Optical and scintillation properties of hybrid manganese(II) bromides with formamidinium and acetamidinium cations.

In recent years, hybrid manganese(II) halides (HMHs) have attracted wide attention due to their impressive optical properties, low toxicity, and facile synthetic processibility. Being effective reabsorption-free phosphors, these compounds demonstrate the potential to be used as low-cost solution-processable scintillators. However, most of the HMHs studied to date contain bulk organic cations and, as a result, are characterized by low density and low X-ray stopping power.

Exceptional structural diversity of hybrid halocuprates(I) with methylammonium and formamidinium cations.

Hybrid halocuprates(I) are nowadays the subject of intensive studies as promising materials for various optoelectronic applications. This class of materials is characterized by wide structural diversity enabled by a great variety in the size and shape of organic cations. Therefore, the study of composition-structure-property relationships is a key step for the rational design of new halocuprate materials with desired properties.

Crystallization Pathways of FABr-PbBr-DMF and FABr-PbBr-DMSO Systems: The Comprehensive Picture of Formamidinium-Based Low-Dimensional Perovskite-Related Phases and Intermediate Solvates.

In this study, we systematically investigated the phase diversity and crystallization pathways of the FABr excessive regions of two ternary systems of FABr-PbBr-DMF and FABr-PbBr-DMSO (where FA-formamidinium cations, DMF-dimethylformamide and DMSO-dimethyl sulfoxide solvents). In these systems, a new FAPbBr phase with a structure containing chains of vertex-connected PbBr octahedra is discovered, and its crystal structure is refined. We experimentally assess fundamental information on differences in the mechanisms of crystallization process in FABr-PbBr-DMF and FABr-PbBr-DMSO systems and determine possible pathways of crystallization of hybrid perovskites.

Nonmonotonic Photostability of BAMAPbI Homologous Layered Perovskites.

Layered lead halide perovskites (2D LHPs) are attracting considerable attention as a promising material for a new generation of solar cell devices. LHPs have been presented as a more stable alternative to the more widespread 3D bulk perovskite materials; however, a critical analysis of their photostability is still lacking. In this work, we perform a comparative study between BAMAPbI (BA─butylammonium and MA─methylammonium) 2D LHPs with different dimensionalities ( = 1-3) and MAPbI 3D perovskites.

Structural Disorder in Layered Hybrid Halide Perovskites: Types of Stacking Faults, Influence on Optical Properties and Their Suppression by Crystallization Engineering.

Layered hybrid halide perovskites (LHHPs) are an emerging type of semiconductor with a set of unique optoelectronic properties. However, the solution processing of high-quality LHHPs films with desired optical properties and phase composition is a challenging task, possibly due to the structural disorder in the LHHP phase. Nevertheless, there is still a lack of experimental evidence and understanding of the nature of the structural disorder in LHHPs and its influence on the optical properties of the material.

Solubility of Hybrid Halide Perovskites in DMF and DMSO.

Solution methods remain the most popular means for the fabrication of hybrid halide perovskites. However, the solubility of hybrid perovskites has not yet been quantitively investigated. In this study, we present accurate solubility data for MAPbI, FAPbI, MAPbBr and FAPbBr in the two most widely used solvents, DMF and DMSO, and demonstrate huge differences in the solubility behavior depending on the solution compositions.

Molecular and Supramolecular Structures of Triiodides and Polyiodobismuthates of Phenylenediammonium and Its N,N-dimethyl Derivative.

Despite remarkable progress in photoconversion efficiency, the toxicity of lead-based hybrid perovskites remains an important issue hindering their applications in consumer optoelectronic devices, such as solar cells, LED displays, and photodetectors. For that reason, lead-free metal halide complexes have attracted great attention as alternative optoelectronic materials. In this work, we demonstrate that reactions of two aromatic diamines with iodine in hydroiodic acid produced phenylenediammonium (PDA) and N,N-dimethyl-phenylenediammonium (DMPDA) triiodides, PDA(I)⋅2HO and DMPDA(I)I, respectively.

New Methylamine-Iodine-Mediated Solvent-Free Approach of Hybrid Perovskite Synthesis via the Redox Conversion of Metallic Lead Films.

The fast progress of lab-scale perovskite solar cells makes the problem of upscaling of perovskite thin-film deposition more and more acute; therefore, the development of new methods for perovskite deposition is highly desired. In this work, we proposed a new solution-free preparation approach for hybrid perovskite films based on the in situ generation of methylammonium iodide from methylamine and iodine vapors in the presence of an organic reducing agent conjugated with a redox process of metallic lead conversion with iodine vapor. At first, we demonstrated that either metallic lead or lead iodide powders can readily react with the solution of methylamine and iodine in the presence of isopropyl alcohol acting as a reducing agent, resulting in a phase-pure polycrystalline CHNHPbI perovskite.

Perovskite Puzzle for Revolutionary Functional Materials.

Widely spread crystal lattices of perovskites represent a natural flexible platform for chemical design of various advanced functional materials with unique features. An interplay between chemical bonding, defects and crystallochemical peculiarities makes the perovskite structure a "LEGO designer" utilizing natural features of chemical elements of the renowned Mendeleev's Periodic Table (PTE) celebrating its 150-year anniversary. In this mini-review, crystal chemistry and bonding features, physical and functional properties, preparation methods and tuning functional properties with periodicity "tools" of the PTE will be exemplified for legendary families of high-temperature superconductive cuprates, colossal magnetoresistive manganites and hybrid lead halides for a new generation of solar cells.

New Acidic Precursor and Acetone-Based Solvent for Fast Perovskite Processing via Proton-Exchange Reaction with Methylamine.

A new solvent system for PbI based on HI solution in acetone with a low boiling point is proposed. High solubility of PbI is caused by the formation of iodoplumbate complexes, and reaches a concentration of 1.6 M.

Methylammonium Polyiodides: Remarkable Phase Diversity of the Simplest and Low-Melting Alkylammonium Polyiodide System.

Newly discovered methylammonium polyiodides (MAI) are unique precursors for innovative solvent-free technologies in perovskite photovoltaics because MAI are liquids at room temperature and demonstrate high chemical reactivity. We investigated the features of an MAI-I system and built up a first phase diagram in wide temperature and composition ranges using data from differential scanning calorimetry, single-crystal X-ray diffraction, and visual thermal analysis. The phase diagram has been found to differ drastically from that of any related systems owing to the unique propensity of methylammonium toward forming a diversity of polyiodides with complicated crystal structures, namely, MAI, MAI, MAI, and MAI, found in this system for the first time.

Strategic advantages of reactive polyiodide melts for scalable perovskite photovoltaics.

Despite tremendous progress in efficiency and stability, perovskite solar cells are still facing the challenge of upscaling. Here we present unique advantages of reactive polyiodide melts for solvent- and adduct-free reactionary fabrication of perovskite films exhibiting excellent quality over large areas. Our method employs a nanoscale layer of metallic Pb coated with stoichiometric amounts of CHNHI (MAI) or mixed CsI/MAI/NHCHNHI (FAI), subsequently exposed to iodine vapour.