structure was found for the first time in a mineral composed by CaTiO 3 in 1839. Since then, multiple metal oxide perovskites (AMO 3 ) were developed, which have interesting properties for ferroelectric, superconductive, and pyroelectric applications. Metal halide perovskites (X is a halide anion such as Cl − , Br − , or I − ), which were developed later, display promising semiconducting properties. In particular, lead halide perovskites (APbX 3 ) are the most widely studied perovskite composition and are classified according to the A cation into hybrid perovskites (methylammonium bromide, MA or formamidinium, FA) and all-inorganic perovskites (cesium, Cs). [2] The electronic properties of the perovskites are related to the M-X bond, while the size of the A cation can introduce crystal distortion and change the symmetry of the ideal cubic crystal structure. [3] Interestingly, by using a large A organic cation, low-dimensional halide perovskites can be formed, including 2D sheets, 1D chains, or 0D clusters. [4] Lead halide perovskites are revolutionizing photovoltaic technology thank to their outstanding optical and electronic properties, low cost, and simple preparation. Compared to silicon-based technology, perovskites are prepared from more abundant and low-cost precursors. The superior performance and high efficiency of perovskite-based solar cells (PSC) are due to i) high optical absorption coefficient, ii) long carrier diffusion length This article delineates the state of the art for several materials used in the harvest, conversion, and storage of energy, and analyzes the challenges to be overcome in the decade ahead for them to reach the market and benefit society. The materials covered have had a special interest in recent years and include perovskites, materials for batteries and supercapacitors, graphene, and materials for hydrogen production and storage. Looking at the common challenges for these different systems, scientists in basic research should carefully consider commercial requirements when designing new materials. These include cost and ease of synthesis, abundance of precursors, recyclability of spent devices, toxicity, and stability. Improvements in these areas deserve more attention, as they can help bridge the gap for these technologies and facilitate the creation of partnerships between academia and industry. These improvements should be pursued in parallel with the design of novel compositions, nanostructures, and devices, which have led most interest during the past decade. Research groups are encouraged to adopt a cross-disciplinary mindset, which may allow more efficient use of existing knowledge and facilitate breakthrough innovation in both basic and applied research of energy-related materials.
