The effect of a mild thermal treatment on the performance of poly(3-allkylthiophene)/fullerene solar cells

A mild thermal treatment of solar cells, made of regioregular poly(3-alkyl) thiophenes and a soluble fulleropyrrolidine substantially enhances the cell performance. A three-fourfold increasing of the power conversion efficiency has been obtained by just heating the devices to 55 °C for 30 min, which marks a departure from previuos works on thermal or solvent treatment of polythiophene-based cells. We speculate that this behavior is mainly due to enhanced diode properties induced by the thermal treatment, besides an increase of the order degree of the material.