Opening charge transport pathways: In perovskite solar cells, the insulating nature of passivation layers needed to boost open-circuit voltage also increases the series resistance of the cell and limits the fill factor. Most improvements in power conversion efficiency have come from higher open-circuit voltage, with most fill factor improvements reported for very small-area cells. Peng et al. used a nanostructured titanium oxide electron transport layer to boost the fill factor of larger-area cells (1 square centimeter) to 0.84 by creating local regions with high conductivity. Science , this issue p. 390

Textiles are essential to humans in a variety of ways, especially clothing. However, the speed at which they end up in landfills is astonishing (one garbage truck per second), posing a severe risk to the environment, if the trend continues. Governments and responsible organizations are starting to make calls to different stakeholders to redesign the textile chain from linear to circular economy. In this perspective, we highlight some of the possible approaches to be undertaken including the need for the creation of renewable raw materials sources, rethinking production, maximum use and reuse of textile products, reproduction, and recycling strategies, redistribution of textiles to new and parallel markets, and improvising means to extend the textiles lifetime.

Sodium‐ion batteries as a prospective alternative to lithium‐ion batteries are facing the challenge of developing high‐performance, low‐cost and sustainable anode materials. Hard carbons are appropriate to store sodium ions, but major energy and environmental concerns during their fabrication process (i.e., high‐temperature carbonization) have not been properly assessed. Furthermore, the rational design of high‐performing hard carbon anodes is usually limited by the conventional direct carbonization of organic precursors. Here, the hydrothermal carbonization process is employed as a versatile pre‐treatment method of renewable precursors, followed by high‐temperature carbonization, for producing advanced hard carbon anodes. The critical role of hydrothermal pre‐treatment in regulating the structure for an optimized performance of hard carbon anodes is elucidated, while revealing the sodium‐ion storage mechanism using electrochemical kinetic calculations, advanced characterization and multi‐scale modeling. Furthermore, the environmental impacts of hydrothermal pre‐treatment and subsequent carbonization are evaluated using life cycle assessment compared to direct carbonization. By comparing hard carbon anodes with and without the hydrothermal pre‐treatment, it is verified that the additional hydrothermal process is responsible for enhanced electrochemical performance, increased carbon yields and reduced carbon emissions. The work provides a systematic understanding of functions and energy consumptions of hydrothermal systems to achieve next‐generation sustainable sodium‐ion batteries.