The state of the art in photovoltaic materials and device research

Photovoltaic (PV) technology is crucial for the transition to a carbon-neutral and sustainable society. In this Review, we provide a comprehensive overview of PV materials and technologies, including mechanisms that limit PV solar-cell and module efficiencies. First, we introduce the PV effect and efficiency losses within the framework of the Shockley–Queisser model for solar-to-electrical power conversion. However, all PV technologies fall short of these idealizations in various aspects, from incomplete sunlight absorption to the loss of photocurrent and photovoltage caused by the recombination of photogenerated charge carriers in the cells. Approaching the efficiency limits of PV technology requires material innovations and device designs that minimize these losses. Solar-cell research and development presents several solutions to these problems that are intimately related to the properties of the specific PV materials. To increase efficiencies beyond the Shockley–Queisser limit (around 33%) for a single junction, research has focused on producing multi-junction solar cells. Although these cells do provide higher efficiencies, there are differences in performance between individual cells and full modules in single-junction technologies when integrated into multi-junction configurations, highlighting the challenges in moving from laboratory experiments to commercial products.