Multiple-Noncovalent-Interaction-Stabilized Layered Dion-Jacobson Perovskite for Efficient Solar Cells.

Two-dimensional Dion-Jacobson (DJ) perovskites have shown improved structure stability in comparison with Ruddlesden-Popper (RP) perovskites. However, the mechanism behind the improved stability is still largely unexplored. Here a multifluorinated aromatic spacer, namely, 4F-PhDMA, has been successfully developed for 2D DJ perovskites. It is found that the 2D DJ perovskite with a 4F-PhDMA spacer exhibits a high dissociation energy due to the multiple noncovalent interactions. The optimized 2D DJ device based on the 4F-PhDMA spacer (n = 4) exhibits a champion efficiency of 16.62% with much improved light and thermal stability. This efficiency is much higher than that of the control device using an unfluorinated spacer (n = 4, PCE = 10.11%) and is among the highest efficiencies in aromatic-spacer-based 2D DJ perovskite solar cells (PSCs). Our work highlights the importance of incorporating multiple noncovalent interactions in the 2D DJ perovskite by employing a multifluorinated aromatic spacer to achieve DJ PSCs with both high efficiency and high stability.

Construction of chitosan/polyacrylate/graphene oxide composite physical hydrogel by semi-dissolution/acidification/sol-gel transition method and its simultaneous cationic and anionic dye adsorption properties.

In the current study, a novel CTS/PAA/GO composite polyampholyte physical hydrogel was prepared by the SD-A-SGT method to achieve desired adsorption properties for printing and dyeing wastewater treatment. The hydrogels exhibited controllable and stable structure. The linear PAA significantly improved the swelling and adsorption properties of the hydrogel, and the composition of GO enhanced its mechanical and adsorption properties. The batch adsorption experiments revealed the ability to simultaneously absorb the cationic model dye, MB, and anionic model dye, FY3, with the similar equilibrium adsorption capacities of 296.5±31.7 mg·g-1 and 280.3±23.9 mg·g-1, respectively. The factors affecting the dye adsorption performance, including the hydrogel composition, initial dye concentration and dye solution pH, were investigated. The dye adsorption kinetics was studied and the adsorption mechanisms were proposed. The unique structure and properties of the hydrogel make it a great candidate adsorbent for wastewater treatments.