Sustainable and Transparent Fish Gelatin Films for Flexible Electroluminescent Devices

In the past decades, various alternating current electroluminescent (ACEL) devices, especially the flexible ones, have been developed and used in flat panel display, large-scale decorating, logo display lighting, optical signaling, etc. Transparent plastics are usually used as substrates in ACEL devices; however, they are undegradable and may cause serious environmental pollution. Herein, we have developed a flexible transient ACEL device based on transparent fish gelatin (FG) films. The FG films were made from fish scales, which are sustainable, cost-efficient, and eco-friendly. These films could dissolve in water within seconds at 60 °C and degrade completely within 24 days in soil. The transmittance of these FG films was up to 91.1% in the visible spectrum, comparable to that of polyethylene terephthalate (PET) (90.4%). After forming a composite with silver nanowires (Ag NWs), the Ag NWs-FG film showed a transmittance up to 82.3% and a sheet resistance down to 22.4 Ω sq^-1. The fabricated ACEL device based on the Ag NWs-FG film exhibited high flexibility and luminance up to 56.0 cd m^-2. The device could be dissolved in water within 3 min. Our work demonstrates that the sustainable, flexible, and transparent FG films are a promising alternative for green and degradable substrates in the field of flexible electronics, including foldable displays, wearable devices, and health monitoring.