ИСТИНА

Toxicity and bio-availablity compromise lead perovskites, which have shown themselves as wonderful materials for modern photovoltaics. Despite high efficiency of light-to-current conversion and low cost, ecological and environmental issues hinder widespread uses of lead perovskites as light-harvesting materials. In response to this issue, other compounds, first of all, iodometallates and polyiodometallates have become increasingly attractive. In this paper, we present and discuss our recent discoveries in the field of chemistry of inorganic and hybrid iodobismuthates and polyiodobismuthates. These compounds are non-toxic and provide no harm to the environment but their photovoltaic prospects have not yet been studied in detail. We consider complex bismuth iodides and polyiodides formed with different cations ranging from those of alkali and rare-earth metals to various singly or doubly charged organic ammonium cations. We discuss their structural features paying utmost attention to dimensionality of iodobismuthate substructures and their assembling into supramolecular structures by using various weaker interactions, including hydrogen and halogen bonds. We also observe their electronic structures; in particular, we will show that the fine structure near the Fermi level is less sensitive to the nature of a cation and that the optical absorption is primarily associated with the charge transfer from the I 5p orbitals at the top of the valence band to the Bi 6p orbitals at the bottom of the conduction band. Moreover, we will show that a number of non-covalent interactions influence the electronic structure and hence optical absorption properties allowing their fine tuning. Finally, we discuss synthetic methods and pay attention to polyiodides as intermediate products, which can be used as media for the synthesis