Theoretical analysis on light-extraction efficiency of organic light-emitting diodes using FDTD and mode-expansion methods

We report a theoretical analysis on light-extraction efficiency of the organic light-emitting diodes. We utilize both a numerical method such as the finite-difference time-domain method and an analytic method such as the mode-expansion method. The results of both methods are compared to confirm the accuracy of the results. It is found that even though the refractive index contrast between the Indium-tin-oxide (ITO) anode and the glass substrate is as small as 0.5, more than 40% of emitted light power is trapped in the ITO layer.