Super Stretchable and Durable Electroluminescent Devices Based on Double‐Network Ionogels

Abstract

Ionogels are good candidates for flexible electronics owing to their excellent mechanical and electrical properties, including stretchability, high conductivity, and stability. In this study, conducting ionogels comprising a double network (DN) of poly(N‐isopropylacrylamide‐co‐N,N′‐diethylacrylamide)/chitosan which are further reinforced by the ionic and covalent crosslinking of the chitosan network by tripolyphosphate and glutaraldehyde, respectively, are prepared. Based on their excellent mechanical properties and high conductivity, the developed DN ionogels are envisioned as stretchable ionic conductors for extremely stretchable alternating‐current electroluminescent (ACEL) devices. The ACEL device fabricated with the developed ionogel exhibits stable working operation under an ultrahigh elongation of over 1200% as well as severe mechanical deformations such as bending, rolling, and twisting. Furthermore, the developed ACEL devices also display stable luminescence over 1000 stretch/release cycles or at temperatures as harsh as 200 °C.

Mechanically tough dry‐free ionic hydrogel microfibers swollen in aqueous electrolyte prepared by microfluidic devices

“…Figure 2A shows further reinforcement of the hydrogel microfibers through covalent and ionic crosslinking of the Ch chains using a reported immersion method 15 . The prepared PNN/Ch hydrogel microfibers were immersed in an aqueous solution containing tripolyphosphate (TPP) and glutaraldehyde (GA) to establish ionic and covalent bonds, respectively, with a Ch network (Figure 2A).…”

“…12,25,26 Figure 2A shows further reinforcement of the hydrogel microfibers through covalent and ionic crosslinking of the Ch chains using a reported immersion method. 15 The prepared PNN/Ch hydrogel microfibers were immersed in an aqueous solution containing tripolyphosphate (TPP) and glutaraldehyde (GA) to establish ionic and covalent bonds, respectively, with a Ch network (Figure 2A). Further crosslinking of Ch with GA occurs via the Schiff's base reaction between the aldehyde groups of GA and free pendant amine groups of Ch, forming a stable imine bond.…”

“…With the emerging research on soft electronic devices such as on‐skin electronics and wearable devices for human motion detection, stretchable conductive materials have attracted significant attention 2–24 . These next‐generation soft electronic materials are highly deformable and stretchable for wearable applications, beyond flexible and bendable.…”

“…Therefore, the development of mechanically strong soft materials with high conductivities is crucial. Recently, various types of deformable electronics have been fabricated with soft materials, mainly from polymeric systems such as hydrogels, 1–14 ionogels, 15–19 and elastomers 20–24 owing to their excellent mechanical and electrical properties. Among them, hydrogels consisting of hydrophilic polymer networks, have been considered as attractive based material for soft electronic system because they are stretchable, transparent, and able to be designed as conductive materials.…”

Double-Network Hydrogel for Stretchable Triboelectric Nanogenerator and Integrated Electroluminescent Skin with Self-Powered Rapid Visual Sensing

“…Copper-doped zinc sulfide (ZnS:Cu) in the phosphor layer has excellent chemical stability and electroluminescence properties. In particular, ZnS as the primary material while Cu as the luminescent element in the center emits green or blue light upon excitation [29][30][31][32][33]. Emission materials can be easily tuned using doping with different concentrations and types of elements; incorporating and co-doping with different transition metals is an important way to prepare inorganic luminescent materials.…”