Optical determination of the junction temperature of OLEDs

This paper describes a novel optical measurement technique for the in situ determination of the spatial temperature distribution at the organic layer level in large-area organic light-emitting diodes (OLEDs). The local junction temperature of OLEDs is a very important factor with respect to the luminance uniformity. Moreover the variation of local temperatures leads to a non-uniform depreciation of its light output, which in turn increases the luminance non-uniformity over time and affects the lifetime expectancy of the OLED.