The Diversity of Layered Halide Perovskites

Abstract

The two-dimensional congeners of the well-known three-dimensional perovskites display new properties enabled by their reduced dimensionality. Here, organic molecules separate inorganic sheets, affording the properties of both discrete molecules and extended solids in single, well-defined materials. The choice of organic and inorganic components engenders a large range of structural motifs, which yield diverse properties such as electroluminescence, white-light emission, photoconductivity, porosity, and reactivity. Layered halide perovskites have been known for decades. Their recent resurgence compels us to understand the fundamental studies that set the stage for their current technological relevance. We are not providing a comprehensive review of this vast and rapidly growing field. Instead, we highlight some of the discoveries that have directed current research in this field. We hope to introduce new researchers to layered halide perovskites to bring fresh perspectives to study this venerable family of materials that continue to surprise us today.

Two‐Dimensional Halide Perovskites in Solar Cells: 2D or not 2D?

“…However,a st he focus of this Minireview is their use in solar cells, we will only makea brief overview of the most relevant structuralf eatures and properties of this family of materials for such applications. For ac omprehensive discussion on the chemistry,h istory, and properties of 2D halide perovskites there are somee xcellent reviews [8][9][10] which are highly recommended. Perovskite-type compounds are structures that can consist of aw ide variety of metal ions and organic cations and anions.…”

“…Cutting layers along the h110i direction of the 3D perovskite structurep rovides the h110i-oriented family A 2 A' m B m X 3m + 2 , m > 1. This family is less common (around nine reported exam-ples) [9] and consists of corrugated inorganic sheets that can be derived from the face diagonal of the cubic 3D lattice. For instance, when2 ,2'-(ethylenedioxy)bis(ethylamine) (EDBE) is incorporated into an EDBEPbBr 4 perovskite, hydrogen-bond interactions are enabled between the two ether groups in the EDBE cation and the terminal ammonium of an adjacent EDBE cation,i mposing as taggered configuration in the organic layer,t hust emplating the h110i sheets.H owever,t od ate, there are no reports of the use of h110i-layered perovskites as absorbers in solar cells, perhaps because of the difficulty of modulating the thickness of the inorganic layers in these materials.…”

The Role of Chloride Incorporation in Lead‐Free 2D Perovskite (BA)2SnI4: Morphology, Photoluminescence, Phase Transition, and Charge Transport

“…Except for the long‐term environmental stability, the toxicity of lead casts a shadow on the large‐scale perovskite‐based optoelectronic applications in practice in both 2D and 3D perovskite materials . There has been a growing effort to replace lead perovskites with environment‐friendly lead‐free compounds by substituting the divalent lead (Pb) with nontoxic metals including bismuth (Bi), germanium (Ge), and tin (Sn) .…”

Compositional and Dimensional Control of 2D and Quasi‐2D Lead Halide Perovskites in Water

“…The crystal structures of perovskite powders were determined by powder X‐ray diffraction (PXRD) measurement ( Figure ). The PXRD of 1–8 supports the orthorhombic crystal structure and 2D molecular geometry, where the layered structure is self‐organized via hydrogen bonds between the metal bonded halogens and the organic ammonium cations as well as van der Waals interactions between adjacent tails of those cations . All the compounds have very sharp diffraction peaks which indicate high crystallinity of the compounds.…”