Ce(III)‐Based Coordination‐Complex‐Based Efficient Radical Scavenger for Exceptional Durability Enhancement of Polymer Application in Proton‐Exchange Membrane Fuel Cells and Organic Photovoltaics

To realize the practical application of energy conversion and storage devices for a sustainable future, improving their durability is critically important. The main problem with their durability is the chemical degradation of the active polymers used as material transport layers, photoactive layers, membranes, etc., for the device functions, mainly caused by detrimental radical species from unwanted side reactions. Introducing additives that scavenge radicals before their attack of the device‐configuring polymers is one of the promising strategies to significantly improve their life. In particular, Ce‐based radical scavengers including free Ce 3+ are considered to be highly efficient radical scavengers, with a rapid and regenerative redox reaction. However, those radical scavengers possess detrimental interaction with the active materials in the devices, which hinders charge carrier and material transport for the device function, thereby reducing the device efficiency. Herein, an organometallic complex of Ce 3+ is applied, and is coordinated by dipicolinate ligands as a radical scavenger for the chemical stability of polymers employed and durability enhancement in fuel cell and organic photovoltaic (OPV) device applications. Owing to the stabilizing effect of dipicolinate ligands toward Ce 3+ , disadvantageous interaction between radical scavenger and polymer material is suppressed, which results in the improved device stability without reducing the initial performance.