Three-Dimensional Perovskite Phase Transition Materials with Switchable Second Harmonic Generation Properties Introduced by Homochiral (1<i>S</i>,4<i>S</i>)-2,5-Diazabicyclo[2.2.1]-heptane
Bo Li, Wenjun Rao, Xiuli You, Pan Wang, Jing Wei, Zhenhong Wei, Haina Zhang, Hu Cai
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-dimensional (3D) perovskite materials [1 S,4 S 2,5-2.2.1-H 2 dabch]RbX 3 ·0.5H 2 O (X = Cl, 1; Br, 2; I, 3 ) based on the chiral 1 S,4 S -2,5-diazabicyclo[2.2.1]heptane (1 S,4 S -2,5-2.2.1-dabch). The selection of homochiral organic cations ensures that the compounds 1 ∼ 3 crystallize in the noncentrosymmetric and chiral space group P 2 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 [1 S,4 S -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.