The past five years have witnessed remarkable advances in the field of solar cells and light-emitting devices with the perovskite metal halide, CH₃NH₃PbI₃, and related family of materials. These semiconductors form nearly defect free, crystalline films at low temperatures that exhibit high optical absorption, long-range charge transport, and efficient charge collection, yielding high performance LEDs and solar cells. The prospects for advancing device efficiencies are contingent upon exploring new perovskite compositions and structures. One such structural variant is represented by lower-dimensionality layered perovskite derived from their 3D counterparts (ABX₃) by increasing the distance between the interconnected inorganic sheets with the appropriate organic cations. Lower-dimensionality layered perovskites formulations permit for band gaps and exciton binding energy tuning, carrier mobility facilitated by the inorganic moeities, with the organic moieties providing additional controls for stability, light harvesting, and intralayer charge transport. Nanocrystals is yet another variant in perovskites that promises to yield new opportunities in advancing device performance. Perovskites are typically synthesised via wet-chemistry routes, allowing for mixing at a molecular level, and resulting in materials with high phase purity. By carefully controlling the reaction conditions such as temperature, solvent, and ligands, hybrid perovskites of morphologies ranging from 0D quantum dots to 3D single crystals; and sizes stretching 6 orders of magnitude can be prepared. This presentation will outline a broad palette of elemental substitutions, solid solutions, and multidimensional families that will provide the next step towards the advances of the perovskite solar cells and light-emitting devices. Challenges and opportunities in perovskite materials beyond methyl ammonium lead iodide, with emphasis on their recombination dynamics, optoelectronic properties, and integration into solar cells and light-emitting devices, will also be addressed.

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