Perovskite-Like Organic-Inorganic Hybrid Lead Iodide with a Large Organic Cation Incorporated within the Layers.

A great effort has been made to investigate 2D perovskites to improve the stability and controllability in the fabrication of photoelectronic devices. As far as we know, only small organic cations such as methylammonium can incorporate into the multilayered perovskite structure except the cations sandwiched between the inorganic layers. We report here a new layered lead iodide, (H2Aepz)3Pb4I14 (1), where larger organic cations, bis-protonated 2-(2-aminoethyl)pyrazole (Aepz), not only were sandwiched between the inorganic layers but also were incorporated within the perovskite-like PbI layered structure. Another 2D compound, (H2Aepz)PbI4 (2), was also prepared that was a one-layer perovskite. A simple Schottky device was prepared to investigate the photoelectroresponsive properties of the compounds in comparison with that of a typical organic-inorganic hybrid perovskite. In general, the energy gap is decreased with an increase in the perovskite layers, but the band gap of two-layered 1 is larger than that of one-layered 2. The photocurrent densities of the compounds are in the order of 1 < 2 < (CH3NH3)PbI3, which is discussed based on the crystal structures and band energy gaps.

A lanthanide-titanium (LnTi11) oxo-cluster, a potential molecule based fluorescent labelling agent and photocatalyst.

Although a lot of titanium oxo-clusters (TOCs) have been synthesized and characterized, research studies on their application properties are still limited. The work described here is not only aimed at the synthesis and crystal structures of the TOCs, but also aimed at exploration of their potential applications in molecule based fluorescence labelling and photocatalysis. Three heterometallic TOC compounds with lanthanide (Ln) elements Sm(iii) (1), Eu(iii) (2) and Gd(iii) (3) are prepared and their cluster structures are characterized as LnTi11 cages. Compound 2 exhibits the characteristic fluorescence of Eu(iii) and the emission intensity can be decreased upon irradiation and recovered by air oxidation, which is attributed to the energy transfer between Eu(iii) and photo-induced Ti(iii) of the oxo-TiO cluster. The fluorescence intensity of 2 can be significantly increased when treated with 1,10-phenanthroline. The catalytic properties of 2 were determined by the degradation of dyes on a paper substrate. Compound 2 has potential applications as a molecule based fluorescent labelling agent and photodegeneration catalyst.