Effect of thermal and electrical stress on photometric, radiometric, and colorimetric characteristics of large area white organic light emitting diodes

The aim of this paper is to identify the photometric, radiometric, and colorimetric signatures of degradations of large area white organic light emitting diodes (Philips GL55, 41cm
²
active area), subjected to various stress conditions. Nine devices have been stressed at a constant current density of 11.25mA/cm
²
, 13mA/cm
²
and 15mA/cm
²
at 23°C (room temperature), 40°C and 60°C. We have also stocked three devices under purely thermal stress at the same temperatures. Thus, we can make comparison between electrical-thermal stress and purely thermal stress. Over aging time, an increase of both the correlated color temperature and the general rendering index was observed. The degradation rate of the blue emitter is more significant than the other emitters, which induced a color shift toward a green-yellow.