Although research on organic–inorganic hybrid perovskites (OIHPs) has grown exponentially in the past two decades, the high phase transition temperature of OIHP materials is still one of the insurmountable difficulties. Herein, a series of A2BX4 type OIHP materials [(2,n-DFBA)2PbCl4] (n = 3, for 1; n = 4, for 2; n = 5, for 3; n = 6, for 4) have been prepared by reactions of double-substituted difluorobenzylamine (difluorobenzylamine = DFBA) with lead chloride in concentrated HCl aqueous solution. It was found the OIHP compounds 1–3 proceed a switchable phase transition with phase transition temperatures (T c) at 449 K (1), 462 K (2) and 500 K (3), higher than that of the parent compound [(BA)2PbCl4] (BA = benzylammonium) at 438 K, but compound 4 exhibits no phase transition. A crystal structure analysis elucidated that the organic template ligands DFBA lead in the inorganic part in compounds 1–3 to a two-dimensional (2D) perovskite structure, while that in compound 4 leads to a one-dimensional (1D) chain structure. The different double-substituted positions of fluorine atoms on benzylamine have important influences on the phase transition in compounds 1–4.

Two 3D organic–inorganic hybrid perovskite ferroelectrics [3.2.2-dabcn]RbX3 (X = Br for 1; X = I for 2) with Curie temperatures at 342 K and 293 K were designed and prepared by reaction of 1,5-diazabicyclo[3.2.2]nonane with RbX.

No abstract

Switchable second harmonic generation (SHG) materials have potential applications in information storage, signal processing, and so on because they can switch between SHG-on and SHG-off states. In this work, we designed and synthesized three organic−inorganic hybrid Rb halide three-dimensionalThe selection of homochiral organic cations ensures that the compounds 1∼3 crystallize in the noncentrosymmetric and chiral space group P2 1 2 1 2 1 , which further leads to reversible SHG responses of the three compounds. Through differential scanning calorimetry (DSC) and dielectric measurements, it revealed that the phase transition point of the compounds 1∼3 increased with RbCl, RbBr, and RbI. This is because the hydrogen interaction H•••X between the inorganic framework [RbX 3 ] n and the organic cation [1S,4S-2,5-2.2.1-H 2 dabch] 2+ is increased with the order of I > Br > Cl. This study can provide an effective molecular design strategy for the exploration and construction of temperature-tunable SHG switching materials.

No abstract