Two-dimensional innovative materials for photovoltaics

Two-dimensional materials provide an excellent example of how the discovery of new material compounds and nanophasescan drive sudden and exciting advances in technologicalapplications. Unexpected physicochemical effects havebeen reported in 2D materials, starting from graphene, the firstdiscovered stable 2D compound, and up to the most complex2D crystals, as hybrid perovskites. Such unexpected propertiesare induced by the low dimensionality and go well beyondthe expected physical changes induced by quantum confinement.In this review, general properties of 2D materials areshortly presented. We focus on the most advanced methodsused in material science to design and optimize 2D systemsproperties and report on the most interesting materials recentlycharacterized, including transition metal dichalcogenidemonolayers and van der Waals heterostructures. Issues andlimitations for 2D design and usage are also highlighted, withpossible routes and efforts to optimize electronic and opticalproperties for energy-related and photovoltaics applications.