Transient thermal characterization of organic light-emitting diodes

Abstract

In this paper, a novel measurement approach of junction temperature and thermal resistance of organic light-emitting diodes (OLEDs) is reported. Transient thermal measurement is utilized to carry out the thermal study of OLEDs. A linear relationship between forward voltage and junction temperature is obtained at the sensor current of 0.56 µA for each pixel. The effects of input current and cooling conditions on the junction temperature and thermal resistance are discussed. It is found that the optical performance is greatly affected by the junction temperature. The average junction temperature of the OLED panel with the current density of 0.014 A cm−2 is 64.5 °C, while there exists a temperature difference of 14.5 °C and 43.5 °C with the center case and ambient temperature. In contrast to the natural cooling condition, a much smaller junction temperature rise and thermal resistance are obtained under the forced cooling condition. The thermal resistance from junction to ambient has an inverse relationship with input power under both natural and forced cooling conditions.