Organic photovoltaic cells (OPVs), combining electron-donor (usually conjugated polymers) and electron-acceptor (commonly fullerenes) in the active layer, have demonstrated a great potential to become an efficient solar energy technology, now achieving maximum power conversion efficiencies around 10-13 %, [1-3]. These organic devices present unique advantages not observed in the inorganic counterparts, such as lightweight and mechanical flexibility. However, to put this technology into the market as a competitive technology their stability still needs to be increased.
Here, we present OPVs with enhanced performance stability measured after annealing at 100 °C and over a period of 24 days at room temperature. This enhancement was achieved upon chemical cross-linking of the devices active layer, combining a cross-linkable polymer and a fullerene, PC61BM. The cells efficiency decayed by up to 14 % upon heating at 100 °C and by 37 % after the 24 days period, while the efficiency of control devices based on non cross-linked layers decreased 58 % and 55 %, respectively.