While considerable academic and industrial research lead to the successful establishment of organic light emitting diodes (OLED) on the market, several fundamental challenges still remain. Only by overcoming them, the technology’s full potential can be realized. Especially for applications requiring high luminous flux, like lighting, the so far largely overlooked thermal properties of the organic material become highly relevant. Contrary to inorganic light emitting diodes (LED), the nature of the physical processes taking place in the organic layers of an OLED can result in an increased efficiency when operating the device at elevated temperatures. The main goal of this project is to accurately and self-consistently describe the coupling of thermal and electric processes within an OLED considering its full geometric complexity and by combining theoretical and experimental investigation develop the knowledge to predict and realize the most efficient operating temperature of an OLED.