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Recently, organic–inorganic hybrid perovskites exhibiting facile structural phase transitions have accumulated significant attention due to their switchable second-order nonlinear optical (NLO) properties, which hold significant promise for next-generation intelligent optoelectronic devices. In this study, we present a novel one-dimensional hexagonal hybrid perovskite, (4-methoxypiperidinium)CdCl3, which undergoes a reversible high-temperature structural phase transition at 389 K. Notably, (4-methoxypiperidinium)CdCl3demonstrates switchable second-order NLO and dielectric properties, accompanied by symmetry breaking from the centrosymmetric Pnmato noncentrosymmetric Pna21space group. Variable-temperature structure analyses reveal that this transition is mainly driven by the order–disorder transformation of the 4-methoxypiperidinium cations. Furthermore, it also features a promising photoluminescence performance with blue-light emission and a long lifetime of 25.34 ns. It is anticipated that this study will expand the family of hybrid perovskites exhibiting high-temperature phase transitions and offer valuable guidance for the design of new NLO switching materials with superior optoelectronic properties.

Organic–inorganic hybrid perovskite materials have attracted much attention because they combine the advantages of the organic and inorganic components at the molecular level. Organic–inorganic hybrid materials have both the structural variability and the flexibility of organic components, as well as magnetic, electrical, and thermal properties of inorganic components. A novel one-dimensional organic–inorganic hybrid halide perovskite material [Et3NCH2Br][PbBr3] (compound 1) undergoes a high-temperature phase transition at around 429.3 K, which is triggered by the order–disorder change of cations. Differential scanning calorimetry, a dielectric test, and single-crystal X-ray diffraction indicate that compound 1exhibits structural phase transition from the P21/cto P63/mspace group and a prominent dielectric anomaly. Strikingly, the bandgap of compound 1is 3.12 eV. It is believed that our findings will contribute to an alternative pathway for the design of multifunctional materials.

Hybrid organic–inorganic perovskites with structural transformation have garnered continued interest in recent years for their potential as multifunctional materials in the field of optoelectronics and smart devices. Herein, we report a novel hybrid organic–inorganic halide, [C5NOH12]2[Cd1.5Cl5(H2O)] (1). Remarkably, the centrosymmetric compound 1undergoes a structural transformation to a novel noncentrosymmetric hybrid perovskite [C5NOH12][CdCl3] (2) after dehydration. Accompanied by the chemical bond cleavage and reorganization, the zero-dimensional (0D) trinuclear cluster in compound 1transforms into an intriguing one-dimensional (1D) hexagonal perovskite structure in compound 2, generating multiple optoelectronic switching behaviors. It is worth mentioning that compound 2demonstrates successive structural phase transitions at 353 and 405 K, resulting in switchable second harmonic generation (SHG) and a dual dielectric response. In addition, compounds 1and 2both feature blue-light luminescence, with respective photoluminescence lifetimes of 0.73 and 1.42 ns. This work will offer a pioneering approach and expansive potential for the preparation and development of hybrid organic–inorganic perovskite materials with superior properties.

In recent years, organic-inorganic hybrid materials are widely designed and synthesized as switching materials for temperature response. However, due to the change of molecular arrangement inside the crystal during solid-solid phase transition, the distortion of crystal lattice and the great change of lattice parameters are often caused, which result in a poor repeatability and short life. Thus, designing phase change materials with small lattice changes helps to improve product life. In this article, a novel organic-inorganic hybrid material 3HDMAPAPbBr4(1, 3HDMAPA is 3-(hydroxydimethylammonio)propan-1-aminium) was successfully synthesized and characterized. For 1, organic cations filled in the van der Waals gap are connected by hydrogen bonds with halogens in the two-dimensional inorganic layer, forming a stable sandwich structure. During the solid-solid phase transition driven by temperature, the changes of inorganic skeleton are relatively small, and the disorder movement of organic cations does not affect the existence of hydrogen bonds, maintaining a relatively stable crystal structure. In addition, electrical property, optical property and crystal structures are analyzed and discussed in detail. We believe that our work will contribute to the development and application of phase change materials in response materials.

Organic–inorganic hybrid phase-transition materials have attracted widespread attention in energy storage and sensor applications due to their structural adaptability and facile synthesis. However, increasing the phase-transition temperature (Tc) effectively remains a formidable challenge. In this study, we employed a strategy to regulate intermolecular interactions (different types of hydrogen bonds and other weak interactions), utilizing bismuth chloride as an inorganic framework and azetidine, 3,3-difluoro azetidine, and 3-carboxyl azetidine as organic components to synthesize three compounds with different Tcvalues: [C3H8N]2BiCl5(1, 234 K), [C3H6NF2]3BiCl6(2, 256 K), and [C4H8O2N]3BiCl6(3, 350 K). 1is a one-dimensional chain structure and 2and 3are zero-dimensional structures. Analysis of the crystal structure and the Hirshfeld surface and 2D fingerprints further suggests that the intermolecular forces are efficiently modulated. These findings emphasize the efficacy of our strategy in enhancing Tcand may facilitate further research in this area.

A new tin(IV)-based perovskite-type hybrid semiconductor, bis(trimethyliodomethylammonium) hexachloridostannate(IV) ([TMIM]2SnCl6), has been synthesized as a switchable dielectric phase transition material, featuring a zero-dimensional inorganic architecture of [SnCl6]2–octahedra and organic [TMIM]+cations. It is found that [TMIM]2SnCl6displays a reversible structural phase transition at 329 K, demonstrated by the differential scanning calorimetry (DSC) measurements. The dielectric constant exhibits remarkable steplike anomaly around the phase transition temperature (Tc), indicating switchable dielectric behaviors. Variable-temperature structure analyses disclose that the drastic symmetry breaking occurs with the structure transferring from Fm3̅mto C2/cby the temperature decreasing. The mechanism of such a transition is associated with the order–disorder transformation of organic ammonium and the displacement of the inorganic framework, which benefits from the discrete anionic architectures that provide enough space. Meanwhile, [TMIM]2SnCl6shows a semiconducting property with a wide optical bandgap of ∼4.83 eV. This finding of the Sn(IV)-based metal halide with prominent phase transition and semiconducting behaviors will direct an executable pathway for designing novel multifunctional perovskite-type switchable materials.

[C6N2H18][SbI5] (1), a novel metal halide semiconductor with dielectric relaxation behavior, has been successfully synthesized, in which the cavities between the one-dimensional [SbI5]n2–polyanions are occupied by 2-methyl-1,5-pentanediammonium (2-MPDA) cations. 1undergoes a reversible solid-state phase transition at TC= 192.7 K and shows a step-like dielectric anomaly. Interestingly, above TC, distinct dielectric dispersion in a wide temperature range is also witnessed. Remarkably, the solid state UV–vis diffuse reflectance spectrum of 1exhibits a slightly gentler absorption edge at about 650 nm; that is, 1adopts an indirect band gap with 1.92 electron volts. The combined narrow band gap, strong photoconductivity effect, and excellent dielectric relaxation might shed light on the exploitation of lead-free hybrid metal halide molecular materials with promising application prospects in thermoresponsive relaxation-type dielectric materials and photovoltaic conversion devices.

Organic–inorganic hybrid perovskite, [CH3NH3]PbI3, holds a great potential for next-generation solar devices. However, whether the ferroelectricity exists in [CH3NH3]PbI3and results in the ultrahigh performance is not at present clear. Beyond that, no hybrid lead iodide perovskite ferroelectric has yet been found. Here, using precise molecular modifications, we successfully designed a room-temperature hybrid perovskite ferroelectric, [(CH3)3NCH2I]PbI3. Because of the high-symmetry and nearly spherical shape of [(CH3)4N]+cation, [(CH3)4N]PbI3crystallizes in a centrosymmetric space group P63/mat room temperature and undergoes a structural phase transition at 184 K. Accompanied by the introduction of halogen atoms on the cation from F to I, the phase transition temperature gradually increases to 312 K and the space group transforms into a polar C2 at room temperature. The strongest halogen bond energy of [(CH3)3NCH2I]–I and the largest volume of [(CH3)3NCH2I]+among these compounds might be possible reasons for the stabilization of ordered [(CH3)3NCH2I]+cation array and further reservation of its ferroelectricity at relatively high temperature. This work provides an efficient molecular design strategy toward the targeted harvest of room-temperature organic–inorganic perovskite ferroelectrics, and should inspire further exploration of the interplay between structure and ferroelectricity. The discovery of lead iodide perovskite ferroelectric also offers a foothold to the possibility for the existence of ferroelectricity in [CH3NH3]PbI3.

Molecular ferroelastic materials with high-temperature reversible crystal phase transition behavior are very rare and have currently become one of the hotspots in the field of ferroelastic materials. However, it is still a great challenge to synthesize a high-temperature ferroelastic phase transition material due to the insufficient theoretical knowledge about the structure transition. Here, we try to combine molecular design and crystal engineering to design molecular ferroelastic crystals with high phase transition temperatures. As expected, a new organic–inorganic hybrid, [(CH3)3NCH2Br]2–ZnBr4(1), is synthesized by molecular modifications, in which the directionality of the halogen···halogen interactions seems to play a crucial role in achieving a much higher temperature phase transition behavior. Intriguingly, the strip-type ferroelastic domains of 1were observed at room temperature.

Significant attention has been dovoted to the organic–inorganic hybrid perovskites in the realm of scientific research arising from their distinctive optical and dielectric properties along with structural tunability, rendering them highly versatile and adaptable materials. Herein, two novel one-dimensional organic–inorganic hybrid perovskites of (4-MPD)MnX3(4-MPD = 4-methylpiperidinium, X = Cl (1), X = Br (2)) were synthesized and demonstrated to, respectively, undergo reversible phase transitions at 376 and 368 K, characterized by differential scanning calorimetry and dielectric measurements. It is instresting to note that the replacement of Br by the Cl halogen atom has maintained the crsytal structures but devoted a slight increase in phase transition temperature. Variable-temperature structural analyses signify that the order–disorder change of 4-MPD cations acts as the driving force for such phase transitions from the Pnmato P1̅ space group. In addition, compounds 1and 2both emit strong red photoluminescence under UV excitation. The two compounds with high-temperature dielectric switching and photoluminescent properties will offer fresh insights for the design and investigation of novel multifunctional organic–inorganic hybrid perovskites.