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A high efficiency of laser-light conversion and short cutoff edge is essential to an ultraviolet (UV) nonlinear-optical (NLO) material. Previous researches on phosphates were mainly centered on alkali-metal or alkali-earth-metal phosphate systems, resulting in relatively weak NLO responses. Through the introduction of transition-metal cadmium and alkali-metal cesium elements with large radii into the phosphate system, a new UV NLO pyrophosphate, CsLiCdP2O7, has been synthesized. It exhibits a high second-harmonic-generation (SHG) efficiency of 1.5KH2PO4and is transparent down to 200 nm. This work provides a new path for the design of UV NLO materials with high SHG efficiencies and short cutoff edges by introducing a transition metal with a d10electron configuration and an alkali metal with a large radius into phosphate systems.

Hybrid organic–inorganic perovskite materials have demonstrated great potential in the field of photovoltaics and photoelectronics. On the basis of the high degree of structural flexibility and compatibility, diverse molecular functional materials have been assembled by modifying the length of the organic components and/or dimensionality of the inorganic frameworks. In this paper, we present a chiral lead-free organic–inorganic hybrid, (piperidinium)2SbCl5(1), which follows the one-dimensional inorganic frameworks of the corner-sharing SbCl6octahedra. Strikingly, 1displays a dielectric phase transition at Tc= 338 K, changing from the chiral space group of P212121to polar Pna21upon heating. Crystal structure analyses reveal that an unusual thermally activated conformation change of the piperidinium cations affords the driving force to the phase transition of 1. That is, organic piperidinium moieties display a chairlike conformation below Tc, which transforms to a boatlike structure above Tc. Such an unprecedented change is strongly coupled to the dielectric transition along with notable steplike anomalies, which suggest that 1could be used as a potential switchable dielectric material. Besides, the temperature-dependent conductivity and theoretical analysis of its electronic structure disclose the semiconducting behavior of 1. This study paves the pathway to the design of new lead-free semiconducting perovskites with targeted properties for optoelectronic application.

A new one-dimensional ABX3-type organic–inorganic hybrid phase transition compound, 1-pentyl-3-methylimidazolium tribromoplumbate (1), where the PbIIion exhibits hemicoordination geometry, resulting in anionic (PbBr3)nchains of an edge-shared PbBr5polyhedron, has been successfully synthesized. 1undergoes a reversible second-order phase transition at about 136 K. The dielectric constants of 1exhibit an obvious steplike anomaly tuned between a high dielectric state in the high-temperature phase and a low state in the low-temperature phase. The origin of its phase transition is ascribed to the order–disorder transformation of the cation coupled with the relative displacement of the Br atoms. These findings provide a new approach to exploring a novel ABX3-type compound with functional phase transition properties.

Organic–inorganic hybrid lead halide (e.g., CH3NH3PbX3, where X = CI, Br, and I) nanowires (NWs) with remarkable electric and optical properties have recently garnered increasing attention, owing to their structural flexibility and tunability compared to inorganic semiconducting NWs. While most recently reported NWs are limited to methylammonium/formamidinium three-dimensional lead halide perovskites, it is urgent to develop new organic–inorganic hybrid semiconducting NWs. Here, broad-band-emissive single-crystal semiconductive NWs based on a new ABX3-type organic–inorganic chain hybrid, (2-methylpiperidine)lead tribromide, are reported. It is believed that this work will enrich the organic–inorganic hybrid semiconducting NWs and may provide potential applications for LED displaying.

A one-dimensional (1D) organic–inorganic hybrid iodoplumbate crystal (1, C4H12NPbI3, TMAPbI3) can undergo two reversible phase transitions as the temperature decreases. Its dynamic phase-transition behaviors were carefully studied by dielectric measurements, thermal analysis, and variable-temperature crystallographic studies. These results indicate that the phase transitions possess a disorder–order feature with a noncentrosymmetrical intermediate phase structure. Due to the existence of the ordered motion and reorientation of the C4H12N+cation, 1undergoes two phase transitions: the first one from space group P63/mat room temperature to Pmat 163 K with symmetry breaking, and the second one from space group Pmat 163 K to P61at 142 K with partial symmetry restoration. Our results indicate that there is an existence of a transitional structure with a low symmetry space group during the disorder–order-type phase transitions, which can provide us valuable information to deeply understand the disorder–order phase transition in organic–inorganic hybrids.