I don't know exactly about organic electronics simulations in general, but we have developed and posted two tools to evaluate emission zone properties from optical measurements, which can be accessed freely via our lab website http://webee.technion.ac.il/orgelect/.
One of which is a simple applet, works for simple OLED configurations, requires only a handful of parameters, and can be found in http://webee.technion.ac.il/orgelect/WhereIsMyEmissionZone.html (see readme file there for more info). The other one is a set of MATLAB scripts, works for more complicated OLEDs, enables extended data sets as input and provides information regarding the emission zone position and width. The latter bundle can be downloaded via https://www.dropbox.com/sh/8b3f1rl1zvl0kav/I8sbVWJ8Co (see readme file there for more info). There is also an email for correspondence, questions, etc. Hope this is helpful.