Reviving the "Schottky" Barrier for Flexible Polymer Dielectrics with a Superior 2D Nanoassembly Coating.

The organic insulator-metal interface is the most important junction in flexible electronics. The strong band offset of organic insulators over the Fermi level of electrodes should theoretically impart a sufficient impediment for charge injection known as the Schottky barrier. However, defect formation through Anderson localization due to topological disorder in polymers leads to reduced barriers and hence cumbersome devices. A facile nanocoating comprising hundreds of highly oriented organic/inorganic alternating nanolayers is self-coassembled on the surface of polymer films to revive the Schottky barrier. Carrier injection over the enhanced barrier is further shunted by anisotropic 2D conduction. This new interface engineering strategy allows a significant elevation of the operating field for organic insulators by 45% and a 7× improvement in discharge efficiency for Kapton at 150 °C. This superior 2D nanocoating thus provides a defect-tolerant approach for effective reviving of the Schottky barrier, one century after its discovery, broadly applicable for flexible electronics.

Super Stretchable and Compressible Hydrogels Inspired by Hook-and-Loop Fasteners.

Inspired by hook-and-loop fasteners, we designed a hydrogel network containing α-zirconium phosphate (ZrP) two-dimensional nanosheets with a high density of surface hydroxyl groups serving as nanopatches with numerous "hooks," while polymer chains with plentiful amine functional groups serve as "loops." Our multiscale molecular simulations confirm that both the high density of hydroxyl groups on nanosheets and the large number of amine functional groups on polymer chains are essential to achieve reversible interactions at the molecular scale, functioning as nano hook-and-loop fasteners to dissipate energy. As a result, the synthesized hydrogel possesses superior stretchability (>2100% strain), resilience to compression (>90% strain), and durability. Remarkably, the hydrogel can sustain >5000 cycles of compression with torsion in a solution mimicking synovial fluid, thus promising for potential biomedical applications such as artificial articular cartilage. This hook-and-loop model can be adopted and generalized to design a wide range of multifunctional materials with exceptional mechanical properties.