Organic–Inorganic Hybrid Heterometallic Halides with Low-Dimensional Structures and Red Photoluminescence Emissions

In recent years, although low-dimensional hybrid lead halides have received great attention due to the fascinating photoluminescent (PL) properties, the research is still on the early stage and only limited phases have been explored and characterized. Here, by introducing heterometals as mixed structural compositions and optical activity centers, we prepared a series of low-dimensional hybrid heterometallic halides, namely as, [(Me)-DABCO]₂Cu₂PbI₆, [(Me)₂-DABCO]₂M₅Pb₂I₁₃ (M = Cu and Ag) and [(Me)₂-DABCO]Ag₂PbBr₆ (Me = methyl group, DABCO = 1,4-diazabicyclo[2.2.2]octane). These hybrid halides feature a low-dimensional 0D [Cu₂PbI₆]^2- cluster, a 1D [M₅Pb₂I₁₃]^4- chain, and a 2D [Ag₂PbBr₆]^2- layer, respectively, on the basis of corner-, edge- and face-sharing connecting of [MX₄] tetrahedrons, [PbX₅] quadrangular pyramids, and [PbX₆] octahedrons. Under the photoexcitation, these hybrid heterometallic halides exhibit deep-red luminescent emissions from 711 to 801 nm with the largest Stocks shift of 395 nm. The temperature-dependent PL emissions, PL lifetime, and theoretical calculations are also investigated to probe into the intrinsic nature of photoluminescent emissions. This work affords new types of hybrid halides by introducing different metal centers to probe into the structural evolution and photoluminescent properties.