Electrically induced light emission from proton-conducting materials. Protonic light-emitting diodes
Water doped with H+ and HO− enables the formation of a protonic p–n junction, which works similarly to a typical, electron-based p–n junction, including light emission when electrically powered. In the model examined, polymer scaffolding maintains the mechanical stability of the water-based system, and at the same time the side groups (acidic or basic) play the role of dopants, creating a stable proton gradient system. The chemically generated proton gradient system (protonic p–n junction) emits light owing to the proton current flow when the device is electrically powered. The results of experiments not only demonstrate the crucial role of protons in the light emission processes (the system with a protonic p–n junction), but also open the new way for light generation with proton-conducting materials (proton-based light emitting diodes, protonic LEDs).