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The present work reports on the experimental structures, and optoelectronic and luminescence properties of a series of low-dimensional hybrid organic–inorganic (1,5-pentanediamine) PbX4 (X = Cl, Br, I) perovskites. Single-crystal XRD data revealed that the chloride and bromide compounds form quasi 2D perovskite-like structures, whereas the iodide is a quasi 1D compound. In accordance with the experiment, DFT modeling predicts that the chloride and bromide are direct bandgap semiconductors. In contrast, the iodide is an indirect bandgap semiconductor. The experimentally and theoretically established bandgap widths of the perovskites follow the same trend. Finally, the luminescent properties of the perovskites were investigated. The study shows that the halogen anions determine the degree of disorder of the perovskite crystal lattices and the degree of distortion of the PbX6 octahedra therein. Both structural phenomena affect the dimensionality, optoelectronic, and luminescent properties of the studied perovskites. [ABSTRACT FROM AUTHOR]

In this work, the synthesis, crystal structure, morphology, and optoelectronic properties of novel quasi low-dimensional hybrid (bromomethyl)pyridinium crystalline phases (2-BrCH 2 PyH)Pb 2 Br 5 , (3-BrCH 2 PyH)PbBr 3 , and (4-BrCH 2 PyH)PbBr 3 are reported. The first compound formed quasi 2D crystals, while the other two species crystallized as quasi 1D structures. DFT calculations predicted that the bromides are semiconductors featuring electronic VB-to-CB transitions of ∼3.2 eV. (2-BrCH 2 PyH)Pb 2 Br 5 and (3-BrCH 2 PyH)PbBr 3 exhibited low-temperature (77 K) photoluminescence (PL). However, PL was not observed in (4-BrCH 2 PyH)PbBr 3 , which was presumably due to the small distance between the lead cations and bromine atoms of the 4-BrCH 2 PyH cations, resulting in a radiationless electronic transition. Furthermore, the studied species demonstrated quantum size effects.