Impact of Joule heating on the brightness homogeneity of organic light emitting devices

Joule heating and its impact on the brightness homogeneity are investigated since the luminance distribution is a key issue in large area organic light emitting diodes. In addition to previous reports, it is also important to consider the device temperature as a main factor for determining the luminance homogeneity. At a luminance of 1000cd∕m2 the active area reaches an average temperature of 40.6°C and a peak of 46.2°C. The increased device temperature is leading to higher local current densities resulting in a reduced brightness homogeneity. Modeling confirms these results and can be used for further device layout optimization.