Quantification of energy loss mechanisms in organic light-emitting diodes

The external quantum efficiency of organic light-emitting diodes (OLEDs) is limited by several loss mechanisms. By applying a numerical model for the efficiency analysis of OLED devices, we analyze the distribution of the different energy loss mechanisms in bottom and top emission organic light-emitting diodes. We validate the findings by the comparison with experimental data measured on red state-of-the-art p-i-n devices containing the red phosphorescent emitting dye iridium(III)bis2-methyldibenzo-(f, h)quinoxaline(acetylacetonate) Ir(MDQ)2(acac). The model is used to design extremely efficient bottom and top emission diodes with 21% and 27% external quantum efficiencies, respectively.