The effect of the halogen on the structural, optoelectronic, and luminescent properties of hybrid (1,5-pentanediamine)PbX₄ (X = Cl, Br, I) perovskites

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.