Highly Transparent, Stretchable, and Self‐Healing Ionic‐Skin Triboelectric Nanogenerators for Energy Harvesting and Touch Applications

Abstract

Recently developed triboelectric nanogenerators (TENGs) act as a promising power source for self-powered electronic devices. However, the majority of TENGs are fabricated using metallic electrodes and cannot achieve high stretchability and transparency, simultaneously. Here, slime-based ionic conductors are used as transparent current-collecting layers of TENG, thus significantly enhancing their energy generation, stretchability, transparency, and instilling self-healing characteristics. This is the first demonstration of using an ionic conductor as the current collector in a mechanical energy harvester. The resulting ionic-skin TENG (IS-TENG) has a transparency of 92% transmittance, and its energy-harvesting performance is 12 times higher than that of the silver-based electronic current collectors. In addition, they are capable of enduring a uniaxial strain up to 700%, giving the highest performance compared to all other transparent and stretchable mechanical-energy harvesters. Additionally, this is the first demonstration of an autonomously self-healing TENG that can recover its performance even after 300 times of complete bifurcation. The IS-TENG represents the first prototype of a highly deformable and transparent power source that is able to autonomously self-heal quickly and repeatedly at room temperature, and thus can be used as a power supply for digital watches, touch sensors, artificial intelligence, and biointegrated electronics.

Self‐Healable and Mechanically Reinforced Multidimensional‐Carbon/Polyurethane Dielectric Nanocomposite Incorporates Various Functionalities for Capacitive Strain Sensor Applications

“…Functional materials are susceptible to breakdown due to the mechanical deformation–induced or accidental damage, resulting in the loss of structure and functionality which affects seriously the durability and lifetime of device. To address the key challenge, several self‐healing materials have been developed that can restore autonomously their structures and functions after mechanical damage . Disulfide bond, as a kind of dynamic covalent bond based on thiol/disulfide dynamic exchange reactions, can accomplish efficiently the self‐healing process in polymer through various external stimuli such as heat, light, and pH .…”

“…To address the key challenge, several selfhealing materials have been developed that can restore autonomously their structures and functions after mechanical damage. [18][19][20][21][22] Disulfide bond, as a kind of dynamic covalent bond based on thiol/disulfide dynamic exchange reactions, can accomplish efficiently the self-healing process in polymer through various external stimuli such as heat, [23] light, [24] and pH. [25] Moreover, the mild healing condition [26] and high healing efficiency [27] of self-healing polymer based on disulfide bond make it an ideal candidate for healed wearable applications.…”

Deformable and Transparent Ionic and Electronic Conductors for Soft Energy Devices

“…[44] We demonstrated a TENG, with PVA slime as the STIC and silicone rubber as an active triboelectic layer (Figure 18a). The PVA slime (100% transmittance for visible light) is a borate ion cross-linked PVA hydrogel, formed by weak hydrogen bonding between the OH group of PVA and borate ions.…”

“…Our group demonstrated that PVA slime formed by the weak hydrogen bonding between the OH groups of PVA and the tetrafunctional borate ions produces a self-healing effect. [44] The bonds are in a state of dynamic equilibrium, which can be easily broken and formed without any external stimuli. Zhi and co-workers also reported a self-healing PAA hydrogel using vinyl hybrid silica nanoparticles and hydrogen bonding.…”

“…For example, polar polymer networks cross-linked with high ionic strength salt have been demonstrated as stretchable/ transparent/self-healing ionic conductors by using the dynamic bond formed by ion-dipole interactions [43] or hydrogen bonding interactions. [44,45] This entirely new, out-of-the-box approach to using STIC in electronic devices has gained considerable attention in the last two years, despite its nascent stage of development. Although appreciable effort has been made to fabricate various forms of deformable and transparent materials and devices, a comprehensive review with a focus on the STICs or STECs and their roles in soft energy devices is noticeably absent.…”