low acoustical impedance. Although great advances have been made in recent years, topological defects such as vortices remain relatively unexplored in the organic ferroelectric system. Here, from [quinuclidinium]ReO₄ ([Q]ReO₄), we applied the molecular design strategy of H/F substitution to successfully synthesize the organic ferroelectric [4-fluoroquinuclidinium]ReO₄ ([4-F-Q]ReO₄). Through H/F substitution, the Curie temperature and spontaneous polarization are respectively increased from 367 K and 5.83 μC/cm² in [Q]ReO₄ to 466 K and 11.37 μC/cm² in [4-F-Q]ReO₄. Moreover, under mechanical stress fields, three kinds of stripelike domains with various polarization directions emerge to form a windmill-like domain pattern in the thin film of [4-F-Q]ReO₄, in which intriguing vortex-antivortex topological configurations can exist stably. This work provides an efficient strategy for optimizing the properties of organic ferroelectrics and exploring emergent phenomena.