I was thinking about this the other day, in that since the photovoltaic effect is a probabilistic thing (you need your photon to be absorbed so that you can spit off an exciton), if you had transparent cells you might be able to boost your efficiency by creating a light trap with mirrors to bounce them through the cells 10 - 20 times and thus increase the chance that they generate an exciton by that much.
it's important to mention that they doubled the efficiency of their own previous solar cell, clocking in at 7.3%. a mass produced amorphous silicon cell achieves around 8%. however the advantage of polymer solar cells might be much lower production costs.
Is anyone looking into manufacturing this? I think it would be awesome to have this as a film that could be put on windows. Of course the main issue there is getting that energy back into the home and power grid.