Fig. 5: Lifetime measurements.
From: High efficiency blue organic light-emitting diodes with below-bandgap electroluminescence

a Variation of normalized luminance vs. time and driving voltage vs. time for initial luminance of 1000 or 5000 cd m−2. b Electroluminescence spectra of the fresh and degraded device. TOF-SIMS profiles of the c fresh and d degraded OLED stack: the x-axis represents the materials depth distribution starting with the cathode interface from data point 0 and reaching to the ITO anode electrode.