Dielectric polymers are widely used in solar cells, organic light-emitting diodes, and insulating components of electronic devices. However, prolonged exposure to intense light or strong electric fields can trigger chain scission and radical formation, leading to performance degradation and, in severe cases, catastrophic device failure.

In a study published in Advanced Materials, a research group led by Prof. HUANG Weiguo from Fujian Institute of Research on the Structure of Matter of the Chinese Academy of Sciences reported the autonomous signaling and recording of electrical and photodegradation in dielectric polymers by leveraging the fluorescent response of free-radical indicators.

Researchers designed phenanthridine-based fluorescent indicators. The indicators can selectively react with reactive oxygen species generated during polymer degradation, and produce fluorescence redshifts of up to 195 nm which serve as visible and quantitative warning signals.

Besides, these indicators demonstrated outstanding sensitivity with detection limits down to 100 nM, an ultrafast response time of less than 5 s, and stable memory behavior which preserves degradation records even after the removal of light or electrical stimuli.

When incorporated into poly(methyl methacrylate) films, the indicators enabled real-time visualization of polymer degradation under ultraviolet irradiation and electrical discharge. Distinct color changes appeared at degraded regions, allowing spatial mapping of the extent and severity of damage.

Similar performance was achieved in other dielectric polymers, including polystyrene, epoxy resin, polybutadiene, and polydimethylsiloxane, confirming the broad applicability of this approach.

This study offers a reliable and practical approach for the early detection and assessment of electrical and photodegradation in dielectric polymers, which helps to mitigate the risk of device failure.