Magnetic Electroluminescent response as a predictive indicator of operational lifetime in phosphorescent blue OLEDs

Improving operational lifetime remains a major challenge for blue organic light-emitting diodes (OLEDs) harvesting triplet excitons. Achieving substantial lifetime enhancement requires analytical techniques that elucidate degradation mechanisms. Because conventional lifetime analysis involves destructive aging tests, developing non-invasive methods that correlate strongly with device longevity is highly desirable. Here, we show that the operational lifetime of blue phosphorescent OLEDs quantitatively correlates with the electroluminescence (EL) response under magnetic fields. This behavior is explained by a magneto-EL response function that reflects degradation-sensitive spin-pair kinetics under magnetic fields. A strong linear correlation (confidence > 95%) is identified between the magneto-EL response strength (f_MEL) and device lifetime, with longer-operable OLEDs exhibiting lower f_MEL values. These findings establish a non-destructive approach for analyzing and predicting the stability of blue phosphorescent OLEDs.