Self-Integratable, Healable, and Stretchable Electroluminescent Device Fabricated via Dynamic Urea Bonds Equipped in Polyurethane

Abstract

Reversible bonding between polymer chains has been used primarily to induce self-healing of damaged polymers. Inspired by the dynamic nature of such bonding, we have developed a polyurethane equipped with dynamic urea bonds (PEDUB) that has high strength sufficient to make it be freestanding and have a healing capability and self-bonding property. This allowed subsequent heterogeneous multicomponent device integration of electrodes/substrate and light-emitting pixels into a light-emitting device. We first used the PEDUB to individually fabricate a highly stretchable electrode containing Ag nanowires and stretchable composites with ZnSbased particles. They were successfully assembled into a stretchable, waterproof electroluminescent (EL) device even under mild conditions (60 °C for 10 min) owing to the reversible exchange of urea bonds and low glass transition temperature of PEDUB. The assembled device with an AC-driven EL architecture retained excellent EL characteristics even after stretching, submersion in water, and cutting owing to the robust solid-state bonding interfaces induced by the dynamic urea bonds. Consequently, various shapes of the illuminating elastomer and an illuminated picture were realized for the first time using the mosaic-like assembly method. This first demonstration of multicomponent assembly paves the way for future stretchable multifunctional devices.

Enhancement of Luminance in Powder Electroluminescent Devices by Substrates of Smooth and Transparent Cellulose Nanofiber Films

“…They can also be used as sensors for ammonia [7], carbon dioxide [8], humidity [9], and temperature [10]. Unique functionalities, such as the self-recovery of their structure [11][12][13] and the generation of sound [14][15][16], have also been developed through the powder EL system. However, the practical use of powder EL devices has only been based on indirect illumination, owing to their low luminance.…”

Novel powder electroluminescent device enabling control of emission color by thermal response

“…At 20°C, the device exhibited an orange color (Figure 4a), and upon application of the AC voltage, a weak sapphire‐blue emission was observed (Figure 4b), and an EL spectrum with emission peaks at 450, 490, and 550 nm was obtained (Figure 5, blue line). Generally, the peaks corresponding to the ZnS phosphors in the EL spectrum do not split, 5–8 because energy transfer from the excited state of the phosphor to the TC materials takes place. Indeed, through observation of the thermal image, the temperature of the device was found to be 20°C upon voltage application, as shown in Figure 5b.…”

“…Despite such advantages, the commercial application of this device in its present state remains a niche market, and so to extend its application, a powder EL device with multiple functionalities is required. Indeed, a number of new functionalities have been reported for powder EL devices, such as sound generation, 3 stretchability, 4 light emission through external mechanical stimulation without an electric power source, 5 and structure recovery due to the presence of self‐recovering materials 6 . In addition, powder EL devices have been found to be applicable as sensors for ammonia, 7 carbon dioxide, 8 and humidity 9 …”

Fabrication of Flexible Electrode with Sub-Tenth Micron Thickness Using Heat-Induced Peelable Pressure-Sensitive Adhesive Containing Amide Groups

“…Flexible electrodes (e.g., graphene composites [ 8 , 9 ], silver composites [ 10 , 11 , 12 , 13 , 14 ], and ionic conductors [ 15 ]), which are light, thin, and shapeable, have received much attention as main components for the production of next-generation displays. Given that the thicker the electrode, the more is the applied stress on the electrode, the use of thin films for electrode fabrication is beneficial for securing its mechanical durability [ 16 ].…”