Theoretical investigation on two‐dimensional monofluorinated phenylethylammonium perovskite

Abstract

AbstractMore and more two‐dimensional (2D) perovskites are synthesized and used in solar cells. Theoretical investigations on their structural and electronic properties can explore the origin of crystal structural and optoelectronic differences caused by organic spacers. Here, formation energy, non‐covalent interaction, band structure, exciton binding energy, carrier mobility, and optical absorption spectra of 2D monofluorinated phenylethylammonium lead iodide perovskite were calculated using density functional theory. Results show that steric effect leads to the orientational disorder of spacers in ortho‐fluorinating phenylethylammonium perovskite, which further lead to a poor photovoltaic performance and weak interaction leads to the herringbone configuration of spacers in meta‐fluorinating phenylethylammonium perovskite. Exciton binding energy significantly influences the short circuit current density (JSC) which can well explain the experimental trends of JSC. This research shows that para‐fluorinating is the best choice and the important of weak interactions and inductive effect, providing a guideline for new spacer designing.