Structural and optoelectronic properties of quasi 1D hybrid 3-halogenopyridinium lead bromides

Abstract

The present work focuses on synthesis and structural, electronic, and optical properties of pyridinium lead bromides with halogen substituents in the meta position of the pyridine ring. All the compounds crystallize isotypically (spatial symmetry P21/c; four formula units in a unit cell). This makes the comparison of their properties straightforward. Both theoretical and experimental studies demonstrate dependence of the bandgap energies on the type of the halogen substituent in pyridinium ring due to an alteration of the crystallographic a-axes. Another effect caused by the type of the halogen substituent on electronic structure of the materials is an alteration of the valence band maxima positions and blue shift of the photoluminescence excitation maxima originated from contribution of the iodine states into valence band and overlapping of the conduction band states with π* orbitals of organic cations, respectively. The observed room-temperature photoluminescence of the synthesized materials demonstrates their principal applicability to optoelectronics.