Role of Dispersive Interactions in Determining Structural Properties of Organic–Inorganic Halide Perovskites: Insights from First-Principles Calculations

A microscopic picture of structure and bonding in organic–inorganic perovskites is imperative to understanding their remarkable semiconducting and photovoltaic properties. On the basis of a density functional theory treatment that includes both spin–orbit coupling and dispersive interactions, we provide detailed insight into the crystal binding of lead–halide perovskites and quantify the effect of different types of interactions on the structural properties. Our analysis reveals that cohesion in these materials is characterized by a variety of interactions that includes important contributions from both van der Waals interactions among the halide atoms and hydrogen bonding. We also assess the role of spin–orbit coupling and show that it causes slight changes in lead–halide bonding that do not significantly affect the lattice parameters. Our results establish that consideration of dispersive effects is essential for understanding the structure and bonding in organic–inorganic perovskites in general and for providing reliable theoretical predictions of structural parameters in particular.