Dielectric relaxation and C-F…π (benzene ring) halo-bond interactions in a lead halide hybrid crystal with bromine/iodine heterogeneous double-chain layer

Hybrid materials of lead halide have numerous structural variations and superior optoelectronic capabilities. The hybrid crystal 1 prepared by the hybrid halogen method has the chemical formula [ p -F-Bz-1-APy][Pb 2 Br 3.2 I 2.8 ] (C 24 H 20 F 2 N 4 Br 3.2 I 2.8 Pb 2 ) ( p -F-Bz-1-APy =  p -fluoro-phenyl-1-aminopyridinium) with a space group of P 2 1 / c , two unequal [F1/F2-Bz-1-APy] + cations, and a heterogeneous double-chain inorganic layer made of edge-sharing Pb 2 Br 3.2 I 2.8 octahedron. The two cations adopt a lower-energy and more stable structural configuration, according to potential energy scans of the dihedral angles of the benzene and pyridine rings. The stacked structures are held together by a variety of intermolecular interactions, including hydrogen bonds (anion-cation, cation-cation), stacking (cation-cation), and the rare C-F2…π halo-bond. Hirshfeld surface analysis quantifies intermolecular interactions, revealing that interactions involving Br atoms and [F2-Bz-1-APy] + cations contribute more to the formation of stacking structures than interactions involving I atoms and [F1-Bz-1-APy] + cations. The logarithmic derivative method clearly reveals two dielectric relaxation processes, one in the low frequency region (<10 2 Hz) masked by the DC conductance and one in the high frequency region (10 2 -10 7 Hz), which were then fitted by the Arrhenius formula to obtain their corresponding activation energies of 77.75 KJ/mol and 144.14 KJ/mol, respectively. Our research offers inspiration and a framework for the development of novel lead halide-based optoelectronic materials and dielectric analyses.