Device annealing effect in organic solar cells with blends of regioregular poly(3-hexylthiophene) and soluble fullerene

Here we report enhanced efficiency bulk heterojunction organic solar cells using blend films of regioregular poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C-61 (PCBM) that are subjected to a thermal annealing process. Blend films (P3HT: PCBM = 1:1 by weight) were prepared using chlorobenzene and 1,2-dichlorobenzene in order to investigate the role of the solvent. Irrespective of the chosen solvent, the optimal device annealing temperature was found to be 140 degreesC. The highest power conversion efficiency, 3% under air mass 1.5 simulated solar illumination (100 mW/cm(2)), was achieved by device annealing at 140 degreesC for 15 min using blend films prepared from chlorobenzene (2.3% for 1,2-dichlorobenzene). (C) 2005 American Institute of Physics.