H/OH substitution achieving high-temperature multiferroicity in a Sn(Ⅳ)-based hybrid perovskite

Organic-inorganic hybrid perovskites (OIHPs) have always been regarded as great potential platforms for obtaining ferroicity due to their easy structural tunability and derivativity. However, compared with the common halogen substitution, there is still a lack of understanding of ferroelectricity design through H/OH substitution. Herein, based on a Sn(Ⅳ)-based OIHP [1, (Piperidinium)2SnCl6], hybrid multiferroic crystal 2 [(R-3-OH-Piperidinium)2SnCl6] and 3 [(S-3-OH-Piperidinium)2SnCl6] were obtained by H/OH substitution on the organic component. Besides, where 3 has a high Curie temperature (Tc) 401 K and a spontaneous polarization (Ps) of 3.62 µC cm‒2, accompanied by a significant dielectric response and second harmonic generation (SHG) switching. The experimental results and molecular structural analysis reveal that ferroelectricity is mainly attributed to the homochirality group. Our work provides deep insight into the design of multiferroic materials and ferroelectric performance optimization at the molecular level.