Morphology-dependent performance of thin film organic solar cells.

The photoactive film morphology of ternary molecules blend bulk heterojunction organic solar cell was investigated using various solvent additives. Two donor polymers namely poly(3-hexylthiophene) (P3HT) and thieno[3,4-b]thiophene/benzodithiophene (PTB7) at (1:1) stoichiometric ratio were employed together with (PCBM) fullerene molecule in the preparation of the solar cells. The photoactive films were treated with either uni- or binary solvent additives to improve film morphology and the miscibility of the molecules in the medium. The significant improvement on the performances of the devices were recorded using binary solvent additives (∼1% vol.) with power conversion efficiency improvement as high as 4.1% compared to 2.9% measured from the films treated with single additive solvent. The correlation between solar cell performance and film morphology have been discussed in terms of optical, electrical and surface morphology of the active layers of solution processed organic solar cells. [ABSTRACT FROM AUTHOR]