Dynamic Reversible Oxidation-Reduction of Iodide Ions for Operationally Stable Perovskite Solar Cells under ISOS-L-3 Protocol.

Despite rapid advancements in the photovoltaic efficiencies of perovskite solar cells (PSCs), their operational stability remains a significant challenge for commercialization. This instability mainly arises from light-induced halide ion migration and subsequent oxidation into iodine (I2). The situation is exacerbated when considering the heat effects at elevated temperatures, leading to the volatilization of I2 and resulting in irreversible device degradation. Mercaptoethylammonium iodide (ESAI) is thus incorporated into perovskite as an additive to inhibit the oxidation of iodide anion (I-) and  the light-induced degradation pathway of FAPbI3→FAI+PbI2. Additionally, the formation of a thiol-disulfide/I--I2 redox pair within the perovskite film provides a dynamic mechanism for the continuous reduction of I2 under light and thermal stresses, facilitating the healing of iodine-induced degradations. This approach significantly enhances the operational stability of PSCs. Under the ISOS-L-3 testing protocol (maximum power point (MPP) tracking in an environment with relative humidity of ≈50% at ≈65 °C), the treated PSCs maintain 97% of their original power conversion efficieney (PCE) after 300 h of aging. In contrast, control devices exhibit almost complete degradation, primarily due to rapid thermal-induced I2 volatilization. These results demonstrate a promising strategy to overcome critical stability challenges in PSCs, particularly in scenarios involving thermal effects.

How Micro-/Nanostructure Evolution Influences Dynamic Wetting and Natural Deicing Abilities of Bionic Lotus Surfaces.

Anti-icing materials have become increasingly urgent for many fields such as power transmission, aviation, energy, telecommunications, and so on. Bionic lotus hydrophobic surfaces with hierarchical micro-/nanostructures show good potential of delaying ice formation; however, their icephobicity (deicing ability) has been controversial. It is mainly attributed to lack of deep understanding of the correlation between micro-/nanoscale structures, wettability, and icephobicity, as well as effective methods for evaluating the deicing ability close to natural environments. In this article, the natural deicing ability is innovatively proposed on the basis of ice adhesion and the influence of microscale structure evolution on dynamic wetting and deicing ability (both ice adhesion strength and natural deicing time) was systematically investigated. Interestingly, different modes (sticky or slippery) were found in natural deicing of hierarchical hydrophobic surfaces, although their ice adhesion strength was higher than that of smooth surfaces. The mechanism was analyzed from three aspects: mechanics, heat transfer, and dynamic wetting. It is highlighted that the sliding of melted interface is not equal to water droplet sliding (dynamic wetting) before freezing or after deicing but significantly depends on the microscale structure. The fundamental understanding on natural deicing of bionic hydrophobic surfaces will open up a new window for developing new anti-icing materials and technology.