The first salicylaldehyde Schiff base organic-inorganic hybrid lead iodide perovskite ferroelectric

Nonlinear Optical Switching in a Tin-Based Multilayered Halide Perovskite Activated by Stereoactive Lone Pairs and Confined Rotators

In recent years, there has been a surge in research enthusiasm on searching for solid-state nonlinear optical (NLO) switching materials in halide perovskites owing to their exceptional structural flexibility, compositional diversity, and broad property tenability. However, the majority of reported halide perovskite NLO switching materials contain toxic elements (e.g., Pb), which raise significant environmental concerns. Herein, we present a novel lead-free multilayered halide perovskite NLO switching material, (BA)2(EA)2Sn3Br10 (1, where BA is butylammonium and EA is ethylammonium). Driven by the stereochemically active lone-pair electrons of the Sn2+ cation and the cage-confined effect of EA rotators, 1 undergoes a phase transition with symmetry breaking from P4/mnc to Cmc21, which gives rise to a highly efficient modulation of the quadratic NLO property (0.7 times that of KH2PO4) at a high temperature of 353 K. Furthermore, crystallographic investigation combined with theoretical calculations reveals that the efficient modulation of NLO properties in 1 stems from the synergistic effects between stereochemically active lone pair-induced octahedral distortions and order/disorder transformation of organic cations. This study opens up an instructive avenue for designing and advancing environmentally friendly solid-state NLO switches in halide perovskites.

Dehydration Induced a Structural Transformation into a One-Dimensional Hybrid Perovskite with Second Harmonic Generation and Dual Dielectric Switching

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 1 undergoes 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 1 transforms into an intriguing one-dimensional (1D) hexagonal perovskite structure in compound 2, generating multiple optoelectronic switching behaviors. It is worth mentioning that compound 2 demonstrates successive structural phase transitions at 353 and 405 K, resulting in switchable second harmonic generation (SHG) and a dual dielectric response. In addition, compounds 1 and 2 both 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.

Photofunctions in Hybrid Systems of Schiff Base Metal Complexes and Metal or Semiconductor (Nano)Materials

Composite materials very often provide new catalytic, optical or other physicochemical properties not observed for each component separately. Photofunctions in hybrid systems are an interesting topic of great importance for industry. This review presents the recent advances, trends and possible applications of photofunctions of hybrid systems composed of Schiff base metal complexes and metal or semiconductor (nano)materials. We focus on photocatalysis, sensitization in solar cells (DSSC-dye sensitized solar cell), ligand-induced chirality and applications in environmental protection for Cr(VI) to Cr(III) reduction, in cosmetology as sunscreens, in real-time visualization of cellular processes, in bio-labeling, and in light activated prodrug applications.