2D halide perovskite‐like semiconductors are attractive materials for various optoelectronic applications, from photovoltaics to lasing. To date, the most studied families of such low‐dimensional halide perovskite‐like compounds are Ruddlesden–Popper, Dion–Jacobson, and other phases that can be derived from 3D halide perovskites by slicing along different crystallographic directions, which leads to the spatially isotropic corner‐sharing connectivity type of metal‐halide octahedra in the 2D layer plane. In this work, a new family of hybrid organic–inorganic 2D lead halides is introduced, by reporting the first example of the hybrid organic–inorganic post‐perovskite 3‐cyanopyridinium lead tribromide (3cp)PbBr3. The post‐perovskite structure has unique octahedra connectivity type in the layer plane: a typical “perovskite‐like” corner‐sharing connectivity pattern in one direction, and the rare edge‐sharing connectivity pattern in the other. Such connectivity leads to significant anisotropy in the material properties within the inorganic layer plane. Moreover, the dense organic cation packing results in the formation of 1D fully organic bands in the electronic structure, offering the prospects of the involvement of the organic subsystem into material's optoelectronic properties. The (3cp)PbBr3 clearly shows the 2D quantum size effect with a bandgap around 3.2 eV and typical broadband self‐trapped excitonic photoluminescence at temperatures below 200 K.

Using density functional theory (DFT) in conjunction with ultraviolet (UPS) and X‐ray photoelectron spectroscopy (XPS), we investigated a number of complexes and macromolecules. We have shown on a large set of UPS, XPS, and DFT data that the calculated Kohn–Sham energies of organic and metalorganic complexes can be used as approximate ionization energies (IEs). It is possible to evaluate IEs with an accuracy of 0.1 eV with the density functional approximation (DFA) defect approach. This method has been successfully tested on a large number of boron β‐diketonates and d‐metal chelate and sandwich complexes. We interpreted the bands in the valence region of the XP spectra of macromolecular organosilicon compounds in the solid state by taking into account the density of states and the ionization cross‐sections. According to DFT calculation results, the one‐electron states in the valence region of the model compounds correlate with the positions of the spectral band maxima. © 2015 Wiley Periodicals, Inc.

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In this work, we apply polarized Raman spectroscopy for study of internal vibrations of the 3-cyanopyridinium cation in the halide post-perovskite (3cp)­PbBr3 (3cp = 3-CN-C5H5NH+). For a single cation, the vibrational frequencies and intensities of the Raman signal were calculated using the density functional theory. Selection rules were established for vibrations of cations in the crystal. These rules together with modeling results were used to identify the internal vibrations of the cation in the Raman spectrum of the crystal. Narrow and isolated internal vibrations of cations could be used as spectators of the crystalline environment.

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