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Multiferroics refer to materials with two or more ferroic orders in one phase within a specific temperature range, including ferroelectricity, ferroelasticity, and ferromagnetism which have been widely used in sensors, actuators, and memory devices. Among them, hybrid perovskites exhibiting multiferroicity are generally limited to low dimensions (0D–2D). Designing 3D lead‐free perovskite multiferroics remains a challenge due to Goldschmidt's tolerance factor limitation. Here, a multiferroic perovskite (R‐3AP)RbBr3 (1; 3AP = 3‐ammoniopyrrolidinium) is successfully synthesized by introducing homochirality to the 3D ferroelectric (Rac‐3AP)RbBr3, achieving both ferroelasticity and ferroelectricity. Compound 1 undergoes a structure phase transition at 401 K belonging to Aizu notation 432F2(s), which has 12 ferroelectric equivalent polarization directions and 6 polar axes. Furthermore, 1 exhibits reversible second harmonic generation switching effects. Moreover, while the temperature varies, the reversible and rapid changes of ferroelastic domains in 1 are observed using a polarizing microscope, indicating that it is a ferroelastic material. This work provides a practical method for designing and synthesizing molecule‐based multiferroics. [ABSTRACT FROM AUTHOR]

Hybrid metal halides (HMHs) based phase transition materials have received widespread attention due to their excellent performance and potential applications in energy harvesting, optoelectronics, ferroics, and actuators. Nevertheless, effectively regulating the properties of phase transitions is still a thorny problem. In this work, two chiral lead‐free HMHs (R‐3FP)2SbCl5 (1; 3FP=3‐fluoropyrrolidinium) and (R‐3FP)2SbBr5 (2) were synthesized. By replacing the halide ions in the inorganic skeleton, the phase transition temperature of 2 changes with an increase of about 20 K, compared with 1. Meanwhile, both compounds display reversible dielectric switching properties. Through crystal structure analysis and Hirshfeld surface analysis, their phase transitions are ascribed to the disorder of the cations and deformation of the inorganic chains. [ABSTRACT FROM AUTHOR]

Integrating multiple switching behaviors in a single material is conducive to the development of smart devices, but still faces challenges, especially in finding new types of multiresponsive materials. Hybrid metal halides have been becoming promising candidates with the potential to exhibit changes in various physical and chemical properties upon structural phase transitions. Herein, a pair of enantiomers (R/S‐3‐OHPD)PbI3 (1R/1S; 3‐HOPD = 3‐hydroxypiperidine cation) is reported to show multichannel switching behaviors around room temperature triggered by a combined order‐disorder and displacive type phase transition that arouses a large lattice reorganization and shape change of the crystals. Owing to the inherent chiral, noncentrosymmetric, and semiconducting characteristics of the compounds, five other switching behaviors are realized besides the macroscopic deformation, that is, enthalpy, dielectric permittivity, photoluminescence, circularly polarized light excited photoluminescence, and photoelectric response. This study provides an exciting example of phase transition crystals for the development of integrated multifunctional materials. [ABSTRACT FROM AUTHOR]