Cavity effects on light extraction in organic light emitting devices

We have demonstrated that the light extraction efficiency of an organic light emitting device is a strong function of device geometry. Specifically, we have found that the ratio of the extracted mode to the substrate-guided mode varies from 22% to 55% depending on the location of the recombination zone. Our simulation results also indicate that more light is trapped in the substrate as the optical length of device increases. We further show that the light intensity profile varies from a Lambertian shape to a non-Lambertian shape depending on the device geometry due to the cavity effect. (C) 2008 American Institute of Physics.