The Outstanding Role of Dielectricity in Hybrid Solar Cell Absorbers

The perovskite crystal structure has been hosting a multitude of functionalities discovered over the last seventy years spanning from magnetism, ferroelectricity to supraconductivity. The most recent developments have brought forward hybrid halide perovskites containing a halide ion and small organic molecules as constituents of the crystal structure. The forerunner material is methylammonium lead iodide. One of the most remarkable properties of these emergent materials is their high charge carrier mobility and an outstanding robustness of the electronic properties towards lattice defects. In this presentation the role of dielectric effects will be discussed covering a very broad frequency range. Paraelectric effects will be contrasted to the role of apparent ferroelectricity, charge disorder and the potential misinterpretation of a number of experiments in this context. The hyperpolaron is shown as the charge carrier type peculiar for the hybrid perovskites.