Dear Gustav,
the theoretical limit in the standard Scharber model which we are using is 11.2% power conversion efficiency and we have a handful of compounds with the right prerequisites to hit this limit. But a proper answer to your question is a good bit more complex - you can read the details about predictions etc in our recent E&ES paper which you can find on our project webpage (it is a bit technical though). You cannot see the results in realtime, but the best of list gets periodically uploaded to the CEPDB on molecularspace.org.
Best wishes,
Your Harvard CEP team