I just came across this press release from the before-mentioned organic solar cell company Konarka. I mention it particularly, as our research group participates in this BMBF project to improve the stability of organic solar cells.
A somewhat older press release (see here and here) by the belgian research institute IMEC shows how they managed to improve the stability of the donor material, a conjugated polymer. The improvement is apparent from electrical characteristics and TEM images.
Not being quite as fancy as efficiency improvements, the lifespan of organic solar cells is probably more important for a ssuccessful commercialisation. As you know now that we are “officially” involved, stay tuned: this topics interests me from a fundamental research perspective.