Ionically Conductive Pastes as Conformable Collector for Transparent, Nonplanar Triboelectric Devices

As an alternative to opaque electronic conductors, ionic conductors have been recently adopted to construct flexible, transparent devices. When integrated into devices, however, liquid ionic conductors can easily leak while it is difficult to shape solid ones to accommodate three‐dimensional (3D) surfaces. A paste‐like ionic conductor is fabricated by mixing an amorphous fluoropolymer with 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide. The low surface electrostatic potential of [NTf2]− makes the latter compatible with the polymer, forming a transparent ionic conductor without obvious phase separation. This ionic conductor displays a unique viscoelastic behavior, which combines solid‐like elasticity and liquid‐like plasticity at different time scales. Therefore, it exhibits a series of favorable mechanical properties, including large stretchability and self‐healing capability, and demonstrates a remarkable ability to transfer onto arbitrary surfaces and comply with the locomotion of substrates. To demonstrate its practical applications, this paste‐like ionic conductor is reconfigured on a plastic tube to develop a transparent triboelectric device, which is capable of detecting the sliding of water droplets and providing visual information of inside. A paste‐like ionic conductor that exhibits high stretchability, self‐healing capability, and a remarkable ability to transfer onto arbitrary surfaces and comply with the locomotion of substrates is fabricated. This material is reconfigured into a plastic tube to develop a transparent triboelectric device, which is capable of detecting the sliding of water droplets and providing visual information of inside.