Bistable switches (electrical switching between "ON" and "OFF" bistable states) have gradually developed into an ideal category of highly intelligent materials, due to their significant applications in optical technology, signal processors, data storage and other switchable media applications in the field of electrical devices. Here, we successfully designed and synthesized4fluoro-phenethylamine; M = Cd (1), Mn (2)), which realized the coupling of thermo-dielectric switching characteristics, semi-conductor characteristics and photo-luminescent properties. DSC (differential scanning calorimetry) and dielectric measurements show that 1 is a sensitive dielectric bistable switch between the high dielectric (ON) and low dielectric (OFF) states. The temperature-variable single crystal structure shows that the both 1 and 2 undergo a high-temperature reversible phase transition around 383 K/380 K, which is caused by the order-disordered transformation of organic cations and the slight distortion of the inorganic framework. In particular, 1 shows outstanding switchable dielectric behavior and semiconducting properties. Further, 1 and 2 emit strong green and yellow luminescence at 527 and 595 nm, respectively.

Due to the existence of some cross properties such as SHG (second-harmonic generation), ferroelectricity, piezoelectricity, and thermoelectricity, molecular ferroelectrics have been widely used as a composite multipurpose material. Particularly, organic–inorganic molecular ferroelectrics have received much interest recently because of their unique flexible structures, friendly environment, ease of synthesis, etc. Also, these hybrids show great flexibility in band-gap engineering. Here we report a new molecular halide, [C6H13N3SbBr5] n (1; C6H13N3 = 1-(3-aminopropyl)­imidazole), which experiences a unique ferroelectric to paraelectric phase transition at around 230 K from space group P21 to P21/c. Significantly, compound 1 exhibits a narrow band gap with a value of 2.52 eV, large pronounced SHG-active, perfect rectangle hysteresis loops with a large spontaneous polarization of 6.86 μC/cm2. DSC (differential scanning calorimetry) and dielectric dependence on temperature tests and the volume change before and after the phase transition show that compound 1 is characterized by a second-order phase transition. These findings will contribute to the multifunctional materials field of organic–inorganic hybrids.

Two novel semiconductor organic–inorganic hybrid perovskites [(C6H15BrNO)2MBr4] (M = Cd for 1 and Zn for 2) were successfully synthesized, which undergo a high-temperature reversible transition at T c (T c = 379 K for 1, 407 K for 2). Differential scanning calorimetry (DSC) curve test shows that there is a pair of reversible thermal abnormal peaks at 379/348 K for compound 1 during the heating/cooling process, and the thermal hysteresis loop is ∼31 K. For compound 2, there is a pair of reversible thermal anomaly peaks at 407/375 K, and the thermal hysteresis loop is ∼33 K, indicating that the phase transition to a first-order phase transition. The dielectric test further confirmed the phase transition. X-ray single-crystal diffraction analysis showed that the space groups of compounds 1 and 2 at 300 K belong to C2/c and P 21/ c , and the temperature-variable powder X-ray diffraction (PXRD) test proved that compounds 1 and 2 had reversible structural phase transition. In addition, both UV–vis diffuse reflectance spectroscopy and density functional theory (DFT) calculations have confirmed that both compounds 1 and 2 are direct band gaps, with values of 4.116 and 4.205 eV, respectively. The above results show that 1 and 2 have fast switchable dielectric properties and potential applications in semiconductor materials.

The multifunctional two‐dimensional (2D) organic‐inorganic hybrid perovskites have potential applications in many fields, such as, semiconductor, energy storage and fluorescent device etc. Here, a 2D Ruddlesden‐Popper (RP) perovskite (IPA)2(FA)Pb2I7 (1, IPA+=C3H9NI+, FA+=CN2H5+) is determined for its photophysical properties. Strikingly, 1 reveals a solid reversible phase transition with Tc of 382 K accompanied by giant entropy change of 40 J mol−1 K−1. Further optical investigations indicate that 1 reveals a narrow direct bandgap (2.024 eV) attributed to the slight bending of I−Pb‐I edge and inorganic [Pb2I7]n layer and a superior photoluminescence (PL) emission with super long lifetime of 0.1607 ms. It is believed that this work will pave an avenue to further design multifunctional semiconductors that combines energy storage and photoelectric materials.

Piezoelectric responsive molecular ferroelectrics have become a research hotspot due to their advantages of simple fabrication, environmental friendliness, light weight and good mechanical flexibility. Here we proposed a new kind...