Synergetic Exterior and Interfacial Approaches by Colloidal Carbon Quantum Dots for More Stable Perovskite Solar Cells Against UV.

The achievement of both efficiency and stability in perovskite solar cells (PSCs) remains a challenging and actively researched topic. In particular, among different environmental factors, ultraviolet (UV) photons play a pivotal role in contributing to device degradation. In this work, by harvesting simultaneously both the optical and the structural properties of bottom-up-synthesized colloidal carbon quantum dots (CQDs), a cost-effective means is provided to circumvent the UV-induced degradation in PSCs without scarification on their power conversion efficiencies (PCEs). By exploring and optimizing the number of CQDs and the different locations/interfaces of the solar cells where CQDs are applied, a synergetic configuration is achieved where the photovoltaic performance drop due to optical loss is completely compensated by the increased perovskite crystallinity due to interfacial modification. As a result, on the optimized configurations where CQDs are applied both on the exterior front side as an optical layer and at the interface between the electron transport layer and the perovskite absorber, unencapsulated PSCs with PCEs >20% are fabricated which can maintain up to ≈94% of their initial PCE after 100 h of degradation in ambient air under continuous UV illumination (5 mW cm-2).

Highly Cross-linked Epoxy Coating for Barring Organophosphate Chemical Warfare Agent Permeation.

Chemical warfare agents (CWAs) can be absorbed in polymeric coatings through absorption and permeation, thus presenting a lethal touch and vapor hazards to people. Developing a highly impermeable polymer coating against CWAs, especially against organophosphate CWAs (OPs), is challenging and desirable. Herein, fluorinated epoxy (F-EP) and epoxy (EP) coatings with different cross-link densities were prepared to resist OPs. The effects of the polymer coating structure, including cross-link density, chemical composition and free volume, on the chemical resistance to dimethyl methylphosphonate (DMMP, Soman simulant) were investigated in detail. Meanwhile, the chemical resistance to Soman and VX was examined. The results reveal that the cross-link density is a critical factor in determining the chemical resistance of the coatings. Highly cross-linked EP and F-EP coatings with dense and solid cross-linked networks can fully bar DMMP and OPs permeation during the test time. At low or medium cross-link densities, the EP coating with a lower retention of DMMP exhibited a higher resistance than the F-EP coating due to the lower interaction with DMMP and smaller free-volume holes and lower relative fractional free volume. These results suggest that increasing the cross-link density is a reasonable approach to control the chemical resistance of polymer networks against OPs.

Fluorinated Carbon Nanotube Superamphiphobic Coating for High-Efficiency and Long-Lasting Underwater Antibiofouling Surfaces.

Biofilm formation on the surface of materials has brought great troubles to various industries. Designing surfaces with long-lasting antibiofouling properties can help restrain primary bacterial and protein attachment and subsequent biofilm formation for a long time, which is also of great significance for industrial applications. In this work, we successfully prepared fluorinated carbon nanotubes through a one-step fluorination method using fluorosilane and fabricated a superamphiphobic coating using a simple spray method. This coating with ultralow surface free energy and stable micro/nano structures achieved highly efficient and long-term underwater antibiofouling properties. Tea, milk, BSA, and bacterial solution can bounce highly on this surface without wetting the surface in air. The long-term existence of the underwater air-bubble layer on the surface of the superamphiphobic coating was observed. Thus, this surface can effectively resist BSA and bacterial attachment (E. coli), and the efficiency, respectively, reaches 97.5 and 98.2%. Even if it is fully soaked in BSA and BS solution for 120 h, the whole surface is still able to repel water, BSA, and BS solution very well. In addition, the coating possessed excellent wear resistance, the CAs of BSA and BS solution just decreased slightly (higher than 158°), and the sliding angles increased slightly (lower than 4°) after 50 tape abrasion cycles. Therefore, this superamphiphobic coating may have promising applications for marine devices, biomedical materials, protective clothing, and chemical shielding.