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Ionic polarization and dielectric function play a fundamental role in the optoelectronic properties of hybrid perovskites, currently one of the most studied materials for next generation photovoltaics. The hybrid nature of the crystal, with molecular dipoles that can reorient within the inorganic lattice, gives rise to a complex dielectric response in the bulk material that has been largely studied and debated. Here, we investigate the nature and the relaxation properties of the dielectric polarization of hybrid perovskites at finite temperature by means of classical molecular dynamics. We provide evidence that a simple ionic model of classical interatomic forces is able to explain qualitatively the temperature and frequency dependence of the dielectric constant providing a picture that is fully consistent with experimental data. The constant dielectric function in the low-temperature phase is controlled by ionic displacements, while the temperature-dependent paraelectric behavior of the tetragonal phase is due to reorientation of dipoles that are responsible for the discontinuity at the orthorhombic-to-tetragonal transition. In the frequency domain, the molecular reorientations give rise to a broad band that is located in the 0.1 THz timescale at room temperature and that shifts down to the GHz timescale when cooling the system toward the tetragonal-to-orthorhombic phase transition. The relation between relaxation time and maximum absorption frequency is also clarified. [ABSTRACT FROM AUTHOR]

Hybrid lead halide perovskites have progressively overcome the horizon of materials for novel, highly efficient solar cells and are now proposed for a variety of optoelectronic, nanoelectronic, and thermoelectric applications. In this Perspective, we focus on a still scarcely explored and yet extremely thrilling playground: the use of lead halide perovskites to design efficient magneto-electronic and magneto-optic applications. Our analysis is pointed to emphasize the unique combination of strong spin–orbit coupling and wide structural and chemical flexibility, which characterize the lead halide perovskites. Using model calculations, we furnish a qualitative evidence of their capabilities for what concerns the charge–spin conversion mechanism, which is basic to some of the most visionary spin-orbitronic implementations, such as the magnetoelectric switching and the spin-diffusive transistor. [ABSTRACT FROM AUTHOR]