Ternary Solvent System to Control the Morphology of Active Blend in Inverted Organic Solar Cells

摘要

Bulk heterojunction blend of poly(3-hexylthiophene)-6,6-phenyl-C-61-butyric acid methyl ester prepared using the ternary solvent mixture was used as the active layer of an inverted organic solar cell. The ternary solvent mixture consisted of a good solvent such as ortho-dichlorobenzene and two marginal solvents such as cyclohexanone and toluene offering limited solubility to the poly(3-hexylthiophene) component. Power conversion efficiency of inverted device was found to decrease from 2.74 +/- 0.05 in the unmodified device to 2.64 +/- 0.07 in the modified device. UV-visible measurement revealed less efficient photoabsorption in the mixed cosolvent-casted active layer due to insufficient and disordered crystallization of poly(3-hexylthiophene) domains.